QtOpenGL.QGLPixelBuffer Class Reference

The QGLPixelBuffer class encapsulates an OpenGL pbuffer. More...

Inheritance diagram for QtOpenGL.QGLPixelBuffer:

Collaboration diagram for QtOpenGL.QGLPixelBuffer:

Public Member Functions
	QGLPixelBuffer (QSize size)
	QGLPixelBuffer (QSize size, QGLFormat format, QGLWidget shareWidget=null)
	QGLPixelBuffer (int width, int height)
	QGLPixelBuffer (int width, int height, QGLFormat format, QGLWidget shareWidget=null)
override void	CreateProxy ()
new uint	BindTexture (QImage image)
new uint	BindTexture (QPixmap pixmap)
new uint	BindTexture (QImage image, int target)
new uint	BindTexture (QPixmap pixmap, int target)
new uint	BindTexture (string fileName)
new bool	BindToDynamicTexture (uint texture)
new void	DeleteTexture (uint texture_id)
override int	DevType ()
new bool	DoneCurrent ()
new void	DrawTexture (QRectF target, uint textureId)
new void	DrawTexture (QPointF point, uint textureId)
new void	DrawTexture (QRectF target, uint textureId, int textureTarget)
new void	DrawTexture (QPointF point, uint textureId, int textureTarget)
new QGLFormat	Format ()
new uint	GenerateDynamicTexture ()
new bool	IsValid ()
new bool	MakeCurrent ()
override QPaintEngine	PaintEngine ()
new void	ReleaseFromDynamicTexture ()
new QSize	Size ()
new QImage	ToImage ()
new void	UpdateDynamicTexture (uint texture_id)
new void	Dispose ()
Public Member Functions inherited from QtGui.QPaintDevice
new int	ColorCount ()
new int	Depth ()
virtual System.IntPtr	GetDC ()
new int	Height ()
new int	HeightMM ()
new int	LogicalDpiX ()
new int	LogicalDpiY ()
new int	NumColors ()
new bool	PaintingActive ()
new int	PhysicalDpiX ()
new int	PhysicalDpiY ()
virtual void	ReleaseDC (System.IntPtr hdc)
new int	Width ()
new int	WidthMM ()
new void	Dispose ()
Public Member Functions inherited from QtGui.IQPaintDevice
new int	ColorCount ()
new int	Depth ()
int	DevType ()
System.IntPtr	GetDC ()
new int	Height ()
new int	HeightMM ()
new int	LogicalDpiX ()
new int	LogicalDpiY ()
new int	NumColors ()
QPaintEngine	PaintEngine ()
new bool	PaintingActive ()
new int	PhysicalDpiX ()
new int	PhysicalDpiY ()
void	ReleaseDC (System.IntPtr hdc)
new int	Width ()
new int	WidthMM ()

Static Public Member Functions
static bool	HasOpenGLPbuffers ()

Protected Member Functions
	QGLPixelBuffer (System.Type dummy)
override int	Metric (QPaintDevice.PaintDeviceMetric metric)
Protected Member Functions inherited from QtGui.QPaintDevice
	QPaintDevice (System.Type dummy)
	QPaintDevice ()

Additional Inherited Members
Public Types inherited from QtGui.QPaintDevice
enum	PaintDeviceMetric {   PdmDepth = 6, PdmDpiX = 7, PdmDpiY = 8, PdmHeight = 2,   PdmHeightMM = 4, PdmNumColors = 5, PdmPhysicalDpiX = 9, PdmPhysicalDpiY = 10,   PdmWidth = 1, PdmWidthMM = 3 }
	More...
Protected Attributes inherited from QtGui.QPaintDevice
SmokeInvocation	interceptor
Properties inherited from QtGui.QPaintDevice
virtual System.IntPtr	SmokeObject [get, set]
new ushort	Painters [get, set]

Detailed Description

The QGLPixelBuffer class encapsulates an OpenGL pbuffer.

Rendering into a pbuffer is normally done using full hardware acceleration. This can be significantly faster than rendering into a QPixmap.

There are three approaches to using this class:

We can draw into the pbuffer and convert it to a QImage using toImage(). This is normally much faster than calling QGLWidget::renderPixmap().

We can draw into the pbuffer and copy the contents into an OpenGL texture using updateDynamicTexture(). This allows us to create dynamic textures and works on all systems with pbuffer support.

On systems that support it, we can bind the pbuffer to an OpenGL texture. The texture is then updated automatically when the pbuffer contents change, eliminating the need for additional copy operations. This is supported only on Windows and Mac OS X systems that provide the render_texture extension. Note that under Windows, a multi-sampled pbuffer can't be used in conjunction with the render_texture extension. If a multi-sampled pbuffer is requested under Windows, the render_texture extension is turned off for that pbuffer.

Threading

As of Qt 4.8, it's possible to render into a QGLPixelBuffer using a QPainter in a separate thread. Note that OpenGL 2.0 or OpenGL ES 2.0 is required for this to work. Also, under X11, it's necessary to set the Qt::AA_X11InitThreads application attribute.

Pbuffers are provided by the OpenGL pbuffer extension; call hasOpenGLPbuffer() to find out if the system provides pbuffers.

See also Pbuffers Example.

Constructor & Destructor Documentation

QtOpenGL.QGLPixelBuffer.QGLPixelBuffer ( System.Type  dummy )

protected

QtOpenGL.QGLPixelBuffer.QGLPixelBuffer

(

QSize

size

)

Constructs an OpenGL pbuffer of the given size. If no format is specified, the default format is used. If the shareWidget parameter points to a valid QGLWidget, the pbuffer will share its context with shareWidget.

If you intend to bind this pbuffer as a dynamic texture, the width and height components of size must be powers of two (e.g., 512 x 128).

See also size() and format().

QtOpenGL.QGLPixelBuffer.QGLPixelBuffer	(	QSize	size,
		QGLFormat	format,
		QGLWidget	shareWidget = null
	)

Constructs an OpenGL pbuffer of the given size. If no format is specified, the default format is used. If the shareWidget parameter points to a valid QGLWidget, the pbuffer will share its context with shareWidget.

If you intend to bind this pbuffer as a dynamic texture, the width and height components of size must be powers of two (e.g., 512 x 128).

See also size() and format().

QtOpenGL.QGLPixelBuffer.QGLPixelBuffer	(	int	width,
		int	height
	)

Constructs an OpenGL pbuffer of the given size. If no format is specified, the default format is used. If the shareWidget parameter points to a valid QGLWidget, the pbuffer will share its context with shareWidget.

If you intend to bind this pbuffer as a dynamic texture, the width and height components of size must be powers of two (e.g., 512 x 128).

See also size() and format().

QtOpenGL.QGLPixelBuffer.QGLPixelBuffer	(	int	width,
		int	height,
		QGLFormat	format,
		QGLWidget	shareWidget = null
	)

Constructs an OpenGL pbuffer of the given size. If no format is specified, the default format is used. If the shareWidget parameter points to a valid QGLWidget, the pbuffer will share its context with shareWidget.

If you intend to bind this pbuffer as a dynamic texture, the width and height components of size must be powers of two (e.g., 512 x 128).

See also size() and format().

Member Function Documentation

new uint QtOpenGL.QGLPixelBuffer.BindTexture

(

QImage

image

)

Generates and binds a 2D GL texture to the current context, based on image. The generated texture id is returned and can be used in later glBindTexture() calls.

The target parameter specifies the texture target.

Equivalent to calling QGLContext::bindTexture().

See also deleteTexture().

new uint QtOpenGL.QGLPixelBuffer.BindTexture

(

QPixmap

pixmap

)

Generates and binds a 2D GL texture to the current context, based on image. The generated texture id is returned and can be used in later glBindTexture() calls.

The target parameter specifies the texture target.

Equivalent to calling QGLContext::bindTexture().

See also deleteTexture().

new uint QtOpenGL.QGLPixelBuffer.BindTexture	(	QImage	image,
		int	target
	)

Generates and binds a 2D GL texture to the current context, based on image. The generated texture id is returned and can be used in later glBindTexture() calls.

The target parameter specifies the texture target.

Equivalent to calling QGLContext::bindTexture().

See also deleteTexture().

new uint QtOpenGL.QGLPixelBuffer.BindTexture	(	QPixmap	pixmap,
		int	target
	)

This is an overloaded function.

Generates and binds a 2D GL texture based on pixmap.

Equivalent to calling QGLContext::bindTexture().

See also deleteTexture().

new uint QtOpenGL.QGLPixelBuffer.BindTexture

(

string

fileName

)

This is an overloaded function.

Reads the DirectDrawSurface (DDS) compressed file fileName and generates a 2D GL texture from it.

Equivalent to calling QGLContext::bindTexture().

See also deleteTexture().

new bool QtOpenGL.QGLPixelBuffer.BindToDynamicTexture

(

uint

texture

)

Binds the texture specified by texture_id to this pbuffer. Returns true on success; otherwise returns false.

The texture must be of the same size and format as the pbuffer.

To unbind the texture, call releaseFromDynamicTexture(). While the texture is bound, it is updated automatically when the pbuffer contents change, eliminating the need for additional copy operations.

Example:

QGLPixelBuffer pbuffer(...);

...

pbuffer.makeCurrent();

GLuint dynamicTexture = pbuffer.generateDynamicTexture();

pbuffer.bindToDynamicTexture(dynamicTexture);

...

pbuffer.releaseFromDynamicTexture();

Warning: This function uses the render_texture extension, which is currently not supported under X11. An alternative that works on all systems (including X11) is to manually copy the pbuffer contents to a texture using updateDynamicTexture().

Warning: For the bindToDynamicTexture() call to succeed on the Mac OS X, the pbuffer needs a shared context, i.e. the QGLPixelBuffer must be created with a share widget.

See also generateDynamicTexture() and releaseFromDynamicTexture().

override void QtOpenGL.QGLPixelBuffer.CreateProxy ( )

virtual

Reimplemented from QtGui.QPaintDevice.

new void QtOpenGL.QGLPixelBuffer.DeleteTexture

(

uint

texture_id

)

Removes the texture identified by texture_id from the texture cache.

Equivalent to calling QGLContext::deleteTexture().

override int QtOpenGL.QGLPixelBuffer.DevType ( )

virtual

Reimplemented from QtGui.QPaintDevice.

new void QtOpenGL.QGLPixelBuffer.Dispose

(

)

new bool QtOpenGL.QGLPixelBuffer.DoneCurrent

(

)

Makes no context the current OpenGL context. Returns true on success; otherwise returns false.

new void QtOpenGL.QGLPixelBuffer.DrawTexture	(	QRectF	target,
		uint	textureId
	)

Draws the given texture, textureId, to the given target rectangle, target, in OpenGL model space. The textureTarget should be a 2D texture target.

Equivalent to the corresponding QGLContext::drawTexture().

This function was introduced in Qt 4.4.

new void QtOpenGL.QGLPixelBuffer.DrawTexture	(	QPointF	point,
		uint	textureId
	)

Draws the given texture, textureId, to the given target rectangle, target, in OpenGL model space. The textureTarget should be a 2D texture target.

Equivalent to the corresponding QGLContext::drawTexture().

This function was introduced in Qt 4.4.

new void QtOpenGL.QGLPixelBuffer.DrawTexture	(	QRectF	target,
		uint	textureId,
		int	textureTarget
	)

Draws the given texture, textureId, to the given target rectangle, target, in OpenGL model space. The textureTarget should be a 2D texture target.

Equivalent to the corresponding QGLContext::drawTexture().

This function was introduced in Qt 4.4.

new void QtOpenGL.QGLPixelBuffer.DrawTexture	(	QPointF	point,
		uint	textureId,
		int	textureTarget
	)

Draws the given texture, textureId, at the given point in OpenGL model space. The textureTarget parameter should be a 2D texture target.

Equivalent to the corresponding QGLContext::drawTexture().

This function was introduced in Qt 4.4.

new QGLFormat QtOpenGL.QGLPixelBuffer.Format

(

)

Returns the format of the pbuffer. The format may be different from the one that was requested.

new uint QtOpenGL.QGLPixelBuffer.GenerateDynamicTexture

(

)

Generates and binds a 2D GL texture that is the same size as the pbuffer, and returns the texture's ID. This can be used in conjunction with bindToDynamicTexture() and updateDynamicTexture().

See also size().

static bool QtOpenGL.QGLPixelBuffer.HasOpenGLPbuffers ( )

static

Returns true if the OpenGL pbuffer extension is present on this system; otherwise returns false.

new bool QtOpenGL.QGLPixelBuffer.IsValid

(

)

Returns true if this pbuffer is valid; otherwise returns false.

new bool QtOpenGL.QGLPixelBuffer.MakeCurrent

(

)

Makes this pbuffer the current OpenGL rendering context. Returns true on success; otherwise returns false.

See also QGLContext::makeCurrent() and doneCurrent().

override int QtOpenGL.QGLPixelBuffer.Metric ( QPaintDevice.PaintDeviceMetric  metric )

protectedvirtual

Reimplemented from QPaintDevice::metric().

Reimplemented from QtGui.QPaintDevice.

override QPaintEngine QtOpenGL.QGLPixelBuffer.PaintEngine ( )

virtual

Reimplemented from QPaintDevice::paintEngine().

Implements QtGui.QPaintDevice.

new void QtOpenGL.QGLPixelBuffer.ReleaseFromDynamicTexture

(

)

Releases the pbuffer from any previously bound texture.

See also bindToDynamicTexture().

new QSize QtOpenGL.QGLPixelBuffer.Size

(

)

Returns the size of the pbuffer.

new QImage QtOpenGL.QGLPixelBuffer.ToImage

(

)

Returns the contents of the pbuffer as a QImage.

new void QtOpenGL.QGLPixelBuffer.UpdateDynamicTexture

(

uint

texture_id

)

Copies the pbuffer contents into the texture specified with texture_id.

The texture must be of the same size and format as the pbuffer.

Example:

QGLPixelBuffer pbuffer(...);

...

pbuffer.makeCurrent();

GLuint dynamicTexture = pbuffer.generateDynamicTexture();

...

pbuffer.updateDynamicTexture(dynamicTexture);

An alternative on Windows and Mac OS X systems that support the render_texture extension is to use bindToDynamicTexture() to get dynamic updates of the texture.

See also generateDynamicTexture() and bindToDynamicTexture().