The QGLContext class encapsulates an OpenGL rendering context.

An OpenGL rendering context is a complete set of OpenGL state variables. The rendering context’s format is set in the constructor, but it can also be set later with QGLContext.setFormat() . The format options that are actually set are returned by QGLContext.format() ; the options you asked for are returned by QGLContext.requestedFormat() . Note that after a QGLContext object has been constructed, the actual OpenGL context must be created by explicitly calling the QGLContext.create() function. The QGLContext.makeCurrent() function makes this context the current rendering context. You can make no context current using QGLContext.doneCurrent() . The QGLContext.reset() function will reset the context and make it invalid.

You can examine properties of the context with, e.g. QGLContext.isValid() , QGLContext.isSharing() , QGLContext.initialized() , QGLContext.windowCreated() and QGLContext.overlayTransparentColor() .

If you’re using double buffering you can swap the screen contents with the off-screen buffer using QGLContext.swapBuffers() .

Please note that QGLContext is not thread safe.

class PySide.QtOpenGL.QGLContext(format)¶

class PySide.QtOpenGL.QGLContext(format, device)

Parameters:	format – QGLFormat device – QPaintDevice

Constructs an OpenGL context with the given format which specifies several display options for the context.

If the underlying OpenGL/Window system cannot satisfy all the features requested in format , the nearest subset of features will be used. After creation, the QGLContext.format() method will return the actual format obtained.

Note that after a QGLContext object has been constructed, QGLContext.create() must be called explicitly to create the actual OpenGL context. The context will be invalid if it was not possible to obtain a GL context at all.

Constructs an OpenGL context for the given paint device , which can be a widget or a pixmap. The format specifies several display options for the context.

QGLContext.BindOption¶

A set of options to decide how to bind a texture using QGLContext.bindTexture() .

Constant	Description
QGLContext.NoBindOption	Don’t do anything, pass the texture straight through.
QGLContext.InvertedYBindOption	Specifies that the texture should be flipped over the X axis so that the texture coordinate 0,0 corresponds to the top left corner. Inverting the texture implies a deep copy prior to upload.
QGLContext.MipmapBindOption	Specifies that `QGLContext.bindTexture()` should try to generate mipmaps. If the GL implementation supports the `GL_SGIS_generate_mipmap` extension, mipmaps will be automatically generated for the texture. Mipmap generation is only supported for the `GL_TEXTURE_2D` target.
QGLContext.PremultipliedAlphaBindOption	Specifies that the image should be uploaded with premultiplied alpha and does a conversion accordingly.
QGLContext.LinearFilteringBindOption	Specifies that the texture filtering should be set to GL_LINEAR. Default is GL_NEAREST. If mipmap is also enabled, filtering will be set to GL_LINEAR_MIPMAP_LINEAR.
QGLContext.DefaultBindOption	In Qt 4.5 and earlier, `QGLContext.bindTexture()` would mirror the image and automatically generate mipmaps. This option helps preserve this default behavior.

Used by x11 from pixmap to choose wether or not it can bind the pixmap upside down or not.

Used by paint engines to indicate that the pixmap should be memory managed along side with the pixmap/image that it stems from, e.g. installing destruction hooks in them.

static QGLContext.areSharing(context1, context2)¶

Parameters:	context1 – QGLContext context2 – QGLContext
Return type:	bool

Returns true if context1 and context2 are sharing their GL resources such as textures, shader programs, etc; otherwise returns false.

QGLContext.bindTexture(fileName)¶

Parameter:	fileName – QString
Return type:	unsigned int

This is an overloaded function.

Reads the compressed texture file fileName and generates a 2D GL texture from it.

This function can load DirectDrawSurface (DDS) textures in the DXT1, DXT3 and DXT5 DDS formats if the GL_ARB_texture_compression and GL_EXT_texture_compression_s3tc extensions are supported.

Since 4.6.1, textures in the ETC1 format can be loaded if the GL_OES_compressed_ETC1_RGB8_texture extension is supported and the ETC1 texture has been encapsulated in the PVR container format. Also, textures in the PVRTC2 and PVRTC4 formats can be loaded if the GL_IMG_texture_compression_pvrtc extension is supported.

See also

QGLContext.deleteTexture()

QGLContext.bindTexture(pixmap, target, format, options)

Parameters:	pixmap – QPixmap target – unsigned int format – int options – BindOptions
Return type:	unsigned int

QGLContext.bindTexture(image, target, format, options)

Parameters:	image – QImage target – unsigned int format – int options – BindOptions
Return type:	unsigned int

QGLContext.bindTexture(pixmap[, target=0x0DE1, format=0x1908])

Parameters:	pixmap – QPixmap target – unsigned int format – int
Return type:	unsigned int

QGLContext.bindTexture(image[, target=0x0DE1, format=0x1908])

Parameters:	image – QImage target – unsigned int format – int
Return type:	unsigned int

QGLContext.chooseContext([shareContext=0])¶

Parameter:	shareContext – QGLContext
Return type:	bool

This semi-internal function is called by QGLContext.create() . It creates a system-dependent OpenGL handle that matches the QGLContext.format() of shareContext as closely as possible, returning true if successful or false if a suitable handle could not be found.

On Windows, it calls the virtual function choosePixelFormat() , which finds a matching pixel format identifier. On X11, it calls the virtual function QGLContext.chooseVisual() which finds an appropriate X visual. On other platforms it may work differently.

QGLContext.colorIndex(c)¶

Parameter:	c – QColor
Return type:	uint

Returns a colormap index for the color c, in ColorIndex mode. Used by qglColor() and qglClearColor().

QGLContext.create([shareContext=0])¶

Parameter:	shareContext – QGLContext
Return type:	bool

Creates the GL context. Returns true if it was successful in creating a valid GL rendering context on the paint device specified in the constructor; otherwise returns false (i.e. the context is invalid).

After successful creation, QGLContext.format() returns the set of features of the created GL rendering context.

If shareContext points to a valid QGLContext , this method will try to establish OpenGL display list and texture object sharing between this context and the shareContext . Note that this may fail if the two contexts have different formats . Use QGLContext.isSharing() to see if sharing is in effect.

Warning

Implementation note: initialization of C++ class members usually takes place in the class constructor. QGLContext is an exception because it must be simple to customize. The virtual functions QGLContext.chooseContext() (and QGLContext.chooseVisual() for X11) can be reimplemented in a subclass to select a particular context. The problem is that virtual functions are not properly called during construction (even though this is correct C++) because C++ constructs class hierarchies from the bottom up. For this reason we need a QGLContext.create() function.

static QGLContext.currentContext()¶

Return type:	QGLContext

Returns the current context, i.e. the context to which any OpenGL commands will currently be directed. Returns 0 if no context is current.

See also

QGLContext.makeCurrent()

QGLContext.deleteTexture(tx_id)¶

Parameter:	tx_id – unsigned int

QGLContext.device()¶

Return type:	QPaintDevice

Returns the paint device set for this context.

See also

QGLContext.QGLContext()

QGLContext.deviceIsPixmap()¶

Return type:	bool

Returns true if the paint device of this context is a pixmap; otherwise returns false.

QGLContext.doneCurrent()¶: Makes no GL context the current context. Normally, you do not need to call this function; QGLContext calls it as necessary.

QGLContext.drawTexture(point, textureId[, textureTarget=0x0DE1])¶

Parameters:	point – QPointF textureId – unsigned int textureTarget – unsigned int

QGLContext.drawTexture(target, textureId[, textureTarget=0x0DE1])

Parameters:	target – QRectF textureId – unsigned int textureTarget – unsigned int

QGLContext.format()¶

Return type:	QGLFormat

Returns the frame buffer format that was obtained (this may be a subset of what was requested).

QGLContext.initialized()¶

Return type:	bool

Returns true if this context has been initialized, i.e. if QGLWidget.initializeGL() has been performed on it; otherwise returns false.

See also

QGLContext.setInitialized()

QGLContext.isSharing()¶

Return type:	bool

Returns true if this context is sharing its GL context with another QGLContext , otherwise false is returned. Note that context sharing might not be supported between contexts with different formats.

QGLContext.isValid()¶

Return type:	bool

Returns true if a GL rendering context has been successfully created; otherwise returns false.

QGLContext.makeCurrent()¶

Makes this context the current OpenGL rendering context. All GL functions you call operate on this context until another context is made current.

In some very rare cases the underlying call may fail. If this occurs an error message is output to stderr.

QGLContext.operator=(arg__1)

Parameter:	arg__1 – QGLContext
Return type:	QGLContext

QGLContext.overlayTransparentColor()¶

Return type:	QColor

If this context is a valid context in an overlay plane, returns the plane’s transparent color. Otherwise returns an invalid color.

The returned color’s QColor.pixel() value is the index of the transparent color in the colormap of the overlay plane. (Naturally, the color’s RGB values are meaningless.)

The returned QColor object will generally work as expected only when passed as the argument to QGLWidget.qglColor() or QGLWidget.qglClearColor() . Under certain circumstances it can also be used to draw transparent graphics with a QPainter . See the examples/opengl/overlay_x11 example for details.

QGLContext.requestedFormat()¶

Return type:	QGLFormat

Returns the frame buffer format that was originally requested in the constructor or QGLContext.setFormat() .

See also

QGLContext.format()

QGLContext.reset()¶: Resets the context and makes it invalid.

See also

QGLContext.create() QGLContext.isValid()

QGLContext.setFormat(format)¶

Parameter:	format – QGLFormat

Sets a format for this context. The context is QGLContext.reset() .

Call QGLContext.create() to create a new GL context that tries to match the new format.

cx = QGLContext()
#  ...
f = QGLFormat()
f.setStereo(True)
cx.setFormat(f)
if !cx.create():
    exit() # no OpenGL support, or cannot render on the specified paintdevice
if !cx.format().stereo():
    exit() # could not create stereo context

QGLContext.setInitialized(on)¶

Parameter:	on – bool

If on is true the context has been initialized, i.e. QGLContext.setInitialized() has been called on it. If on is false the context has not been initialized.

See also

QGLContext.initialized()

static QGLContext.setTextureCacheLimit(size)¶

Parameter:	size – int

This function sets the limit for the texture cache to size , expressed in kilobytes.

By default, the cache limit is approximately 64 MB.

See also

QGLContext.textureCacheLimit()

QGLContext.setValid(valid)¶

Parameter:	valid – bool

Forces the GL rendering context to be valid.

See also

QGLContext.isValid()

QGLContext.setWindowCreated(on)¶

Parameter:	on – bool

If on is true the context has had a window created for it. If on is false no window has been created for the context.

See also

QGLContext.windowCreated()

QGLContext.swapBuffers()¶: Swaps the screen contents with an off-screen buffer. Only works if the context is in double buffer mode.

See also

QGLFormat.setDoubleBuffer()

static QGLContext.textureCacheLimit()¶