PySide.QtGui.QPaintEngine class provides an abstract definition of how PySide.QtGui.QPainter 绘制到给定设备在给定平台。
Qt 4.0 provides several premade implementations of PySide.QtGui.QPaintEngine for the different painter backends we support. We provide one paint engine for each window system and painting framework we support. This includes X11 on Unix/Linux and CoreGraphics on Mac OS X. In addition we provide PySide.QtGui.QPaintEngine implementations for OpenGL (accessible through PySide.QtOpenGL.QGLWidget ) and PostScript (accessible through QPSPrinter on X11). Additionally there is a raster-based paint engine that is a fallback for when an engine does not support a certain capability.
If one wants to use PySide.QtGui.QPainter to draw to a different backend, one must subclass PySide.QtGui.QPaintEngine and reimplement all its virtual functions. The PySide.QtGui.QPaintEngine implementation is then made available by subclassing PySide.QtGui.QPaintDevice and reimplementing the virtual function QPaintDevice.paintEngine() .
PySide.QtGui.QPaintEngine is created and owned by the PySide.QtGui.QPaintDevice that created it.
The big advantage of the PySide.QtGui.QPaintEngine approach opposed to Qt 3's PySide.QtGui.QPainter /QPaintDevice::cmd() approach is that it is now possible to adapt to multiple technologies on each platform and take advantage of each to the fullest.
| 参数： | features – PySide.QtGui.QPaintEngine.PaintEngineFeatures |
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| 常量 | 描述 |
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| 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. |
| 常量 | 描述 |
|---|---|
| QPaintEngine.X11 | |
| QPaintEngine.Windows | |
| QPaintEngine.MacPrinter | |
| QPaintEngine.CoreGraphics | Mac OS X's Quartz2D ( CoreGraphics ) |
| QPaintEngine.QuickDraw | Mac OS X's QuickDraw |
| QPaintEngine.QWindowSystem | Qt for Embedded Linux |
| QPaintEngine.PostScript | |
| QPaintEngine.OpenGL | |
| QPaintEngine.Picture | PySide.QtGui.QPicture format |
| QPaintEngine.SVG | Scalable Vector Graphics XML format |
| QPaintEngine.Raster | |
| QPaintEngine.Direct3D | Windows only, Direct3D 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 |
This enum is used to describe the features or capabilities that the paint engine has. If a feature is not supported by the engine, PySide.QtGui.QPainter will do a best effort to emulate that feature through other means and pass on an alpha blended PySide.QtGui.QImage to the engine with the emulated results. Some features cannot be emulated: AlphaBlend and PorterDuff .
| 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 QPainter.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 QGradient.ObjectBoundingMode . Otherwise, if QPaintEngine.PatternTransform is supported, object bounding mode gradients are converted to gradients with coordinate mode QGradient.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 Qt.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. |
| 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 QPaintEngine.updateState() . |
| QPaintEngine.AllDirty | Convenience enum used internally. |
These types are used by PySide.QtGui.QPainter to trigger lazy updates of the various states in the PySide.QtGui.QPaintEngine 使用 QPaintEngine.updateState() .
描绘引擎必须更新每脏点状态。
| 返回类型： | PySide.QtCore.bool |
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| 参数： | pdev – PySide.QtGui.QPaintDevice |
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| 返回类型： | PySide.QtCore.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.
| 参数： | df – PySide.QtGui.QPaintEngine.DirtyFlags |
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| 返回类型： | PySide.QtCore.QPoint |
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Returns the offset from the painters origo to the engines origo. This value is used by PySide.QtGui.QPainter for engines who have internal double buffering.
This function only makes sense when the engine is active.
| 参数： | r – PySide.QtCore.QRectF |
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Reimplement this function to draw the largest ellipse that can be contained within rectangle rect .
| 参数： | r – PySide.QtCore.QRect |
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The default implementation of this function calls the floating point version of this function
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The default implementation splits the list of lines in lines into lineCount separate calls to PySide.QtGui.QPaintEngine.drawPath() or PySide.QtGui.QPaintEngine.drawPolygon() depending on the feature set of the paint engine.
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这是重载函数。
The default implementation converts the first lineCount lines in lines 到 PySide.QtCore.QLineF and calls the floating point version of this function.
| 参数： | path – PySide.QtGui.QPainterPath |
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The default implementation ignores the path and does nothing.
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Reimplement this function to draw the part of the pm specified by the sr rectangle in the given r .
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Draws the first pointCount points in the buffer points
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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.
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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 PySide.QtGui.QPaintEngine.drawPolygon() functions must be reimplemented.
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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 PySide.QtGui.QPaintEngine.drawPolygon() functions must be reimplemented.
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这是重载函数。
The default implementation converts the first rectCount rectangles in the buffer rects 到 PySide.QtCore.QRectF and calls the floating point version of this function.
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Draws the first rectCount rectangles in the buffer rects . The default implementation of this function calls PySide.QtGui.QPaintEngine.drawPath() or PySide.QtGui.QPaintEngine.drawPolygon() depending on the feature set of the paint engine.
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This function draws the text item textItem 在位置 p . The default implementation of this function converts the text to a PySide.QtGui.QPainterPath and paints the resulting path.
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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.
| 返回类型： | PySide.QtCore.bool |
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Reimplement this function to finish painting on the current paint device. Return true if painting was finished successfully; otherwise return false.
| 参数： | feature – PySide.QtGui.QPaintEngine.PaintEngineFeatures |
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| 返回类型： | PySide.QtCore.bool |
| 返回类型： | PySide.QtCore.bool |
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Returns true if the paint engine is actively drawing; otherwise returns false.
| 返回类型： | PySide.QtCore.bool |
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Returns true if the paint engine is a QPaintEngineEx derivative.
| 返回类型： | PySide.QtGui.QPaintDevice |
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Returns the device that this engine is painting on, if painting is active; otherwise returns 0.
| 返回类型： | PySide.QtGui.QPainter |
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Returns the paint engine's painter.
| 参数： | newState – PySide.QtCore.bool |
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Sets the active state of the paint engine to state .
| 参数： | autoDestr – PySide.QtCore.bool |
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| 参数： | df – PySide.QtGui.QPaintEngine.DirtyFlags |
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| 参数： | baseClip – PySide.QtGui.QRegion |
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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 be an intersection with the system clip.
Reset the systemclip to no clip by setting an empty region.
| 参数： | rect – PySide.QtCore.QRect |
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Sets the target rect for drawing within the backing store. This function should ONLY be used by the backing store.
Updates all dirty states in this engine. This function should ONLY be used when drawing with native handles directly and immediate sync from QPainters state to the native state is required.
| 返回类型： | PySide.QtGui.QRegion |
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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.
| 返回类型： | PySide.QtCore.QRect |
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Retrieves the rect for drawing within the backing store. This function should ONLY be used by the backing store.
| 参数： | df – PySide.QtGui.QPaintEngine.DirtyFlags |
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| 返回类型： | PySide.QtCore.bool |
| 返回类型： | PySide.QtGui.QPaintEngine.Type |
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Reimplement this function to return the paint engine QPaintEngine.Type .
| 参数： | state – PySide.QtGui.QPaintEngineState |
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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 QPaintEngineState.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.
