Use opaque render list when client content is opaque

If the client says it's fully opaque through the
set_opaque_region request, we can disable blending
for the item and potentially improve performance a
little bit.

[ChangeLog][QtWaylandCompositor] The compositor now respects
the opaque region set by the client and no longer applies
blending or overdraw for fully opaque windows.

Fixes: QTBUG-100373
Change-Id: Iaa68fbf1f086d926c9c1867d981a63810f4ca855
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

4 files changed, 37 insertions, 5 deletions

diff --git a/src/compositor/compositor_api/qwaylandquickitem.cpp b/src/compositor/compositor_api/qwaylandquickitem.cpp
index bf1d0a447..07130a8a6 100644
--- a/src/compositor/compositor_api/qwaylandquickitem.cpp
+++ b/src/compositor/compositor_api/qwaylandquickitem.cpp
@@ -372,7 +372,7 @@ void QWaylandBufferMaterial::setBufferRef(QWaylandQuickItem *surfaceItem, const
         if (auto texture = ref.toOpenGLTexture(plane)) {
             QQuickWindow::CreateTextureOptions opt;
             QWaylandQuickSurface *waylandSurface = qobject_cast<QWaylandQuickSurface *>(surfaceItem->surface());
-            if (waylandSurface != nullptr && waylandSurface->useTextureAlpha())
+            if (waylandSurface != nullptr && waylandSurface->useTextureAlpha() && !waylandSurface->isOpaque())
                 opt |= QQuickWindow::TextureHasAlphaChannel;
             QSGTexture *scenegraphTexture;
             if (ref.bufferFormatEgl() == QWaylandBufferRef::BufferFormatEgl_EXTERNAL_OES) {
@@ -422,7 +422,7 @@ public:
 #if QT_CONFIG(opengl)
                 QQuickWindow::CreateTextureOptions opt;
                 QWaylandQuickSurface *surface = qobject_cast<QWaylandQuickSurface *>(surfaceItem->surface());
-                if (surface && surface->useTextureAlpha()) {
+                if (surface && surface->useTextureAlpha()  && !surface->isOpaque()) {
                     opt |= QQuickWindow::TextureHasAlphaChannel;
                 }
 
diff --git a/src/compositor/compositor_api/qwaylandsurface.cpp b/src/compositor/compositor_api/qwaylandsurface.cpp
index b07a93e91..4523080b2 100644
--- a/src/compositor/compositor_api/qwaylandsurface.cpp
+++ b/src/compositor/compositor_api/qwaylandsurface.cpp
@@ -257,6 +257,7 @@ void QWaylandSurfacePrivate::surface_commit(Resource *)
     QSize surfaceSize = bufferSize / bufferScale;
     sourceGeometry = !pending.sourceGeometry.isValid() ? QRect(QPoint(), surfaceSize) : pending.sourceGeometry;
     destinationSize = pending.destinationSize.isEmpty() ? sourceGeometry.size().toSize() : pending.destinationSize;
+    QRect destinationRect(QPoint(), destinationSize);
     if (!pending.damageInBufferCoordinates || pending.bufferScale == 1) {
         // pending.damage is already in surface coordinates
         damage = pending.damage.intersected(QRect(QPoint(), destinationSize));
@@ -272,13 +273,19 @@ void QWaylandSurfacePrivate::surface_commit(Resource *)
         };
         damage = {};
         for (const QRect &r : pending.damage) {
-            damage |= xform(r, bufferScale).intersected(QRect{{}, destinationSize});
+            damage |= xform(r, bufferScale).intersected(destinationRect);
         }
     }
     hasContent = bufferRef.hasContent();
     frameCallbacks << pendingFrameCallbacks;
-    inputRegion = pending.inputRegion.intersected(QRect(QPoint(), destinationSize));
-    opaqueRegion = pending.opaqueRegion.intersected(QRect(QPoint(), destinationSize));
+    inputRegion = pending.inputRegion.intersected(destinationRect);
+    opaqueRegion = pending.opaqueRegion.intersected(destinationRect);
+    bool becameOpaque = opaqueRegion.boundingRect().contains(destinationRect);
+    if (becameOpaque != isOpaque) {
+        isOpaque = becameOpaque;
+        emit q->isOpaqueChanged();
+    }
+
     QPoint offsetForNextFrame = pending.offset;
 
     if (viewport)
@@ -857,6 +864,27 @@ bool QWaylandSurface::inhibitsIdle() const
     return !d->idleInhibitors.isEmpty();
 }
 
+/*!
+ *  \qmlproperty bool QtWaylandCompositor::WaylandSurface::isOpaque
+ *  \since 6.4
+ *
+ *  This property holds whether the surface is fully opaque, as reported by the
+ *  client through the set_opaque_region request.
+ */
+
+/*!
+ *  \property bool QWaylandSurface::isOpaque
+ *  \since 6.4
+ *
+ *  This property holds whether the surface is fully opaque, as reported by the
+ *  client through the set_opaque_region request.
+ */
+bool QWaylandSurface::isOpaque() const
+{
+    Q_D(const QWaylandSurface);
+    return d->isOpaque;
+}
+
 #if QT_CONFIG(im)
 QWaylandInputMethodControl *QWaylandSurface::inputMethodControl() const
 {
diff --git a/src/compositor/compositor_api/qwaylandsurface.h b/src/compositor/compositor_api/qwaylandsurface.h
index 61ba570fc..8b377c9bc 100644
--- a/src/compositor/compositor_api/qwaylandsurface.h
+++ b/src/compositor/compositor_api/qwaylandsurface.h
@@ -78,6 +78,7 @@ class Q_WAYLANDCOMPOSITOR_EXPORT QWaylandSurface : public QWaylandObject
     Q_PROPERTY(bool hasContent READ hasContent NOTIFY hasContentChanged)
     Q_PROPERTY(bool cursorSurface READ isCursorSurface WRITE markAsCursorSurface NOTIFY cursorSurfaceChanged)
     Q_PROPERTY(bool inhibitsIdle READ inhibitsIdle NOTIFY inhibitsIdleChanged REVISION(1, 14))
+    Q_PROPERTY(bool isOpaque READ isOpaque NOTIFY isOpaqueChanged REVISION(6, 4))
     Q_MOC_INCLUDE("qwaylanddrag.h")
     Q_MOC_INCLUDE("qwaylandcompositor.h")
 
@@ -138,6 +139,7 @@ public:
     bool isCursorSurface() const;
 
     bool inhibitsIdle() const;
+    bool isOpaque() const;
 
 #if QT_CONFIG(im)
     QWaylandInputMethodControl *inputMethodControl() const;
@@ -170,6 +172,7 @@ Q_SIGNALS:
     void dragStarted(QWaylandDrag *drag);
     void cursorSurfaceChanged();
     Q_REVISION(14) void inhibitsIdleChanged();
+    Q_REVISION(6, 4) void isOpaqueChanged();
 
     void configure(bool hasBuffer);
     void redraw();
diff --git a/src/compositor/compositor_api/qwaylandsurface_p.h b/src/compositor/compositor_api/qwaylandsurface_p.h
index 6cf8121ff..fe8e1207b 100644
--- a/src/compositor/compositor_api/qwaylandsurface_p.h
+++ b/src/compositor/compositor_api/qwaylandsurface_p.h
@@ -172,6 +172,7 @@ public: //member variables
     bool destroyed = false;
     bool hasContent = false;
     bool isInitialized = false;
+    bool isOpaque = false;
     Qt::ScreenOrientation contentOrientation = Qt::PrimaryOrientation;
     QWindow::Visibility visibility;
 #if QT_CONFIG(im)