[vlc-commits] [Git][videolan/vlc][master] 2 commits: qt: enable Windows 11 22H2 native acrylic backdrop effect if `WS_EX_NOREDIRECTIONBITMAP` is used

[Steve Lhomme (@robUx4)]

Steve Lhomme pushed to branch master at VideoLAN / VLC


Commits:
befecc46 by Fatih Uzunoglu at 2025-01-09T15:29:39+00:00
qt: enable Windows 11 22H2 native acrylic backdrop effect if `WS_EX_NOREDIRECTIONBITMAP` is used

- - - - -
874925c0 by Fatih Uzunoglu at 2025-01-09T15:29:39+00:00
qt: use `WS_EX_NOREDIRECTIONBITMAP` for the main window in CompositorDirectComposition

- This fixes the window flashing white when opened, which is really annoying when
the interface is dark.
- This fixes the white background getting exposed until the scene covers the new
area when the window is resized.
- This increases performance due to not having to copy buffers (within GPU, or inter
GPU-CPU unlike WS_EX_LAYERED).
- This makes it possible to use the native acrylic backdrop effect that Windows 11
22H2 provides.

- - - - -


2 changed files:

- modules/gui/qt/maininterface/compositor_dcomp.cpp
- modules/gui/qt/maininterface/win32windoweffects_module.cpp


Changes:

=====================================
modules/gui/qt/maininterface/compositor_dcomp.cpp
=====================================
@@ -253,7 +253,37 @@ bool CompositorDirectComposition::makeMainInterface(MainCtx* mainCtx)
             &CompositorDirectComposition::setup,
             Qt::SingleShotConnection);
 
-    m_quickView->create();
+    {
+        // Express the desire to use WS_EX_NOREDIRECTIONBITMAP, it has the following advantages:
+        // - Increased performance due to not having to copy buffers (within GPU, or inter GPU-CPU unlike WS_EX_LAYERED).
+        // - Win32 window background brush is invalidated, so window does not flash white when opened.
+        // - No more resize artifact until the opaque scene covers the new area when the window is resized.
+        // - Make it possible to use the Windows 11 22H2 native acrylic backdrop effect, because the white background does not remain as an artifact.
+        //   When the window has a frame (currently it is the case for both SSD and CSD), clear color does not clear that background, which means
+        //   that the window should not be exposed (transparent UI). Currently there is either the acrylic simulation visual in the background which is
+        //   completely opaque or the video visual or the UI visual does not get transparent, so we don't suffer from this issue. With `WS_EX_NOREDIRECTIONBITMAP`,
+        //   the background does not paint a rectangle with `WNDCLASSEX::hbrBackground`, even if `WS_EX_LAYERED` is not used, so we are fine. The scene graph
+        //   does not have anything in the window to clear, so clear color can be transparent which means that the UI can be transparent and expose the window
+        //   for the window to provide the (native) backdrop acrylic effect.
+
+        // WS_EX_NOREDIRECTIONBITMAP is only compatible with the flip swapchain model and D3D backend.
+        // In CompositorDirectComposition::init(), we already ensure that D3D is used (no OpenGL or Vulkan).
+        // Flip model is supported since Windows 8 and Qt does not use it only if the following environment
+        // variable is set. Since it targets Windows 10+, it does *not* check if flip model is supported and
+        // use the legacy swapchain model. For D3D12, flip model is always used.
+        const bool legacySwapchainModelIsExplicitlyWanted = qEnvironmentVariableIntValue("QT_D3D_NO_FLIP");
+
+        const char* const envDisableRedirectionSurface = "QT_QPA_DISABLE_REDIRECTION_SURFACE";
+        const bool redirectionSurfaceIsExplicitlyWanted = !qEnvironmentVariableIsEmpty(envDisableRedirectionSurface) && !qEnvironmentVariableIntValue(envDisableRedirectionSurface);
+
+        if (!legacySwapchainModelIsExplicitlyWanted && !redirectionSurfaceIsExplicitlyWanted)
+            qputenv(envDisableRedirectionSurface, "1"); // TODO: Other QQuickWindow (toolbar editor, independent popups)
+
+        m_quickView->create();
+
+        if (!legacySwapchainModelIsExplicitlyWanted && !redirectionSurfaceIsExplicitlyWanted)
+            qunsetenv(envDisableRedirectionSurface); // NOTE: We need to disable it, otherwise regular QWidget windows would have issues
+    }
 
     const bool ret = commonGUICreate(quickViewPtr, quickViewPtr, CompositorVideo::CAN_SHOW_PIP | CompositorVideo::HAS_ACRYLIC);
 


=====================================
modules/gui/qt/maininterface/win32windoweffects_module.cpp
=====================================
@@ -24,6 +24,7 @@
 #include <cassert>
 
 #include <dwmapi.h>
+#include <winuser.h>
 
 static bool isEffectAvailable(const QWindow* window, const WindowEffectsModule::Effect effect)
 {
@@ -50,8 +51,13 @@ static bool isEffectAvailable(const QWindow* window, const WindowEffectsModule::
         //       the custom solution has more chance to cause issues.
         if (!window->flags().testFlag(Qt::FramelessWindowHint))
         {
-            qDebug("Target window is not frameless, window can not be translucent for the Windows 11 22H2 native acrylic backdrop effect.");
-            return false;
+            const auto extendedStyle = GetWindowLong((HWND)window->winId(), GWL_EXSTYLE);
+            if (!(extendedStyle & 0x00200000L /* WS_EX_NOREDIRECTIONBITMAP */))
+            {
+                qDebug("Target window is not frameless and does not use WS_EX_NOREDIRECTIONBITMAP, " \
+                       "window can not be translucent for the Windows 11 22H2 native acrylic backdrop effect.");
+                return false;
+            }
         }
         return true;
     default:



View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/1ba2a2db89c832be6b553f155f4cff445b703e2c...874925c0fbcabf7490c938fdcaefe03e3cb6337c

-- 
View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/1ba2a2db89c832be6b553f155f4cff445b703e2c...874925c0fbcabf7490c938fdcaefe03e3cb6337c
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