QQuickPaintedItem ¶

概要 ¶

详细描述 ¶

QQuickPaintedItem makes it possible to use the QPainter API with the QML Scene Graph. It sets up a textured rectangle in the Scene Graph and uses a QPainter to paint onto the texture. The render target can be either a QImage or, when OpenGL is in use, a QOpenGLFramebufferObject . When the render target is a QImage , QPainter first renders into the image then the content is uploaded to the texture. When a QOpenGLFramebufferObject is used, QPainter paints directly onto the texture. Call update() to trigger a repaint.

To enable QPainter to do anti-aliased rendering, use setAntialiasing() .

To write your own painted item, you first create a subclass of QQuickPaintedItem , and then start by implementing its only pure virtual public function: paint() , which implements the actual painting. The painting will be inside the rectangle spanning from 0,0 to width() , height() .

注意

It important to understand the performance implications such items can incur. See RenderTarget and renderTarget .

class QQuickPaintedItem ( [ parent=None ] ) ¶

param parent

QQuickItem

构造 QQuickPaintedItem 采用给定 parent 项。

PySide2.QtQuick.QQuickPaintedItem. RenderTarget ¶

This enum describes QQuickPaintedItem ‘s render targets. The render target is the surface QPainter paints onto before the item is rendered on screen.

常量	描述
QQuickPaintedItem.Image	The default; QPainter paints into a QImage using the raster paint engine. The image’s content needs to be uploaded to graphics memory afterward, this operation can potentially be slow if the item is large. This render target allows high quality anti-aliasing and fast item resizing.
QQuickPaintedItem.FramebufferObject	QPainter paints into a QOpenGLFramebufferObject using the GL paint engine. Painting can be faster as no texture upload is required, but anti-aliasing quality is not as good as if using an image. This render target allows faster rendering in some cases, but you should avoid using it if the item is resized often.
QQuickPaintedItem.InvertedYFramebufferObject	Exactly as for above, except once the painting is done, prior to rendering the painted image is flipped about the x-axis so that the top-most pixels are now at the bottom. Since this is done with the OpenGL texture coordinates it is a much faster way to achieve this effect than using a painter transform.

另请参阅

setRenderTarget()

PySide2.QtQuick.QQuickPaintedItem. PerformanceHint ¶

This enum describes flags that you can enable to improve rendering performance in QQuickPaintedItem . By default, none of these flags are set.

常量	描述
QQuickPaintedItem.FastFBOResizing	Resizing an FBO can be a costly operation on a few OpenGL driver implementations. To work around this, one can set this flag to let the QQuickPaintedItem allocate one large framebuffer object and instead draw into a subregion of it. This saves the resize at the cost of using more memory. Please note that this is not a common problem.

PySide2.QtQuick.QQuickPaintedItem. contentsBoundingRect ( ) ¶

返回类型

QRectF

This function is provided for compatibility, use size in combination with textureSize to decide the size of what you are drawing.

另请参阅

width() height() textureSize()

PySide2.QtQuick.QQuickPaintedItem. contentsScale ( ) ¶

返回类型

qreal

另请参阅

setContentsScale()

PySide2.QtQuick.QQuickPaintedItem. contentsScaleChanged ( ) ¶

PySide2.QtQuick.QQuickPaintedItem. contentsSize ( ) ¶

返回类型

QSize

另请参阅

setContentsSize()

PySide2.QtQuick.QQuickPaintedItem. contentsSizeChanged ( ) ¶

PySide2.QtQuick.QQuickPaintedItem. fillColor ( ) ¶

返回类型

QColor

另请参阅

setFillColor()

PySide2.QtQuick.QQuickPaintedItem. fillColorChanged ( ) ¶

PySide2.QtQuick.QQuickPaintedItem. mipmap ( ) ¶

返回类型

bool

Returns true if mipmaps are enabled; otherwise, false is returned.

By default, mipmapping is not enabled.

另请参阅

setMipmap()

PySide2.QtQuick.QQuickPaintedItem. opaquePainting ( ) ¶

返回类型

bool

Returns true if this item is opaque; otherwise, false is returned.

By default, painted items are not opaque.

另请参阅

setOpaquePainting()

PySide2.QtQuick.QQuickPaintedItem. paint ( painter ) ¶

参数

painter – QPainter

This function, which is usually called by the QML Scene Graph, paints the contents of an item in local coordinates.

The underlying texture will have a size defined by textureSize when set, or the item’s size, multiplied by the window’s device pixel ratio.

The function is called after the item has been filled with the fillColor .

Reimplement this function in a QQuickPaintedItem subclass to provide the item’s painting implementation, using painter .

注意

The QML Scene Graph uses two separate threads, the main thread does things such as processing events or updating animations while a second thread does the actual OpenGL rendering. As a consequence, is not called from the main GUI thread but from the GL enabled renderer thread. At the moment is called, the GUI thread is blocked and this is therefore thread-safe.

警告

Extreme caution must be used when creating QObjects, emitting signals, starting timers and similar inside this function as these will have affinity to the rendering thread.

另请参阅

width() height() textureSize

PySide2.QtQuick.QQuickPaintedItem. performanceHints ( ) ¶

返回类型

PerformanceHints

Returns the performance hints.

By default, no performance hint is enabled.

另请参阅

setPerformanceHint() setPerformanceHints()

PySide2.QtQuick.QQuickPaintedItem. renderTarget ( ) ¶

返回类型

RenderTarget

另请参阅

setRenderTarget()

PySide2.QtQuick.QQuickPaintedItem. renderTargetChanged ( ) ¶

PySide2.QtQuick.QQuickPaintedItem. resetContentsSize ( ) ¶

This convenience function is equivalent to calling setContentsSize (QSize()).

PySide2.QtQuick.QQuickPaintedItem. setContentsScale ( arg__1 ) ¶

参数

arg__1 – qreal

另请参阅

contentsScale()

PySide2.QtQuick.QQuickPaintedItem. setContentsSize ( arg__1 ) ¶

参数

arg__1 – QSize

另请参阅

contentsSize()

PySide2.QtQuick.QQuickPaintedItem. setFillColor ( arg__1 ) ¶

参数

arg__1 – QColor

另请参阅

fillColor()

PySide2.QtQuick.QQuickPaintedItem. setMipmap ( enable ) ¶

参数

enable – bool

若 enable is true, mipmapping is enabled on the associated texture.

Mipmapping increases rendering speed and reduces aliasing artifacts when the item is scaled down.

By default, mipmapping is not enabled.

另请参阅

mipmap()

PySide2.QtQuick.QQuickPaintedItem. setOpaquePainting ( opaque ) ¶

参数

opaque – bool

若 opaque is true, the item is opaque; otherwise, it is considered as translucent.

Opaque items are not blended with the rest of the scene, you should set this to true if the content of the item is opaque to speed up rendering.

By default, painted items are not opaque.

另请参阅

opaquePainting()

PySide2.QtQuick.QQuickPaintedItem. setPerformanceHint ( hint [ , enabled=true ] ) ¶

参数

• hint – PerformanceHint

• enabled – bool

Sets the given performance hint on the item if enabled is true; otherwise clears the performance hint.

By default, no performance hint is enabled/

另请参阅

setPerformanceHints() performanceHints()

PySide2.QtQuick.QQuickPaintedItem. setPerformanceHints ( hints ) ¶

参数

hints – PerformanceHints

Sets the performance hints to hints

By default, no performance hint is enabled/

另请参阅

setPerformanceHint() performanceHints()

PySide2.QtQuick.QQuickPaintedItem. setRenderTarget ( target ) ¶

参数

target – RenderTarget

另请参阅

renderTarget()

PySide2.QtQuick.QQuickPaintedItem. setTextureSize ( size ) ¶

参数

size – QSize

另请参阅

textureSize()

PySide2.QtQuick.QQuickPaintedItem. textureSize ( ) ¶

返回类型

QSize

另请参阅

setTextureSize()

PySide2.QtQuick.QQuickPaintedItem. textureSizeChanged ( ) ¶

PySide2.QtQuick.QQuickPaintedItem. update ( [ rect=QRect() ] ) ¶

参数

rect – QRect

Schedules a redraw of the area covered by rect in this item. You can call this function whenever your item needs to be redrawn, such as if it changes appearance or size.

This function does not cause an immediate paint; instead it schedules a paint request that is processed by the QML Scene Graph when the next frame is rendered. The item will only be redrawn if it is visible.

另请参阅

paint()