QOffscreenSurface¶
The
QOffscreenSurface
class represents an offscreen surface in the underlying platform. More…
New in version 5.1.
Synopsis¶
Functions¶
def
create
()def
destroy
()def
isValid
()def
nativeHandle
()def
requestedFormat
()def
screen
()def
setFormat
(format)def
setNativeHandle
(handle)def
setScreen
(screen)
Signals¶
def
screenChanged
(screen)
Detailed Description¶
QOffscreenSurface
is intended to be used withQOpenGLContext
to allow rendering with OpenGL in an arbitrary thread without the need to create aQWindow
.Even though the surface is typically renderable, the surface’s pixels are not accessible.
QOffscreenSurface
should only be used to create OpenGL resources such as textures or framebuffer objects.An application will typically use
QOffscreenSurface
to perform some time-consuming tasks in a separate thread in order to avoid stalling the main rendering thread. Resources created in theQOffscreenSurface
‘s context can be shared with the main OpenGL context. Some common use cases are asynchronous texture uploads or rendering into aQOpenGLFramebufferObject
.How the offscreen surface is implemented depends on the underlying platform, but it will typically use a pixel buffer (pbuffer). If the platform doesn’t implement or support offscreen surfaces,
QOffscreenSurface
will use an invisibleQWindow
internally.Note
Due to the fact that
QOffscreenSurface
is backed by aQWindow
on some platforms, cross-platform applications must ensure thatcreate()
is only called on the main (GUI) thread. TheQOffscreenSurface
is then safe to be used withmakeCurrent()
on other threads, but the initialization and destruction must always happen on the main (GUI) thread.Note
In order to create an offscreen surface that is guaranteed to be compatible with a given context and window, make sure to set the format to the context’s or the window’s actual format, that is, the
QSurfaceFormat
returned fromformat()
orformat()
after the context or window has been created . Passing the format returned fromrequestedFormat()
tosetFormat()
may result in an incompatible offscreen surface since the underlying windowing system interface may offer a different set of configurations for window and pbuffer surfaces.Note
Some platforms may utilize a surfaceless context extension (for example EGL_KHR_surfaceless_context) when available. In this case there will be no underlying native surface. For the use cases of
QOffscreenSurface
(rendering to FBOs, texture upload) this is not a problem.
- class PySide2.QtGui.QOffscreenSurface([screen=None])¶
PySide2.QtGui.QOffscreenSurface(screen, parent)
- param parent:
- param screen:
Creates an offscreen surface for the
targetScreen
.The underlying platform surface is not created until
create()
is called.See also
Creates an offscreen surface for the
targetScreen
with the givenparent
.The underlying platform surface is not created until
create()
is called.See also
- PySide2.QtGui.QOffscreenSurface.create()¶
Allocates the platform resources associated with the offscreen surface.
It is at this point that the surface format set using
setFormat()
gets resolved into an actual native surface.Call
destroy()
to free the platform resources if necessary.Note
Some platforms require this function to be called on the main (GUI) thread.
See also
- PySide2.QtGui.QOffscreenSurface.destroy()¶
Releases the native platform resources associated with this offscreen surface.
See also
- PySide2.QtGui.QOffscreenSurface.isValid()¶
- Return type:
bool
Returns
true
if this offscreen surface is valid; otherwise returnsfalse
.The offscreen surface is valid if the platform resources have been successfuly allocated.
See also
- PySide2.QtGui.QOffscreenSurface.nativeHandle()¶
- Return type:
void
Returns an optional native handle to which the offscreen surface is connected.
See also
- PySide2.QtGui.QOffscreenSurface.requestedFormat()¶
- Return type:
Returns the requested surfaceformat of this offscreen surface.
If the requested format was not supported by the platform implementation, the will differ from the actual offscreen surface format.
This is the value set with
setFormat()
.See also
setFormat()
format()
- PySide2.QtGui.QOffscreenSurface.screen()¶
- Return type:
Returns the screen to which the offscreen surface is connected.
See also
- PySide2.QtGui.QOffscreenSurface.screenChanged(screen)¶
- Parameters:
screen –
PySide2.QtGui.QScreen
- PySide2.QtGui.QOffscreenSurface.setFormat(format)¶
- Parameters:
format –
PySide2.QtGui.QSurfaceFormat
Sets the offscreen surface
format
.The surface format will be resolved in the
create()
function. Calling this function aftercreate()
will not re-resolve the surface format of the native surface.
- PySide2.QtGui.QOffscreenSurface.setNativeHandle(handle)¶
- Parameters:
handle –
void
Sets the native handle to which the offscreen surface is connected to
handle
.The native handle will be resolved in the
create()
function. Calling this function aftercreate()
will not re-create a native surface.Note
The interpretation of the native handle is platform specific. Only some platforms will support adopting native handles of offscreen surfaces and platforms that do not implement this support will ignore the handle.
See also
- PySide2.QtGui.QOffscreenSurface.setScreen(screen)¶
- Parameters:
screen –
PySide2.QtGui.QScreen
Sets the screen to which the offscreen surface is connected.
If the offscreen surface has been created, it will be recreated on the
newScreen
.See also
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