Plot widget fundamentals ¶

QwtPlot.autoRefresh()[source]¶: Replots the plot if autoReplot() is True.

QwtPlot.setAutoReplot(tf)[source]¶

Set or reset the autoReplot option

If the autoReplot option is set, the plot will be updated implicitly by manipulating member functions. Since this may be time-consuming, it is recommended to leave this option switched off and call replot() explicitly if necessary.

The autoReplot option is set to false by default, which means that the user has to call replot() in order to make changes visible.

Parameters:	tf (bool) – True or False. Defaults to True.

See also

QwtPlot.autoReplot()[source]¶

Returns:	True if the autoReplot option is set.

See also

setAutoReplot()

QwtPlot.setTitle(title)[source]¶

Change the plot’s title

Parameters:	title (str or qwt.text.QwtText) – New title

See also

QwtPlot.title()[source]¶

Returns:	Title of the plot

See also

updateAxes(), setAutoReplot()

QwtPlot.titleLabel()[source]¶

Returns:	Title label widget.

QwtPlot.setFooter(text)[source]¶

Change the text the footer

Parameters:	text (str or qwt.text.QwtText) – New text of the footer

See also

footer()

QwtPlot.footer()[source]¶

Returns:	Text of the footer

See also

setFooter()

QwtPlot.footerLabel()[source]¶

Returns:	Footer label widget.

QwtPlot.setPlotLayout(layout)[source]¶

Assign a new plot layout

Parameters:	layout (qwt.plot_layout.QwtPlotLayout) – Layout

See also

plotLayout()

QwtPlot.plotLayout()[source]¶

Returns:	the plot’s layout

See also

setPlotLayout()

QwtPlot.legend()[source]¶

Returns:	the plot’s legend

See also

insertLegend()

QwtPlot.canvas()[source]¶

Returns:	the plot’s canvas

QwtPlot.sizeHint()[source]¶

Returns:	Size hint for the plot widget

See also

minimumSizeHint()

QwtPlot.minimumSizeHint()[source]¶

Returns:	Return a minimum size hint

QwtPlot.replot()[source]¶

Redraw the plot

If the autoReplot option is not set (which is the default) or if any curves are attached to raw data, the plot has to be refreshed explicitly in order to make changes visible.

See also

QwtPlot.updateLayout()[source]¶: Adjust plot content to its current size.

See also

resizeEvent()

QwtPlot.getCanvasMarginsHint(maps, canvasRect)[source]¶

Calculate the canvas margins

Parameters:	maps (list) – QwtPlot.axisCnt maps, mapping between plot and paint device coordinates canvasRect (QRectF) – Bounding rectangle where to paint

Plot items might indicate, that they need some extra space at the borders of the canvas by the QwtPlotItem.Margins flag.

See also

updateCanvasMargins(), getCanvasMarginHint()

QwtPlot.updateCanvasMargins()[source]¶

Update the canvas margins

Plot items might indicate, that they need some extra space at the borders of the canvas by the QwtPlotItem.Margins flag.

QwtPlot.drawCanvas(painter)[source]¶

Redraw the canvas.

Parameters:	painter (QPainter) – Painter used for drawing

Warning

drawCanvas calls drawItems what is also used for printing. Applications that like to add individual plot items better overload drawItems()

QwtPlot.drawItems(painter, canvasRect, maps)[source]¶

Redraw the canvas.

Parameters:	painter (QPainter) – Painter used for drawing canvasRect (QRectF) – Bounding rectangle where to paint maps (list) – QwtPlot.axisCnt maps, mapping between plot and paint device coordinates

Note

Usually canvasRect is contentsRect() of the plot canvas. Due to a bug in Qt this rectangle might be wrong for certain frame styles ( f.e QFrame.Box ) and it might be necessary to fix the margins manually using QWidget.setContentsMargins()

QwtPlot.canvasMap(axisId)[source]¶

Parameters:	axisId (int) – Axis
Returns:	Map for the axis on the canvas. With this map pixel coordinates can translated to plot coordinates and vice versa.

See also

qwt.scale_map.QwtScaleMap, transform(), invTransform()

QwtPlot.setCanvasBackground(brush)[source]¶

Change the background of the plotting area

Sets brush to QPalette.Window of all color groups of the palette of the canvas. Using canvas().setPalette() is a more powerful way to set these colors.

Parameters:	brush (QBrush) – New background brush

See also

canvasBackground()

QwtPlot.canvasBackground()[source]¶

Returns:	Background brush of the plotting area.

See also

setCanvasBackground()

QwtPlot.axisValid(axisId)[source]¶

Parameters:	axisId (int) – Axis
Returns:	True if the specified axis exists, otherwise False

QwtPlot.insertLegend(legend, pos=None, ratio=-1)[source]¶

Insert a legend

If the position legend is QwtPlot.LeftLegend or QwtPlot.RightLegend the legend will be organized in one column from top to down. Otherwise the legend items will be placed in a table with a best fit number of columns from left to right.

insertLegend() will set the plot widget as parent for the legend. The legend will be deleted in the destructor of the plot or when another legend is inserted.

Legends, that are not inserted into the layout of the plot widget need to connect to the legendDataChanged() signal. Calling updateLegend() initiates this signal for an initial update. When the application code wants to implement its own layout this also needs to be done for rendering plots to a document ( see QwtPlotRenderer ).

Parameters:	legend (qwt.legend.QwtAbstractLegend) – Legend pos (QwtPlot.LegendPosition) – The legend’s position. ratio (float) – Ratio between legend and the bounding rectangle of title, canvas and axes

Note

For top/left position the number of columns will be limited to 1, otherwise it will be set to unlimited.

Note

The legend will be shrunk if it would need more space than the given ratio. The ratio is limited to ]0.0 .. 1.0]. In case of <= 0.0 it will be reset to the default ratio. The default vertical/horizontal ratio is 0.33/0.5.

QwtPlot.updateLegend(plotItem=None)[source]¶

If plotItem is None, emit QwtPlot.SIG_LEGEND_DATA_CHANGED for all plot item. Otherwise, emit the signal for passed plot item.

Parameters:	plotItem (qwt.plot.QwtPlotItem) – Plot item

See also

QwtPlotItem.legendData(), QwtPlot.SIG_LEGEND_DATA_CHANGED

QwtPlot.updateLegendItems(plotItem, legendData)[source]¶

Update all plot items interested in legend attributes

Call QwtPlotItem.updateLegend(), when the QwtPlotItem.LegendInterest flag is set.

Parameters:	plotItem (qwt.plot.QwtPlotItem) – Plot item legendData (list) – Entries to be displayed for the plot item ( usually 1 )

See also

QwtPlotItem.LegendInterest(), QwtPlotItem.updateLegend()

QwtPlot.attachItem(plotItem, on)[source]¶

Attach/Detach a plot item

Parameters:	plotItem (qwt.plot.QwtPlotItem) – Plot item on (bool) – When true attach the item, otherwise detach it

QwtPlot.print_(printer)[source]¶

Print plot to printer

Parameters:	printer (QPaintDevice or QPrinter or QSvgGenerator) – Printer

QwtPlot.exportTo(filename, size=(800, 600), size_mm=None, resolution=72.0, format_=None)[source]¶

Export plot to PDF or image file (SVG, PNG, ...)

Parameters:	filename (str) – Filename size (tuple) – (width, height) size in pixels size_mm (tuple) – (width, height) size in millimeters resolution (float) – Image resolution format (str) – File format (PDF, SVG, PNG, ...)

QwtPlotItem¶

class qwt.plot.QwtPlotItem(title=None)[source]¶

Base class for items on the plot canvas

A plot item is “something”, that can be painted on the plot canvas, or only affects the scales of the plot widget. They can be categorized as:

Representator

A “Representator” is an item that represents some sort of data on the plot canvas. The different representator classes are organized according to the characteristics of the data:
- qwt.plot_marker.QwtPlotMarker: Represents a point or a horizontal/vertical coordinate
- qwt.plot_curve.QwtPlotCurve: Represents a series of points
Decorators

A “Decorator” is an item, that displays additional information, that is not related to any data:
- qwt.plot_grid.QwtPlotGrid

Depending on the QwtPlotItem.ItemAttribute flags, an item is included into autoscaling or has an entry on the legend.

Before misusing the existing item classes it might be better to implement a new type of plot item ( don’t implement a watermark as spectrogram ). Deriving a new type of QwtPlotItem primarily means to implement the YourPlotItem.draw() method.

See also

The cpuplot example shows the implementation of additional plot items.

class QwtPlotItem([title=None])¶

Constructor

Parameters:	title (qwt.text.QwtText or str) – Title of the item

QwtPlotItem.attach(plot)[source]¶

Attach the item to a plot.

This method will attach a QwtPlotItem to the QwtPlot argument. It will first detach the QwtPlotItem from any plot from a previous call to attach (if necessary). If a None argument is passed, it will detach from any QwtPlot it was attached to.

Parameters:	plot (qwt.plot.QwtPlot) – Plot widget

See also

detach()

QwtPlotItem.detach()[source]¶

Detach the item from a plot.

This method detaches a QwtPlotItem from any QwtPlot it has been associated with.

See also

attach()

QwtPlotItem.rtti()[source]¶

Return rtti for the specific class represented. QwtPlotItem is simply a virtual interface class, and base classes will implement this method with specific rtti values so a user can differentiate them.

Returns:	rtti value

QwtPlotItem.plot()[source]¶

Returns:	attached plot

QwtPlotItem.z()[source]¶

Plot items are painted in increasing z-order.

Returns:	item z order

See also

setZ(), QwtPlotDict.itemList()

QwtPlotItem.setZ(z)[source]¶

Set the z value

Plot items are painted in increasing z-order.

Parameters:	z (float) – Z-value

See also

z(), QwtPlotDict.itemList()

QwtPlotItem.setTitle(title)[source]¶

Set a new title

Parameters:	title (qwt.text.QwtText or str) – Title

See also

QwtPlotItem.title()[source]¶

Returns:	Title of the item

See also

legendIconSize(), legendIcon()

QwtPlotItem.setItemAttribute(attribute, on=True)[source]¶

Toggle an item attribute

Parameters:	attribute (int) – Attribute type on (bool) – True/False

See also

testItemAttribute()

QwtPlotItem.testItemAttribute(attribute)[source]¶

Test an item attribute

Parameters:	attribute (int) – Attribute type
Returns:	True/False

See also

setItemAttribute()

QwtPlotItem.setItemInterest(interest, on)[source]¶

Toggle an item interest

Parameters:	attribute (int) – Interest type on (bool) – True/False

See also

testItemInterest()

QwtPlotItem.testItemInterest(interest)[source]¶

Test an item interest

Parameters:	attribute (int) – Interest type
Returns:	True/False

See also

setItemInterest()

QwtPlotItem.setRenderHint(hint, on=True)[source]¶

Toggle a render hint

Parameters:	hint (int) – Render hint on (bool) – True/False

See also

testRenderHint()

QwtPlotItem.testRenderHint(hint)[source]¶

Test a render hint

Parameters:	attribute (int) – Render hint
Returns:	True/False

See also

setRenderHint()

QwtPlotItem.setLegendIconSize(size)[source]¶

Set the size of the legend icon

The default setting is 8x8 pixels

Parameters:	size (QSize) – Size

See also

QwtPlotItem.legendIconSize()[source]¶

Returns:	Legend icon size

See also

setLegendIconSize(), legendIcon()

QwtPlotItem.legendIcon(index, size)[source]¶

Parameters:	index (int) – Index of the legend entry (usually there is only one) size (QSizeF) – Icon size
Returns:	Icon representing the item on the legend

The default implementation returns an invalid icon

See also

setLegendIconSize(), legendData()

QwtPlotItem.defaultIcon(brush, size)[source]¶

Return a default icon from a brush

The default icon is a filled rectangle used in several derived classes as legendIcon().

Parameters:	brush (QBrush) – Fill brush size (QSizeF) – Icon size
Returns:	A filled rectangle

QwtPlotItem.show()[source]¶: Show the item

QwtPlotItem.hide()[source]¶: Hide the item

QwtPlotItem.setVisible(on)[source]¶

Show/Hide the item

Parameters:	on (bool) – Show if True, otherwise hide

See also

isVisible(), show(), hide()

QwtPlotItem.isVisible()[source]¶

Returns:	True if visible

See also

setVisible(), show(), hide()

QwtPlotItem.itemChanged()[source]¶: Update the legend and call QwtPlot.autoRefresh() for the parent plot.

See also

QwtPlot.legendChanged(), QwtPlot.autoRefresh()

QwtPlotItem.legendChanged()[source]¶: Update the legend of the parent plot.

See also

QwtPlot.updateLegend(), itemChanged()

QwtPlotItem.setAxes(xAxis, yAxis)[source]¶

Set X and Y axis

The item will painted according to the coordinates of its Axes.

Parameters:	xAxis (int) – X Axis (QwtPlot.xBottom or QwtPlot.xTop) yAxis (int) – Y Axis (QwtPlot.yLeft or QwtPlot.yRight)

QwtPlotItem.setAxis(xAxis, yAxis)[source]¶: Set X and Y axis

Warning

setAxis has been removed in Qwt6: please use setAxes() instead

QwtPlotItem.setXAxis(axis)[source]¶

Set the X axis

The item will painted according to the coordinates its Axes.

Parameters:	axis (int) – X Axis (QwtPlot.xBottom or QwtPlot.xTop)

QwtPlotItem.setYAxis(axis)[source]¶

Set the Y axis

The item will painted according to the coordinates its Axes.

Parameters:	axis (int) – Y Axis (QwtPlot.yLeft or QwtPlot.yRight)

QwtPlotItem.xAxis()[source]¶

Returns:	xAxis

QwtPlotItem.yAxis()[source]¶

Returns:	yAxis

QwtPlotItem.boundingRect()[source]¶

Returns:	An invalid bounding rect: QRectF(1.0, 1.0, -2.0, -2.0)

Note

A width or height < 0.0 is ignored by the autoscaler

QwtPlotItem.getCanvasMarginHint(xMap, yMap, canvasRect)[source]¶

Calculate a hint for the canvas margin

When the QwtPlotItem::Margins flag is enabled the plot item indicates, that it needs some margins at the borders of the canvas. This is f.e. used by bar charts to reserve space for displaying the bars.

The margins are in target device coordinates ( pixels on screen )

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates. canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates

QwtPlotItem.legendData()[source]¶

Return all information, that is needed to represent the item on the legend

QwtLegendData is basically a list of QVariants that makes it possible to overload and reimplement legendData() to return almost any type of information, that is understood by the receiver that acts as the legend.

The default implementation returns one entry with the title() of the item and the legendIcon().

Returns:	Data, that is needed to represent the item on the legend

QwtPlotItem.updateLegend(item, data)[source]¶

Update the item to changes of the legend info

Plot items that want to display a legend ( not those, that want to be displayed on a legend ! ) will have to implement updateLegend().

updateLegend() is only called when the LegendInterest interest is enabled. The default implementation does nothing.

Parameters:	item (qwt.plot.QwtPlotItem) – Plot item to be displayed on a legend data (list) – Attributes how to display item on the legend

Note

Plot items, that want to be displayed on a legend need to enable the QwtPlotItem.Legend flag and to implement legendData() and legendIcon()

QwtPlotItem.scaleRect(xMap, yMap)[source]¶

Calculate the bounding scale rectangle of 2 maps

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
Returns:	Bounding scale rect of the scale maps, not normalized

QwtPlotItem.paintRect(xMap, yMap)[source]¶

Calculate the bounding paint rectangle of 2 maps

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
Returns:	Bounding paint rectangle of the scale maps, not normalized

class qwt.plot.QwtPlotDict[source]¶

A dictionary for plot items

QwtPlotDict organizes plot items in increasing z-order. If autoDelete() is enabled, all attached items will be deleted in the destructor of the dictionary. QwtPlotDict can be used to get access to all QwtPlotItem items - or all items of a specific type - that are currently on the plot.

setAutoDelete(autoDelete)[source]¶

En/Disable Auto deletion

If Auto deletion is on all attached plot items will be deleted in the destructor of QwtPlotDict. The default value is on.

Parameters:	autoDelete (bool) – enable/disable

See also

autoDelete(), insertItem()

autoDelete()[source]¶

Returns:	true if auto deletion is enabled

See also

setAutoDelete(), insertItem()

insertItem(item)[source]¶

Insert a plot item

Parameters:	item (qwt.plot.QwtPlotItem) – PlotItem

See also

removeItem()

removeItem(item)[source]¶

Remove a plot item

Parameters:	item (qwt.plot.QwtPlotItem) – PlotItem

See also

insertItem()

detachItems(rtti, autoDelete)[source]¶

Detach items from the dictionary

Parameters:	rtti (int) – In case of QwtPlotItem.Rtti_PlotItem detach all items otherwise only those items of the type rtti. autoDelete (bool) – If true, delete all detached items

itemList(rtti=None)[source]¶

A list of attached plot items.

Use caution when iterating these lists, as removing/detaching an item will invalidate the iterator. Instead you can place pointers to objects to be removed in a removal list, and traverse that list later.

Parameters:	rtti (int) – In case of QwtPlotItem.Rtti_PlotItem detach all items otherwise only those items of the type rtti.
Returns:	List of all attached plot items of a specific type. If rtti is None, return a list of all attached plot items.

class qwt.plot.QwtPlot(*args)[source]

A 2-D plotting widget

QwtPlot is a widget for plotting two-dimensional graphs. An unlimited number of plot items can be displayed on its canvas. Plot items might be curves (qwt.plot_curve.QwtPlotCurve), markers (qwt.plot_marker.QwtPlotMarker), the grid (qwt.plot_grid.QwtPlotGrid), or anything else derived from QwtPlotItem.

A plot can have up to four axes, with each plot item attached to an x- and a y axis. The scales at the axes can be explicitly set (QwtScaleDiv), or are calculated from the plot items, using algorithms (QwtScaleEngine) which can be configured separately for each axis.

The following example is a good starting point to see how to set up a plot widget:

from qwt.qt.QtGui import QApplication
from qwt import QwtPlot, QwtPlotCurve
import numpy as np

app = QApplication([])

x = np.linspace(-10, 10, 500)
y1, y2 = np.cos(x), np.sin(x)

my_plot = QwtPlot("Two curves")
curve1, curve2 = QwtPlotCurve("Curve 1"), QwtPlotCurve("Curve 2")
curve1.setData(x, y1)
curve2.setData(x, y2)
curve1.attach(my_plot)
curve2.attach(my_plot)
my_plot.resize(600, 300)
my_plot.replot()
my_plot.show()

app.exec_()

class QwtPlot([title=""][, parent=None])

Parameters:	title (str) – Title text parent (QWidget) – Parent widget

QwtPlot.initAxesData()[source]: Initialize axes

QwtPlot.axisWidget(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	Scale widget of the specified axis, or None if axisId is invalid.

QwtPlot.setAxisScaleEngine(axisId, scaleEngine)[source]

Change the scale engine for an axis

Parameters:	axisId (int) – Axis index scaleEngine (qwt.scale_engine.QwtScaleEngine) – Scale engine

See also

axisScaleEngine()

QwtPlot.axisScaleEngine(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	Scale engine for a specific axis

See also

setAxisScaleEngine()

QwtPlot.axisAutoScale(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	True, if autoscaling is enabled

QwtPlot.axisEnabled(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	True, if a specified axis is enabled

QwtPlot.axisFont(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	The font of the scale labels for a specified axis

QwtPlot.axisMaxMajor(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	The maximum number of major ticks for a specified axis

QwtPlot.axisMaxMinor(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	The maximum number of minor ticks for a specified axis

QwtPlot.axisScaleDiv(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	The scale division of a specified axis

axisScaleDiv(axisId).lowerBound(), axisScaleDiv(axisId).upperBound() are the current limits of the axis scale.

QwtPlot.axisScaleDraw(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	Specified scaleDraw for axis, or NULL if axis is invalid.

QwtPlot.axisStepSize(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	step size parameter value

This doesn’t need to be the step size of the current scale.

QwtPlot.axisInterval(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	The current interval of the specified axis

This is only a convenience function for axisScaleDiv(axisId).interval()

QwtPlot.axisTitle(axisId)[source]

Parameters:	axisId (int) – Axis index
Returns:	Title of a specified axis

QwtPlot.enableAxis(axisId, tf=True)[source]

Enable or disable a specified axis

When an axis is disabled, this only means that it is not visible on the screen. Curves, markers and can be attached to disabled axes, and transformation of screen coordinates into values works as normal.

Only xBottom and yLeft are enabled by default.

Parameters:	axisId (int) – Axis index tf (bool) – True (enabled) or False (disabled)

QwtPlot.invTransform(axisId, pos)[source]

Transform the x or y coordinate of a position in the drawing region into a value.

Parameters:	axisId (int) – Axis index pos (int) – position

Warning

The position can be an x or a y coordinate, depending on the specified axis.

QwtPlot.transform(axisId, value)[source]

Transform a value into a coordinate in the plotting region

Parameters:	axisId (int) – Axis index value (fload) – Value
Returns:	X or Y coordinate in the plotting region corresponding to the value.

QwtPlot.setAxisFont(axisId, font)[source]

Change the font of an axis

Parameters:	axisId (int) – Axis index font (QFont) – Font

Warning

This function changes the font of the tick labels, not of the axis title.

QwtPlot.setAxisAutoScale(axisId, on)[source]

Enable autoscaling for a specified axis

This member function is used to switch back to autoscaling mode after a fixed scale has been set. Autoscaling is enabled by default.

Parameters:	axisId (int) – Axis index on (bool) – On/Off

Note

The autoscaling flag has no effect until updateAxes() is executed ( called by replot() ).

QwtPlot.setAxisScale(axisId, min_, max_, stepSize=0)[source]

Disable autoscaling and specify a fixed scale for a selected axis.

In updateAxes() the scale engine calculates a scale division from the specified parameters, that will be assigned to the scale widget. So updates of the scale widget usually happen delayed with the next replot.

Parameters:	axisId (int) – Axis index min (float) – Minimum of the scale max (float) – Maximum of the scale stepSize (float) – Major step size. If <code>step == 0</code>, the step size is calculated automatically using the maxMajor setting.

QwtPlot.setAxisScaleDiv(axisId, scaleDiv)[source]

Disable autoscaling and specify a fixed scale for a selected axis.

The scale division will be stored locally only until the next call of updateAxes(). So updates of the scale widget usually happen delayed with the next replot.

Parameters:	axisId (int) – Axis index scaleDiv (qwt.scale_div.QwtScaleDiv) – Scale division

See also

setAxisScale(), setAxisAutoScale()

QwtPlot.setAxisScaleDraw(axisId, scaleDraw)[source]

Set a scale draw

Parameters:	axisId (int) – Axis index scaleDraw (qwt.scale_draw.QwtScaleDraw) – Object responsible for drawing scales.

By passing scaleDraw it is possible to extend QwtScaleDraw functionality and let it take place in QwtPlot. Please note that scaleDraw has to be created with new and will be deleted by the corresponding QwtScale member ( like a child object ).

See also

qwt.scale_draw.QwtScaleDraw, qwt.scale_widget.QwtScaleWigdet

Warning

The attributes of scaleDraw will be overwritten by those of the previous QwtScaleDraw.

QwtPlot.setAxisLabelAlignment(axisId, alignment)[source]

Change the alignment of the tick labels

Parameters:	axisId (int) – Axis index alignment (Qt.Alignment) – Or’d Qt.AlignmentFlags

QwtPlot.setAxisLabelRotation(axisId, rotation)[source]

Rotate all tick labels

Parameters:	axisId (int) – Axis index rotation (float) – Angle in degrees. When changing the label rotation, the label alignment might be adjusted too.

See also

setLabelRotation(), setAxisLabelAlignment()

QwtPlot.setAxisMaxMinor(axisId, maxMinor)[source]

Set the maximum number of minor scale intervals for a specified axis

Parameters:	axisId (int) – Axis index maxMinor (int) – Maximum number of minor steps

See also

axisMaxMinor()

QwtPlot.setAxisMaxMajor(axisId, maxMajor)[source]

Set the maximum number of major scale intervals for a specified axis

Parameters:	axisId (int) – Axis index maxMajor (int) – Maximum number of major steps

See also

axisMaxMajor()

QwtPlot.setAxisTitle(axisId, title)[source]

Change the title of a specified axis

Parameters:	axisId (int) – Axis index title (qwt.text.QwtText or str) – axis title

QwtPlot.updateAxes()[source]

Rebuild the axes scales

In case of autoscaling the boundaries of a scale are calculated from the bounding rectangles of all plot items, having the QwtPlotItem.AutoScale flag enabled (QwtScaleEngine.autoScale()). Then a scale division is calculated (QwtScaleEngine.didvideScale()) and assigned to scale widget.

When the scale boundaries have been assigned with setAxisScale() a scale division is calculated (QwtScaleEngine.didvideScale()) for this interval and assigned to the scale widget.

When the scale has been set explicitly by setAxisScaleDiv() the locally stored scale division gets assigned to the scale widget.

The scale widget indicates modifications by emitting a QwtScaleWidget.scaleDivChanged() signal.

updateAxes() is usually called by replot().

QwtPlot.setCanvas(canvas)[source]

Set the drawing canvas of the plot widget.

The default canvas is a QwtPlotCanvas.

Parameters:	canvas (QWidget) – Canvas Widget

See also

QwtPlot.autoRefresh()[source]: Replots the plot if autoReplot() is True.

QwtPlot.setAutoReplot(tf)[source]

Set or reset the autoReplot option

If the autoReplot option is set, the plot will be updated implicitly by manipulating member functions. Since this may be time-consuming, it is recommended to leave this option switched off and call replot() explicitly if necessary.

The autoReplot option is set to false by default, which means that the user has to call replot() in order to make changes visible.

Parameters:	tf (bool) – True or False. Defaults to True.

See also

QwtPlot.autoReplot()[source]

Returns:	True if the autoReplot option is set.

See also

setAutoReplot()

QwtPlot.setTitle(title)[source]

Change the plot’s title

Parameters:	title (str or qwt.text.QwtText) – New title

See also

QwtPlot.title()[source]

Returns:	Title of the plot

See also

updateAxes(), setAutoReplot()

QwtPlot.titleLabel()[source]

Returns:	Title label widget.

QwtPlot.setFooter(text)[source]

Change the text the footer

Parameters:	text (str or qwt.text.QwtText) – New text of the footer

See also

footer()

QwtPlot.footer()[source]

Returns:	Text of the footer

See also

setFooter()

QwtPlot.footerLabel()[source]

Returns:	Footer label widget.

QwtPlot.setPlotLayout(layout)[source]

Assign a new plot layout

Parameters:	layout (qwt.plot_layout.QwtPlotLayout) – Layout

See also

plotLayout()

QwtPlot.plotLayout()[source]

Returns:	the plot’s layout

See also

setPlotLayout()

QwtPlot.legend()[source]

Returns:	the plot’s legend

See also

insertLegend()

QwtPlot.canvas()[source]

Returns:	the plot’s canvas

QwtPlot.sizeHint()[source]

Returns:	Size hint for the plot widget

See also

minimumSizeHint()

QwtPlot.minimumSizeHint()[source]

Returns:	Return a minimum size hint

QwtPlot.replot()[source]

Redraw the plot

If the autoReplot option is not set (which is the default) or if any curves are attached to raw data, the plot has to be refreshed explicitly in order to make changes visible.

See also

QwtPlot.updateLayout()[source]: Adjust plot content to its current size.

See also

resizeEvent()

QwtPlot.getCanvasMarginsHint(maps, canvasRect)[source]

Calculate the canvas margins

Parameters:	maps (list) – QwtPlot.axisCnt maps, mapping between plot and paint device coordinates canvasRect (QRectF) – Bounding rectangle where to paint

Plot items might indicate, that they need some extra space at the borders of the canvas by the QwtPlotItem.Margins flag.

See also

updateCanvasMargins(), getCanvasMarginHint()

QwtPlot.updateCanvasMargins()[source]

Update the canvas margins

Plot items might indicate, that they need some extra space at the borders of the canvas by the QwtPlotItem.Margins flag.

QwtPlot.drawCanvas(painter)[source]

Redraw the canvas.

Parameters:	painter (QPainter) – Painter used for drawing

Warning

drawCanvas calls drawItems what is also used for printing. Applications that like to add individual plot items better overload drawItems()

QwtPlot.drawItems(painter, canvasRect, maps)[source]

Redraw the canvas.

Parameters:	painter (QPainter) – Painter used for drawing canvasRect (QRectF) – Bounding rectangle where to paint maps (list) – QwtPlot.axisCnt maps, mapping between plot and paint device coordinates

Note

Usually canvasRect is contentsRect() of the plot canvas. Due to a bug in Qt this rectangle might be wrong for certain frame styles ( f.e QFrame.Box ) and it might be necessary to fix the margins manually using QWidget.setContentsMargins()

QwtPlot.canvasMap(axisId)[source]

Parameters:	axisId (int) – Axis
Returns:	Map for the axis on the canvas. With this map pixel coordinates can translated to plot coordinates and vice versa.

See also

qwt.scale_map.QwtScaleMap, transform(), invTransform()

QwtPlot.setCanvasBackground(brush)[source]

Change the background of the plotting area

Sets brush to QPalette.Window of all color groups of the palette of the canvas. Using canvas().setPalette() is a more powerful way to set these colors.

Parameters:	brush (QBrush) – New background brush

See also

canvasBackground()

QwtPlot.canvasBackground()[source]

Returns:	Background brush of the plotting area.

See also

setCanvasBackground()

QwtPlot.axisValid(axisId)[source]

Parameters:	axisId (int) – Axis
Returns:	True if the specified axis exists, otherwise False

QwtPlot.insertLegend(legend, pos=None, ratio=-1)[source]

Insert a legend

If the position legend is QwtPlot.LeftLegend or QwtPlot.RightLegend the legend will be organized in one column from top to down. Otherwise the legend items will be placed in a table with a best fit number of columns from left to right.

insertLegend() will set the plot widget as parent for the legend. The legend will be deleted in the destructor of the plot or when another legend is inserted.

Legends, that are not inserted into the layout of the plot widget need to connect to the legendDataChanged() signal. Calling updateLegend() initiates this signal for an initial update. When the application code wants to implement its own layout this also needs to be done for rendering plots to a document ( see QwtPlotRenderer ).

Parameters:	legend (qwt.legend.QwtAbstractLegend) – Legend pos (QwtPlot.LegendPosition) – The legend’s position. ratio (float) – Ratio between legend and the bounding rectangle of title, canvas and axes

Note

For top/left position the number of columns will be limited to 1, otherwise it will be set to unlimited.

Note

The legend will be shrunk if it would need more space than the given ratio. The ratio is limited to ]0.0 .. 1.0]. In case of <= 0.0 it will be reset to the default ratio. The default vertical/horizontal ratio is 0.33/0.5.

QwtPlot.updateLegend(plotItem=None)[source]

If plotItem is None, emit QwtPlot.SIG_LEGEND_DATA_CHANGED for all plot item. Otherwise, emit the signal for passed plot item.

Parameters:	plotItem (qwt.plot.QwtPlotItem) – Plot item

See also

QwtPlotItem.legendData(), QwtPlot.SIG_LEGEND_DATA_CHANGED

QwtPlot.updateLegendItems(plotItem, legendData)[source]

Update all plot items interested in legend attributes

Call QwtPlotItem.updateLegend(), when the QwtPlotItem.LegendInterest flag is set.

Parameters:	plotItem (qwt.plot.QwtPlotItem) – Plot item legendData (list) – Entries to be displayed for the plot item ( usually 1 )

See also

QwtPlotItem.LegendInterest(), QwtPlotItem.updateLegend()

QwtPlot.attachItem(plotItem, on)[source]

Attach/Detach a plot item

Parameters:	plotItem (qwt.plot.QwtPlotItem) – Plot item on (bool) – When true attach the item, otherwise detach it

QwtPlot.print_(printer)[source]

Print plot to printer

Parameters:	printer (QPaintDevice or QPrinter or QSvgGenerator) – Printer

QwtPlot.exportTo(filename, size=(800, 600), size_mm=None, resolution=72.0, format_=None)[source]

Export plot to PDF or image file (SVG, PNG, ...)

Parameters:	filename (str) – Filename size (tuple) – (width, height) size in pixels size_mm (tuple) – (width, height) size in millimeters resolution (float) – Image resolution format (str) – File format (PDF, SVG, PNG, ...)

class qwt.plot.QwtPlotItem(title=None)[source]

Base class for items on the plot canvas

A plot item is “something”, that can be painted on the plot canvas, or only affects the scales of the plot widget. They can be categorized as:

Representator

A “Representator” is an item that represents some sort of data on the plot canvas. The different representator classes are organized according to the characteristics of the data:
- qwt.plot_marker.QwtPlotMarker: Represents a point or a horizontal/vertical coordinate
- qwt.plot_curve.QwtPlotCurve: Represents a series of points
Decorators

A “Decorator” is an item, that displays additional information, that is not related to any data:
- qwt.plot_grid.QwtPlotGrid

Depending on the QwtPlotItem.ItemAttribute flags, an item is included into autoscaling or has an entry on the legend.

Before misusing the existing item classes it might be better to implement a new type of plot item ( don’t implement a watermark as spectrogram ). Deriving a new type of QwtPlotItem primarily means to implement the YourPlotItem.draw() method.

See also

The cpuplot example shows the implementation of additional plot items.

class QwtPlotItem([title=None])

Constructor

Parameters:	title (qwt.text.QwtText or str) – Title of the item

QwtPlotItem.attach(plot)[source]

Attach the item to a plot.

This method will attach a QwtPlotItem to the QwtPlot argument. It will first detach the QwtPlotItem from any plot from a previous call to attach (if necessary). If a None argument is passed, it will detach from any QwtPlot it was attached to.

Parameters:	plot (qwt.plot.QwtPlot) – Plot widget

See also

detach()

QwtPlotItem.detach()[source]

Detach the item from a plot.

This method detaches a QwtPlotItem from any QwtPlot it has been associated with.

See also

attach()

QwtPlotItem.rtti()[source]

Return rtti for the specific class represented. QwtPlotItem is simply a virtual interface class, and base classes will implement this method with specific rtti values so a user can differentiate them.

Returns:	rtti value

QwtPlotItem.plot()[source]

Returns:	attached plot

QwtPlotItem.z()[source]

Plot items are painted in increasing z-order.

Returns:	item z order

See also

setZ(), QwtPlotDict.itemList()

QwtPlotItem.setZ(z)[source]

Set the z value

Plot items are painted in increasing z-order.

Parameters:	z (float) – Z-value

See also

z(), QwtPlotDict.itemList()

QwtPlotItem.setTitle(title)[source]

Set a new title

Parameters:	title (qwt.text.QwtText or str) – Title

See also

QwtPlotItem.title()[source]

Returns:	Title of the item

See also

legendIconSize(), legendIcon()

QwtPlotItem.setItemAttribute(attribute, on=True)[source]

Toggle an item attribute

Parameters:	attribute (int) – Attribute type on (bool) – True/False

See also

testItemAttribute()

QwtPlotItem.testItemAttribute(attribute)[source]

Test an item attribute

Parameters:	attribute (int) – Attribute type
Returns:	True/False

See also

setItemAttribute()

QwtPlotItem.setItemInterest(interest, on)[source]

Toggle an item interest

Parameters:	attribute (int) – Interest type on (bool) – True/False

See also

testItemInterest()

QwtPlotItem.testItemInterest(interest)[source]

Test an item interest

Parameters:	attribute (int) – Interest type
Returns:	True/False

See also

setItemInterest()

QwtPlotItem.setRenderHint(hint, on=True)[source]

Toggle a render hint

Parameters:	hint (int) – Render hint on (bool) – True/False

See also

testRenderHint()

QwtPlotItem.testRenderHint(hint)[source]

Test a render hint

Parameters:	attribute (int) – Render hint
Returns:	True/False

See also

setRenderHint()

QwtPlotItem.setLegendIconSize(size)[source]

Set the size of the legend icon

The default setting is 8x8 pixels

Parameters:	size (QSize) – Size

See also

QwtPlotItem.legendIconSize()[source]

Returns:	Legend icon size

See also

setLegendIconSize(), legendIcon()

QwtPlotItem.legendIcon(index, size)[source]

Parameters:	index (int) – Index of the legend entry (usually there is only one) size (QSizeF) – Icon size
Returns:	Icon representing the item on the legend

The default implementation returns an invalid icon

See also

setLegendIconSize(), legendData()

QwtPlotItem.defaultIcon(brush, size)[source]

Return a default icon from a brush

The default icon is a filled rectangle used in several derived classes as legendIcon().

Parameters:	brush (QBrush) – Fill brush size (QSizeF) – Icon size
Returns:	A filled rectangle

QwtPlotItem.show()[source]: Show the item

QwtPlotItem.hide()[source]: Hide the item

QwtPlotItem.setVisible(on)[source]

Show/Hide the item

Parameters:	on (bool) – Show if True, otherwise hide

See also

isVisible(), show(), hide()

QwtPlotItem.isVisible()[source]

Returns:	True if visible

See also

setVisible(), show(), hide()

QwtPlotItem.itemChanged()[source]: Update the legend and call QwtPlot.autoRefresh() for the parent plot.

See also

QwtPlot.legendChanged(), QwtPlot.autoRefresh()

QwtPlotItem.legendChanged()[source]: Update the legend of the parent plot.

See also

QwtPlot.updateLegend(), itemChanged()

QwtPlotItem.setAxes(xAxis, yAxis)[source]

Set X and Y axis

The item will painted according to the coordinates of its Axes.

Parameters:	xAxis (int) – X Axis (QwtPlot.xBottom or QwtPlot.xTop) yAxis (int) – Y Axis (QwtPlot.yLeft or QwtPlot.yRight)

QwtPlotItem.setAxis(xAxis, yAxis)[source]: Set X and Y axis

Warning

setAxis has been removed in Qwt6: please use setAxes() instead

QwtPlotItem.setXAxis(axis)[source]

Set the X axis

The item will painted according to the coordinates its Axes.

Parameters:	axis (int) – X Axis (QwtPlot.xBottom or QwtPlot.xTop)

QwtPlotItem.setYAxis(axis)[source]

Set the Y axis

The item will painted according to the coordinates its Axes.

Parameters:	axis (int) – Y Axis (QwtPlot.yLeft or QwtPlot.yRight)

QwtPlotItem.xAxis()[source]

Returns:	xAxis

QwtPlotItem.yAxis()[source]

Returns:	yAxis

QwtPlotItem.boundingRect()[source]

Returns:	An invalid bounding rect: QRectF(1.0, 1.0, -2.0, -2.0)

Note

A width or height < 0.0 is ignored by the autoscaler

QwtPlotItem.getCanvasMarginHint(xMap, yMap, canvasRect)[source]

Calculate a hint for the canvas margin

When the QwtPlotItem::Margins flag is enabled the plot item indicates, that it needs some margins at the borders of the canvas. This is f.e. used by bar charts to reserve space for displaying the bars.

The margins are in target device coordinates ( pixels on screen )

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates. canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates

QwtPlotItem.legendData()[source]

Return all information, that is needed to represent the item on the legend

QwtLegendData is basically a list of QVariants that makes it possible to overload and reimplement legendData() to return almost any type of information, that is understood by the receiver that acts as the legend.

The default implementation returns one entry with the title() of the item and the legendIcon().

Returns:	Data, that is needed to represent the item on the legend

QwtPlotItem.updateLegend(item, data)[source]

Update the item to changes of the legend info

Plot items that want to display a legend ( not those, that want to be displayed on a legend ! ) will have to implement updateLegend().

updateLegend() is only called when the LegendInterest interest is enabled. The default implementation does nothing.

Parameters:	item (qwt.plot.QwtPlotItem) – Plot item to be displayed on a legend data (list) – Attributes how to display item on the legend

Note

Plot items, that want to be displayed on a legend need to enable the QwtPlotItem.Legend flag and to implement legendData() and legendIcon()

QwtPlotItem.scaleRect(xMap, yMap)[source]

Calculate the bounding scale rectangle of 2 maps

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
Returns:	Bounding scale rect of the scale maps, not normalized

QwtPlotItem.paintRect(xMap, yMap)[source]

Calculate the bounding paint rectangle of 2 maps

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
Returns:	Bounding paint rectangle of the scale maps, not normalized

QwtPlotCanvas¶

class qwt.plot_canvas.QwtPlotCanvas(plot=None)[source]¶

Canvas of a QwtPlot.

Canvas is the widget where all plot items are displayed

See also

Paint attributes:

QwtPlotCanvas.BackingStore:

Paint double buffered reusing the content of the pixmap buffer when possible.

Using a backing store might improve the performance significantly, when working with widget overlays (like rubber bands). Disabling the cache might improve the performance for incremental paints (using qwt.plot_directpainter.QwtPlotDirectPainter).

QwtPlotCanvas.Opaque:

Try to fill the complete contents rectangle of the plot canvas

When using styled backgrounds Qt assumes, that the canvas doesn’t fill its area completely (f.e because of rounded borders) and fills the area below the canvas. When this is done with gradients it might result in a serious performance bottleneck - depending on the size.

When the Opaque attribute is enabled the canvas tries to identify the gaps with some heuristics and to fill those only.

Warning

Will not work for semitransparent backgrounds

QwtPlotCanvas.HackStyledBackground:

Try to improve painting of styled backgrounds

QwtPlotCanvas supports the box model attributes for customizing the layout with style sheets. Unfortunately the design of Qt style sheets has no concept how to handle backgrounds with rounded corners - beside of padding.

When HackStyledBackground is enabled the plot canvas tries to separate the background from the background border by reverse engineering to paint the background before and the border after the plot items. In this order the border gets perfectly antialiased and you can avoid some pixel artifacts in the corners.

QwtPlotCanvas.ImmediatePaint:

When ImmediatePaint is set replot() calls repaint() instead of update().

See also

replot(), QWidget.repaint(), QWidget.update()

Focus indicators:

QwtPlotCanvas.NoFocusIndicator:

Don’t paint a focus indicator

QwtPlotCanvas.CanvasFocusIndicator:

The focus is related to the complete canvas. Paint the focus indicator using paintFocus()

QwtPlotCanvas.ItemFocusIndicator:

The focus is related to an item (curve, point, ...) on the canvas. It is up to the application to display a focus indication using f.e. highlighting.

class QwtPlotCanvas([plot=None])¶

Constructor

Parameters:	plot (qwt.plot.QwtPlot) – Parent plot widget

See also

QwtPlotCanvas.plot()[source]¶

Returns:	Parent plot widget

QwtPlotCanvas.setPaintAttribute(attribute, on=True)[source]¶

Changing the paint attributes

Paint attributes:

QwtPlotCanvas.BackingStore

QwtPlotCanvas.Opaque

QwtPlotCanvas.HackStyledBackground

QwtPlotCanvas.ImmediatePaint

Parameters:	attribute (int) – Paint attribute on (bool) – On/Off

QwtPlotCanvas.testPaintAttribute(attribute)[source]¶

Test whether a paint attribute is enabled

Parameters:	attribute (int) – Paint attribute
Returns:	True, when attribute is enabled

See also

QwtPlotCanvas.backingStore()[source]¶

Returns:	Backing store, might be None

QwtPlotCanvas.invalidateBackingStore()[source]¶: Invalidate the internal backing store

QwtPlotCanvas.setFocusIndicator(focusIndicator)[source]¶

Set the focus indicator

Focus indicators:

QwtPlotCanvas.NoFocusIndicator

QwtPlotCanvas.CanvasFocusIndicator

QwtPlotCanvas.ItemFocusIndicator

Parameters:	focusIndicator (int) – Focus indicator

See also

focusIndicator()

QwtPlotCanvas.focusIndicator()[source]¶

Returns:	Focus indicator

See also

setFocusIndicator()

QwtPlotCanvas.setBorderRadius(radius)[source]¶

Set the radius for the corners of the border frame

Parameters:	radius (float) – Radius of a rounded corner

See also

borderRadius()

QwtPlotCanvas.borderRadius()[source]¶

Returns:	Radius for the corners of the border frame

See also

QwtPlotCanvas.drawBorder(painter)[source]¶

Draw the border of the plot canvas

Parameters:	painter (QPainter) – Painter

See also

QwtPlotCanvas.drawFocusIndicator(painter)[source]¶

Draw the focus indication

Parameters:	painter (QPainter) – Painter

QwtPlotCanvas.replot()[source]¶: Invalidate the paint cache and repaint the canvas

QwtPlotCanvas.updateStyleSheetInfo()[source]¶: Update the cached information about the current style sheet

QwtPlotCanvas.borderPath(rect)[source]¶

Calculate the painter path for a styled or rounded border

When the canvas has no styled background or rounded borders the painter path is empty.

Parameters:	rect (QRect) – Bounding rectangle of the canvas
Returns:	Painter path, that can be used for clipping

class qwt.plot_canvas.QwtPlotCanvas(plot=None)[source]

Canvas of a QwtPlot.

Canvas is the widget where all plot items are displayed

See also

Paint attributes:

QwtPlotCanvas.BackingStore:

Paint double buffered reusing the content of the pixmap buffer when possible.

Using a backing store might improve the performance significantly, when working with widget overlays (like rubber bands). Disabling the cache might improve the performance for incremental paints (using qwt.plot_directpainter.QwtPlotDirectPainter).

QwtPlotCanvas.Opaque:

Try to fill the complete contents rectangle of the plot canvas

When using styled backgrounds Qt assumes, that the canvas doesn’t fill its area completely (f.e because of rounded borders) and fills the area below the canvas. When this is done with gradients it might result in a serious performance bottleneck - depending on the size.

When the Opaque attribute is enabled the canvas tries to identify the gaps with some heuristics and to fill those only.

Warning

Will not work for semitransparent backgrounds

QwtPlotCanvas.HackStyledBackground:

Try to improve painting of styled backgrounds

QwtPlotCanvas supports the box model attributes for customizing the layout with style sheets. Unfortunately the design of Qt style sheets has no concept how to handle backgrounds with rounded corners - beside of padding.

When HackStyledBackground is enabled the plot canvas tries to separate the background from the background border by reverse engineering to paint the background before and the border after the plot items. In this order the border gets perfectly antialiased and you can avoid some pixel artifacts in the corners.

QwtPlotCanvas.ImmediatePaint:

When ImmediatePaint is set replot() calls repaint() instead of update().

See also

replot(), QWidget.repaint(), QWidget.update()

Focus indicators:

QwtPlotCanvas.NoFocusIndicator:

Don’t paint a focus indicator

QwtPlotCanvas.CanvasFocusIndicator:

The focus is related to the complete canvas. Paint the focus indicator using paintFocus()

QwtPlotCanvas.ItemFocusIndicator:

The focus is related to an item (curve, point, ...) on the canvas. It is up to the application to display a focus indication using f.e. highlighting.

class QwtPlotCanvas([plot=None])

Constructor

Parameters:	plot (qwt.plot.QwtPlot) – Parent plot widget

See also

QwtPlotCanvas.plot()[source]

Returns:	Parent plot widget

QwtPlotCanvas.setPaintAttribute(attribute, on=True)[source]

Changing the paint attributes

Paint attributes:

QwtPlotCanvas.BackingStore

QwtPlotCanvas.Opaque

QwtPlotCanvas.HackStyledBackground

QwtPlotCanvas.ImmediatePaint

Parameters:	attribute (int) – Paint attribute on (bool) – On/Off

QwtPlotCanvas.testPaintAttribute(attribute)[source]

Test whether a paint attribute is enabled

Parameters:	attribute (int) – Paint attribute
Returns:	True, when attribute is enabled

See also

QwtPlotCanvas.backingStore()[source]

Returns:	Backing store, might be None

QwtPlotCanvas.invalidateBackingStore()[source]: Invalidate the internal backing store

QwtPlotCanvas.setFocusIndicator(focusIndicator)[source]

Set the focus indicator

Focus indicators:

QwtPlotCanvas.NoFocusIndicator

QwtPlotCanvas.CanvasFocusIndicator

QwtPlotCanvas.ItemFocusIndicator

Parameters:	focusIndicator (int) – Focus indicator

See also

focusIndicator()

QwtPlotCanvas.focusIndicator()[source]

Returns:	Focus indicator

See also

setFocusIndicator()

QwtPlotCanvas.setBorderRadius(radius)[source]

Set the radius for the corners of the border frame

Parameters:	radius (float) – Radius of a rounded corner

See also

borderRadius()

QwtPlotCanvas.borderRadius()[source]

Returns:	Radius for the corners of the border frame

See also

QwtPlotCanvas.drawBorder(painter)[source]

Draw the border of the plot canvas

Parameters:	painter (QPainter) – Painter

See also

QwtPlotCanvas.drawFocusIndicator(painter)[source]

Draw the focus indication

Parameters:	painter (QPainter) – Painter

QwtPlotCanvas.replot()[source]: Invalidate the paint cache and repaint the canvas

QwtPlotCanvas.updateStyleSheetInfo()[source]: Update the cached information about the current style sheet

QwtPlotCanvas.borderPath(rect)[source]

Calculate the painter path for a styled or rounded border

When the canvas has no styled background or rounded borders the painter path is empty.

Parameters:	rect (QRect) – Bounding rectangle of the canvas
Returns:	Painter path, that can be used for clipping

Plot items¶

QwtPlotGrid¶

class qwt.plot_grid.QwtPlotGrid[source]¶

A class which draws a coordinate grid

The QwtPlotGrid class can be used to draw a coordinate grid. A coordinate grid consists of major and minor vertical and horizontal grid lines. The locations of the grid lines are determined by the X and Y scale divisions which can be assigned with setXDiv() and setYDiv(). The draw() member draws the grid within a bounding rectangle.

rtti()[source]¶

Returns:	Return QwtPlotItem.Rtti_PlotGrid

enableX(on)[source]¶

Enable or disable vertical grid lines

Parameters:	on (bool) – Enable (true) or disable

See also

enableY(on)[source]¶

Enable or disable horizontal grid lines

Parameters:	on (bool) – Enable (true) or disable

See also

enableXMin(on)[source]¶

Enable or disable minor vertical grid lines.

Parameters:	on (bool) – Enable (true) or disable

See also

enableYMin(on)[source]¶

Enable or disable minor horizontal grid lines.

Parameters:	on (bool) – Enable (true) or disable

See also

setXDiv(scaleDiv)[source]¶

Assign an x axis scale division

Parameters:	scaleDiv (qwt.scale_div.QwtScaleDiv) – Scale division

setYDiv(scaleDiv)[source]¶

Assign an y axis scale division

Parameters:	scaleDiv (qwt.scale_div.QwtScaleDiv) – Scale division

setPen(*args)[source]¶

Build and/or assign a pen for both major and minor grid lines

setPen(color, width, style)[source]

Build and assign a pen for both major and minor grid lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setPen(pen)[source]

Assign a pen for both major and minor grid lines

Parameters:	pen (QPen) – New pen

See also

pen(), brush()

setMajorPen(*args)[source]¶

Build and/or assign a pen for both major grid lines

setMajorPen(color, width, style)[source]

Build and assign a pen for both major grid lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setMajorPen(pen)[source]

Assign a pen for the major grid lines

Parameters:	pen (QPen) – New pen

See also

majorPen(), setMinorPen(), setPen(), pen(), brush()

setMinorPen(*args)[source]¶

Build and/or assign a pen for both minor grid lines

setMinorPen(color, width, style)[source]

Build and assign a pen for both minor grid lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setMinorPen(pen)[source]

Assign a pen for the minor grid lines

Parameters:	pen (QPen) – New pen

See also

minorPen(), setMajorPen(), setPen(), pen(), brush()

draw(painter, xMap, yMap, canvasRect)[source]¶

Draw the grid

The grid is drawn into the bounding rectangle such that grid lines begin and end at the rectangle’s borders. The X and Y maps are used to map the scale divisions into the drawing region screen.

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – X axis map yMap (qwt.scale_map.QwtScaleMap) – Y axis canvasRect (QRectF) – Contents rectangle of the plot canvas

majorPen()[source]¶

Returns:	the pen for the major grid lines

minorPen()[source]¶

Returns:	the pen for the minor grid lines

xEnabled()[source]¶

Returns:	True if vertical grid lines are enabled

See also

yEnabled()[source]¶

Returns:	True if horizontal grid lines are enabled

See also

xMinEnabled()[source]¶

Returns:	True if minor vertical grid lines are enabled

See also

yMinEnabled()[source]¶

Returns:	True if minor horizontal grid lines are enabled

See also

xScaleDiv()[source]¶

Returns:	the scale division of the x axis

yScaleDiv()[source]¶

Returns:	the scale division of the y axis

updateScaleDiv(xScaleDiv, yScaleDiv)[source]¶

Update the grid to changes of the axes scale division

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Scale division of the x-axis yMap (qwt.scale_map.QwtScaleMap) – Scale division of the y-axis

See also

updateAxes()

class qwt.plot_grid.QwtPlotGrid[source]

A class which draws a coordinate grid

The QwtPlotGrid class can be used to draw a coordinate grid. A coordinate grid consists of major and minor vertical and horizontal grid lines. The locations of the grid lines are determined by the X and Y scale divisions which can be assigned with setXDiv() and setYDiv(). The draw() member draws the grid within a bounding rectangle.

rtti()[source]

Returns:	Return QwtPlotItem.Rtti_PlotGrid

enableX(on)[source]

Enable or disable vertical grid lines

Parameters:	on (bool) – Enable (true) or disable

See also

enableY(on)[source]

Enable or disable horizontal grid lines

Parameters:	on (bool) – Enable (true) or disable

See also

enableXMin(on)[source]

Enable or disable minor vertical grid lines.

Parameters:	on (bool) – Enable (true) or disable

See also

enableYMin(on)[source]

Enable or disable minor horizontal grid lines.

Parameters:	on (bool) – Enable (true) or disable

See also

setXDiv(scaleDiv)[source]

Assign an x axis scale division

Parameters:	scaleDiv (qwt.scale_div.QwtScaleDiv) – Scale division

setYDiv(scaleDiv)[source]

Assign an y axis scale division

Parameters:	scaleDiv (qwt.scale_div.QwtScaleDiv) – Scale division

setPen(*args)[source]

Build and/or assign a pen for both major and minor grid lines

setPen(color, width, style)[source]

Build and assign a pen for both major and minor grid lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setPen(pen)[source]

Assign a pen for both major and minor grid lines

Parameters:	pen (QPen) – New pen

See also

pen(), brush()

setMajorPen(*args)[source]

Build and/or assign a pen for both major grid lines

setMajorPen(color, width, style)[source]

Build and assign a pen for both major grid lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setMajorPen(pen)[source]

Assign a pen for the major grid lines

Parameters:	pen (QPen) – New pen

See also

majorPen(), setMinorPen(), setPen(), pen(), brush()

setMinorPen(*args)[source]

Build and/or assign a pen for both minor grid lines

setMinorPen(color, width, style)[source]

Build and assign a pen for both minor grid lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setMinorPen(pen)[source]

Assign a pen for the minor grid lines

Parameters:	pen (QPen) – New pen

See also

minorPen(), setMajorPen(), setPen(), pen(), brush()

draw(painter, xMap, yMap, canvasRect)[source]

Draw the grid

The grid is drawn into the bounding rectangle such that grid lines begin and end at the rectangle’s borders. The X and Y maps are used to map the scale divisions into the drawing region screen.

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – X axis map yMap (qwt.scale_map.QwtScaleMap) – Y axis canvasRect (QRectF) – Contents rectangle of the plot canvas

majorPen()[source]

Returns:	the pen for the major grid lines

minorPen()[source]

Returns:	the pen for the minor grid lines

xEnabled()[source]

Returns:	True if vertical grid lines are enabled

See also

yEnabled()[source]

Returns:	True if horizontal grid lines are enabled

See also

xMinEnabled()[source]

Returns:	True if minor vertical grid lines are enabled

See also

yMinEnabled()[source]

Returns:	True if minor horizontal grid lines are enabled

See also

xScaleDiv()[source]

Returns:	the scale division of the x axis

yScaleDiv()[source]

Returns:	the scale division of the y axis

updateScaleDiv(xScaleDiv, yScaleDiv)[source]

Update the grid to changes of the axes scale division

Parameters:	xMap (qwt.scale_map.QwtScaleMap) – Scale division of the x-axis yMap (qwt.scale_map.QwtScaleMap) – Scale division of the y-axis

See also

updateAxes()

QwtPlotCurve¶

class qwt.plot_curve.QwtPlotCurve(title=None)[source]¶

A plot item, that represents a series of points

A curve is the representation of a series of points in the x-y plane. It supports different display styles, interpolation ( f.e. spline ) and symbols.

See also

qwt.symbol.QwtSymbol(), qwt.scale_map.QwtScaleMap()

Curve styles:

QwtPlotCurve.NoCurve:

Don’t draw a curve. Note: This doesn’t affect the symbols.

QwtPlotCurve.Lines:

Connect the points with straight lines. The lines might be interpolated depending on the ‘Fitted’ attribute. Curve fitting can be configured using setCurveFitter().

QwtPlotCurve.Sticks:

Draw vertical or horizontal sticks ( depending on the orientation() ) from a baseline which is defined by setBaseline().

QwtPlotCurve.Steps:

Connect the points with a step function. The step function is drawn from the left to the right or vice versa, depending on the QwtPlotCurve::Inverted attribute.

QwtPlotCurve.Dots:

Draw dots at the locations of the data points. Note: This is different from a dotted line (see setPen()), and faster as a curve in QwtPlotCurve::NoStyle style and a symbol painting a point.

QwtPlotCurve.UserCurve:

Styles >= QwtPlotCurve.UserCurve are reserved for derived classes of QwtPlotCurve that overload drawCurve() with additional application specific curve types.

Curve attributes:

QwtPlotCurve.Inverted:

For QwtPlotCurve.Steps only. Draws a step function from the right to the left.

QwtPlotCurve.Fitted:

Warning

This option is not supported in python-qwt.

Legend attributes:

QwtPlotCurve.LegendNoAttribute:

QwtPlotCurve tries to find a color representing the curve and paints a rectangle with it.

QwtPlotCurve.LegendShowLine:

If the style() is not QwtPlotCurve.NoCurve a line is painted with the curve pen().

QwtPlotCurve.LegendShowSymbol:

If the curve has a valid symbol it is painted.

QwtPlotCurve.LegendShowBrush:

If the curve has a brush a rectangle filled with the curve brush() is painted.

Paint attributes:

QwtPlotCurve.ClipPolygons:

Clip polygons before painting them. In situations, where points are far outside the visible area (f.e when zooming deep) this might be a substantial improvement for the painting performance

Warning

This option is currently not supported in python-qwt.

QwtPlotCurve.FilterPoints:

Tries to reduce the data that has to be painted, by sorting out duplicates, or paintings outside the visible area. Might have a notable impact on curves with many close points. Only a couple of very basic filtering algorithms are implemented.

QwtPlotCurve.MinimizeMemory:

Warning

This option was removed as it has no sense in python-qwt (the polyline plotting is not taking more memory than the array data that is already there).

QwtPlotCurve.ImageBuffer:

Render the points to a temporary image and paint the image. This is a very special optimization for Dots style, when having a huge amount of points. With a reasonable number of points QPainter.drawPoints() will be faster.

class QwtPlotCurve([title=None])¶

Constructor

Parameters:	title (qwt.text.QwtText or str or None) – Curve title

QwtPlotCurve.init()[source]¶: Initialize internal members

QwtPlotCurve.rtti()[source]¶

Returns:	QwtPlotItem.Rtti_PlotCurve

QwtPlotCurve.setPaintAttribute(attribute, on=True)[source]¶

Specify an attribute how to draw the curve

Supported paint attributes:

QwtPlotCurve.FilterPoints

QwtPlotCurve.ImageBuffer

Parameters:	attribute (int) – Paint attribute on (bool) – On/Off

See also

testPaintAttribute()

QwtPlotCurve.testPaintAttribute(attribute)[source]¶

Parameters:	attribute (int) – Paint attribute
Returns:	True, when attribute is enabled

See also

testLegendAttribute(), legendIcon()

QwtPlotCurve.setLegendAttribute(attribute, on=True)[source]¶

Specify an attribute how to draw the legend icon

Legend attributes:

QwtPlotCurve.LegendNoAttribute

QwtPlotCurve.LegendShowLine

QwtPlotCurve.LegendShowSymbol

QwtPlotCurve.LegendShowBrush

Parameters:	attribute (int) – Legend attribute on (bool) – On/Off

See also

QwtPlotCurve.testLegendAttribute(attribute)[source]¶

Parameters:	attribute (int) – Legend attribute
Returns:	True, when attribute is enabled

See also

setLegendAttribute()

QwtPlotCurve.setStyle(style)[source]¶

Set the curve’s drawing style

Valid curve styles:

QwtPlotCurve.NoCurve

QwtPlotCurve.Lines

QwtPlotCurve.Sticks

QwtPlotCurve.Steps

QwtPlotCurve.Dots

QwtPlotCurve.UserCurve

Parameters:	style (int) – Curve style

See also

style()

QwtPlotCurve.style()[source]¶

Returns:	Style of the curve

See also

setStyle()

QwtPlotCurve.setSymbol(symbol)[source]¶

Assign a symbol

The curve will take the ownership of the symbol, hence the previously set symbol will be delete by setting a new one. If symbol is None no symbol will be drawn.

Parameters:	symbol (qwt.symbol.QwtSymbol) – Symbol

See also

QwtPlotCurve.symbol()[source]¶

Returns:	Current symbol or None, when no symbol has been assigned

See also

drawCurve(), drawSymbols()

QwtPlotCurve.setPen(*args)[source]¶

Build and/or assign a pen, depending on the arguments.

setPen(color, width, style)[source]

Build and assign a pen

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setPen(pen)[source]

Assign a pen

Parameters:	pen (QPen) – New pen

See also

pen(), brush()

QwtPlotCurve.pen()[source]¶

Returns:	Pen used to draw the lines

See also

setPen(), brush()

QwtPlotCurve.setBrush(brush)[source]¶

Assign a brush.

In case of brush.style() != QBrush.NoBrush and style() != QwtPlotCurve.Sticks the area between the curve and the baseline will be filled.

In case not brush.color().isValid() the area will be filled by pen.color(). The fill algorithm simply connects the first and the last curve point to the baseline. So the curve data has to be sorted (ascending or descending).

Parameters:	brush (QBrush or QColor) – New brush

QwtPlotCurve.brush()[source]¶

Returns:	Brush used to fill the area between lines and the baseline

QwtPlotCurve.directPaint(from_, to)[source]¶

When observing a measurement while it is running, new points have to be added to an existing seriesItem. This method can be used to display them avoiding a complete redraw of the canvas.

Setting plot().canvas().setAttribute(Qt.WA_PaintOutsidePaintEvent, True) will result in faster painting, if the paint engine of the canvas widget supports this feature.

Parameters:	from (int) – Index of the first point to be painted to (int) – Index of the last point to be painted

See also

drawSeries()

QwtPlotCurve.drawSeries(painter, xMap, yMap, canvasRect, from_, to)[source]¶

Draw an interval of the curve

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

See also

QwtPlotCurve.drawCurve(painter, style, xMap, yMap, canvasRect, from_, to)[source]¶

Draw the line part (without symbols) of a curve interval.

Parameters:

painter (QPainter) – Painter
style (int) – curve style, see QwtPlotCurve.CurveStyle
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawLines(painter, xMap, yMap, canvasRect, from_, to)[source]¶

Draw lines

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawSticks(painter, xMap, yMap, canvasRect, from_, to)[source]¶

Draw sticks

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawDots(painter, xMap, yMap, canvasRect, from_, to)[source]¶

Draw dots

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawSteps(painter, xMap, yMap, canvasRect, from_, to)[source]¶

Draw steps

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.setCurveAttribute(attribute, on=True)[source]¶

Specify an attribute for drawing the curve

Supported curve attributes:

QwtPlotCurve.Inverted

Parameters:	attribute (int) – Curve attribute on (bool) – On/Off

See also

testCurveAttribute()

QwtPlotCurve.testCurveAttribute(attribute)[source]¶

Returns:	True, if attribute is enabled

See also

setCurveAttribute()

QwtPlotCurve.fillCurve(painter, xMap, yMap, canvasRect, polygon)[source]¶

Fill the area between the curve and the baseline with the curve brush

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates. canvasRect (QRectF) – Contents rectangle of the canvas polygon (QPolygonF) – Polygon - will be modified !

QwtPlotCurve.closePolyline(painter, xMap, yMap, polygon)[source]¶

Complete a polygon to be a closed polygon including the area between the original polygon and the baseline.

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates. polygon (QPolygonF) – Polygon to be completed

QwtPlotCurve.drawSymbols(painter, symbol, xMap, yMap, canvasRect, from_, to)[source]¶

Draw symbols

Parameters:

painter (QPainter) – Painter
symbol (qwt.symbol.QwtSymbol) – Curve symbol
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.setBaseline(value)[source]¶

Set the value of the baseline

The baseline is needed for filling the curve with a brush or the Sticks drawing style.

The interpretation of the baseline depends on the orientation(). With Qt.Horizontal, the baseline is interpreted as a horizontal line at y = baseline(), with Qt.Vertical, it is interpreted as a vertical line at x = baseline().

The default value is 0.0.

Parameters:	value (float) – Value of the baseline

QwtPlotCurve.baseline()[source]¶

Returns:	Value of the baseline

See also

setBaseline()

QwtPlotCurve.closestPoint(pos)[source]¶

Find the closest curve point for a specific position

Parameters:	pos (QPoint) – Position, where to look for the closest curve point
Returns:	tuple (index, dist)

dist is the distance between the position and the closest curve point. index is the index of the closest curve point, or -1 if none can be found ( f.e when the curve has no points ).

Note

closestPoint() implements a dumb algorithm, that iterates over all points

QwtPlotCurve.legendIcon(index, size)[source]¶

Parameters:	index (int) – Index of the legend entry (ignored as there is only one) size (QSizeF) – Icon size
Returns:	Icon representing the curve on the legend

QwtPlotCurve.setData(*args)[source]¶: Compatibility with Qwt5

QwtPlotCurve.setSamples(*args)[source]¶

Initialize data with an array of points.

setSamples(samples):

Same as setData(QwtPointArrayData(samples))

Parameters:	samples – List/array of points

setSamples(xData, yData, [size=None]):

Same as setData(QwtPointArrayData(xData, yData, [size=None]))

Parameters:	xData – List/array of x values yData – List/array of y values size (int or None) – size of xData and yData

See also

qwt.point_data.QwtPointArrayData,

class qwt.plot_curve.QwtPlotCurve(title=None)[source]

A plot item, that represents a series of points

A curve is the representation of a series of points in the x-y plane. It supports different display styles, interpolation ( f.e. spline ) and symbols.

See also

qwt.symbol.QwtSymbol(), qwt.scale_map.QwtScaleMap()

Curve styles:

QwtPlotCurve.NoCurve:

Don’t draw a curve. Note: This doesn’t affect the symbols.

QwtPlotCurve.Lines:

Connect the points with straight lines. The lines might be interpolated depending on the ‘Fitted’ attribute. Curve fitting can be configured using setCurveFitter().

QwtPlotCurve.Sticks:

Draw vertical or horizontal sticks ( depending on the orientation() ) from a baseline which is defined by setBaseline().

QwtPlotCurve.Steps:

Connect the points with a step function. The step function is drawn from the left to the right or vice versa, depending on the QwtPlotCurve::Inverted attribute.

QwtPlotCurve.Dots:

Draw dots at the locations of the data points. Note: This is different from a dotted line (see setPen()), and faster as a curve in QwtPlotCurve::NoStyle style and a symbol painting a point.

QwtPlotCurve.UserCurve:

Styles >= QwtPlotCurve.UserCurve are reserved for derived classes of QwtPlotCurve that overload drawCurve() with additional application specific curve types.

Curve attributes:

QwtPlotCurve.Inverted:

For QwtPlotCurve.Steps only. Draws a step function from the right to the left.

QwtPlotCurve.Fitted:

Warning

This option is not supported in python-qwt.

Legend attributes:

QwtPlotCurve.LegendNoAttribute:

QwtPlotCurve tries to find a color representing the curve and paints a rectangle with it.

QwtPlotCurve.LegendShowLine:

If the style() is not QwtPlotCurve.NoCurve a line is painted with the curve pen().

QwtPlotCurve.LegendShowSymbol:

If the curve has a valid symbol it is painted.

QwtPlotCurve.LegendShowBrush:

If the curve has a brush a rectangle filled with the curve brush() is painted.

Paint attributes:

QwtPlotCurve.ClipPolygons:

Clip polygons before painting them. In situations, where points are far outside the visible area (f.e when zooming deep) this might be a substantial improvement for the painting performance

Warning

This option is currently not supported in python-qwt.

QwtPlotCurve.FilterPoints:

Tries to reduce the data that has to be painted, by sorting out duplicates, or paintings outside the visible area. Might have a notable impact on curves with many close points. Only a couple of very basic filtering algorithms are implemented.

QwtPlotCurve.MinimizeMemory:

Warning

This option was removed as it has no sense in python-qwt (the polyline plotting is not taking more memory than the array data that is already there).

QwtPlotCurve.ImageBuffer:

Render the points to a temporary image and paint the image. This is a very special optimization for Dots style, when having a huge amount of points. With a reasonable number of points QPainter.drawPoints() will be faster.

class QwtPlotCurve([title=None])

Constructor

Parameters:	title (qwt.text.QwtText or str or None) – Curve title

QwtPlotCurve.init()[source]: Initialize internal members

QwtPlotCurve.rtti()[source]

Returns:	QwtPlotItem.Rtti_PlotCurve

QwtPlotCurve.setPaintAttribute(attribute, on=True)[source]

Specify an attribute how to draw the curve

Supported paint attributes:

QwtPlotCurve.FilterPoints

QwtPlotCurve.ImageBuffer

Parameters:	attribute (int) – Paint attribute on (bool) – On/Off

See also

testPaintAttribute()

QwtPlotCurve.testPaintAttribute(attribute)[source]

Parameters:	attribute (int) – Paint attribute
Returns:	True, when attribute is enabled

See also

testLegendAttribute(), legendIcon()

QwtPlotCurve.setLegendAttribute(attribute, on=True)[source]

Specify an attribute how to draw the legend icon

Legend attributes:

QwtPlotCurve.LegendNoAttribute

QwtPlotCurve.LegendShowLine

QwtPlotCurve.LegendShowSymbol

QwtPlotCurve.LegendShowBrush

Parameters:	attribute (int) – Legend attribute on (bool) – On/Off

See also

QwtPlotCurve.testLegendAttribute(attribute)[source]

Parameters:	attribute (int) – Legend attribute
Returns:	True, when attribute is enabled

See also

setLegendAttribute()

QwtPlotCurve.setStyle(style)[source]

Set the curve’s drawing style

Valid curve styles:

QwtPlotCurve.NoCurve

QwtPlotCurve.Lines

QwtPlotCurve.Sticks

QwtPlotCurve.Steps

QwtPlotCurve.Dots

QwtPlotCurve.UserCurve

Parameters:	style (int) – Curve style

See also

style()

QwtPlotCurve.style()[source]

Returns:	Style of the curve

See also

setStyle()

QwtPlotCurve.setSymbol(symbol)[source]

Assign a symbol

The curve will take the ownership of the symbol, hence the previously set symbol will be delete by setting a new one. If symbol is None no symbol will be drawn.

Parameters:	symbol (qwt.symbol.QwtSymbol) – Symbol

See also

QwtPlotCurve.symbol()[source]

Returns:	Current symbol or None, when no symbol has been assigned

See also

drawCurve(), drawSymbols()

QwtPlotCurve.setPen(*args)[source]

Build and/or assign a pen, depending on the arguments.

setPen(color, width, style)[source]

Build and assign a pen

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setPen(pen)[source]

Assign a pen

Parameters:	pen (QPen) – New pen

See also

pen(), brush()

QwtPlotCurve.pen()[source]

Returns:	Pen used to draw the lines

See also

setPen(), brush()

QwtPlotCurve.setBrush(brush)[source]

Assign a brush.

In case of brush.style() != QBrush.NoBrush and style() != QwtPlotCurve.Sticks the area between the curve and the baseline will be filled.

In case not brush.color().isValid() the area will be filled by pen.color(). The fill algorithm simply connects the first and the last curve point to the baseline. So the curve data has to be sorted (ascending or descending).

Parameters:	brush (QBrush or QColor) – New brush

QwtPlotCurve.brush()[source]

Returns:	Brush used to fill the area between lines and the baseline

QwtPlotCurve.directPaint(from_, to)[source]

When observing a measurement while it is running, new points have to be added to an existing seriesItem. This method can be used to display them avoiding a complete redraw of the canvas.

Setting plot().canvas().setAttribute(Qt.WA_PaintOutsidePaintEvent, True) will result in faster painting, if the paint engine of the canvas widget supports this feature.

Parameters:	from (int) – Index of the first point to be painted to (int) – Index of the last point to be painted

See also

drawSeries()

QwtPlotCurve.drawSeries(painter, xMap, yMap, canvasRect, from_, to)[source]

Draw an interval of the curve

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

See also

QwtPlotCurve.drawCurve(painter, style, xMap, yMap, canvasRect, from_, to)[source]

Draw the line part (without symbols) of a curve interval.

Parameters:

painter (QPainter) – Painter
style (int) – curve style, see QwtPlotCurve.CurveStyle
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawLines(painter, xMap, yMap, canvasRect, from_, to)[source]

Draw lines

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawSticks(painter, xMap, yMap, canvasRect, from_, to)[source]

Draw sticks

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawDots(painter, xMap, yMap, canvasRect, from_, to)[source]

Draw dots

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.drawSteps(painter, xMap, yMap, canvasRect, from_, to)[source]

Draw steps

Parameters:

painter (QPainter) – Painter
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.setCurveAttribute(attribute, on=True)[source]

Specify an attribute for drawing the curve

Supported curve attributes:

QwtPlotCurve.Inverted

Parameters:	attribute (int) – Curve attribute on (bool) – On/Off

See also

testCurveAttribute()

QwtPlotCurve.testCurveAttribute(attribute)[source]

Returns:	True, if attribute is enabled

See also

setCurveAttribute()

QwtPlotCurve.fillCurve(painter, xMap, yMap, canvasRect, polygon)[source]

Fill the area between the curve and the baseline with the curve brush

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates. canvasRect (QRectF) – Contents rectangle of the canvas polygon (QPolygonF) – Polygon - will be modified !

QwtPlotCurve.closePolyline(painter, xMap, yMap, polygon)[source]

Complete a polygon to be a closed polygon including the area between the original polygon and the baseline.

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates. yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates. polygon (QPolygonF) – Polygon to be completed

QwtPlotCurve.drawSymbols(painter, symbol, xMap, yMap, canvasRect, from_, to)[source]

Draw symbols

Parameters:

painter (QPainter) – Painter
symbol (qwt.symbol.QwtSymbol) – Curve symbol
xMap (qwt.scale_map.QwtScaleMap) – Maps x-values into pixel coordinates.
yMap (qwt.scale_map.QwtScaleMap) – Maps y-values into pixel coordinates.
canvasRect (QRectF) – Contents rectangle of the canvas
from (int) – Index of the first point to be painted
to (int) – Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

QwtPlotCurve.setBaseline(value)[source]

Set the value of the baseline

The baseline is needed for filling the curve with a brush or the Sticks drawing style.

The interpretation of the baseline depends on the orientation(). With Qt.Horizontal, the baseline is interpreted as a horizontal line at y = baseline(), with Qt.Vertical, it is interpreted as a vertical line at x = baseline().

The default value is 0.0.

Parameters:	value (float) – Value of the baseline

QwtPlotCurve.baseline()[source]

Returns:	Value of the baseline

See also

setBaseline()

QwtPlotCurve.closestPoint(pos)[source]

Find the closest curve point for a specific position

Parameters:	pos (QPoint) – Position, where to look for the closest curve point
Returns:	tuple (index, dist)

dist is the distance between the position and the closest curve point. index is the index of the closest curve point, or -1 if none can be found ( f.e when the curve has no points ).

Note

closestPoint() implements a dumb algorithm, that iterates over all points

QwtPlotCurve.legendIcon(index, size)[source]

Parameters:	index (int) – Index of the legend entry (ignored as there is only one) size (QSizeF) – Icon size
Returns:	Icon representing the curve on the legend

QwtPlotCurve.setData(*args)[source]: Compatibility with Qwt5

QwtPlotCurve.setSamples(*args)[source]

Initialize data with an array of points.

setSamples(samples):

Same as setData(QwtPointArrayData(samples))

Parameters:	samples – List/array of points

setSamples(xData, yData, [size=None]):

Same as setData(QwtPointArrayData(xData, yData, [size=None]))

Parameters:	xData – List/array of x values yData – List/array of y values size (int or None) – size of xData and yData

See also

qwt.point_data.QwtPointArrayData,

QwtPlotMarker¶

class qwt.plot_marker.QwtPlotMarker(title=None)[source]¶

A class for drawing markers

A marker can be a horizontal line, a vertical line, a symbol, a label or any combination of them, which can be drawn around a center point inside a bounding rectangle.

The setSymbol() member assigns a symbol to the marker. The symbol is drawn at the specified point.

With setLabel(), a label can be assigned to the marker. The setLabelAlignment() member specifies where the label is drawn. All the Align*-constants in Qt.AlignmentFlags (see Qt documentation) are valid. The interpretation of the alignment depends on the marker’s line style. The alignment refers to the center point of the marker, which means, for example, that the label would be printed left above the center point if the alignment was set to Qt.AlignLeft | Qt.AlignTop.

Line styles:

QwtPlotMarker.NoLine: No line

QwtPlotMarker.HLine: A horizontal line

QwtPlotMarker.VLine: A vertical line

QwtPlotMarker.Cross: A crosshair

rtti()[source]¶

Returns:	QwtPlotItem.Rtti_PlotMarker

value()[source]¶

Returns:	Value

xValue()[source]¶

Returns:	x Value

yValue()[source]¶

Returns:	y Value

setValue(*args)[source]¶

Set Value

setValue(pos):

Parameters:	pos (QPointF) – Position

setValue(x, y):

Parameters:	x (float) – x position y (float) – y position

setXValue(x)[source]¶

Set X Value

Parameters:	x (float) – x position

setYValue(y)[source]¶

Set Y Value

Parameters:	y (float) – y position

draw(painter, xMap, yMap, canvasRect)[source]¶

Draw the marker

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – x Scale Map yMap (qwt.scale_map.QwtScaleMap) – y Scale Map canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates

drawLines(painter, canvasRect, pos)[source]¶

Draw the lines marker

Parameters:	painter (QPainter) – Painter canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates pos (QPointF) – Position of the marker, translated into widget coordinates

drawLabel(painter, canvasRect, pos)[source]¶

Align and draw the text label of the marker

Parameters:	painter (QPainter) – Painter canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates pos (QPointF) – Position of the marker, translated into widget coordinates

setLineStyle(style)[source]¶

Set the line style

Parameters:	style (int) – Line style

Line styles:

QwtPlotMarker.NoLine: No line

QwtPlotMarker.HLine: A horizontal line

QwtPlotMarker.VLine: A vertical line

QwtPlotMarker.Cross: A crosshair

See also

lineStyle()

lineStyle()[source]¶

Returns:	the line style

See also

setLineStyle()

setSymbol(symbol)[source]¶

Assign a symbol

Parameters:	symbol (qwt.symbol.QwtSymbol) – New symbol

See also

symbol()[source]¶

Returns:	the symbol

See also

spacing(), setLabelAlignment()

setLabel(label)[source]¶

Set the label

Parameters:	label (qwt.text.QwtText or str) – Label text

See also

label()

label()[source]¶

Returns:	the label

See also

setLabel()

setLabelAlignment(align)[source]¶

Set the alignment of the label

In case of QwtPlotMarker.HLine the alignment is relative to the y position of the marker, but the horizontal flags correspond to the canvas rectangle. In case of QwtPlotMarker.VLine the alignment is relative to the x position of the marker, but the vertical flags correspond to the canvas rectangle.

In all other styles the alignment is relative to the marker’s position.

Parameters:	align (Qt.Alignment) – Alignment

labelAlignment()[source]¶

Returns:	the label alignment

setLabelOrientation(orientation)[source]¶

Set the orientation of the label

When orientation is Qt.Vertical the label is rotated by 90.0 degrees (from bottom to top).

Parameters:	orientation (Qt.Orientation) – Orientation of the label

labelOrientation()[source]¶

Returns:	the label orientation

setSpacing(spacing)[source]¶

Set the spacing

When the label is not centered on the marker position, the spacing is the distance between the position and the label.

Parameters:	spacing (int) – Spacing

See also

spacing()[source]¶

Returns:	the spacing

See also

setSpacing()

setLinePen(*args)[source]¶

Build and/or assigna a line pen, depending on the arguments.

setPen(color, width, style)¶

Build and assign a line pen

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic (see QPen.isCosmetic()). This method signature has been introduced to hide this incompatibility.

Parameters:	color (QColor) – Pen color width (float) – Pen width style (Qt.PenStyle) – Pen style

setPen(pen)

Specify a pen for the line.

Parameters:	pen (QPen) – New pen

See also

pen(), brush()

linePen()[source]¶

Returns:	the line pen

See also

setLinePen()

legendIcon(index, size)[source]¶

Parameters:	index (int) – Index of the legend entry (ignored as there is only one) size (QSizeF) – Icon size
Returns:	Icon representing the marker on the legend

class qwt.plot_marker.QwtPlotMarker(title=None)[source]

A class for drawing markers

A marker can be a horizontal line, a vertical line, a symbol, a label or any combination of them, which can be drawn around a center point inside a bounding rectangle.

The setSymbol() member assigns a symbol to the marker. The symbol is drawn at the specified point.

With setLabel(), a label can be assigned to the marker. The setLabelAlignment() member specifies where the label is drawn. All the Align*-constants in Qt.AlignmentFlags (see Qt documentation) are valid. The interpretation of the alignment depends on the marker’s line style. The alignment refers to the center point of the marker, which means, for example, that the label would be printed left above the center point if the alignment was set to Qt.AlignLeft | Qt.AlignTop.

Line styles:

QwtPlotMarker.NoLine: No line

QwtPlotMarker.HLine: A horizontal line

QwtPlotMarker.VLine: A vertical line

QwtPlotMarker.Cross: A crosshair

rtti()[source]

Returns:	QwtPlotItem.Rtti_PlotMarker

value()[source]

Returns:	Value

xValue()[source]

Returns:	x Value

yValue()[source]

Returns:	y Value

setValue(*args)[source]

Set Value

setValue(pos):

Parameters:	pos (QPointF) – Position

setValue(x, y):

Parameters:	x (float) – x position y (float) – y position

setXValue(x)[source]

Set X Value

Parameters:	x (float) – x position

setYValue(y)[source]

Set Y Value

Parameters:	y (float) – y position

draw(painter, xMap, yMap, canvasRect)[source]

Draw the marker

Parameters:	painter (QPainter) – Painter xMap (qwt.scale_map.QwtScaleMap) – x Scale Map yMap (qwt.scale_map.QwtScaleMap) – y Scale Map canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates

drawLines(painter, canvasRect, pos)[source]

Draw the lines marker

Parameters:	painter (QPainter) – Painter canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates pos (QPointF) – Position of the marker, translated into widget coordinates

drawLabel(painter, canvasRect, pos)[source]

Align and draw the text label of the marker

Parameters:	painter (QPainter) – Painter canvasRect (QRectF) – Contents rectangle of the canvas in painter coordinates pos (QPointF) – Position of the marker, translated into widget coordinates

setLineStyle(style)[source]

Set the line style

Parameters:	style (int) – Line style

Line styles:

QwtPlotMarker.NoLine: No line

QwtPlotMarker.HLine: A horizontal line

QwtPlotMarker.VLine: A vertical line

QwtPlotMarker.Cross: A crosshair

See also

lineStyle()

lineStyle()[source]

Returns:	the line style

See also

setLineStyle()

setSymbol(symbol)[source]

Assign a symbol

Parameters:	symbol (qwt.symbol.QwtSymbol) – New symbol

See also

symbol()[source]

Returns:	the symbol

See also