QOpenGLTextureBlitter#
The QOpenGLTextureBlitter
class provides a convenient way to draw textured quads via OpenGL. More…
Synopsis#
Functions#
def
bind
([target=GL_TEXTURE_2D])def
blit
(texture, targetTransform, sourceOrigin)def
blit
(texture, targetTransform, sourceTransform)def
create
()def
destroy
()def
isCreated
()def
release
()def
setOpacity
(opacity)def
setRedBlueSwizzle
(swizzle)def
supportsExternalOESTarget
()def
supportsRectangleTarget
()
Static functions#
def
sourceTransform
(subTexture, textureSize, origin)def
targetTransform
(target, viewport)
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description#
Drawing textured quads, in order to get the contents of a texture onto the screen, is a common operation when developing 2D user interfaces. QOpenGLTextureBlitter
provides a convenience class to avoid repeating vertex data, shader sources, buffer and program management and matrix calculations.
For example, a QOpenGLWidget
subclass can do the following to draw the contents rendered into a framebuffer at the pixel position (x, y)
:
void OpenGLWidget::initializeGL() { m_blitter.create(); m_fbo = new QOpenGLFramebufferObject(size); } void OpenGLWidget::paintGL() { m_fbo->bind(); // update offscreen content m_fbo->release(); m_blitter.bind(); const QRect targetRect(QPoint(x, y), m_fbo->size()); const QMatrix4x4 target = QOpenGLTextureBlitter::targetTransform(targetRect, QRect(QPoint(0, 0), m_fbo->size())); m_blitter.blit(m_fbo->texture(), target, QOpenGLTextureBlitter::OriginBottomLeft); m_blitter.release(); }
The blitter implements GLSL shaders both for GLSL 1.00 (suitable for OpenGL (ES) 2.x and compatibility profiles of newer OpenGL versions) and version 150 (suitable for core profile contexts with OpenGL 3.2 and newer).
- class PySide6.QtOpenGL.QOpenGLTextureBlitter#
Constructs a new QOpenGLTextureBlitter
instance.
Note
no graphics resources are initialized in the constructor. This makes it safe to place plain QOpenGLTextureBlitter
members into classes because the actual initialization that depends on the OpenGL context happens only in create()
.
- PySide6.QtOpenGL.QOpenGLTextureBlitter.Origin#
Constant
Description
QOpenGLTextureBlitter.OriginBottomLeft
Indicates that the data in the texture follows the OpenGL convention of coordinate systems, meaning Y is running from bottom to top.
QOpenGLTextureBlitter.OriginTopLeft
Indicates that the data in the texture has Y running from top to bottom, which is typical with regular, unflipped image data.
See also
- PySide6.QtOpenGL.QOpenGLTextureBlitter.bind([target=GL_TEXTURE_2D])#
- Parameters:
target – int
Binds the graphics resources used by the blitter. This must be called before calling blit()
. Code modifying the OpenGL state should be avoided between the call to bind() and blit()
because otherwise conflicts may arise.
target
is the texture target for the source texture and must be either GL_TEXTURE_2D
, GL_TEXTURE_RECTANGLE
, or GL_OES_EGL_image_external
.
- PySide6.QtOpenGL.QOpenGLTextureBlitter.blit(texture, targetTransform, sourceOrigin)#
- Parameters:
texture – int
targetTransform –
PySide6.QtGui.QMatrix4x4
sourceOrigin –
Origin
- PySide6.QtOpenGL.QOpenGLTextureBlitter.blit(texture, targetTransform, sourceTransform)
- Parameters:
texture – int
targetTransform –
PySide6.QtGui.QMatrix4x4
sourceTransform –
PySide6.QtGui.QMatrix3x3
- PySide6.QtOpenGL.QOpenGLTextureBlitter.create()#
- Return type:
bool
Initializes the graphics resources used by the blitter.
Returns true
if successful, false
if there was a failure. Failures can occur when there is no OpenGL context current on the current thread, or when shader compilation fails for some reason.
See also
- PySide6.QtOpenGL.QOpenGLTextureBlitter.destroy()#
Frees all graphics resources held by the blitter. Assumes that the OpenGL context, or another context sharing resources with it, that was current on the thread when invoking create()
is current.
The function has no effect when the blitter is not in created state.
See also
- PySide6.QtOpenGL.QOpenGLTextureBlitter.isCreated()#
- Return type:
bool
Returns true
if create()
was called and succeeded. false
otherwise.
- PySide6.QtOpenGL.QOpenGLTextureBlitter.release()#
Unbinds the graphics resources used by the blitter.
See also
- PySide6.QtOpenGL.QOpenGLTextureBlitter.setOpacity(opacity)#
- Parameters:
opacity – float
Changes the opacity to opacity
. The default opacity is 1.0.
Note
the blitter does not alter the blend state. It is up to the caller of blit()
to ensure the correct blend settings are active.
- PySide6.QtOpenGL.QOpenGLTextureBlitter.setRedBlueSwizzle(swizzle)#
- Parameters:
swizzle – bool
Sets whether swizzling is enabled for the red and blue color channels to swizzle
. An BGRA to RGBA conversion (occurring in the shader on the GPU, instead of a slow CPU-side transformation) can be useful when the source texture contains data from a QImage with a format like QImage::Format_ARGB32 which maps to BGRA on little endian systems.
By default the red-blue swizzle is disabled since this is what a texture attached to an framebuffer object or a texture based on a byte ordered QImage format (like QImage::Format_RGBA8888) needs.
- static PySide6.QtOpenGL.QOpenGLTextureBlitter.sourceTransform(subTexture, textureSize, origin)#
- Parameters:
subTexture –
PySide6.QtCore.QRectF
textureSize –
PySide6.QtCore.QSize
origin –
Origin
- Return type:
Calculates a 3x3 matrix suitable as the input to blit()
. This is used when only a part of the texture is to be used in the blit.
subTexture
is the desired source rectangle in pixels, textureSize
is the full width and height of the texture data. origin
specifies the orientation of the image data when it comes to the Y axis.
See also
blit()
Origin
- PySide6.QtOpenGL.QOpenGLTextureBlitter.supportsExternalOESTarget()#
- Return type:
bool
Returns true
when bind()
accepts GL_TEXTURE_EXTERNAL_OES
as its target argument.
- PySide6.QtOpenGL.QOpenGLTextureBlitter.supportsRectangleTarget()#
- Return type:
bool
Returns true
when bind()
accepts GL_TEXTURE_RECTANGLE
as its target argument.
- static PySide6.QtOpenGL.QOpenGLTextureBlitter.targetTransform(target, viewport)#
- Parameters:
target –
PySide6.QtCore.QRectF
viewport –
PySide6.QtCore.QRect
- Return type:
Calculates a target transform suitable for blit()
.
target
is the target rectangle in pixels. viewport
describes the source dimensions and will in most cases be set to (0, 0, image width, image height).
For unscaled output the size of target
and viewport
should match.
See also