com.trolltech.qt.opengl
Class QGLFramebufferObject

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.opengl.QGLFramebufferObject
All Implemented Interfaces:
QPaintDeviceInterface, QtJambiInterface

public class QGLFramebufferObject
extends QtJambiObject
implements QPaintDeviceInterface

The QGLFramebufferObject class encapsulates an OpenGL framebuffer object. The QGLFramebufferObject class encapsulates an OpenGL framebuffer object, defined by the GL_EXT_framebuffer_object extension. In addition it provides a rendering surface that can be painted on with a QPainter, rendered to using native GL calls, or both. This surface can be bound and used as a regular texture in your own GL drawing code. By default, the QGLFramebufferObject class generates a 2D GL texture (using the GL_TEXTURE_2D target), which is used as the internal rendering target.

It is important to have a current GL context when creating a QGLFramebufferObject, otherwise initialization will fail.

OpenGL framebuffer objects and pbuffers (see QGLPixelBuffer) can both be used to render to offscreen surfaces, but there are a number of advantages with using framebuffer objects instead of pbuffers:

  1. A framebuffer object does not require a separate rendering context, so no context switching will occur when switching rendering targets. There is an overhead involved in switching targets, but in general it is cheaper than a context switch to a pbuffer.
  2. Rendering to dynamic textures (i.e. render-to-texture functionality) works on all platforms. No need to do explicit copy calls from a render buffer into a texture, as was necessary on systems that did not support the render_texture extension.
  3. It is possible to attach several rendering buffers (or texture objects) to the same framebuffer object, and render to all of them without doing a context switch.
  4. The OpenGL framebuffer extension is a pure GL extension with no system dependant WGL, CGL, or GLX parts. This makes using framebuffer objects more portable.
Note that primitives drawn to a QGLFramebufferObject with QPainter will only be antialiased if the QPainter::HighQualityAntialiasing render hint is set. This is because there is currently no support for the GL_EXT_framebuffer_multisample extension, which is required to do multisample based antialiasing. Also note that the QPainter::HighQualityAntialiasing render hint requires the GL_ARB_fragment_program extension to work in OpenGL.

See also:
Framebuffer Object Example.


Nested Class Summary
static class QGLFramebufferObject.Attachment
          This enum type is used to configure the depth and stencil buffers attached to the framebuffer object when it is created.
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QGLFramebufferObject(int width, int height)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(int width, int height, int target)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(int width, int height, QGLFramebufferObject.Attachment attachment)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(int width, int height, QGLFramebufferObject.Attachment attachment, int target)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(int width, int height, QGLFramebufferObject.Attachment attachment, int target, int internal_format)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(QSize size)
          Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the size size.
QGLFramebufferObject(QSize size, int target)
          Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the size size.
QGLFramebufferObject(QSize size, QGLFramebufferObject.Attachment attachment)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(QSize size, QGLFramebufferObject.Attachment attachment, int target)
          This is an overloaded member function, provided for convenience.
QGLFramebufferObject(QSize size, QGLFramebufferObject.Attachment attachment, int target, int internal_format)
          This is an overloaded member function, provided for convenience.
 
Method Summary
 QGLFramebufferObject.Attachment attachment()
          Returns the status of the depth and stencil buffers attached to this framebuffer object.
 boolean bind()
          Switches rendering from the default, windowing system provided framebuffer to this framebuffer object.
 int depth()
          Returns the bit depth (number of bit planes) of the paint device.
 void drawTexture(QPointF point, int textureId)
          Draws the given texture, textureId, at the given point in OpenGL model space.
 void drawTexture(QPointF point, int textureId, int textureTarget)
          Draws the given texture, textureId, at the given point in OpenGL model space.
 void drawTexture(QRectF target, int textureId)
          Draws the given texture, textureId, to the given target rectangle, target, in OpenGL model space.
 void drawTexture(QRectF target, int textureId, int textureTarget)
          Draws the given texture, textureId, to the given target rectangle, target, in OpenGL model space.
 int handle()
          Returns the GL framebuffer object handle for this framebuffer object (returned by the glGenFrameBuffersEXT() function).
static boolean hasOpenGLFramebufferObjects()
          Returns true if the OpenGL GL_EXT_framebuffer_object extension is present on this system; otherwise returns false.
 int height()
          Returns the height of the paint device in default coordinate system units (e.
 int heightMM()
          Returns the height of the paint device in millimeters.
 boolean isBound()
          Returns true if the framebuffer object is currently bound to a context, otherwise false is returned.
 boolean isValid()
          Returns true if the framebuffer object is valid.
 int logicalDpiX()
          Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes.
 int logicalDpiY()
          Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes.
 int metric(QPaintDevice.PaintDeviceMetric metric)
          Returns the metric information for the given paint device metric.
 int numColors()
          Returns the number of different colors available for the paint device.
 QPaintEngine paintEngine()
          Returns a pointer to the paint engine used for drawing on the device.
 boolean paintingActive()
          Returns true if the device is currently being painted on, i.
 int physicalDpiX()
          Returns the horizontal resolution of the device in dots per inch.
 int physicalDpiY()
          Returns the horizontal resolution of the device in dots per inch.
 boolean release()
          Switches rendering back to the default, windowing system provided framebuffer.
 QSize size()
          Returns the size of the texture attached to this framebuffer object.
 int texture()
          Returns the texture id for the texture attached as the default rendering target in this framebuffer object.
 QImage toImage()
          Returns the contents of this framebuffer object as a QImage.
 int width()
          Returns the width of the paint device in default coordinate system units (e.
 int widthMM()
          Returns the width of the paint device in millimeters.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QGLFramebufferObject

public QGLFramebufferObject(QSize size)
Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the size size. The texture is bound to the GL_COLOR_ATTACHMENT0 target in the framebuffer object.

The target parameter is used to specify the GL texture target. The default target is GL_TEXTURE_2D. Keep in mind that GL_TEXTURE_2D textures must have a power of 2 width and height (e.g. 256x512), unless you are using OpenGL 2.0 or higher.

By default, no depth and stencil buffers are attached. This behavior can be toggled using one of the overloaded constructors.

The default internal texture format is GL_RGBA8.

It is important that you have a current GL context set when creating the QGLFramebufferObject, otherwise the initialization will fail.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(QSize size,
                            int target)
Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the size size. The texture is bound to the GL_COLOR_ATTACHMENT0 target in the framebuffer object.

The target parameter is used to specify the GL texture target. The default target is GL_TEXTURE_2D. Keep in mind that GL_TEXTURE_2D textures must have a power of 2 width and height (e.g. 256x512), unless you are using OpenGL 2.0 or higher.

By default, no depth and stencil buffers are attached. This behavior can be toggled using one of the overloaded constructors.

The default internal texture format is GL_RGBA8.

It is important that you have a current GL context set when creating the QGLFramebufferObject, otherwise the initialization will fail.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(QSize size,
                            QGLFramebufferObject.Attachment attachment,
                            int target)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a texture to the buffer of the given size.

The attachment parameter describes the depth/stencil buffer configuration, target the texture target and internal_format the internal texture format. The default texture target is GL_TEXTURE_2D, while the default internal format is GL_RGBA8.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(QSize size,
                            QGLFramebufferObject.Attachment attachment)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a texture to the buffer of the given size.

The attachment parameter describes the depth/stencil buffer configuration, target the texture target and internal_format the internal texture format. The default texture target is GL_TEXTURE_2D, while the default internal format is GL_RGBA8.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(QSize size,
                            QGLFramebufferObject.Attachment attachment,
                            int target,
                            int internal_format)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a texture to the buffer of the given size.

The attachment parameter describes the depth/stencil buffer configuration, target the texture target and internal_format the internal texture format. The default texture target is GL_TEXTURE_2D, while the default internal format is GL_RGBA8.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(int width,
                            int height)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the given width and height.

See also:
size(), and texture().


QGLFramebufferObject

public QGLFramebufferObject(int width,
                            int height,
                            int target)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the given width and height.

See also:
size(), and texture().


QGLFramebufferObject

public QGLFramebufferObject(int width,
                            int height,
                            QGLFramebufferObject.Attachment attachment,
                            int target)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a texture to the buffer of the given width and height.

The attachment parameter describes the depth/stencil buffer configuration, target the texture target and internal_format the internal texture format. The default texture target is GL_TEXTURE_2D, while the default internal format is GL_RGBA8.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(int width,
                            int height,
                            QGLFramebufferObject.Attachment attachment)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a texture to the buffer of the given width and height.

The attachment parameter describes the depth/stencil buffer configuration, target the texture target and internal_format the internal texture format. The default texture target is GL_TEXTURE_2D, while the default internal format is GL_RGBA8.

See also:
size(), texture(), and attachment().


QGLFramebufferObject

public QGLFramebufferObject(int width,
                            int height,
                            QGLFramebufferObject.Attachment attachment,
                            int target,
                            int internal_format)
This is an overloaded member function, provided for convenience.

Constructs an OpenGL framebuffer object and binds a texture to the buffer of the given width and height.

The attachment parameter describes the depth/stencil buffer configuration, target the texture target and internal_format the internal texture format. The default texture target is GL_TEXTURE_2D, while the default internal format is GL_RGBA8.

See also:
size(), texture(), and attachment().

Method Detail

attachment

public final QGLFramebufferObject.Attachment attachment()
Returns the status of the depth and stencil buffers attached to this framebuffer object.


bind

public final boolean bind()
Switches rendering from the default, windowing system provided framebuffer to this framebuffer object. Returns true upon success, false otherwise.


depth

public final int depth()
Returns the bit depth (number of bit planes) of the paint device.

Specified by:
depth in interface QPaintDeviceInterface

drawTexture

public final void drawTexture(QPointF point,
                              int textureId)
Draws the given texture, textureId, at the given point in OpenGL model space. The textureTarget should be a 2D texture target.

The framebuffer object should be bound when calling this function.

Equivalent to the corresponding QGLContext::drawTexture().


drawTexture

public final void drawTexture(QPointF point,
                              int textureId,
                              int textureTarget)
Draws the given texture, textureId, at the given point in OpenGL model space. The textureTarget should be a 2D texture target.

The framebuffer object should be bound when calling this function.

Equivalent to the corresponding QGLContext::drawTexture().


drawTexture

public final void drawTexture(QRectF target,
                              int textureId)
Draws the given texture, textureId, to the given target rectangle, target, in OpenGL model space. The textureTarget should be a 2D texture target.

The framebuffer object should be bound when calling this function.

Equivalent to the corresponding QGLContext::drawTexture().


drawTexture

public final void drawTexture(QRectF target,
                              int 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.

The framebuffer object should be bound when calling this function.

Equivalent to the corresponding QGLContext::drawTexture().


handle

public final int handle()
Returns the GL framebuffer object handle for this framebuffer object (returned by the glGenFrameBuffersEXT() function). This handle can be used to attach new images or buffers to the framebuffer. The user is responsible for cleaning up and destroying these objects.


height

public final int height()
Returns the height of the paint device in default coordinate system units (e. . pixels for QPixmap and QWidget).

See also:
heightMM().

Specified by:
height in interface QPaintDeviceInterface

heightMM

public final int heightMM()
Returns the height of the paint device in millimeters. Due to platform limitations it may not be possible to use this function to determine the actual physical size of a widget on the screen.

See also:
height().

Specified by:
heightMM in interface QPaintDeviceInterface

isBound

public final boolean isBound()
Returns true if the framebuffer object is currently bound to a context, otherwise false is returned.


isValid

public final boolean isValid()
Returns true if the framebuffer object is valid.

The framebuffer can become invalid if the initialization process fails, the user attaches an invalid buffer to the framebuffer object, or a non-power of 2 width/height is specified as the texture size if the texture target is GL_TEXTURE_2D.


logicalDpiX

public final int logicalDpiX()
Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes. For X11, this is usually the same as could be computed from widthMM().

Note that if the logicalDpiX() doesn't equal the physicalDpiX(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
logicalDpiY(), and physicalDpiX().

Specified by:
logicalDpiX in interface QPaintDeviceInterface

logicalDpiY

public final int logicalDpiY()
Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes. For X11, this is usually the same as could be computed from heightMM().

Note that if the logicalDpiY() doesn't equal the physicalDpiY(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
logicalDpiX(), and physicalDpiY().

Specified by:
logicalDpiY in interface QPaintDeviceInterface

numColors

public final int numColors()
Returns the number of different colors available for the paint device. Since this value is an int, it will not be sufficient to represent the number of colors on 32 bit displays, in this case INT_MAX is returned instead.

Specified by:
numColors in interface QPaintDeviceInterface

paintingActive

public final boolean paintingActive()
Returns true if the device is currently being painted on, i. . someone has called QPainter::begin() but not yet called QPainter::end() for this device; otherwise returns false.

See also:
QPainter::isActive().

Specified by:
paintingActive in interface QPaintDeviceInterface

physicalDpiX

public final int physicalDpiX()
Returns the horizontal resolution of the device in dots per inch. For example, when printing, this resolution refers to the physical printer's resolution. The logical DPI on the other hand, refers to the resolution used by the actual paint engine.

Note that if the physicalDpiX() doesn't equal the logicalDpiX(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
physicalDpiY(), and logicalDpiX().

Specified by:
physicalDpiX in interface QPaintDeviceInterface

physicalDpiY

public final int physicalDpiY()
Returns the horizontal resolution of the device in dots per inch. For example, when printing, this resolution refers to the physical printer's resolution. The logical DPI on the other hand, refers to the resolution used by the actual paint engine.

Note that if the physicalDpiY() doesn't equal the logicalDpiY(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
physicalDpiX(), and logicalDpiY().

Specified by:
physicalDpiY in interface QPaintDeviceInterface

release

public final boolean release()
Switches rendering back to the default, windowing system provided framebuffer. Returns true upon success, false otherwise.


size

public final QSize size()
Returns the size of the texture attached to this framebuffer object.


texture

public final int texture()
Returns the texture id for the texture attached as the default rendering target in this framebuffer object. This texture id can be bound as a normal texture in your own GL code.


toImage

public final QImage toImage()
Returns the contents of this framebuffer object as a QImage.


width

public final int width()
Returns the width of the paint device in default coordinate system units (e. . pixels for QPixmap and QWidget).

See also:
widthMM().

Specified by:
width in interface QPaintDeviceInterface

widthMM

public final int widthMM()
Returns the width of the paint device in millimeters. Due to platform limitations it may not be possible to use this function to determine the actual physical size of a widget on the screen.

See also:
width().

Specified by:
widthMM in interface QPaintDeviceInterface

metric

public int metric(QPaintDevice.PaintDeviceMetric metric)
Returns the metric information for the given paint device metric.

See also:
PaintDeviceMetric .

Specified by:
metric in interface QPaintDeviceInterface

paintEngine

public QPaintEngine paintEngine()
Returns a pointer to the paint engine used for drawing on the device.

Specified by:
paintEngine in interface QPaintDeviceInterface

hasOpenGLFramebufferObjects

public static boolean hasOpenGLFramebufferObjects()
Returns true if the OpenGL GL_EXT_framebuffer_object extension is present on this system; otherwise returns false.