QwtPlotCanvas(3) Qwt User's Guide QwtPlotCanvas(3) NAME QwtPlotCanvas - Canvas of a QwtPlot. SYNOPSIS #include Inherits QFrame, and QwtPlotAbstractCanvas. Public Types enum PaintAttribute { BackingStore = 1, Opaque = 2, HackStyledBackground = 4, ImmediatePaint = 8 } Paint attributes. typedef QFlags< PaintAttribute > PaintAttributes Public Slots void replot () Public Member Functions QwtPlotCanvas (QwtPlot *=NULL) Constructor. virtual ~QwtPlotCanvas () Destructor. void setPaintAttribute (PaintAttribute, bool on=true) Changing the paint attributes. bool testPaintAttribute (PaintAttribute) const const QPixmap * backingStore () const Q_INVOKABLE void invalidateBackingStore () Invalidate the internal backing store. virtual bool event (QEvent *) override Q_INVOKABLE QPainterPath borderPath (const QRect &) const Protected Member Functions virtual void paintEvent (QPaintEvent *) override virtual void resizeEvent (QResizeEvent *) override virtual void drawBorder (QPainter *) override Detailed Description Canvas of a QwtPlot. Canvas is the widget where all plot items are displayed See also QwtPlot::setCanvas(), QwtPlotGLCanvas, QwtPlotOpenGLCanvas Definition at line 29 of file qwt_plot_canvas.h. Member Typedef Documentation typedef QFlags QwtPlotCanvas::PaintAttributes An ORed combination of PaintAttribute values. Definition at line 102 of file qwt_plot_canvas.h. Member Enumeration Documentation enum QwtPlotCanvas::PaintAttribute Paint attributes. The default setting enables BackingStore and Opaque. See also setPaintAttribute(), testPaintAttribute() Enumerator 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 QwtPlotDirectPainter ). See also backingStore(), invalidateBackingStore() 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 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. ImmediatePaint When ImmediatePaint is set replot() calls repaint() instead of update(). See also replot(), QWidget::repaint(), QWidget::update() Definition at line 44 of file qwt_plot_canvas.h. Constructor & Destructor Documentation QwtPlotCanvas::QwtPlotCanvas (QwtPlot * plot = NULL) [explicit] Constructor. Parameters plot Parent plot widget See also QwtPlot::setCanvas() Definition at line 41 of file qwt_plot_canvas.cpp. Member Function Documentation const QPixmap * QwtPlotCanvas::backingStore () const Returns Backing store, might be null Definition at line 133 of file qwt_plot_canvas.cpp. QPainterPath QwtPlotCanvas::borderPath (const QRect & rect) const 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 Bounding rectangle of the canvas Returns Painter path, that can be used for clipping Definition at line 320 of file qwt_plot_canvas.cpp. void QwtPlotCanvas::drawBorder (QPainter * painter) [override], [protected], [virtual] Draw the border of the plot canvas Parameters painter Painter See also setBorderRadius() Reimplemented from QwtPlotAbstractCanvas. Definition at line 276 of file qwt_plot_canvas.cpp. bool QwtPlotCanvas::event (QEvent * event) [override], [virtual] Qt event handler for QEvent::PolishRequest and QEvent::StyleChange Parameters event Qt Event Returns See QFrame::event() Definition at line 151 of file qwt_plot_canvas.cpp. void QwtPlotCanvas::paintEvent (QPaintEvent * event) [override], [protected], [virtual] Paint event Parameters event Paint event Definition at line 178 of file qwt_plot_canvas.cpp. void QwtPlotCanvas::replot () [slot] Invalidate the paint cache and repaint the canvas See also invalidatePaintCache() Definition at line 301 of file qwt_plot_canvas.cpp. void QwtPlotCanvas::resizeEvent (QResizeEvent * event) [override], [protected], [virtual] Resize event Parameters event Resize event Definition at line 291 of file qwt_plot_canvas.cpp. void QwtPlotCanvas::setPaintAttribute (PaintAttribute attribute, bool on = true) Changing the paint attributes. Parameters attribute Paint attribute on On/Off See also testPaintAttribute(), backingStore() Definition at line 70 of file qwt_plot_canvas.cpp. bool QwtPlotCanvas::testPaintAttribute (PaintAttribute attribute) const Test whether a paint attribute is enabled Parameters attribute Paint attribute Returns true, when attribute is enabled See also setPaintAttribute() Definition at line 127 of file qwt_plot_canvas.cpp. Author Generated automatically by Doxygen for Qwt User's Guide from the source code. Version 6.2.0 Sun Jul 18 2021 QwtPlotCanvas(3)