[−][src]Struct qt_gui::QOffscreenSurface

#[repr(C)]pub struct QOffscreenSurface { /* fields omitted */ }

The QOffscreenSurface class represents an offscreen surface in the underlying platform.

C++ class: QOffscreenSurface.

C++ documentation:

The QOffscreenSurface class represents an offscreen surface in the underlying platform.

QOffscreenSurface is intended to be used with QOpenGLContext to allow rendering with OpenGL in an arbitrary thread without the need to create a QWindow.

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 the QOffscreenSurface's context can be shared with the main OpenGL context. Some common use cases are asynchronous texture uploads or rendering into a QOpenGLFramebufferObject.

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 invisible QWindow internally.

Note: Due to the fact that QOffscreenSurface is backed by a QWindow on some platforms, cross-platform applications must ensure that create() is only called on the main (GUI) thread. The QOffscreenSurface is then safe to be used with makeCurrent() 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 from QOpenGLContext::format() or QWindow::format() after the context or window has been created. Passing the format returned from QWindow::requestedFormat() to setFormat() 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.

Methods

`impl QOffscreenSurface`[src]

`pub fn screen_changed(&self) -> Signal<(*mut QScreen,)>`[src]

This signal is emitted when an offscreen surface's screen changes, either by being set explicitly with setScreen(), or automatically when the window's screen is removed.

Returns a built-in Qt signal QOffscreenSurface::screenChanged that can be passed to qt_core::Signal::connect.

C++ documentation:

This signal is emitted when an offscreen surface's screen changes, either by being set explicitly with setScreen(), or automatically when the window's screen is removed.

`pub fn slot_screen_destroyed(&self) -> Receiver<(*mut QObject,)>`[src]

Returns a built-in Qt slot QOffscreenSurface::screenDestroyed that can be passed to qt_core::Signal::connect.

`pub unsafe fn create(&self)`[src]

Allocates the platform resources associated with the offscreen surface.

Calls C++ function: void QOffscreenSurface::create().

C++ documentation:

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 destroy().

`pub unsafe fn destroy(&self)`[src]

Releases the native platform resources associated with this offscreen surface.

Calls C++ function: void QOffscreenSurface::destroy().

C++ documentation:

Releases the native platform resources associated with this offscreen surface.

See also create().

`pub unsafe fn format(&self) -> CppBox<QSurfaceFormat>`[src]

Reimplemented from QSurface::format().

Calls C++ function: virtual QSurfaceFormat QOffscreenSurface::format() const.

C++ documentation:

Reimplemented from QSurface::format().

Returns the actual format of this offscreen surface.

After the offscreen surface has been created, this function will return the actual surface format of the surface. It might differ from the requested format if the requested format could not be fulfilled by the platform.

See also setFormat(), create(), and requestedFormat().

`pub unsafe fn is_valid(&self) -> bool`[src]

Returns true if this offscreen surface is valid; otherwise returns false.

Calls C++ function: bool QOffscreenSurface::isValid() const.

C++ documentation:

Returns true if this offscreen surface is valid; otherwise returns false.

The offscreen surface is valid if the platform resources have been successfuly allocated.

See also create().

`pub unsafe fn meta_object(&self) -> Ptr<QMetaObject>`[src]

Calls C++ function: virtual const QMetaObject* QOffscreenSurface::metaObject() const.

`pub unsafe fn native_handle(&self) -> *mut c_void`[src]

Returns an optional native handle to which the offscreen surface is connected.

Calls C++ function: void* QOffscreenSurface::nativeHandle() const.

C++ documentation:

Returns an optional native handle to which the offscreen surface is connected.

This function was introduced in Qt 5.9.

See also setNativeHandle().

`pub unsafe fn new_1a( screen: impl CastInto<Ptr<QScreen>> ) -> QBox<QOffscreenSurface>`[src]

Creates an offscreen surface for the targetScreen.

Calls C++ function: [constructor] void QOffscreenSurface::QOffscreenSurface(QScreen* screen = …).

C++ documentation:

Creates an offscreen surface for the targetScreen.

The underlying platform surface is not created until create() is called.

See also setScreen() and create().

`pub unsafe fn new_0a() -> QBox<QOffscreenSurface>`[src]

The QOffscreenSurface class represents an offscreen surface in the underlying platform.

Calls C++ function: [constructor] void QOffscreenSurface::QOffscreenSurface().