diff options
Diffstat (limited to 'src/gui/opengl/qopenglframebufferobject.cpp')
| -rw-r--r-- | src/gui/opengl/qopenglframebufferobject.cpp | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/src/gui/opengl/qopenglframebufferobject.cpp b/src/gui/opengl/qopenglframebufferobject.cpp index 83cfaf8f93..124d9d53f6 100644 --- a/src/gui/opengl/qopenglframebufferobject.cpp +++ b/src/gui/opengl/qopenglframebufferobject.cpp @@ -1203,9 +1203,23 @@ Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, If used together with QOpenGLPaintDevice, \a flipped should be the opposite of the value of QOpenGLPaintDevice::paintFlipped(). - Will try to return a premultiplied ARBG32 or RGB32 image. Since 5.2 it will fall back to - a premultiplied RGBA8888 or RGBx8888 image when reading to ARGB32 is not supported. Since 5.4 an - A2BGR30 image is returned if the internal format is RGB10_A2. + The returned image has a format of premultiplied ARGB32 or RGB32. The latter is used + only when internalTextureFormat() is set to \c GL_RGB. + + If the rendering in the framebuffer was not done with premultiplied alpha in mind, + create a wrapper QImage with a non-premultiplied format. This is necessary before + performing operations like QImage::save() because otherwise the image data would get + unpremultiplied, even though it was not premultiplied in the first place. To create + such a wrapper without performing a copy of the pixel data, do the following: + + \code + QImage fboImage(fbo.toImage()); + QImage image(fboImage.constBits(), fboImage.width(), fboImage.height(), QImage::Format_ARGB32); + \endcode + + Since Qt 5.2 the function will fall back to premultiplied RGBA8888 or RGBx8888 when + reading to (A)RGB32 is not supported. Since 5.4 an A2BGR30 image is returned if the + internal format is RGB10_A2. For multisampled framebuffer objects the samples are resolved using the \c{GL_EXT_framebuffer_blit} extension. If the extension is not available, the contents |