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Make QOpenGLContext::globalShareContext() lazy creation thread-safe

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We move the context to the main thread (or the thread of qGuiApp),
as that's where it will be deleted.

Amends 4a7ccb65f0065e878c5762db05eca9c5cd6731e5.

Caught-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Change-Id: I8e5dc512dce02d22980730a46474b2262684a713
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
This commit is contained in:
Tor Arne Vestbø 2025-05-28 20:45:12 +02:00
parent 11f149d987
commit e9dbdaa499
2 changed files with 23 additions and 0 deletions
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5
src/gui/kernel/qopenglcontext.cpp
View File

@ -968,11 +968,16 @@ bool QOpenGLContext::supportsThreadedOpenGL()
QOpenGLContext *QOpenGLContext::globalShareContext()
{
Q_ASSERT(qGuiApp);
static QMutex mutex;
QMutexLocker locker(&mutex);
// Lazily create a global share context when enabled unless there is already one
if (!qt_gl_global_share_context() && qGuiApp->testAttribute(Qt::AA_ShareOpenGLContexts)) {
QOpenGLContext *ctx = new QOpenGLContext;
ctx->setFormat(QSurfaceFormat::defaultFormat());
ctx->create();
ctx->moveToThread(qGuiApp->thread());
qt_gl_set_global_share_context(ctx);
QGuiApplicationPrivate::instance()->ownGlobalShareContext = true;
}

18
tests/auto/gui/kernel/qguiapplication/tst_qguiapplication.cpp
View File

@ -1292,6 +1292,24 @@ void tst_QGuiApplication::globalShareContext()
QCoreApplication::setAttribute(Qt::AA_ShareOpenGLContexts, true);
ctx = QOpenGLContext::globalShareContext();
QVERIFY(ctx);
// Test that the global share context is lazily created,
// even from secondary threads.
app.reset();
app.reset(new QGuiApplication(argc, argv));
QCoreApplication::setAttribute(Qt::AA_ShareOpenGLContexts, true);
class Thread : public QThread
{
void run() override
{
auto *ctx = QOpenGLContext::globalShareContext();
QVERIFY(ctx);
QCOMPARE(ctx->thread(), qGuiApp->thread());
}
};
Thread thread;
thread.start();
thread.wait();
#else
QSKIP("No OpenGL support");
#endif