class QOpenGLPaintDevice¶

The QOpenGLPaintDevice class enables painting to an OpenGL context using QPainter. More…

Synopsis¶

Methods¶

def __init__()
def context()
def dotsPerMeterX()
def dotsPerMeterY()
def paintFlipped()
def setDevicePixelRatio()
def setDotsPerMeterX()
def setDotsPerMeterY()
def setPaintFlipped()
def setSize()
def size()

Virtual methods¶

def ensureActiveTarget()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description¶

The QOpenGLPaintDevice uses the current QOpenGL context to render QPainter draw commands. The context is captured upon construction. It requires support for OpenGL (ES) 2.0 or higher.

Performance¶

The QOpenGLPaintDevice is almost always hardware accelerated and has the potential of being much faster than software rasterization. However, it is more sensitive to state changes, and therefore requires the drawing commands to be carefully ordered to achieve optimal performance.

Antialiasing and Quality¶

Antialiasing in the OpenGL paint engine is done using multisampling. Most hardware require significantly more memory to do multisampling and the resulting quality is not on par with the quality of the software paint engine. The OpenGL paint engine’s strength lies in its performance, not its visual rendering quality.

State Changes¶

When painting to a QOpenGLPaintDevice using QPainter, the state of the current OpenGL context will be altered by the paint engine to reflect its needs. Applications should not rely upon the OpenGL state being reset to its original conditions, particularly the current shader program, OpenGL viewport, texture units, and drawing modes.

Mixing QPainter and OpenGL¶

When intermixing QPainter and OpenGL, it is important to notify QPainter that the OpenGL state may have been cluttered so it can restore its internal state. This is achieved by calling QPainter::beginNativePainting() before starting the OpenGL rendering and calling QPainter::endNativePainting() after finishing.

See also

OpenGL Window Example

__init__()¶

Constructs a QOpenGLPaintDevice .

The QOpenGLPaintDevice is only valid for the current context.

See also

currentContext()

__init__(size)

Parameters:: size – QSize

Constructs a QOpenGLPaintDevice with the given size.

The QOpenGLPaintDevice is only valid for the current context.

See also

currentContext()

__init__(width, height)

Parameters:

width – int
height – int

Constructs a QOpenGLPaintDevice with the given width and height.

The QOpenGLPaintDevice is only valid for the current context.

See also

currentContext()

context()¶

Return type:: QOpenGLContext

Returns the OpenGL context associated with the paint device.

dotsPerMeterX()¶

Return type:: float

Returns the number of pixels per meter horizontally.

See also

setDotsPerMeterX()

dotsPerMeterY()¶

Return type:: float

Returns the number of pixels per meter vertically.

See also

setDotsPerMeterY()

ensureActiveTarget()¶

This virtual method is provided as a callback to allow re-binding a target frame buffer object or context when different QOpenGLPaintDevice instances are issuing draw calls alternately.

beginNativePainting() will also trigger this method.

The default implementation does nothing.

paintFlipped()¶

Return type:: bool

Returns true if painting is flipped around the Y-axis.

See also

setPaintFlipped()

setDevicePixelRatio(devicePixelRatio)¶

Parameters:: devicePixelRatio – float

Sets the device pixel ratio for the paint device to devicePixelRatio.

setDotsPerMeterX(arg__1)¶

Parameters:: arg__1 – float

Sets the number of pixels per meter horizontally to dpmx.

See also

dotsPerMeterX()

setDotsPerMeterY(arg__1)¶

Parameters:: arg__1 – float

Sets the number of pixels per meter vertically to dpmy.

See also

dotsPerMeterY()

setPaintFlipped(flipped)¶

Parameters:: flipped – bool

Sets whether painting should be flipped around the Y-axis or not to flipped.

See also

paintFlipped()

setSize(size)¶

Parameters:: size – QSize

Sets the pixel size of the paint device to size.

See also

size()

size()¶

Return type:: QSize

Returns the pixel size of the paint device.

See also

setSize()