e6a969954a
Changing anything on a QWindow's QSurfaceFormat has zero and null
effects once the underlying native window has been created. Letting
QWidget update the format is wrong in this case, because we always
expect that the value returned from QWindow::format() reflects
reality.
(reality being the settings with which the underlying native resource
was created, which is typically frozen after QWindow::create(), not
the state of some QWidget attribute. There are certain exceptions to
this, such as when preparing to recreate the underlying native window,
in which case one will want to update all relevant fields of the
format based on the current values of the widget attributes, which is
exactly what QWidgetPrivate::create() implements, and that's good.)
Such a mismatch can have fatal consequences when OpenGL and friends
are involved, but this always depends heavily on the platform and
windowing system. For example, claiming that the alpha buffer size is
0 when the native window was created with 8, or vice versa, can break
OpenGL-related code (both in Qt itself and in applications), that
tries to create a QOpengGLContext configured based on what
QWindow::format() returns. If that format describes settings that are
incompatible with the actual underlying native window, we end up with
the classic Invalid pixel format, EGL_BAD_MATCH, and alike errors.
This is exactly what is happening when a QOpenGLWidget (or
QQuickWidget) is placed in a QDockWidget where one of the ancestors is
forced to native (winId() was called or WA_NativeWindow was set). When
undocking, various code paths in QWidget will try to update the opaque
flag of the widget, which in turn calls updateIsTranslucent. Now, if
this function unconditionally changes the alphaBufferSize in the
QWindow's QSurfaceFormat (even though this is completely futile to do,
it has no visible effect in practice), we get the problem described
above: rendering breaking down due to OpenGL contexts created with a
pixel format incompatible with the native window.
Prevent all this by not touching the format once the QWindow has a
QPlatformWindow. This is the right thing to do, regardless of the bug
in question: a window's (or context's or any other native resource
wrapping class's) format must describe the underlying native resource
and must never deviate, unless we are preparing to create a new native
resource underneath.
When it comes to the autotest, this changes the test added in
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| .. | ||
| auto | ||
| baselineserver | ||
| benchmarks | ||
| global | ||
| libfuzzer | ||
| manual | ||
| shared | ||
| testserver | ||
| CMakeLists.txt | ||
| README | ||
This directory contains autotests and benchmarks based on Qt Test. In order
to run the autotests reliably, you need to configure a desktop to match the
test environment that these tests are written for.
Linux X11:
* The user must be logged in to an active desktop; you can't run the
autotests without a valid DISPLAY that allows X11 connections.
* The tests are run against a KDE3 or KDE4 desktop.
* Window manager uses "click to focus", and not "focus follows mouse". Many
tests move the mouse cursor around and expect this to not affect focus
and activation.
* Disable "click to activate", i.e., when a window is opened, the window
manager should automatically activate it (give it input focus) and not
wait for the user to click the window.