From 97da4519ba94164d6c6ddad6ffa9a16153d74a55 Mon Sep 17 00:00:00 2001
From: Laszlo Agocs <laszlo.agocs@qt.io>
Date: Mon, 4 Jan 2021 10:27:11 +0100
Subject: Add a dedicated QWindow surface type for D3D
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Even though there is no D3D-specific logic in the windows platform
plugin, meaning a QWindow with either OpenGLSurface or VulkanSurface
(or anything really) is DXGI/D3D-compatible, it now looks like it is
beneficial, and more future proof, if there is a dedicated surface
type.

As the linked report shows, there are OpenGL-specific workarounds
accumulated in the platform plugin, while not being clear if these
are relevant to non-OpenGL content, or if they are relevant at all
still. (and some of these can be difficult/impossible to retest and
verify in practice)

When D3D-based windows use the same surface type, all these are
active for those windows as well, while Vulkan-based windows have
their own type and so some of these old workarounds are not active
for those. To reduce confusion, having a dedicated surface type for
D3D as well allows the logic to skip the old OpenGL workarounds,
giving us (and users) a more clear overall behavior when it comes
to OpenGL vs. Vulkan vs. D3D.

The change is compatible with any existing code in other modules
because any code that uses OpenGLSurface for D3D will continue to
work, using the new type can be introduced incrementally.

Task-number: QTBUG-89715
Change-Id: Ieba86a580bf5a3636730952184dc3a3ab7669b26
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
---
 src/plugins/platforms/windows/qwindowswindow.cpp | 36 ++++++++++++++----------
 1 file changed, 21 insertions(+), 15 deletions(-)

(limited to 'src/plugins/platforms/windows/qwindowswindow.cpp')

diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 5987324ac1..7528bf4155 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -351,6 +351,8 @@ static inline bool windowIsAccelerated(const QWindow *w)
         return qt_window_private(const_cast<QWindow *>(w))->compositing;
     case QSurface::VulkanSurface:
         return true;
+    case QSurface::Direct3DSurface:
+        return true;
     default:
         return false;
     }
@@ -1365,14 +1367,12 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const QWindowsWindowData &data)
     const Qt::WindowType type = aWindow->type();
     if (type == Qt::Desktop)
         return; // No further handling for Qt::Desktop
-#ifndef QT_NO_OPENGL
-    if (aWindow->surfaceType() == QWindow::OpenGLSurface) {
-        if (QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGL)
-            setFlag(OpenGLSurface);
-        else
-            setFlag(OpenGL_ES2);
-    }
-#endif // QT_NO_OPENGL
+    if (aWindow->surfaceType() == QWindow::Direct3DSurface)
+        setFlag(Direct3DSurface);
+#if QT_CONFIG(opengl)
+    if (aWindow->surfaceType() == QWindow::OpenGLSurface)
+        setFlag(OpenGLSurface);
+#endif
 #if QT_CONFIG(vulkan)
     if (aWindow->surfaceType() == QSurface::VulkanSurface)
         setFlag(VulkanSurface);
@@ -1831,8 +1831,11 @@ void QWindowsWindow::handleHidden()
 void QWindowsWindow::handleCompositionSettingsChanged()
 {
     const QWindow *w = window();
-    if ((w->surfaceType() == QWindow::OpenGLSurface || w->surfaceType() == QWindow::VulkanSurface)
-            && w->format().hasAlpha()) {
+    if ((w->surfaceType() == QWindow::OpenGLSurface
+         || w->surfaceType() == QWindow::VulkanSurface
+         || w->surfaceType() == QWindow::Direct3DSurface)
+        && w->format().hasAlpha())
+    {
         applyBlurBehindWindow(handle());
     }
 }
@@ -2008,9 +2011,10 @@ void QWindowsWindow::handleGeometryChange()
         return; // QGuiApplication will send resize when screen actually changes
     }
     QWindowSystemInterface::handleGeometryChange(window(), m_data.geometry);
-    // QTBUG-32121: OpenGL/normal windows (with exception of ANGLE) do not receive
-    // expose events when shrinking, synthesize.
-    if (!testFlag(OpenGL_ES2) && isExposed()
+    // QTBUG-32121: OpenGL/normal windows (with exception of ANGLE
+    // which we no longer support in Qt 6) do not receive expose
+    // events when shrinking, synthesize.
+    if (isExposed()
         && m_data.geometry.size() != previousGeometry.size() // Exclude plain move
         // One dimension grew -> Windows will send expose, no need to synthesize.
         && !(m_data.geometry.width() > previousGeometry.width() || m_data.geometry.height() > previousGeometry.height())) {
@@ -2139,7 +2143,9 @@ bool QWindowsWindow::handleWmPaint(HWND hwnd, UINT message,
 
     // Observed painting problems with Aero style disabled (QTBUG-7865).
     if (Q_UNLIKELY(!dwmIsCompositionEnabled())
-            && ((testFlag(OpenGLSurface) && testFlag(OpenGLDoubleBuffered)) || testFlag(VulkanSurface)))
+        && ((testFlag(OpenGLSurface) && testFlag(OpenGLDoubleBuffered))
+            || testFlag(VulkanSurface)
+            || testFlag(Direct3DSurface)))
     {
         SelectClipRgn(ps.hdc, nullptr);
     }
@@ -2523,7 +2529,7 @@ void QWindowsWindow::setOpacity(qreal level)
         m_opacity = level;
         if (m_data.hwnd)
             setWindowOpacity(m_data.hwnd, m_data.flags,
-                             window()->format().hasAlpha(), testFlag(OpenGLSurface) || testFlag(VulkanSurface),
+                             window()->format().hasAlpha(), testFlag(OpenGLSurface) || testFlag(VulkanSurface) || testFlag(Direct3DSurface),
                              level);
     }
 }
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