QPaintEngine ¶

概要 ¶

详细描述 ¶

Qt provides several premade implementations of QPaintEngine for the different painter backends we support. The primary paint engine provided is the raster paint engine, which contains a software rasterizer which supports the full feature set on all supported platforms. This is the default for painting on QWidget -based classes in e.g. on Windows, X11 and macOS, it is the backend for painting on QImage and it is used as a fallback for paint engines that do not support a certain capability. In addition we provide QPaintEngine implementations for OpenGL (accessible through QOpenGLWidget ) and printing (which allows using QPainter to draw on a QPrinter 对象)。

If one wants to use QPainter to draw to a different backend, one must subclass QPaintEngine and reimplement all its virtual functions. The QPaintEngine implementation is then made available by subclassing QPaintDevice and reimplementing the virtual function paintEngine() .

QPaintEngine is created and owned by the QPaintDevice that created it.

另请参阅

QPainter paintEngine() 描绘系统

class QPaintEngine ( [ features=QPaintEngine.PaintEngineFeatures() ] ) ¶

param features

PaintEngineFeatures

Creates a paint engine with the featureset specified by caps .

PySide2.QtGui.QPaintEngine. PaintEngineFeature ¶

This enum is used to describe the features or capabilities that the paint engine has. If a feature is not supported by the engine, QPainter will do a best effort to emulate that feature through other means and pass on an alpha blended QImage to the engine with the emulated results. Some features cannot be emulated: and .

常量	描述
QPaintEngine.AlphaBlend	引擎可以 alpha 融合原语。
QPaintEngine.Antialiasing	The engine can use antialising to improve the appearance of rendered primitives.
QPaintEngine.BlendModes	引擎支持融合模式。
QPaintEngine.BrushStroke	The engine supports drawing strokes that contain brushes as fills, not just solid colors (e.g. a dashed gradient line of width 2).
QPaintEngine.ConicalGradientFill	The engine supports conical gradient fills.
QPaintEngine.ConstantOpacity	The engine supports the feature provided by setOpacity() .
QPaintEngine.LinearGradientFill	The engine supports linear gradient fills.
QPaintEngine.MaskedBrush	The engine is capable of rendering brushes that has a texture with an alpha channel or a mask.
QPaintEngine.ObjectBoundingModeGradients	The engine has native support for gradients with coordinate mode ObjectBoundingMode . Otherwise, if is supported, object bounding mode gradients are converted to gradients with coordinate mode LogicalMode and a brush transform for the coordinate mapping.
QPaintEngine.PainterPaths	The engine has path support.
QPaintEngine.PaintOutsidePaintEvent	The engine is capable of painting outside of paint events.
QPaintEngine.PatternBrush	The engine is capable of rendering brushes with the brush patterns specified in BrushStyle .
QPaintEngine.PatternTransform	The engine has support for transforming brush patterns.
QPaintEngine.PerspectiveTransform	The engine has support for performing perspective transformations on primitives.
QPaintEngine.PixmapTransform	The engine can transform pixmaps, including rotation and shearing.
QPaintEngine.PorterDuff	The engine supports Porter-Duff operations
QPaintEngine.PrimitiveTransform	The engine has support for transforming drawing primitives.
QPaintEngine.RadialGradientFill	The engine supports radial gradient fills.
QPaintEngine.RasterOpModes	The engine supports bitwise raster operations.
QPaintEngine.AllFeatures	All of the above features. This enum value is usually used as a bit mask.

PySide2.QtGui.QPaintEngine. DirtyFlag ¶

常量	描述
QPaintEngine.DirtyPen	The pen is dirty and needs to be updated.
QPaintEngine.DirtyBrush	The brush is dirty and needs to be updated.
QPaintEngine.DirtyBrushOrigin	The brush origin is dirty and needs to updated.
QPaintEngine.DirtyFont	The font is dirty and needs to be updated.
QPaintEngine.DirtyBackground	The background is dirty and needs to be updated.
QPaintEngine.DirtyBackgroundMode	The background mode is dirty and needs to be updated.
QPaintEngine.DirtyTransform	The transform is dirty and needs to be updated.
QPaintEngine.DirtyClipRegion	The clip region is dirty and needs to be updated.
QPaintEngine.DirtyClipPath	The clip path is dirty and needs to be updated.
QPaintEngine.DirtyHints	The render hints is dirty and needs to be updated.
QPaintEngine.DirtyCompositionMode	The composition mode is dirty and needs to be updated.
QPaintEngine.DirtyClipEnabled	Whether clipping is enabled or not is dirty and needs to be updated.
QPaintEngine.DirtyOpacity	The constant opacity has changed and needs to be updated as part of the state change in updateState() .
QPaintEngine.AllDirty	Convenience enum used internally.

These types are used by QPainter to trigger lazy updates of the various states in the QPaintEngine 使用 updateState() .

描绘引擎必须更新每脏点状态。

PySide2.QtGui.QPaintEngine. PolygonDrawMode ¶

常量	描述
QPaintEngine.OddEvenMode	The polygon should be drawn using OddEven fill rule.
QPaintEngine.WindingMode	The polygon should be drawn using Winding fill rule.
QPaintEngine.ConvexMode	The polygon is a convex polygon and can be drawn using specialized algorithms where available.
QPaintEngine.PolylineMode	Only the outline of the polygon should be drawn.

PySide2.QtGui.QPaintEngine. Type ¶

常量	描述
QPaintEngine.X11
QPaintEngine.Windows
QPaintEngine.MacPrinter
QPaintEngine.CoreGraphics	macOS’s Quartz2D ()
QPaintEngine.QuickDraw	macOS’s
QPaintEngine.QWindowSystem	Qt for Embedded Linux
QPaintEngine.PostScript	(No longer supported)
QPaintEngine.OpenGL
QPaintEngine.Picture	QPicture format
QPaintEngine.SVG	Scalable Vector Graphics XML format
QPaintEngine.Raster
QPaintEngine.Direct3D	Windows only, based engine
QPaintEngine.Pdf	PDF (便携式文档格式)
QPaintEngine.OpenVG
QPaintEngine.User	First user type ID
QPaintEngine.MaxUser	Last user type ID
QPaintEngine.OpenGL2
QPaintEngine.PaintBuffer
QPaintEngine.Blitter
QPaintEngine.Direct2D	Windows only, based engine

PySide2.QtGui.QPaintEngine. state ¶

PySide2.QtGui.QPaintEngine. gccaps ¶

PySide2.QtGui.QPaintEngine. active ¶

PySide2.QtGui.QPaintEngine. selfDestruct ¶

PySide2.QtGui.QPaintEngine. extended ¶

PySide2.QtGui.QPaintEngine. begin ( pdev ) ¶

参数

pdev – QPaintDevice

返回类型

bool

Reimplement this function to initialise your paint engine when painting is to start on the paint device pdev . Return true if the initialization was successful; otherwise return false.

另请参阅

end() isActive()

PySide2.QtGui.QPaintEngine. clearDirty ( df ) ¶

参数

df – DirtyFlags

PySide2.QtGui.QPaintEngine. coordinateOffset ( ) ¶

返回类型

QPoint

Returns the offset from the painters origo to the engines origo. This value is used by QPainter for engines who have internal double buffering.

This function only makes sense when the engine is active.

PySide2.QtGui.QPaintEngine. drawEllipse ( r ) ¶

参数

r – QRect

PySide2.QtGui.QPaintEngine. drawEllipse ( r ) ¶

参数

r – QRectF

PySide2.QtGui.QPaintEngine. drawImage ( r , pm , sr [ , flags=Qt.AutoColor ] ) ¶

参数

• r – QRectF

• pm – QImage

• sr – QRectF

• flags – ImageConversionFlags

Reimplement this function to draw the part of the image specified by the sr rectangle in the given rectangle using the given conversion flags flags , to convert it to a pixmap.

PySide2.QtGui.QPaintEngine. drawLines ( lines , lineCount ) ¶

参数

• lines – QLine

• lineCount – int

这是重载函数。

The default implementation converts the first lineCount lines in lines 到 QLineF and calls the floating point version of this function.

PySide2.QtGui.QPaintEngine. drawLines ( lines , lineCount ) ¶

参数

• lines – QLineF

• lineCount – int

The default implementation splits the list of lines in lines into lineCount separate calls to drawPath() or drawPolygon() depending on the feature set of the paint engine.

PySide2.QtGui.QPaintEngine. drawPath ( path ) ¶

参数

path – QPainterPath

The default implementation ignores the path and does nothing.

PySide2.QtGui.QPaintEngine. drawPixmap ( r , pm , sr ) ¶

参数

• r – QRectF

• pm – QPixmap

• sr – QRectF

Reimplement this function to draw the part of the pm specified by the sr rectangle in the given r .

PySide2.QtGui.QPaintEngine. drawPoints ( points , pointCount ) ¶

参数

• points – QPoint

• pointCount – int

Draws the first pointCount points in the buffer points

The default implementation converts the first pointCount QPoints in points to QPointFs and calls the floating point version of drawPoints .

PySide2.QtGui.QPaintEngine. drawPoints ( points , pointCount ) ¶

参数

• points – QPointF

• pointCount – int

Draws the first pointCount points in the buffer points

PySide2.QtGui.QPaintEngine. drawPolygon ( points , pointCount , mode ) ¶

参数

• points – QPoint

• pointCount – int

• mode – PolygonDrawMode

这是重载函数。

Reimplement this virtual function to draw the polygon defined by the pointCount first points in points , using mode mode .

注意

At least one of the drawPolygon() functions must be reimplemented.

PySide2.QtGui.QPaintEngine. drawPolygon ( points , pointCount , mode ) ¶

参数

• points – QPointF

• pointCount – int

• mode – PolygonDrawMode

Reimplement this virtual function to draw the polygon defined by the pointCount first points in points , using mode mode .

注意

At least one of the functions must be reimplemented.

PySide2.QtGui.QPaintEngine. drawRects ( rects , rectCount ) ¶

参数

• rects – QRect

• rectCount – int

这是重载函数。

The default implementation converts the first rectCount rectangles in the buffer rects 到 QRectF and calls the floating point version of this function.

PySide2.QtGui.QPaintEngine. drawRects ( rects , rectCount ) ¶

参数

• rects – QRectF

• rectCount – int

Draws the first rectCount rectangles in the buffer rects . The default implementation of this function calls drawPath() or drawPolygon() depending on the feature set of the paint engine.

PySide2.QtGui.QPaintEngine. drawTextItem ( p , textItem ) ¶

参数

• p – QPointF

• textItem – QTextItem

This function draws the text item textItem 在位置 p . The default implementation of this function converts the text to a QPainterPath and paints the resulting path.

PySide2.QtGui.QPaintEngine. drawTiledPixmap ( r , pixmap , s ) ¶

参数

• r – QRectF

• pixmap – QPixmap

• s – QPointF

Reimplement this function to draw the pixmap 以给定 rect , starting at the given p . The pixmap will be drawn repeatedly until the rect is filled.

PySide2.QtGui.QPaintEngine. end ( ) ¶

返回类型

bool

Reimplement this function to finish painting on the current paint device. Return true if painting was finished successfully; otherwise return false.

另请参阅

begin() isActive()

PySide2.QtGui.QPaintEngine. hasFeature ( feature ) ¶

参数

feature – PaintEngineFeatures

返回类型

bool

返回 true if the paint engine supports the specified feature ；否则返回 false .

PySide2.QtGui.QPaintEngine. isActive ( ) ¶

返回类型

bool

返回 true if the paint engine is actively drawing; otherwise returns false .

另请参阅

setActive()

PySide2.QtGui.QPaintEngine. isExtended ( ) ¶

返回类型

bool

PySide2.QtGui.QPaintEngine. paintDevice ( ) ¶

返回类型

QPaintDevice

Returns the device that this engine is painting on, if painting is active; otherwise returns None .

PySide2.QtGui.QPaintEngine. painter ( ) ¶

返回类型

QPainter

Returns the paint engine’s painter.

PySide2.QtGui.QPaintEngine. setActive ( newState ) ¶

参数

newState – bool

Sets the active state of the paint engine to state .

另请参阅

isActive()

PySide2.QtGui.QPaintEngine. setDirty ( df ) ¶

参数

df – DirtyFlags

PySide2.QtGui.QPaintEngine. setSystemClip ( baseClip ) ¶

参数

baseClip – QRegion

Sets the system clip for this engine. The system clip defines the basis area that the engine has to draw in. All clips that are set will be an intersection with the system clip.

Reset the systemclip to no clip by setting an empty region.

PySide2.QtGui.QPaintEngine. setSystemRect ( rect ) ¶

参数

rect – QRect

Sets the target rect for drawing within the backing store. This function should ONLY be used by the backing store.

PySide2.QtGui.QPaintEngine. syncState ( ) ¶

PySide2.QtGui.QPaintEngine. systemClip ( ) ¶

返回类型

QRegion

Returns the system clip. The system clip is read only while the painter is active. An empty region indicates that system clip is not in use.

PySide2.QtGui.QPaintEngine. systemRect ( ) ¶

返回类型

QRect

Retrieves the rect for drawing within the backing store. This function should ONLY be used by the backing store.

PySide2.QtGui.QPaintEngine. testDirty ( df ) ¶

参数

df – DirtyFlags

返回类型

bool

PySide2.QtGui.QPaintEngine. type ( ) ¶

返回类型

Type

Reimplement this function to return the paint engine Type .

PySide2.QtGui.QPaintEngine. updateState ( state ) ¶

参数

state – QPaintEngineState

Reimplement this function to update the state of a paint engine.

When implemented, this function is responsible for checking the paint engine’s current state and update the properties that are changed. Use the state() function to find out which properties that must be updated, then use the corresponding get function to retrieve the current values for the given properties.

另请参阅

QPaintEngineState