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

typedef QFlags<PaintAttribute > QwtPlotCanvas::PaintAttributes¶

An ORed combination of PaintAttribute values.

Definition at line 102 of file qwt_plot_canvas.h.

enum QwtPlotCanvas::PaintAttribute¶

Paint attributes. The default setting enables BackingStore and Opaque.

See also

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

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

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

Definition at line 44 of file qwt_plot_canvas.h.

QwtPlotCanvas::QwtPlotCanvas (QwtPlot * plot = NULL) [explicit]¶

Constructor.

Parameters

See also

Definition at line 41 of file qwt_plot_canvas.cpp.

const QPixmap * QwtPlotCanvas::backingStore () const¶

Returns

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

Returns

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

See also

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

Returns

Definition at line 151 of file qwt_plot_canvas.cpp.

void QwtPlotCanvas::paintEvent (QPaintEvent * event) [override], [protected], [virtual]¶

Paint event

Parameters

Definition at line 178 of file qwt_plot_canvas.cpp.

void QwtPlotCanvas::replot () [slot]¶

Invalidate the paint cache and repaint the canvas

See also

Definition at line 301 of file qwt_plot_canvas.cpp.

void QwtPlotCanvas::resizeEvent (QResizeEvent * event) [override], [protected], [virtual]¶

Resize event

Parameters

Definition at line 291 of file qwt_plot_canvas.cpp.

void QwtPlotCanvas::setPaintAttribute (PaintAttribute attribute, bool on = true)¶

Changing the paint attributes.

Parameters

See also

Definition at line 70 of file qwt_plot_canvas.cpp.

bool QwtPlotCanvas::testPaintAttribute (PaintAttribute attribute) const¶

Test whether a paint attribute is enabled

Parameters

Returns

See also

Definition at line 127 of file qwt_plot_canvas.cpp.