Document QOpenGLWidget limitations without an alpha channel

Task-number: QTBUG-85869
Change-Id: I20fb70a451fc1ed93089ed699539fa12ac38fe73
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
(cherry picked from commit b5ce973b29875d8cea6302de8ccfaa06d0b7c870)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Laszlo Agocs 2021-01-13 16:45:47 +01:00 committed by Qt Cherry-pick Bot
parent 85fd5b70d6
commit f90b77e101

View File

@ -401,6 +401,19 @@ QT_BEGIN_NAMESPACE
each frame. To restore the preserved behavior, call setUpdateBehavior() with
\c PartialUpdate.
\note Displaying a QOpenGLWidget requires an alpha channel in the associated
top-level window's backing store due to the way composition with other
QWidget-based content works. If there is no alpha channel, the content
rendered by the QOpenGLWidget will not be visible. This can become
particularly relevant on Linux/X11 in remote display setups (such as, with
Xvnc), when using a color depth lower than 24. For example, a color depth of
16 will typically map to using a backing store image with the format
QImage::Format_RGB16 (RGB565), leaving no room for an alpha
channel. Therefore, if experiencing problems with getting the contents of a
QOpenGLWidget composited correctly with other the widgets in the window, make
sure the server (such as, vncserver) is configured with a 24 or 32 bit depth
instead of 16.
\section1 Alternatives
Adding a QOpenGLWidget into a window turns on OpenGL-based