A collection of QPainter workarounds. More...

#include <qwt_painter.h>

Static Public Member Functions
static void	setPolylineSplitting (bool)
	En/Disable line splitting for the raster paint engine.

static bool	polylineSplitting ()

static void	setRoundingAlignment (bool)
	Enable whether coordinates should be rounded, before they are painted to a paint engine that floors to integer values.

static bool	roundingAlignment ()
	Check whether coordinates should be rounded, before they are painted to a paint engine that rounds to integer values.

static bool	roundingAlignment (const QPainter *)

static void	drawText (QPainter *, qreal x, qreal y, const QString &)
	Wrapper for QPainter::drawText()

static void	drawText (QPainter *, const QPointF &, const QString &)
	Wrapper for QPainter::drawText()

static void	drawText (QPainter *, qreal x, qreal y, qreal w, qreal h, int flags, const QString &)
	Wrapper for QPainter::drawText()

static void	drawText (QPainter *, const QRectF &, int flags, const QString &)
	Wrapper for QPainter::drawText()

static void	drawSimpleRichText (QPainter *, const QRectF &, int flags, const QTextDocument &)
	Draw a text document into a rectangle.

static void	drawRect (QPainter *, qreal x, qreal y, qreal w, qreal h)
	Wrapper for QPainter::drawRect()

static void	drawRect (QPainter *, const QRectF &rect)
	Wrapper for QPainter::drawRect()

static void	fillRect (QPainter *, const QRectF &, const QBrush &)
	Wrapper for QPainter::fillRect()

static void	drawEllipse (QPainter *, const QRectF &)
	Wrapper for QPainter::drawEllipse()

static void	drawPie (QPainter *, const QRectF &r, int a, int alen)
	Wrapper for QPainter::drawPie()

static void	drawLine (QPainter *, qreal x1, qreal y1, qreal x2, qreal y2)
	Wrapper for QPainter::drawLine()

static void	drawLine (QPainter *, const QPointF &p1, const QPointF &p2)
	Wrapper for QPainter::drawLine()

static void	drawLine (QPainter *, const QLineF &)
	Wrapper for QPainter::drawLine()

static void	drawPolygon (QPainter *, const QPolygonF &)
	Wrapper for QPainter::drawPolygon()

static void	drawPolyline (QPainter *, const QPolygonF &)
	Wrapper for QPainter::drawPolyline()

static void	drawPolyline (QPainter , const QPointF , int pointCount)
	Wrapper for QPainter::drawPolyline()

static void	drawPolygon (QPainter *, const QPolygon &)
	Wrapper for QPainter::drawPolygon()

static void	drawPolyline (QPainter *, const QPolygon &)
	Wrapper for QPainter::drawPolyline()

static void	drawPolyline (QPainter , const QPoint , int pointCount)
	Wrapper for QPainter::drawPolyline()

static void	drawPoint (QPainter *, const QPoint &)
	Wrapper for QPainter::drawPoint()

static void	drawPoints (QPainter *, const QPolygon &)
	Wrapper for QPainter::drawPoints()

static void	drawPoints (QPainter , const QPoint , int pointCount)
	Wrapper for QPainter::drawPoints()

static void	drawPoint (QPainter *, qreal x, qreal y)
	Wrapper for QPainter::drawPoint()

static void	drawPoint (QPainter *, const QPointF &)
	Wrapper for QPainter::drawPoint()

static void	drawPoints (QPainter *, const QPolygonF &)
	Wrapper for QPainter::drawPoints()

static void	drawPoints (QPainter , const QPointF , int pointCount)
	Wrapper for QPainter::drawPoints()

static void	drawPath (QPainter *, const QPainterPath &)
	Wrapper for QPainter::drawPath()

static void	drawImage (QPainter *, const QRectF &, const QImage &)
	Wrapper for QPainter::drawImage()

static void	drawPixmap (QPainter *, const QRectF &, const QPixmap &)
	Wrapper for QPainter::drawPixmap()

static void	drawRoundFrame (QPainter *, const QRectF &, const QPalette &, int lineWidth, int frameStyle)
	Draw a round frame.

static void	drawRoundedFrame (QPainter *, const QRectF &, qreal xRadius, qreal yRadius, const QPalette &, int lineWidth, int frameStyle)
	Draw a rectangular frame with rounded borders.

static void	drawFrame (QPainter *, const QRectF &rect, const QPalette &palette, QPalette::ColorRole foregroundRole, int lineWidth, int midLineWidth, int frameStyle)
	Draw a rectangular frame.

static void	drawFocusRect (QPainter , const QWidget )
	Draw a focus rectangle on a widget using its style.

static void	drawFocusRect (QPainter , const QWidget , const QRect &)
	Draw a focus rectangle on a widget using its style.

static void	drawColorBar (QPainter *, const QwtColorMap &, const QwtInterval &, const QwtScaleMap &, Qt::Orientation, const QRectF &)
	Draw a color bar into a rectangle.

static bool	isAligning (const QPainter *)
	Check if the painter is using a paint engine, that aligns coordinates to integers.

static bool	isX11GraphicsSystem ()
	Check is the application is running with the X11 graphics system that has some special capabilities that can be used for incremental painting to a widget.

static void	fillPixmap (const QWidget *, QPixmap &, const QPoint &offset=QPoint())
	Fill a pixmap with the content of a widget.

static void	fillRegion (QPainter *painter, const QRegion &region)
	填充区域

static void	fillBackground (QPainter painter, QWidget widget, const QVector< QRectF > &fillRects)
	填充widget背景的指定矩形区域

static void	fillBackground (QPainter painter, QWidget canvas)
	自动检测并填充widget的背景

static void	drawBackgound (QPainter , const QRectF &, const QWidget )
	Fill rect with the background of a widget.

static void	drawCanvasBackgound (QPainter painter, QWidget canvas)
	绘制widget的背景

static void	drawStyledBackground (QWidget w, QPainter painter)
	确保widget背景按照当前GUI风格（如Windows、Fusion等）正确绘制

static QPixmap	backingStore (QWidget *, const QSize &)

static qreal	devicePixelRatio (const QPaintDevice *)

static qreal	effectivePenWidth (const QPen &)

static int	horizontalAdvance (const QFontMetrics &, const QString &)
	Distance appropriate for drawing a subsequent character after text.

static qreal	horizontalAdvance (const QFontMetricsF &, const QString &)
	Distance appropriate for drawing a subsequent character after text.

static int	horizontalAdvance (const QFontMetrics &, QChar)
	Distance appropriate for drawing a subsequent character after ch.

static qreal	horizontalAdvance (const QFontMetricsF &, QChar)
	Distance appropriate for drawing a subsequent character after ch.

static QFont	scaledFont (const QFont &, const QPaintDevice *=nullptr)
	Adjust the DPI value of font according to the DPI value of the paint device.

static QWidget *	findBackgroundWidget (QWidget *w)
	查找具有可见背景的顶层widget

Detailed Description

A collection of QPainter workarounds.

Member Function Documentation

◆ backingStore()

QPixmap QwtPainter::backingStore	(	QWidget *	widget,
		const QSize &	size
	)

static

Returns: A pixmap that can be used as backing store

Parameters

widget	Widget, for which the backingstore is intended
size	Size of the pixmap

◆ devicePixelRatio()

qreal QwtPainter::devicePixelRatio ( const QPaintDevice * paintDevice )

static

Returns: Pixel ratio for a paint device

Parameters

paintDevice Paint device

◆ drawBackgound()

void QwtPainter::drawBackgound	(	QPainter *	painter,
		const QRectF &	rect,
		const QWidget *	widget
	)

static

Fill rect with the background of a widget.

Parameters

painter	Painter
rect	Rectangle to be filled
widget	Widget

See also: QStyle::PE_Widget, QWidget::backgroundRole()

◆ drawCanvasBackgound()

void QwtPainter::drawCanvasBackgound	(	QPainter *	painter,
		QWidget *	canvas
	)

static

绘制widget的背景

绘制指定canvas widget的背景，支持多种背景类型包括纯色、渐变和纹理模式。该函数会处理自定义边界路径裁剪和不同背景类型的优化绘制。

Parameters

painter	用于绘制的QPainter对象
canvas	需要绘制背景的目标widget

绘制过程如下：

保存当前绘图器状态
通过反射调用canvas的borderPath方法获取边界路径用于裁剪
根据背景画刷类型采用不同的绘制策略：
- 纹理模式：创建临时pixmap并使用fillPixmap填充后绘制
- 渐变模式：根据渐变坐标模式选择填充裁剪区域或整个矩形
- 普通模式：直接填充裁剪区域
恢复绘图器状态

Note: 该函数通过Qt的反射机制调用canvas的borderPath方法，因此canvas类需要提供相应的Q_INVOKABLE方法签名：
Q_INVOKABLE QPainterPath borderPath(const QRect& rect) const;

Warning: 如果canvas没有提供borderPath方法，将使用默认矩形边界

See also: QwtPainter::fillPixmap(), QwtPainter::fillRegion(), QWidget::backgroundRole(), QWidget::palette()

◆ drawColorBar()

void QwtPainter::drawColorBar	(	QPainter *	painter,
		const QwtColorMap &	colorMap,
		const QwtInterval &	interval,
		const QwtScaleMap &	scaleMap,
		Qt::Orientation	orientation,
		const QRectF &	rect
	)

static

Draw a color bar into a rectangle.

Parameters

painter	Painter
colorMap	Color map
interval	Value range
scaleMap	Scale map
orientation	Orientation
rect	Target rectangle

◆ drawFrame()

void QwtPainter::drawFrame	(	QPainter *	painter,
		const QRectF &	rect,
		const QPalette &	palette,
		QPalette::ColorRole	foregroundRole,
		int	frameWidth,
		int	midLineWidth,
		int	frameStyle
	)

static

Draw a rectangular frame.

Parameters

painter	Painter
rect	Frame rectangle
palette	Palette
foregroundRole	Foreground role used for QFrame::Plain
frameWidth	Frame width
midLineWidth	Used for QFrame::Box
frameStyle	bitwise OR´ed value of QFrame::Shape and QFrame::Shadow

◆ drawRoundedFrame()

void QwtPainter::drawRoundedFrame	(	QPainter *	painter,
		const QRectF &	rect,
		qreal	xRadius,
		qreal	yRadius,
		const QPalette &	palette,
		int	lineWidth,
		int	frameStyle
	)

static

Draw a rectangular frame with rounded borders.

Parameters

painter	Painter
rect	Frame rectangle
xRadius	x-radius of the ellipses defining the corners
yRadius	y-radius of the ellipses defining the corners
palette	QPalette::WindowText is used for plain borders QPalette::Dark and QPalette::Light for raised or sunken borders
lineWidth	Line width
frameStyle	bitwise OR´ed value of QFrame::Shape and QFrame::Shadow

◆ drawRoundFrame()

void QwtPainter::drawRoundFrame	(	QPainter *	painter,
		const QRectF &	rect,
		const QPalette &	palette,
		int	lineWidth,
		int	frameStyle
	)

static

Draw a round frame.

Parameters

painter	Painter
rect	Frame rectangle
palette	QPalette::WindowText is used for plain borders QPalette::Dark and QPalette::Light for raised or sunken borders
lineWidth	Line width
frameStyle	bitwise OR´ed value of QFrame::Shape and QFrame::Shadow

◆ drawSimpleRichText()

void QwtPainter::drawSimpleRichText	(	QPainter *	painter,
		const QRectF &	rect,
		int	flags,
		const QTextDocument &	text
	)

static

Draw a text document into a rectangle.

Parameters

painter	Painter
rect	Target rectangle
flags	Alignments/Text flags, see QPainter::drawText()
text	Text document

◆ drawStyledBackground()

void QwtPainter::drawStyledBackground	(	QWidget *	w,
		QPainter *	painter
	)

static

确保widget背景按照当前GUI风格（如Windows、Fusion等）正确绘制

支持渐变、纹理、圆角等复杂背景效果

自动适配系统或应用程序的主题设置

Parameters

w
painter

◆ effectivePenWidth()

qreal QwtPainter::effectivePenWidth ( const QPen & pen )

inlinestatic

Returns: pen.widthF() expanded to at least 1.0

Parameters

pen Pen

◆ fillBackground() [1/2]

void QwtPainter::fillBackground	(	QPainter *	painter,
		QWidget *	canvas
	)

static

自动检测并填充widget的背景

根据widget的样式属性自动检测需要填充的背景区域，并调用相应的填充函数。支持样式化背景和圆角边框的背景填充。

Parameters

painter	用于绘制的QPainter对象
canvas	需要填充背景的目标widget

处理逻辑如下：

如果widget启用了样式化背景（WA_StyledBackground）：
- 使用样式表记录器记录背景绘制信息
- 如果背景不透明，使用记录的裁剪矩形列表
- 否则使用整个widget矩形
如果widget设置了borderRadius属性：
- 计算四个角的矩形区域作为填充区域
调用qwtFillBackground进行实际填充

Note: 这个函数是背景填充的入口点，会自动选择合适的填充策略

See also: fillBackground(), QwtStyleSheetRecorder

◆ fillBackground() [2/2]

void QwtPainter::fillBackground	(	QPainter *	painter,
		QWidget *	widget,
		const QVector< QRectF > &	fillRects
	)

static

填充widget背景的指定矩形区域

使用父级widget的背景来填充当前widget的指定矩形区域列表。这个函数主要用于处理透明或半透明widget的背景填充优化。

Parameters

painter	用于绘制的QPainter对象
widget	需要填充背景的目标widget
fillRects	需要填充的矩形区域列表

填充过程如下：

如果填充矩形列表为空，直接返回
确定裁剪区域：如果painter有裁剪设置则使用变换后的裁剪区域，否则使用widget的内容区域
查找能够填充未填充区域的背景widget
遍历每个填充矩形：
- 检查是否与裁剪区域相交
- 创建临时pixmap并使用fillPixmap填充
- 将pixmap绘制到目标位置

Note: 这个函数通常用于处理圆角边框或其他需要局部背景填充的情况

See also: QwtPainter::fillPixmap(), QwtPainter::findBackgroundWidget()

◆ fillPixmap()

void QwtPainter::fillPixmap	(	const QWidget *	widget,
		QPixmap &	pixmap,
		const QPoint &	offset = `QPoint()`
	)

static

Fill a pixmap with the content of a widget.

In Qt >= 5.0 QPixmap::fill() is a nop, in Qt 4.x it is buggy for backgrounds with gradients. Thus fillPixmap() offers an alternative implementation.

Parameters

widget	Widget
pixmap	Pixmap to be filled
offset	Offset

See also: QPixmap::fill()

◆ fillRegion()

void QwtPainter::fillRegion	(	QPainter *	painter,
		const QRegion &	region
	)

static

填充区域

Parameters

painter
region

◆ findBackgroundWidget()

QWidget * QwtPainter::findBackgroundWidget ( QWidget * w )

static

查找具有可见背景的顶层widget

递归地向上遍历widget的父级层次结构，寻找第一个具有不透明背景的widget。这个函数用于优化绘图操作，避免在透明或无背景的widget上进行不必要的背景绘制。

Parameters

w	要检查的起始widget

Returns: 返回第一个具有可见背景的widget，如果找不到则返回根widget

查找逻辑如下：

如果widget没有父级（根widget），直接返回该widget
如果widget启用了自动背景填充且背景不透明，则返回该widget
如果widget使用样式化背景，通过实际绘制测试背景是否可见，如果可见则返回
如果以上条件都不满足，则递归检查父级widget

Note: 这个函数主要用于绘图优化，帮助确定在哪里开始绘制背景以避免重复绘制

See also: QWidget::autoFillBackground(), QWidget::backgroundRole(), QWidget::testAttribute()

◆ horizontalAdvance() [1/4]

int QwtPainter::horizontalAdvance	(	const QFontMetrics &	fontMetrics,
		const QString &	text
	)

static

Distance appropriate for drawing a subsequent character after text.

Parameters

fontMetrics	Font metrics
text	Text

Returns: horizontal advance in pixels

◆ horizontalAdvance() [2/4]

int QwtPainter::horizontalAdvance	(	const QFontMetrics &	fontMetrics,
		QChar	ch
	)

static

Distance appropriate for drawing a subsequent character after ch.

Parameters

fontMetrics	Font metrics
ch	Character

Returns: horizontal advance in pixels

◆ horizontalAdvance() [3/4]

qreal QwtPainter::horizontalAdvance	(	const QFontMetricsF &	fontMetrics,
		const QString &	text
	)

static

Distance appropriate for drawing a subsequent character after text.

Parameters

fontMetrics	Font metrics
text	Text

Returns: horizontal advance in pixels

◆ horizontalAdvance() [4/4]

qreal QwtPainter::horizontalAdvance	(	const QFontMetricsF &	fontMetrics,
		QChar	ch
	)

static

Distance appropriate for drawing a subsequent character after ch.

Parameters

fontMetrics	Font metrics
ch	Character

Returns: horizontal advance in pixels

◆ isAligning()

bool QwtPainter::isAligning ( const QPainter * painter )

static

Check if the painter is using a paint engine, that aligns coordinates to integers.

Today these are all paint engines beside QPaintEngine::Pdf and QPaintEngine::SVG.

If we have an integer based paint engine it is also checked if the painter has a transformation matrix, that rotates or scales.

Parameters

painter Painter

Returns: true, when the painter is aligning

See also: setRoundingAlignment()

◆ isX11GraphicsSystem()

bool QwtPainter::isX11GraphicsSystem ( )

static

Check is the application is running with the X11 graphics system that has some special capabilities that can be used for incremental painting to a widget.

Returns: True, when the graphics system is X11

◆ polylineSplitting()

bool QwtPainter::polylineSplitting ( )

inlinestatic

Returns: True, when line splitting for the raster paint engine is enabled.

See also: setPolylineSplitting()

◆ roundingAlignment() [1/2]

bool QwtPainter::roundingAlignment ( )

inlinestatic

Check whether coordinates should be rounded, before they are painted to a paint engine that rounds to integer values.

For other paint engines ( PDF, SVG ), this flag has no effect.

Returns: True, when rounding is enabled

See also: setRoundingAlignment(), isAligning()

◆ roundingAlignment() [2/2]

bool QwtPainter::roundingAlignment ( const QPainter * painter )

inlinestatic

Returns: roundingAlignment() && isAligning(painter);

Parameters

painter Painter

◆ scaledFont()

QFont QwtPainter::scaledFont	(	const QFont &	font,
		const QPaintDevice *	paintDevice = `nullptr`
	)

static

Adjust the DPI value of font according to the DPI value of the paint device.

Parameters

font	Unscaled font
paintDevice	Paint device providing a DPI value. If paintDevice == null the DPI value of the primary screen will be used

Returns: Font being adjusted to the DPI value of the paint device

◆ setPolylineSplitting()

void QwtPainter::setPolylineSplitting ( bool enable )

static

En/Disable line splitting for the raster paint engine.

In some Qt versions the raster paint engine paints polylines of many points much faster when they are split in smaller chunks: f.e all supported Qt versions >= Qt 5.0 when drawing an antialiased polyline with a pen width >=2.

Also the raster paint engine has a nasty bug in many versions ( Qt 4.8 - ... ) for short lines ( https://codereview.qt-project.org/#/c/99456 ), that is worked around in this mode.

The default setting is true.

See also: polylineSplitting()

◆ setRoundingAlignment()

void QwtPainter::setRoundingAlignment ( bool enable )

static

Enable whether coordinates should be rounded, before they are painted to a paint engine that floors to integer values.

For other paint engines ( PDF, SVG ) this flag has no effect. QwtPainter stores this flag only, the rounding itself is done in the painting code ( f.e the plot items ).

The default setting is true.

See also: roundingAlignment(), isAligning()

The documentation for this class was generated from the following files:

/home/runner/work/QWT/QWT/src/qwt_painter.h
/home/runner/work/QWT/QWT/src/qwt_painter.cpp

Static Public Member Functions

Detailed Description

Member Function Documentation

◆ backingStore()

◆ devicePixelRatio()

◆ drawBackgound()

◆ drawCanvasBackgound()

◆ drawColorBar()

◆ drawFrame()

◆ drawRoundedFrame()

◆ drawRoundFrame()

◆ drawSimpleRichText()

◆ drawStyledBackground()

◆ effectivePenWidth()

◆ fillBackground() [1/2]

◆ fillBackground() [2/2]

◆ fillPixmap()

◆ fillRegion()

◆ findBackgroundWidget()

◆ horizontalAdvance() [1/4]

◆ horizontalAdvance() [2/4]

◆ horizontalAdvance() [3/4]

◆ horizontalAdvance() [4/4]

◆ isAligning()

◆ isX11GraphicsSystem()

◆ polylineSplitting()

◆ roundingAlignment() [1/2]

◆ roundingAlignment() [2/2]

◆ scaledFont()

◆ setPolylineSplitting()

◆ setRoundingAlignment()