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rhi: d3d11: Fix enabling alpha compositing 

Task-number: QTBUG-78089
Change-Id: I4e33665947debe007abcb976641e515224fa8451
Reviewed-by: Christian Strømme <christian.stromme@qt.io>
bb10
Laszlo Agocs 2019-09-09 16:14:55 +02:00
parent 1c63605c10
commit 1fbe3c2316
1 changed files with 16 additions and 5 deletions
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21
src/gui/rhi/qrhid3d11.cpp
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@ -3773,11 +3773,23 @@ bool QD3D11SwapChain::buildOrResize()
const UINT swapChainFlags = 0;
QRHI_RES_RHI(QRhiD3D11);
const bool useFlipDiscard = rhiD->hasDxgi2 && rhiD->supportsFlipDiscardSwapchain;
bool useFlipDiscard = rhiD->hasDxgi2 && rhiD->supportsFlipDiscardSwapchain;
if (!swapChain) {
HWND hwnd = reinterpret_cast<HWND>(window->winId());
sampleDesc = rhiD->effectiveSampleCount(m_sampleCount);
// Take a shortcut for alpha: our QWindow is OpenGLSurface so whatever
// the platform plugin does to enable transparency for OpenGL window
// will be sufficient for us too on the legacy (DISCARD) path. For
// FLIP_DISCARD we'd need to use DirectComposition (create a
// IDCompositionDevice/Target/Visual), avoid that for now.
if (m_flags.testFlag(SurfaceHasPreMulAlpha) || m_flags.testFlag(SurfaceHasNonPreMulAlpha)) {
useFlipDiscard = false;
if (window->requestedFormat().alphaBufferSize() <= 0)
qWarning("Swapchain says surface has alpha but the window has no alphaBufferSize set. "
"This may lead to problems.");
}
HRESULT hr;
if (useFlipDiscard) {
// We use FLIP_DISCARD which implies a buffer count of 2 (as opposed to the
@ -3796,10 +3808,9 @@ bool QD3D11SwapChain::buildOrResize()
desc.BufferCount = BUFFER_COUNT;
desc.Scaling = DXGI_SCALING_STRETCH;
desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
if (m_flags.testFlag(SurfaceHasPreMulAlpha))
desc.AlphaMode = DXGI_ALPHA_MODE_PREMULTIPLIED;
else if (m_flags.testFlag(SurfaceHasNonPreMulAlpha))
desc.AlphaMode = DXGI_ALPHA_MODE_STRAIGHT;
// Do not bother with AlphaMode, if won't work unless we go through
// DirectComposition. Instead, we just take the other (DISCARD)
// path for now when alpha is requested.
desc.Flags = swapChainFlags;
IDXGISwapChain1 *sc1;