Plot widget fundamentals

QwtPlot

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 qtpy import QtWidgets as QW
import qwt
import numpy as np

app = QW.QApplication([])
x = np.linspace(-10, 10, 500)
plot = qwt.QwtPlot("Trigonometric functions")
plot.insertLegend(qwt.QwtLegend(), qwt.QwtPlot.BottomLegend)
qwt.QwtPlotCurve.make(x, np.cos(x), "Cosinus", plot, linecolor="red", antialiased=True)
qwt.QwtPlotCurve.make(x, np.sin(x), "Sinus", plot, linecolor="blue", antialiased=True)
plot.resize(600, 300)
plot.show()
../_images/QwtPlot_example.png
class QwtPlot([title=""][, parent=None])
Parameters:

  • title (str) – Title text

  • parent (QWidget) – Parent widget

itemAttached

A signal indicating, that an item has been attached/detached

Parameters:

  • plotItem – Plot item

  • on – Attached/Detached

legendDataChanged

A signal with the attributes how to update the legend entries for a plot item.

Parameters:

  • itemInfo – Info about a plot item, build from itemToInfo()

  • data – Attributes of the entries (usually <= 1) for the plot item.

insertItem(item)[source]

Insert a plot item

Parameters:

item (qwt.plot.QwtPlotItem) – PlotItem

See also

removeItem()

Note

This was a member of QwtPlotDict in older versions.

removeItem(item)[source]

Remove a plot item

Parameters:

item (qwt.plot.QwtPlotItem) – PlotItem

See also

insertItem()

Note

This was a member of QwtPlotDict in older versions.

detachItems(rtti=None)[source]

Detach items from the dictionary

Parameters:

rtti (int or None) – In case of QwtPlotItem.Rtti_PlotItem or None (default) detach all items otherwise only those items of the type rtti.

Note

This was a member of QwtPlotDict in older versions.

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.

Note

This was a member of QwtPlotDict in older versions.

setFlatStyle(state)[source]

Set or reset the flatStyle option

If the flatStyle option is set, the plot will be rendered without any margin (scales, canvas, layout).

Enabling this option makes the plot look flat and compact.

The flatStyle option is set to True by default.

Parameters:

state (bool) – True or False.

See also

flatStyle()

flatStyle()[source]
Returns:

True if the flatStyle option is set.

See also

setFlatStyle()

initAxesData()[source]

Initialize axes

axisWidget(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

Scale widget of the specified axis, or None if axisId is invalid.

setAxisScaleEngine(axisId, scaleEngine)[source]

Change the scale engine for an axis

Parameters:

See also

axisScaleEngine()

axisScaleEngine(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

Scale engine for a specific axis

See also

setAxisScaleEngine()

axisAutoScale(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

True, if autoscaling is enabled

axisEnabled(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

True, if a specified axis is enabled

axisFont(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

The font of the scale labels for a specified axis

axisMaxMajor(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

The maximum number of major ticks for a specified axis

See also

setAxisMaxMajor(), qwt.scale_engine.QwtScaleEngine.divideScale()

axisMaxMinor(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

The maximum number of minor ticks for a specified axis

See also

setAxisMaxMinor(), qwt.scale_engine.QwtScaleEngine.divideScale()

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.

See also

qwt.scale_div.QwtScaleDiv, setAxisScaleDiv(), qwt.scale_engine.QwtScaleEngine.divideScale()

axisScaleDraw(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

Specified scaleDraw for axis, or NULL if axis is invalid.

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.

See also

setAxisScale(), qwt.scale_engine.QwtScaleEngine.divideScale()

axisMargin(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

Margin in % of the canvas size

See also

setAxisMargin()

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()

See also

qwt.scale_div.QwtScaleDiv, axisScaleDiv()

axisTitle(axisId)[source]
Parameters:

axisId (int) – Axis index

Returns:

Title of a specified axis

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)

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.

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.

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.

setAxisAutoScale(axisId, on=True)[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

See also

setAxisScale(), setAxisScaleDiv(), updateAxes()

Note

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

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.

See also

setAxisMaxMajor(), setAxisAutoScale(), axisStepSize(), qwt.scale_engine.QwtScaleEngine.divideScale()

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:

See also

setAxisScale(), setAxisAutoScale()

setAxisScaleDraw(axisId, scaleDraw)[source]

Set a scale draw

Parameters:

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.

setAxisLabelAlignment(axisId, alignment)[source]

Change the alignment of the tick labels

Parameters:

  • axisId (int) – Axis index

  • alignment (Qt.Alignment) – Or’d Qt.AlignmentFlags

See also

qwt.scale_draw.QwtScaleDraw.setLabelAlignment()

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()

setAxisLabelAutoSize(axisId, state)[source]

Set tick labels automatic size option (default: on)

Parameters:

  • axisId (int) – Axis index

  • state (bool) – On/off

See also

qwt.scale_draw.QwtScaleDraw.setLabelAutoSize()

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()

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()

setAxisMargin(axisId, margin)[source]

Set the margin of the scale widget

Parameters:

  • axisId (int) – Axis index

  • margin (float) – Margin in % of the canvas size

See also

axisMargin()

setAxisTitle(axisId, title)[source]

Change the title of a specified axis

Parameters:
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().

See also

setAxisAutoScale(), setAxisScale(), setAxisScaleDiv(), replot(), QwtPlotItem.boundingRect()

setCanvas(canvas)[source]

Set the drawing canvas of the plot widget.

The default canvas is a QwtPlotCanvas.

Parameters:

canvas (QWidget) – Canvas Widget

See also

canvas()

event(self, e: QEvent | None) → bool[source]
eventFilter(self, a0: QObject | None, a1: QEvent | None) → bool[source]
autoRefresh()[source]

Replots the plot if autoReplot() is True.

setAutoReplot(tf=True)[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

autoReplot()

autoReplot()[source]
Returns:

True if the autoReplot option is set.

See also

setAutoReplot()

setTitle(title)[source]

Change the plot’s title

Parameters:

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

See also

title()

title()[source]
Returns:

Title of the plot

See also

setTitle()

titleLabel()[source]
Returns:

Title label widget.

setFooter(text)[source]

Change the text the footer

Parameters:

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

See also

footer()

footer()[source]
Returns:

Text of the footer

See also

setFooter()

footerLabel()[source]
Returns:

Footer label widget.

setPlotLayout(layout)[source]

Assign a new plot layout

Parameters:

layout (qwt.plot_layout.QwtPlotLayout) – Layout

See also

plotLayout()

plotLayout()[source]
Returns:

the plot’s layout

See also

setPlotLayout()

legend()[source]
Returns:

the plot’s legend

See also

insertLegend()

canvas()[source]
Returns:

the plot’s canvas

sizeHint()[source]
Returns:

Size hint for the plot widget

See also

minimumSizeHint()

minimumSizeHint()[source]
Returns:

Return a minimum size hint

resizeEvent(self, a0: QResizeEvent | None)[source]
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

updateAxes(), setAutoReplot()

updateLayout()[source]

Adjust plot content to its current size.

See also

resizeEvent()

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()

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.

See also

getCanvasMarginsHint(), QwtPlotItem.getCanvasMarginHint()

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()

See also

getCanvasMarginsHint(), QwtPlotItem.getCanvasMarginHint()

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()

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()

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()

canvasBackground()[source]
Returns:

Background brush of the plotting area.

See also

setCanvasBackground()

axisValid(axis_id)[source]
Parameters:

axis_id (int) – Axis

Returns:

True if the specified axis exists, otherwise False

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.

See also

legend(), qwt.plot_layout.QwtPlotLayout.legendPosition(), qwt.plot_layout.QwtPlotLayout.setLegendPosition()

updateLegend(plotItem=None)[source]

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

Parameters:

plotItem (qwt.plot.QwtPlotItem) – Plot item

See also

QwtPlotItem.legendData(), QwtPlot.legendDataChanged

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()

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

print_(printer)[source]

Print plot to printer

Parameters:

printer (QPaintDevice or QPrinter or QSvgGenerator) – Printer

exportTo(filename, size=(800, 600), size_mm=None, resolution=85, 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 (int) – Resolution in dots per Inch (dpi)

  • format (str) – File format (PDF, SVG, PNG, …)

QwtPlotItem

class qwt.plot.QwtPlotItem(title=None, icon=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:

  • Decorators

    A “Decorator” is an item, that displays additional information, that is not related to any data:

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

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()

detach()[source]

Detach the item from a plot.

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

See also

attach()

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

plot()[source]
Returns:

attached plot

z()[source]

Plot items are painted in increasing z-order.

Returns:

item z order

See also

setZ(), QwtPlotDict.itemList()

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()

setTitle(title)[source]

Set a new title

Parameters:

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

See also

title()

title()[source]
Returns:

Title of the item

See also

setTitle()

setIcon(icon)[source]

Set item icon

Parameters:

icon (QIcon) – Icon

See also

icon()

icon()[source]
Returns:

Icon of the item

See also

setIcon()

setItemAttribute(attribute, on=True)[source]

Toggle an item attribute

Parameters:

  • attribute (int) – Attribute type

  • on (bool) – True/False

See also

testItemAttribute()

testItemAttribute(attribute)[source]

Test an item attribute

Parameters:

attribute (int) – Attribute type

Returns:

True/False

See also

setItemAttribute()

setItemInterest(interest, on=True)[source]

Toggle an item interest

Parameters:

  • attribute (int) – Interest type

  • on (bool) – True/False

See also

testItemInterest()

testItemInterest(interest)[source]

Test an item interest

Parameters:

attribute (int) – Interest type

Returns:

True/False

See also

setItemInterest()

setRenderHint(hint, on=True)[source]

Toggle a render hint

Parameters:

  • hint (int) – Render hint

  • on (bool) – True/False

See also

testRenderHint()

testRenderHint(hint)[source]

Test a render hint

Parameters:

attribute (int) – Render hint

Returns:

True/False

See also

setRenderHint()

setLegendIconSize(size)[source]

Set the size of the legend icon

The default setting is 8x8 pixels

Parameters:

size (QSize) – Size

See also

legendIconSize(), legendIcon()

legendIconSize()[source]
Returns:

Legend icon size

See also

setLegendIconSize(), legendIcon()

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()

show()[source]

Show the item

hide()[source]

Hide the item

setVisible(on)[source]

Show/Hide the item

Parameters:

on (bool) – Show if True, otherwise hide

See also

isVisible(), show(), hide()

isVisible()[source]
Returns:

True if visible

See also

setVisible(), show(), hide()

itemChanged()[source]

Update the legend and call QwtPlot.autoRefresh() for the parent plot.

See also

QwtPlot.legendChanged(), QwtPlot.autoRefresh()

legendChanged()[source]

Update the legend of the parent plot.

See also

QwtPlot.updateLegend(), itemChanged()

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)

See also

setXAxis(), setYAxis(), xAxis(), yAxis()

setAxis(xAxis, yAxis)[source]

Set X and Y axis

Warning

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

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)

See also

setAxes(), setYAxis(), xAxis(), yAxis()

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)

See also

setAxes(), setXAxis(), xAxis(), yAxis()

xAxis()[source]
Returns:

xAxis

yAxis()[source]
Returns:

yAxis

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

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:

See also

QwtPlot.getCanvasMarginsHint(), QwtPlot.updateCanvasMargins(),

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

See also

title(), legendIcon(), qwt.legend.QwtLegend

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()

scaleRect(xMap, yMap)[source]

Calculate the bounding scale rectangle of 2 maps

Parameters:
Returns:

Bounding scale rect of the scale maps, not normalized

paintRect(xMap, yMap)[source]

Calculate the bounding paint rectangle of 2 maps

Parameters:
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

qwt.plot.QwtPlot.setCanvas()

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

qwt.plot.QwtPlot.setCanvas()

plot()[source]
Returns:

Parent plot widget

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

See also

testPaintAttribute(), backingStore()

testPaintAttribute(attribute)[source]

Test whether a paint attribute is enabled

Parameters:

attribute (int) – Paint attribute

Returns:

True, when attribute is enabled

See also

setPaintAttribute()

backingStore()[source]
Returns:

Backing store, might be None

invalidateBackingStore()[source]

Invalidate the internal backing store

setFocusIndicator(focusIndicator)[source]

Set the focus indicator

Focus indicators:

  • QwtPlotCanvas.NoFocusIndicator

  • QwtPlotCanvas.CanvasFocusIndicator

  • QwtPlotCanvas.ItemFocusIndicator

Parameters:

focusIndicator (int) – Focus indicator

See also

focusIndicator()

focusIndicator()[source]
Returns:

Focus indicator

See also

setFocusIndicator()

setBorderRadius(radius)[source]

Set the radius for the corners of the border frame

Parameters:

radius (float) – Radius of a rounded corner

See also

borderRadius()

borderRadius()[source]
Returns:

Radius for the corners of the border frame

See also

setBorderRadius()

event(self, e: QEvent | None) → bool[source]
paintEvent(self, a0: QPaintEvent | None)[source]
drawBorder(painter)[source]

Draw the border of the plot canvas

Parameters:

painter (QPainter) – Painter

See also

setBorderRadius()

resizeEvent(self, a0: QResizeEvent | None)[source]
drawFocusIndicator(painter)[source]

Draw the focus indication

Parameters:

painter (QPainter) – Painter

replot()[source]

Invalidate the paint cache and repaint the canvas

updateStyleSheetInfo()[source]

Update the cached information about the current style sheet

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(title='Grid')[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.

classmethod make(plot=None, z=None, enablemajor=None, enableminor=None, color=None, width=None, style=None, mincolor=None, minwidth=None, minstyle=None)[source]

Create and setup a new QwtPlotGrid object (convenience function).

Parameters:

  • plot (qwt.plot.QwtPlot or None) – Plot to attach the curve to

  • z (float or None) – Z-value

  • enablemajor (bool or None) – Tuple of two boolean values (x, y) for enabling major grid lines

  • enableminor (bool or None) – Tuple of two boolean values (x, y) for enabling minor grid lines

  • color (QColor or str or None) – Pen color for both major and minor grid lines (default: Qt.gray)

  • width (float or None) – Pen width for both major and minor grid lines (default: 1.0)

  • style (Qt.PenStyle or None) – Pen style for both major and minor grid lines (default: Qt.DotLine)

  • mincolor (QColor or str or None) – Pen color for minor grid lines only (default: Qt.gray)

  • minwidth (float or None) – Pen width for minor grid lines only (default: 1.0)

  • minstyle (Qt.PenStyle or None) – Pen style for minor grid lines only (default: Qt.DotLine)

See also

setMinorPen(), setMajorPen()

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

enableXMin()

enableY(on)[source]

Enable or disable horizontal grid lines

Parameters:

on (bool) – Enable (true) or disable

See also

enableYMin()

enableXMin(on)[source]

Enable or disable minor vertical grid lines.

Parameters:

on (bool) – Enable (true) or disable

See also

enableX()

enableYMin(on)[source]

Enable or disable minor horizontal grid lines.

Parameters:

on (bool) – Enable (true) or disable

See also

enableY()

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:
majorPen()[source]
Returns:

the pen for the major grid lines

See also

setMajorPen(), setMinorPen(), setPen()

minorPen()[source]
Returns:

the pen for the minor grid lines

See also

setMinorPen(), setMajorPen(), setPen()

xEnabled()[source]
Returns:

True if vertical grid lines are enabled

See also

enableX()

yEnabled()[source]
Returns:

True if horizontal grid lines are enabled

See also

enableY()

xMinEnabled()[source]
Returns:

True if minor vertical grid lines are enabled

See also

enableXMin()

yMinEnabled()[source]
Returns:

True if minor horizontal grid lines are enabled

See also

enableYMin()

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:

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 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.

  • 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.

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.

class QwtPlotCurve([title=None])

Constructor

Parameters:

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

classmethod make(xdata=None, ydata=None, title=None, plot=None, z=None, x_axis=None, y_axis=None, style=None, symbol=None, linecolor=None, linewidth=None, linestyle=None, antialiased=False, size=None, finite=None)[source]

Create and setup a new QwtPlotCurve object (convenience function).

Parameters:

  • xdata – List/array of x values

  • ydata – List/array of y values

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

  • plot (qwt.plot.QwtPlot or None) – Plot to attach the curve to

  • z (float or None) – Z-value

  • x_axis (int or None) – curve X-axis (default: QwtPlot.yLeft)

  • y_axis (int or None) – curve Y-axis (default: QwtPlot.xBottom)

  • style (int or None) – curve style (QwtPlotCurve.NoCurve, QwtPlotCurve.Lines, QwtPlotCurve.Sticks, QwtPlotCurve.Steps, QwtPlotCurve.Dots, QwtPlotCurve.UserCurve)

  • symbol (qwt.symbol.QwtSymbol or None) – curve symbol

  • linecolor (QColor or str or None) – curve line color

  • linewidth (float or None) – curve line width

  • linestyle (Qt.PenStyle or None) – curve pen style

  • antialiased (bool) – if True, enable antialiasing rendering

  • size (int or None) – size of xData and yData

  • finite (bool) – if True, keep only finite array elements (remove all infinity and not a number values), otherwise do not filter array elements

See also

setData(), setPen(), attach()

init()[source]

Initialize internal members

rtti()[source]
Returns:

QwtPlotItem.Rtti_PlotCurve

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

testLegendAttribute(), legendIcon()

testLegendAttribute(attribute)[source]
Parameters:

attribute (int) – Legend attribute

Returns:

True, when attribute is enabled

See also

setLegendAttribute()

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()

style()[source]
Returns:

Style of the curve

See also

setStyle()

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

symbol()

symbol()[source]
Returns:

Current symbol or None, when no symbol has been assigned

See also

setSymbol()

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()

pen()[source]
Returns:

Pen used to draw the lines

See also

setPen(), brush()

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

See also

brush(), setBaseline(), baseline()

brush()[source]
Returns:

Brush used to fill the area between lines and the baseline

See also

setBrush(), setBaseline(), baseline()

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()

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

drawCurve(), drawSymbols()

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.

See also

draw(), drawDots(), drawLines(), drawSteps(), drawSticks()

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.

See also

draw(), drawDots(), drawSteps(), drawSticks()

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.

See also

draw(), drawDots(), drawSteps(), drawLines()

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.

See also

draw(), drawSticks(), drawSteps(), drawLines()

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.

See also

draw(), drawSticks(), drawDots(), drawLines()

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()

testCurveAttribute(attribute)[source]
Returns:

True, if attribute is enabled

See also

setCurveAttribute()

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 !

See also

setBrush(), setBaseline(), setStyle()

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:
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.

See also

setSymbol(), drawSeries(), drawCurve()

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

See also

baseline(), setBrush(), setStyle()

baseline()[source]
Returns:

Value of the baseline

See also

setBaseline()

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

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

See also

qwt.plot.QwtPlotItem.setLegendIconSize(), qwt.plot.QwtPlotItem.legendData()

setData(*args, **kwargs)[source]

Initialize data with a series data object or an array of points.

setData(data):
Parameters:

data (.plot_series.QwtSeriesData) – Series data (e.g. QwtPointArrayData instance)

setData(xData, yData, [size=None], [finite=True]):

Initialize data with x and y arrays.

This signature was removed in Qwt6 and is temporarily maintained here to ensure compatibility with Qwt5.

Same as setSamples(x, y, [size=None], [finite=True])

Parameters:

  • x – List/array of x values

  • y – List/array of y values

  • size (int or None) – size of xData and yData

  • finite (bool) – if True, keep only finite array elements (remove all infinity and not a number values), otherwise do not filter array elements

See also

setSamples()

setSamples(*args, **kwargs)[source]

Initialize data with an array of points.

setSamples(data):
Parameters:

data (.plot_series.QwtSeriesData) – Series data (e.g. QwtPointArrayData instance)

setSamples(samples):

Same as setData(QwtPointArrayData(samples))

Parameters:

samples – List/array of points

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

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

  • finite (bool) – if True, keep only finite array elements (remove all infinity and not a number values), otherwise do not filter array elements

See also

plot_series.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

classmethod make(xvalue=None, yvalue=None, title=None, label=None, symbol=None, plot=None, z=None, x_axis=None, y_axis=None, align=None, orientation=None, spacing=None, linestyle=None, color=None, width=None, style=None, antialiased=False)[source]

Create and setup a new QwtPlotMarker object (convenience function).

Parameters:

  • xvalue (float or None) – x position (optional, default: None)

  • yvalue (float or None) – y position (optional, default: None)

  • title (qwt.text.QwtText or str or None) – Marker title

  • label (qwt.text.QwtText or str or None) – Label text

  • symbol (qwt.symbol.QwtSymbol or None) – New symbol

  • plot (qwt.plot.QwtPlot or None) – Plot to attach the curve to

  • z (float or None) – Z-value

  • x_axis (int) – curve X-axis (default: QwtPlot.yLeft)

  • y_axis (int) – curve Y-axis (default: QwtPlot.xBottom)

  • align (Qt.Alignment or None) – Alignment of the label

  • orientation (Qt.Orientation or None) – Orientation of the label

  • spacing (int or None) – Spacing (distance between the position and the label)

  • linestyle (int) – Line style

  • color (QColor or str or None) – Pen color

  • width (float) – Pen width

  • style (Qt.PenStyle) – Pen style

  • antialiased (bool) – if True, enable antialiasing rendering

See also

setData(), setPen(), attach()

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:
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

See also

drawLabel(), qwt.symbol.QwtSymbol.drawSymbol()

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

See also

drawLabel(), qwt.symbol.QwtSymbol.drawSymbol()

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()

symbol()[source]
Returns:

the symbol

See also

setSymbol()

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

See also

labelAlignment(), labelOrientation()

labelAlignment()[source]
Returns:

the label alignment

See also

setLabelAlignment(), setLabelOrientation()

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

See also

labelOrientation(), setLabelAlignment()

labelOrientation()[source]
Returns:

the label orientation

See also

setLabelOrientation(), labelAlignment()

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(), setLabelAlignment()

spacing()[source]
Returns:

the spacing

See also

setSpacing()

setLinePen(*args)[source]

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

setLinePen(color, width, style)[source]

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

setLinePen(pen)[source]

Specify a pen for the line.

Parameters:

pen (QPen) – New pen

See also

pen(), brush()

linePen()[source]
Returns:

the line pen

See also

setLinePen()

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

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

See also

qwt.plot.QwtPlotItem.setLegendIconSize(), qwt.plot.QwtPlotItem.legendData()

Additional plot features

QwtLegend

class qwt.legend.QwtLegendData[source]

Attributes of an entry on a legend

QwtLegendData is an abstract container ( like QAbstractModel ) to exchange attributes, that are only known between to the plot item and the legend.

By overloading QwtPlotItem.legendData() any other set of attributes could be used, that can be handled by a modified ( or completely different ) implementation of a legend.

See also

qwt.legend.QwtLegend

Note

The stockchart example implements a legend as a tree with checkable items

setValues(map_)[source]

Set the legend attributes

Parameters:

map (dict) – Values

See also

values()

values()[source]
Returns:

Legend attributes

See also

setValues()

hasRole(role)[source]
Parameters:

role (int) – Attribute role

Returns:

True, when the internal map has an entry for role

setValue(role, data)[source]

Set an attribute value

Parameters:

  • role (int) – Attribute role

  • data (QVariant) – Attribute value

See also

value()

value(role)[source]
Parameters:

role (int) – Attribute role

Returns:

Attribute value for a specific role

See also

setValue()

isValid()[source]
Returns:

True, when the internal map is empty

title()[source]
Returns:

Value of the TitleRole attribute

icon()[source]
Returns:

Value of the IconRole attribute

mode()[source]
Returns:

Value of the ModeRole attribute

class qwt.legend.QwtLegendLabel(parent=None)[source]

A widget representing something on a QwtLegend.

setData(legendData)[source]

Set the attributes of the legend label

Parameters:

legendData (QwtLegendData) – Attributes of the label

See also

data()

data()[source]
Returns:

Attributes of the label

See also

setData(), qwt.plot.QwtPlotItem.legendData()

setText(text)[source]

Set the text to the legend item

Parameters:

text (qwt.text.QwtText) – Text label

See also

text()

setItemMode(mode)[source]

Set the item mode. The default is QwtLegendData.ReadOnly.

Parameters:

mode (int) – Item mode

See also

itemMode()

itemMode()[source]
Returns:

Item mode

See also

setItemMode()

setIcon(icon)[source]

Assign the icon

Parameters:

icon (QPixmap) – Pixmap representing a plot item

See also

icon(), qwt.plot.QwtPlotItem.legendIcon()

icon()[source]
Returns:

Pixmap representing a plot item

See also

setIcon()

setSpacing(spacing)[source]

Change the spacing between icon and text

Parameters:

spacing (int) – Spacing

See also

spacing(), qwt.text.QwtTextLabel.margin()

spacing()[source]
Returns:

Spacing between icon and text

See also

setSpacing()

setChecked(on)[source]

Check/Uncheck a the item

Parameters:

on (bool) – check/uncheck

See also

isChecked(), setItemMode()

isChecked()[source]
Returns:

true, if the item is checked

See also

setChecked()

setDown(down)[source]

Set the item being down

Parameters:

on (bool) – true, if the item is down

See also

isDown()

isDown()[source]
Returns:

true, if the item is down

See also

setDown()

sizeHint()[source]
Returns:

a size hint

paintEvent(self, a0: QPaintEvent | None)[source]
mousePressEvent(self, a0: QMouseEvent | None)[source]
mouseReleaseEvent(self, a0: QMouseEvent | None)[source]
keyPressEvent(self, a0: QKeyEvent | None)[source]
keyReleaseEvent(self, a0: QKeyEvent | None)[source]
class qwt.legend.QwtLegend(parent=None)[source]

The legend widget

The QwtLegend widget is a tabular arrangement of legend items. Legend items might be any type of widget, but in general they will be a QwtLegendLabel.

See also

:py:class`qwt.legend.QwtLegendLabel`, :py:class`qwt.plot.QwtPlotItem`, :py:class`qwt.plot.QwtPlot`

class QwtLegend([parent=None])

Constructor

Parameters:

parent (QWidget) – Parent widget

clicked

A signal which is emitted when the user has clicked on a legend label, which is in QwtLegendData.Clickable mode.

Parameters:

  • itemInfo – Info for the item item of the selected legend item

  • index – Index of the legend label in the list of widgets that are associated with the plot item

Note

Clicks are disabled as default

checked

A signal which is emitted when the user has clicked on a legend label, which is in QwtLegendData.Checkable mode

Parameters:

  • itemInfo – Info for the item of the selected legend label

  • index – Index of the legend label in the list of widgets that are associated with the plot item

  • on – True when the legend label is checked

Note

Clicks are disabled as default

setMaxColumns(numColumns)[source]

Set the maximum number of entries in a row

F.e when the maximum is set to 1 all items are aligned vertically. 0 means unlimited

Parameters:

numColumns (int) – Maximum number of entries in a row

See also

maxColumns(), QwtDynGridLayout.setMaxColumns()

maxColumns()[source]
Returns:

Maximum number of entries in a row

See also

setMaxColumns(), QwtDynGridLayout.maxColumns()

setDefaultItemMode(mode)[source]

Set the default mode for legend labels

Legend labels will be constructed according to the attributes in a QwtLegendData object. When it doesn’t contain a value for the QwtLegendData.ModeRole the label will be initialized with the default mode of the legend.

Parameters:

mode (int) – Default item mode

See also

itemMode(), QwtLegendData.value(), QwtPlotItem::legendData()

… note:

Changing the mode doesn't have any effect on existing labels.
defaultItemMode()[source]
Returns:

Default item mode

See also

setDefaultItemMode()

contentsWidget()[source]

The contents widget is the only child of the viewport of the internal QScrollArea and the parent widget of all legend items.

Returns:

Container widget of the legend items

horizontalScrollBar()[source]
Returns:

Horizontal scrollbar

See also

verticalScrollBar()

verticalScrollBar()[source]
Returns:

Vertical scrollbar

See also

horizontalScrollBar()

updateLegend(itemInfo, data)[source]

Update the entries for an item

Parameters:

  • itemInfo (QVariant) – Info for an item

  • data (list) – Default item mode

createWidget(data)[source]

Create a widget to be inserted into the legend

The default implementation returns a QwtLegendLabel.

Parameters:

data (QwtLegendData) – Attributes of the legend entry

Returns:

Widget representing data on the legend

… note:

updateWidget() will called soon after createWidget()
with the same attributes.
updateWidget(widget, data)[source]

Update the widget

Parameters:

  • widget (QWidget) – Usually a QwtLegendLabel

  • data (QwtLegendData) – Attributes to be displayed

See also

createWidget()

… note:

When widget is no QwtLegendLabel updateWidget() does nothing.
sizeHint()[source]

Return a size hint

heightForWidth(width)[source]
Parameters:

width (int) – Width

Returns:

The preferred height, for a width.

eventFilter(object_, event)[source]

Handle QEvent.ChildRemoved andQEvent.LayoutRequest events for the contentsWidget().

Parameters:

  • object (QObject) – Object to be filtered

  • event (QEvent) – Event

Returns:

Forwarded to QwtAbstractLegend.eventFilter()

renderLegend(painter, rect, fillBackground)[source]

Render the legend into a given rectangle.

Parameters:

  • painter (QPainter) – Painter

  • rect (QRectF) – Bounding rectangle

  • fillBackground (bool) – When true, fill rect with the widget background

renderItem(painter, widget, rect, fillBackground)[source]

Render a legend entry into a given rectangle.

Parameters:

  • painter (QPainter) – Painter

  • widget (QWidget) – Widget representing a legend entry

  • rect (QRectF) – Bounding rectangle

  • fillBackground (bool) – When true, fill rect with the widget background

legendWidgets(itemInfo)[source]

List of widgets associated to a item

Parameters:

itemInfo (QVariant) – Info about an item

legendWidget(itemInfo)[source]

First widget in the list of widgets associated to an item

Parameters:

itemInfo (QVariant) – Info about an item

itemInfo(widget)[source]

Find the item that is associated to a widget

Parameters:

widget (QWidget) – Widget on the legend

Returns:

Associated item info

Color maps

QwtColorMap

class qwt.color_map.QwtColorMap(format_=None)[source]

QwtColorMap is used to map values into colors.

For displaying 3D data on a 2D plane the 3rd dimension is often displayed using colors, like f.e in a spectrogram.

Each color map is optimized to return colors for only one of the following image formats:

  • QImage.Format_Indexed8

  • QImage.Format_ARGB32

class QwtColorMap(format_)
Parameters:

format (int) – Preferred format of the color map (QwtColorMap.RGB or QwtColorMap.Indexed)

See also

qwt.QwtScaleWidget

color(interval, value)[source]

Map a value into a color

Parameters:
Returns:

the color corresponding to value

Warning

This method is slow for Indexed color maps. If it is necessary to map many values, its better to get the color table once and find the color using colorIndex().

colorTable(interval)[source]

Build and return a color map of 256 colors

Parameters:

interval (qwt.interval.QwtInterval) – range for the values

Returns:

a color table, that can be used for a QImage

The color table is needed for rendering indexed images in combination with using colorIndex().

QwtLinearColorMap

class qwt.color_map.QwtLinearColorMap(*args)[source]

Build a linear color map with two stops.

class QwtLinearColorMap(format_)

Build a color map with two stops at 0.0 and 1.0. The color at 0.0 is Qt.blue, at 1.0 it is Qt.yellow.

Parameters:

format (int) – Preferred format of the color map (QwtColorMap.RGB or QwtColorMap.Indexed)

QwtLinearColorMap(color1, color2, [format_=QwtColorMap.RGB]):

Build a color map with two stops at 0.0 and 1.0.

Parameters:

  • color1 (QColor) – color at 0.

  • color2 (QColor) – color at 1.

  • format (int) – Preferred format of the color map (QwtColorMap.RGB or QwtColorMap.Indexed)

QwtLinearColorMap.setMode(mode)[source]

Set the mode of the color map

Parameters:

mode (int) – QwtLinearColorMap.FixedColors or QwtLinearColorMap.ScaledColors

FixedColors means the color is calculated from the next lower color stop. ScaledColors means the color is calculated by interpolating the colors of the adjacent stops.

QwtLinearColorMap.mode()[source]
Returns:

the mode of the color map

See also

QwtLinearColorMap.setMode()

QwtAlphaColorMap

class qwt.color_map.QwtAlphaColorMap(color)[source]

QwtAlphaColorMap varies the alpha value of a color

class QwtAlphaColorMap(color)

Build a color map varying the alpha value of a color.

Parameters:

color (QColor) – color of the map

setColor(color)[source]

Set the color of the map

Parameters:

color (QColor) – color of the map

color()[source]
Returns:

the color of the map

See also

QwtAlphaColorMap.setColor()

QwtPlotRenderer

class qwt.plot_renderer.QwtPlotRenderer(parent=None)[source]

Renderer for exporting a plot to a document, a printer or anything else, that is supported by QPainter/QPaintDevice

Discard flags:

  • QwtPlotRenderer.DiscardNone: Render all components of the plot

  • QwtPlotRenderer.DiscardBackground: Don’t render the background of the plot

  • QwtPlotRenderer.DiscardTitle: Don’t render the title of the plot

  • QwtPlotRenderer.DiscardLegend: Don’t render the legend of the plot

  • QwtPlotRenderer.DiscardCanvasBackground: Don’t render the background of the canvas

  • QwtPlotRenderer.DiscardFooter: Don’t render the footer of the plot

  • QwtPlotRenderer.DiscardCanvasFrame: Don’t render the frame of the canvas

Note

The QwtPlotRenderer.DiscardCanvasFrame flag has no effect when using style sheets, where the frame is part of the background

Layout flags:

  • QwtPlotRenderer.DefaultLayout: Use the default layout as on screen

  • QwtPlotRenderer.FrameWithScales: Instead of the scales a box is painted around the plot canvas, where the scale ticks are aligned to.

setDiscardFlag(flag, on=True)[source]

Change a flag, indicating what to discard from rendering

Parameters:

  • flag (int) – Flag to change

  • on (bool) – On/Off

See also

testDiscardFlag(), setDiscardFlags(), discardFlags()

testDiscardFlag(flag)[source]
Parameters:

flag (int) – Flag to be tested

Returns:

True, if flag is enabled.

See also

setDiscardFlag(), setDiscardFlags(), discardFlags()

setDiscardFlags(flags)[source]

Set the flags, indicating what to discard from rendering

Parameters:

flags (int) – Flags

See also

testDiscardFlag(), setDiscardFlag(), discardFlags()

discardFlags()[source]
Returns:

Flags, indicating what to discard from rendering

See also

setDiscardFlag(), setDiscardFlags(), testDiscardFlag()

setLayoutFlag(flag, on=True)[source]

Change a layout flag

Parameters:

flag (int) – Flag to change

See also

testLayoutFlag(), setLayoutFlags(), layoutFlags()

testLayoutFlag(flag)[source]
Parameters:

flag (int) – Flag to be tested

Returns:

True, if flag is enabled.

See also

setLayoutFlag(), setLayoutFlags(), layoutFlags()

setLayoutFlags(flags)[source]

Set the layout flags

Parameters:

flags (int) – Flags

See also

setLayoutFlag(), testLayoutFlag(), layoutFlags()

layoutFlags()[source]
Returns:

Layout flags

See also

setLayoutFlags(), setLayoutFlag(), testLayoutFlag()

renderDocument(plot, filename, sizeMM=(300, 200), resolution=85, format_=None)[source]

Render a plot to a file

The format of the document will be auto-detected from the suffix of the file name.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • fileName (str) – Path of the file, where the document will be stored

  • sizeMM (QSizeF) – Size for the document in millimeters

  • resolution (int) – Resolution in dots per Inch (dpi)

renderTo(plot, dest)[source]

Render a plot to a file

Supported formats are:

  • pdf: Portable Document Format PDF

  • ps: Postcript

  • svg: Scalable Vector Graphics SVG

  • all image formats supported by Qt, see QImageWriter.supportedImageFormats()

Scalable vector graphic formats like PDF or SVG are superior to raster graphics formats.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • dest – QPaintDevice, QPrinter or QSvgGenerator instance

See also

render(), qwt.painter.QwtPainter.setRoundingAlignment()

render(plot, painter, plotRect)[source]

Paint the contents of a QwtPlot instance into a given rectangle.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot to be rendered

  • painter (QPainter) – Painter

  • format (str) – Format for the document

  • plotRect (QRectF) – Bounding rectangle

See also

renderDocument(), renderTo(), qwt.painter.QwtPainter.setRoundingAlignment()

renderTitle(plot, painter, rect)[source]

Render the title into a given rectangle.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • painter (QPainter) – Painter

  • rect (QRectF) – Bounding rectangle

renderFooter(plot, painter, rect)[source]

Render the footer into a given rectangle.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • painter (QPainter) – Painter

  • rect (QRectF) – Bounding rectangle

renderLegend(plot, painter, rect)[source]

Render the legend into a given rectangle.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • painter (QPainter) – Painter

  • rect (QRectF) – Bounding rectangle

renderScale(plot, painter, axisId, startDist, endDist, baseDist, rect)[source]

Paint a scale into a given rectangle. Paint the scale into a given rectangle.

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • painter (QPainter) – Painter

  • axisId (int) – Axis

  • startDist (int) – Start border distance

  • endDist (int) – End border distance

  • baseDist (int) – Base distance

  • rect (QRectF) – Bounding rectangle

renderCanvas(plot, painter, canvasRect, maps)[source]

Render the canvas into a given rectangle.

Parameters:
buildCanvasMaps(plot, canvasRect)[source]

Calculated the scale maps for rendering the canvas

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • canvasRect (QRectF) – Target rectangle

Returns:

Calculated scale maps

exportTo(plot, documentname, sizeMM=None, resolution=85)[source]

Execute a file dialog and render the plot to the selected file

Parameters:

  • plot (qwt.plot.QwtPlot) – Plot widget

  • documentName (str) – Default document name

  • sizeMM (QSizeF) – Size for the document in millimeters

  • resolution (int) – Resolution in dots per Inch (dpi)

Returns:

True, when exporting was successful

See also

renderDocument()