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macOS: Clear NSOpenGLContex's drawable when using offscreen surfaces

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Otherwise the user might accidentally render to the previously active
window, if not explicitly using an FBO.

This will have an performance impact if doing makeCurrent on a real
window and an offscreen window back and forth with the same context,
but that's not really a common or recommended use of QOffscreenSurface,
as you can create FBOs with a normal window current as well. The use
case of QOffscreenSurface is when a real window is not available.

Change-Id: If93d04f82564523e15d5970429afea34c5cd31fe
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
This commit is contained in:
Tor Arne Vestbø 2018-09-05 11:51:50 +02:00
parent 295cd87c6d
commit 3baa9aa3cd
1 changed files with 28 additions and 20 deletions
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48
src/plugins/platforms/cocoa/qcocoaglcontext.mm
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@ -331,34 +331,32 @@ bool QCocoaGLContext::makeCurrent(QPlatformSurface *surface)
Q_ASSERT(surface->surface()->supportsOpenGL());
if (surface->surface()->surfaceClass() == QSurface::Offscreen) {
[m_context makeCurrentContext];
return true;
}
if (!setDrawable(surface))
return false;
[m_context makeCurrentContext];
// Disable high-resolution surfaces when using the software renderer, which has the
// problem that the system silently falls back to a to using a low-resolution buffer
// when a high-resolution buffer is requested. This is not detectable using the NSWindow
// convertSizeToBacking and backingScaleFactor APIs. A typical result of this is that Qt
// will display a quarter of the window content when running in a virtual machine.
if (!m_didCheckForSoftwareContext) {
// FIXME: This ensures we check only once per context,
// but the context may be used for multiple surfaces.
m_didCheckForSoftwareContext = true;
if (surface->surface()->surfaceClass() == QSurface::Window) {
// Disable high-resolution surfaces when using the software renderer, which has the
// problem that the system silently falls back to a to using a low-resolution buffer
// when a high-resolution buffer is requested. This is not detectable using the NSWindow
// convertSizeToBacking and backingScaleFactor APIs. A typical result of this is that Qt
// will display a quarter of the window content when running in a virtual machine.
if (!m_didCheckForSoftwareContext) {
// FIXME: This ensures we check only once per context,
// but the context may be used for multiple surfaces.
m_didCheckForSoftwareContext = true;
const GLubyte* renderer = glGetString(GL_RENDERER);
if (qstrcmp((const char *)renderer, "Apple Software Renderer") == 0) {
NSView *view = static_cast<QCocoaWindow *>(surface)->m_view;
[view setWantsBestResolutionOpenGLSurface:NO];
const GLubyte* renderer = glGetString(GL_RENDERER);
if (qstrcmp((const char *)renderer, "Apple Software Renderer") == 0) {
NSView *view = static_cast<QCocoaWindow *>(surface)->m_view;
[view setWantsBestResolutionOpenGLSurface:NO];
}
}
update();
}
update();
return true;
}
@ -368,7 +366,17 @@ bool QCocoaGLContext::makeCurrent(QPlatformSurface *surface)
*/
bool QCocoaGLContext::setDrawable(QPlatformSurface *surface)
{
Q_ASSERT(surface && surface->surface()->surfaceClass() == QSurface::Window);
if (!surface || surface->surface()->surfaceClass() == QSurface::Offscreen) {
// Clear the current drawable and reset the active window, so that GL
// commands that don't target a specific FBO will not end up stomping
// on the previously set drawable.
qCDebug(lcQpaOpenGLContext) << "Clearing current drawable" << m_context.view << "for" << m_context;
[m_context clearDrawable];
m_currentWindow.clear();
return true;
}
Q_ASSERT(surface->surface()->surfaceClass() == QSurface::Window);
QWindow *window = static_cast<QCocoaWindow *>(surface)->window();
if (window == m_currentWindow.data())