QwtPlotItem(3) Qwt User's Guide QwtPlotItem(3) NAME QwtPlotItem - Base class for items on the plot canvas. SYNOPSIS #include Inherited by QwtPlotGraphicItem, QwtPlotGrid, QwtPlotLegendItem, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, QwtPlotSeriesItem, QwtPlotShapeItem, QwtPlotTextLabel, and QwtPlotZoneItem. Public Types enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotGraphic, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotVectorField, Rtti_PlotUserItem = 1000 } Runtime type information. enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 } Plot Item Attributes. enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 } Plot Item Interests. enum RenderHint { RenderAntialiased = 0x1 } Render hints. typedef QFlags< ItemAttribute > ItemAttributes typedef QFlags< ItemInterest > ItemInterests typedef QFlags< RenderHint > RenderHints Public Member Functions QwtPlotItem () QwtPlotItem (const QString &title) QwtPlotItem (const QwtText &title) virtual ~QwtPlotItem () Destroy the QwtPlotItem. void attach (QwtPlot *plot) Attach the item to a plot. void detach () This method detaches a QwtPlotItem from any QwtPlot it has been associated with. QwtPlot * plot () const Return attached plot. void setTitle (const QString &title) void setTitle (const QwtText &title) const QwtText & title () const virtual int rtti () const void setItemAttribute (ItemAttribute, bool on=true) bool testItemAttribute (ItemAttribute) const void setItemInterest (ItemInterest, bool on=true) bool testItemInterest (ItemInterest) const void setRenderHint (RenderHint, bool on=true) bool testRenderHint (RenderHint) const void setRenderThreadCount (uint numThreads) uint renderThreadCount () const void setLegendIconSize (const QSize &) QSize legendIconSize () const double z () const void setZ (double z) Set the z value. void show () Show the item. void hide () Hide the item. virtual void setVisible (bool) bool isVisible () const void setAxes (QwtAxisId xAxis, QwtAxisId yAxis) void setXAxis (QwtAxisId) QwtAxisId xAxis () const Return xAxis. void setYAxis (QwtAxisId) QwtAxisId yAxis () const Return yAxis. virtual void itemChanged () virtual void legendChanged () virtual void draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const =0 Draw the item. virtual QRectF boundingRect () const virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const Calculate a hint for the canvas margin. virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) Update the item to changes of the axes scale division. virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &) Update the item to changes of the legend info. QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const Calculate the bounding scale rectangle of 2 maps. QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const Calculate the bounding paint rectangle of 2 maps. virtual QList< QwtLegendData > legendData () const Return all information, that is needed to represent the item on the legend. virtual QwtGraphic legendIcon (int index, const QSizeF &) const Protected Member Functions QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const Return a default icon from a brush. Detailed Description 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: o 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: o QwtPlotMarker Represents a point or a horizontal/vertical coordinate o QwtPlotCurve Represents a series of points o QwtPlotSpectrogram ( QwtPlotRasterItem ) Represents raster data o ... o Decorators A 'Decorator' is an item, that displays additional information, that is not related to any data: o QwtPlotGrid o QwtPlotScaleItem o QwtPlotSvgItem o ... 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. Definition at line 66 of file qwt_plot_item.h. Member Typedef Documentation typedef QFlags QwtPlotItem::ItemAttributes An ORed combination of ItemAttribute values. Definition at line 167 of file qwt_plot_item.h. typedef QFlags QwtPlotItem::ItemInterests An ORed combination of ItemInterest values. Definition at line 200 of file qwt_plot_item.h. typedef QFlags QwtPlotItem::RenderHints An ORed combination of RenderHint values. Definition at line 209 of file qwt_plot_item.h. Member Enumeration Documentation enum QwtPlotItem::ItemAttribute Plot Item Attributes. Various aspects of a plot widget depend on the attributes of the attached plot items. If and how a single plot item participates in these updates depends on its attributes. See also setItemAttribute(), testItemAttribute(), ItemInterest Enumerator Legend The item is represented on the legend. AutoScale The boundingRect() of the item is included in the autoscaling calculation as long as its width or height is >= 0.0. Margins The item needs extra space to display something outside its bounding rectangle. See also getCanvasMarginHint() Definition at line 147 of file qwt_plot_item.h. enum QwtPlotItem::ItemInterest Plot Item Interests. Plot items might depend on the situation of the corresponding plot widget. By enabling an interest the plot item will be notified, when the corresponding attribute of the plot widgets has changed. See also setItemAttribute(), testItemAttribute(), ItemInterest Enumerator ScaleInterest The item is interested in updates of the scales See also updateScaleDiv() LegendInterest The item is interested in updates of the legend ( of other items ) This flag is intended for items, that want to implement a legend for displaying entries of other plot item. Note If the plot item wants to be represented on a legend enable QwtPlotItem::Legend instead. See also updateLegend() Definition at line 179 of file qwt_plot_item.h. enum QwtPlotItem::RenderHint Render hints. Enumerator RenderAntialiased Enable antialiasing. Definition at line 203 of file qwt_plot_item.h. enum QwtPlotItem::RttiValues Runtime type information. RttiValues is used to cast plot items, without having to enable runtime type information of the compiler. Enumerator Rtti_PlotItem Unspecific value, that can be used, when it doesn't matter. Rtti_PlotGrid For QwtPlotGrid. Rtti_PlotScale For QwtPlotScaleItem. Rtti_PlotLegend For QwtPlotLegendItem. Rtti_PlotMarker For QwtPlotMarker. Rtti_PlotCurve For QwtPlotCurve. Rtti_PlotSpectroCurve For QwtPlotSpectroCurve. Rtti_PlotIntervalCurve For QwtPlotIntervalCurve. Rtti_PlotHistogram For QwtPlotHistogram. Rtti_PlotSpectrogram For QwtPlotSpectrogram. Rtti_PlotGraphic For QwtPlotGraphicItem, QwtPlotSvgItem. Rtti_PlotTradingCurve For QwtPlotTradingCurve. Rtti_PlotBarChart For QwtPlotBarChart. Rtti_PlotMultiBarChart For QwtPlotMultiBarChart. Rtti_PlotShape For QwtPlotShapeItem. Rtti_PlotTextLabel For QwtPlotTextLabel. Rtti_PlotZone For QwtPlotZoneItem. Rtti_PlotVectorField For QwtPlotVectorField. Rtti_PlotUserItem Values >= Rtti_PlotUserItem are reserved for plot items not implemented in the Qwt library. Definition at line 75 of file qwt_plot_item.h. Constructor & Destructor Documentation QwtPlotItem::QwtPlotItem () [explicit] Constructor Definition at line 55 of file qwt_plot_item.cpp. QwtPlotItem::QwtPlotItem (const QString & title) [explicit] Constructor Parameters title Title of the item Definition at line 64 of file qwt_plot_item.cpp. QwtPlotItem::QwtPlotItem (const QwtText & title) [explicit] Constructor Parameters title Title of the item Definition at line 74 of file qwt_plot_item.cpp. Member Function Documentation void QwtPlotItem::attach (QwtPlot * plot) 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 NULL argument is passed, it will detach from any QwtPlot it was attached to. Parameters plot Plot widget See also detach() Definition at line 98 of file qwt_plot_item.cpp. QRectF QwtPlotItem::boundingRect () const [virtual] 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 Reimplemented in QwtPlotZoneItem, QwtPlotVectorField, QwtPlotTradingCurve, QwtPlotShapeItem, QwtPlotSeriesItem, QwtPlotRasterItem, QwtPlotMultiBarChart, QwtPlotMarker, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotGraphicItem, and QwtPlotBarChart. Definition at line 568 of file qwt_plot_item.cpp. QwtGraphic QwtPlotItem::defaultIcon (const QBrush & brush, const QSizeF & size) const [protected] Return a default icon from a brush. The default icon is a filled rectangle used in several derived classes as legendIcon(). Parameters brush Fill brush size Icon size Returns A filled rectangle Definition at line 422 of file qwt_plot_item.cpp. void QwtPlotItem::detach () This method detaches a QwtPlotItem from any QwtPlot it has been associated with. detach() is equivalent to calling attach( NULL ) See also attach() Definition at line 119 of file qwt_plot_item.cpp. virtual void QwtPlotItem::draw (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect) const [pure virtual] Draw the item. Parameters painter Painter xMap Maps x-values into pixel coordinates. yMap Maps y-values into pixel coordinates. canvasRect Contents rect of the canvas in painter coordinates Implemented in QwtPlotSpectrogram, QwtPlotShapeItem, QwtPlotSeriesItem, QwtPlotScaleItem, QwtPlotRasterItem, QwtPlotLegendItem, QwtPlotGrid, QwtPlotGraphicItem, QwtPlotMarker, QwtPlotZoneItem, and QwtPlotTextLabel. void QwtPlotItem::getCanvasMarginHint (const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, double & left, double & top, double & right, double & bottom) const [virtual] 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 Maps x-values into pixel coordinates. yMap Maps y-values into pixel coordinates. canvasRect Contents rectangle of the canvas in painter coordinates left Returns the left margin top Returns the top margin right Returns the right margin bottom Returns the bottom margin The default implementation returns 0 for all margins See also QwtPlot::getCanvasMarginsHint(), QwtPlot::updateCanvasMargins() Reimplemented in QwtPlotAbstractBarChart. Definition at line 595 of file qwt_plot_item.cpp. bool QwtPlotItem::isVisible () const Returns true if visible See also setVisible(), show(), hide() Definition at line 470 of file qwt_plot_item.cpp. void QwtPlotItem::itemChanged () [virtual] Update the legend and call QwtPlot::autoRefresh() for the parent plot. See also QwtPlot::legendChanged(), QwtPlot::autoRefresh() Definition at line 481 of file qwt_plot_item.cpp. void QwtPlotItem::legendChanged () [virtual] Update the legend of the parent plot. See also QwtPlot::updateLegend(), itemChanged() Definition at line 491 of file qwt_plot_item.cpp. QList< QwtLegendData > QwtPlotItem::legendData () const [virtual] Return all information, that is needed to represent the item on the legend. Most items are represented by one entry on the legend showing an icon and a text, but f.e. QwtPlotMultiBarChart displays one entry for each bar. 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(), QwtLegend, QwtPlotLegendItem Reimplemented in QwtPlotMultiBarChart, and QwtPlotBarChart. Definition at line 626 of file qwt_plot_item.cpp. QwtGraphic QwtPlotItem::legendIcon (int index, const QSizeF & size) const [virtual] Returns Icon representing the item on the legend The default implementation returns an invalid icon Parameters index Index of the legend entry ( usually there is only one ) size Icon size See also setLegendIconSize(), legendData() Reimplemented in QwtPlotVectorField, QwtPlotTradingCurve, QwtPlotShapeItem, QwtPlotMultiBarChart, QwtPlotMarker, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotCurve, and QwtPlotBarChart. Definition at line 402 of file qwt_plot_item.cpp. QSize QwtPlotItem::legendIconSize () const Returns Legend icon size See also setLegendIconSize(), legendIcon() Definition at line 386 of file qwt_plot_item.cpp. QRectF QwtPlotItem::paintRect (const QwtScaleMap & xMap, const QwtScaleMap & yMap) const Calculate the bounding paint rectangle of 2 maps. Parameters xMap Maps x-values into pixel coordinates. yMap Maps y-values into pixel coordinates. Returns Bounding paint rectangle of the scale maps, not normalized Definition at line 720 of file qwt_plot_item.cpp. uint QwtPlotItem::renderThreadCount () const Returns Number of threads to be used for rendering. If numThreads() is set to 0, the system specific ideal thread count is used. Definition at line 360 of file qwt_plot_item.cpp. int QwtPlotItem::rtti () const [virtual] 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. The rtti value is useful for environments, where the runtime type information is disabled and it is not possible to do a dynamic_cast<...>. Returns rtti value See also RttiValues Reimplemented in QwtPlotZoneItem, QwtPlotVectorField, QwtPlotTradingCurve, QwtPlotTextLabel, QwtPlotSpectrogram, QwtPlotSpectroCurve, QwtPlotShapeItem, QwtPlotScaleItem, QwtPlotMultiBarChart, QwtPlotMarker, QwtPlotLegendItem, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotGrid, QwtPlotGraphicItem, QwtPlotCurve, and QwtPlotBarChart. Definition at line 136 of file qwt_plot_item.cpp. QRectF QwtPlotItem::scaleRect (const QwtScaleMap & xMap, const QwtScaleMap & yMap) const Calculate the bounding scale rectangle of 2 maps. Parameters xMap Maps x-values into pixel coordinates. yMap Maps y-values into pixel coordinates. Returns Bounding scale rect of the scale maps, not normalized Definition at line 705 of file qwt_plot_item.cpp. void QwtPlotItem::setAxes (QwtAxisId xAxisId, QwtAxisId yAxisId) Set X and Y axis The item will painted according to the coordinates of its Axes. Parameters xAxisId X Axis yAxisId Y Axis See also setXAxis(), setYAxis(), xAxis(), yAxis() Definition at line 507 of file qwt_plot_item.cpp. void QwtPlotItem::setItemAttribute (ItemAttribute attribute, bool on = true) Toggle an item attribute Parameters attribute Attribute type on true/false See also testItemAttribute(), ItemInterest Definition at line 228 of file qwt_plot_item.cpp. void QwtPlotItem::setItemInterest (ItemInterest interest, bool on = true) Toggle an item interest Parameters interest Interest type on true/false See also testItemInterest(), ItemAttribute Definition at line 279 of file qwt_plot_item.cpp. void QwtPlotItem::setLegendIconSize (const QSize & size) Set the size of the legend icon The default setting is 8x8 pixels Parameters size Size See also legendIconSize(), legendIcon() Definition at line 373 of file qwt_plot_item.cpp. void QwtPlotItem::setRenderHint (RenderHint hint, bool on = true) Toggle an render hint Parameters hint Render hint on true/false See also testRenderHint(), RenderHint Definition at line 312 of file qwt_plot_item.cpp. void QwtPlotItem::setRenderThreadCount (uint numThreads) On multi core systems rendering of certain plot item ( f.e QwtPlotRasterItem ) can be done in parallel in several threads. The default setting is set to 1. Parameters numThreads Number of threads to be used for rendering. If numThreads is set to 0, the system specific ideal thread count is used. The default thread count is 1 ( = no additional threads ) Definition at line 350 of file qwt_plot_item.cpp. void QwtPlotItem::setTitle (const QString & title) Set a new title Parameters title Title See also title() Definition at line 187 of file qwt_plot_item.cpp. void QwtPlotItem::setTitle (const QwtText & title) Set a new title Parameters title Title See also title() Definition at line 198 of file qwt_plot_item.cpp. void QwtPlotItem::setVisible (bool on) [virtual] Show/Hide the item Parameters on Show if true, otherwise hide See also isVisible(), show(), hide() Definition at line 457 of file qwt_plot_item.cpp. void QwtPlotItem::setXAxis (QwtAxisId axisId) Set the X axis The item will painted according to the coordinates its Axes. Parameters axisId X Axis See also setAxes(), setYAxis(), xAxis() Definition at line 526 of file qwt_plot_item.cpp. void QwtPlotItem::setYAxis (QwtAxisId axisId) Set the Y axis The item will painted according to the coordinates its Axes. Parameters axisId Y Axis See also setAxes(), setXAxis(), yAxis() Definition at line 543 of file qwt_plot_item.cpp. void QwtPlotItem::setZ (double z) Set the z value. Plot items are painted in increasing z-order. Parameters z Z-value See also z(), QwtPlotDict::itemList() Definition at line 165 of file qwt_plot_item.cpp. bool QwtPlotItem::testItemAttribute (ItemAttribute attribute) const Test an item attribute Parameters attribute Attribute type Returns true/false See also setItemAttribute(), ItemInterest Definition at line 266 of file qwt_plot_item.cpp. bool QwtPlotItem::testItemInterest (ItemInterest interest) const Test an item interest Parameters interest Interest type Returns true/false See also setItemInterest(), ItemAttribute Definition at line 299 of file qwt_plot_item.cpp. bool QwtPlotItem::testRenderHint (RenderHint hint) const Test a render hint Parameters hint Render hint Returns true/false See also setRenderHint(), RenderHint Definition at line 332 of file qwt_plot_item.cpp. const QwtText & QwtPlotItem::title () const Returns Title of the item See also setTitle() Definition at line 215 of file qwt_plot_item.cpp. void QwtPlotItem::updateLegend (const QwtPlotItem * item, const QList< QwtLegendData > & data) [virtual] 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 Plot item to be displayed on a legend data Attributes how to display item on the legend See also QwtPlotLegendItem Note Plot items, that want to be displayed on a legend need to enable the QwtPlotItem::Legend flag and to implement legendData() and legendIcon() Reimplemented in QwtPlotLegendItem. Definition at line 690 of file qwt_plot_item.cpp. void QwtPlotItem::updateScaleDiv (const QwtScaleDiv & xScaleDiv, const QwtScaleDiv & yScaleDiv) [virtual] Update the item to changes of the axes scale division. Update the item, when the axes of plot have changed. The default implementation does nothing, but items that depend on the scale division (like QwtPlotGrid()) have to reimplement updateScaleDiv() updateScaleDiv() is only called when the ScaleInterest interest is enabled. The default implementation does nothing. Parameters xScaleDiv Scale division of the x-axis yScaleDiv Scale division of the y-axis See also QwtPlot::updateAxes(), ScaleInterest Reimplemented in QwtPlotGrid, QwtPlotSeriesItem, and QwtPlotScaleItem. Definition at line 665 of file qwt_plot_item.cpp. double QwtPlotItem::z () const Plot items are painted in increasing z-order. Returns setZ(), QwtPlotDict::itemList() Definition at line 152 of file qwt_plot_item.cpp. Author Generated automatically by Doxygen for Qwt User's Guide from the source code. Version 6.2.0 Sun Jul 18 2021 QwtPlotItem(3)