NAME¶

QwtPlotCanvas - Canvas of a QwtPlot.

SYNOPSIS¶

#include <qwt_plot_canvas.h>

Public Types¶

enum PaintAttribute { BackingStore = 1, Opaque = 2, HackStyledBackground = 4, ImmediatePaint = 8 } enum FocusIndicator { NoFocusIndicator, CanvasFocusIndicator, ItemFocusIndicator } typedef QFlags< PaintAttribute > PaintAttributes

Public Member Functions¶

QwtPlotCanvas (QwtPlot *) virtual ~QwtPlotCanvas () QwtPlot * plot () const QwtPlot * plot () const void setFocusIndicator (FocusIndicator) FocusIndicator focusIndicator () const void setBorderRadius (double) double borderRadius () const QPainterPath borderPath (const QRect &rect) const QBitmap borderMask (const QSize &) const void setPaintAttribute (PaintAttribute, bool on=true) bool testPaintAttribute (PaintAttribute) const const QPixmap * backingStore () const void invalidateBackingStore () void replot () virtual bool event (QEvent *)

Protected Member Functions¶

virtual void paintEvent (QPaintEvent *) virtual void resizeEvent (QResizeEvent *) virtual void drawFocusIndicator (QPainter *) virtual void drawBorder (QPainter *) void updateStyleSheetInfo ()

Detailed Description¶

Canvas of a QwtPlot. See also:

Member Typedef Documentation¶

typedef QFlags<PaintAttribute> QwtPlotCanvas::PaintAttributes¶

Paint attributes.

Member Enumeration Documentation¶

enum QwtPlotCanvas::FocusIndicator¶

Focus indicator. .IP "•" 2 NoFocusIndicator
Don't paint a focus indicator

•

CanvasFocusIndicator

 

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

•

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.

See also:

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 workin with widget overlays ( like rubberbands ). 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 seperate the background from the background border by reverse engeneering to paint the background before and the border after the plot items. In this order the border gets prefectly antialiased and you can avoid some pixel artifacts in the corners.

ImmediatePaint

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

See also:

Constructor & Destructor Documentation¶

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

Sets a cross cursor, enables QwtPlotCanvas::BackingStore.

QwtPlotCanvas::~QwtPlotCanvas () [virtual]¶

Destructor.

Member Function Documentation¶

const QPixmap * QwtPlotCanvas::backingStore () const¶

Return the backing store, might be null.

QBitmap QwtPlotCanvas::borderMask (const QSize &size) const Calculate a mask, that can be used to clip away the border frame¶

Parameters:

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:

double QwtPlotCanvas::borderRadius () const Returns:¶

See also:

void QwtPlotCanvas::drawBorder (QPainter *painter) [protected, virtual] Draw the border of the plot canvas¶

Parameters: See also:

void QwtPlotCanvas::drawFocusIndicator (QPainter *painter) [protected, virtual] Draw the focus indication¶

Parameters:

bool QwtPlotCanvas::event (QEvent *event) [virtual] Qt event handler for QEvent::PolishRequest and QEvent::StyleChange¶

Parameters:

QwtPlotCanvas::FocusIndicator QwtPlotCanvas::focusIndicator () const Returns:¶

See also:

void QwtPlotCanvas::invalidateBackingStore ()¶

Invalidate the internal backing store.

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

Parameters:

QwtPlot * QwtPlotCanvas::plot ()¶

Return parent plot widget.

const QwtPlot * QwtPlotCanvas::plot () const¶

Return parent plot widget.

void QwtPlotCanvas::replot () Invalidate the paint cache and repaint the canvas¶

See also:

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

Parameters:

void QwtPlotCanvas::setBorderRadius (doubleradius) Set the radius for the corners of the border frame¶

Parameters: See also:

void QwtPlotCanvas::setFocusIndicator (FocusIndicatorfocusIndicator) Set the focus indicator¶

See also:

void QwtPlotCanvas::setPaintAttribute (PaintAttributeattribute, boolon = true)¶

Changing the paint attributes. Parameters: See also:

bool QwtPlotCanvas::testPaintAttribute (PaintAttributeattribute) const Test wether a paint attribute is enabled¶

Parameters: Returns: See also:

void QwtPlotCanvas::updateStyleSheetInfo () [protected]¶

Update the cached informations about the current style sheet.

Author¶

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