Support wl_surface.damage_buffer

Add compositor support for wl_surface.damage_buffer requests.
This also required updating wl_compositor to version 4.

Fixes: QTBUG-74927
Change-Id: I887ed04e60fe14ecce7df6a517950b0091e2ad54
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

3 files changed, 39 insertions, 2 deletions

diff --git a/src/compositor/compositor_api/qwaylandcompositor.cpp b/src/compositor/compositor_api/qwaylandcompositor.cpp
index 8878ce121..fb99f9413 100644
--- a/src/compositor/compositor_api/qwaylandcompositor.cpp
+++ b/src/compositor/compositor_api/qwaylandcompositor.cpp
@@ -190,7 +190,7 @@ void QWaylandCompositorPrivate::init()
         if (socketArg != -1 && socketArg + 1 < arguments.size())
             socket_name = arguments.at(socketArg + 1).toLocal8Bit();
     }
-    wl_compositor::init(display, 3);
+    wl_compositor::init(display, 4);
     wl_subcompositor::init(display, 1);
 
 #if QT_CONFIG(wayland_datadevice)
diff --git a/src/compositor/compositor_api/qwaylandsurface.cpp b/src/compositor/compositor_api/qwaylandsurface.cpp
index 2ebb04a35..efd186fc5 100644
--- a/src/compositor/compositor_api/qwaylandsurface.cpp
+++ b/src/compositor/compositor_api/qwaylandsurface.cpp
@@ -195,9 +195,26 @@ void QWaylandSurfacePrivate::surface_attach(Resource *, struct wl_resource *buff
     pending.newlyAttached = true;
 }
 
+/*
+    Note: The Wayland protocol specifies that buffer scale and damage can be interleaved, so
+    we cannot scale the damage region until commit. We assume that clients will either use
+    surface_damage or surface_damage_buffer within one frame for one surface.
+*/
+
 void QWaylandSurfacePrivate::surface_damage(Resource *, int32_t x, int32_t y, int32_t width, int32_t height)
 {
+    if (Q_UNLIKELY(pending.damageInBufferCoordinates && !pending.damage.isNull()))
+        qCWarning(qLcWaylandCompositor) << "Unsupported: Client is using both wl_surface.damage_buffer and wl_surface.damage.";
+    pending.damage = pending.damage.united(QRect(x, y, width, height));
+    pending.damageInBufferCoordinates = false;
+}
+
+void QWaylandSurfacePrivate::surface_damage_buffer(Resource *, int32_t x, int32_t y, int32_t width, int32_t height)
+{
+    if (Q_UNLIKELY(!pending.damageInBufferCoordinates && !pending.damage.isNull()))
+        qCWarning(qLcWaylandCompositor) << "Unsupported: Client is using both wl_surface.damage_buffer and wl_surface.damage.";
     pending.damage = pending.damage.united(QRect(x, y, width, height));
+    pending.damageInBufferCoordinates = true;
 }
 
 void QWaylandSurfacePrivate::surface_frame(Resource *resource, uint32_t callback)
@@ -240,7 +257,24 @@ 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;
-    damage = pending.damage.intersected(QRect(QPoint(), destinationSize));
+    if (!pending.damageInBufferCoordinates || pending.bufferScale == 1) {
+        // pending.damage is already in surface coordinates
+        damage = pending.damage.intersected(QRect(QPoint(), destinationSize));
+    } else {
+        // We must transform pending.damage from buffer coordinate system to surface coordinates
+        // TODO(QTBUG-85461): Also support wp_viewport setting more complex transformations
+        auto xform = [](const QRect &r, int scale) -> QRect {
+            QRect res{
+                QPoint{ r.x() / scale, r.y() / scale },
+                QPoint{ (r.right() + scale - 1) / scale, (r.bottom() + scale - 1) / scale }
+            };
+            return res;
+        };
+        damage = {};
+        for (const QRect &r : pending.damage) {
+            damage |= xform(r, bufferScale).intersected(QRect{{}, destinationSize});
+        }
+    }
     hasContent = bufferRef.hasContent();
     frameCallbacks << pendingFrameCallbacks;
     inputRegion = pending.inputRegion.intersected(QRect(QPoint(), destinationSize));
@@ -255,6 +289,7 @@ void QWaylandSurfacePrivate::surface_commit(Resource *)
     pending.offset = QPoint();
     pending.newlyAttached = false;
     pending.damage = QRegion();
+    pending.damageInBufferCoordinates = false;
     pendingFrameCallbacks.clear();
 
     // Notify buffers and views
diff --git a/src/compositor/compositor_api/qwaylandsurface_p.h b/src/compositor/compositor_api/qwaylandsurface_p.h
index 3f657c9d0..1150ccf91 100644
--- a/src/compositor/compositor_api/qwaylandsurface_p.h
+++ b/src/compositor/compositor_api/qwaylandsurface_p.h
@@ -116,6 +116,7 @@ protected:
                         struct wl_resource *buffer, int x, int y) override;
     void surface_damage(Resource *resource,
                         int32_t x, int32_t y, int32_t width, int32_t height) override;
+    void surface_damage_buffer(Resource *resource, int32_t x, int32_t y, int32_t width, int32_t height) override;
     void surface_frame(Resource *resource,
                        uint32_t callback) override;
     void surface_set_opaque_region(Resource *resource,
@@ -141,6 +142,7 @@ public: //member variables
     struct {
         QWaylandBufferRef buffer;
         QRegion damage;
+        bool damageInBufferCoordinates = false;
         QPoint offset;
         bool newlyAttached = false;
         QRegion inputRegion;