ash: ozone: apply transformation to events outside the root window

ui/ozone/platform/dri/dri_window.cc

Index: ui/ozone/platform/dri/dri_window.cc
diff --git a/ui/ozone/platform/dri/dri_window.cc b/ui/ozone/platform/dri/dri_window.cc
index 745a2d007a3a5c24c958ad2eff7db961e294ce03..4aec0fc389153ff77628249155810bf1a478d805 100644
--- a/ui/ozone/platform/dri/dri_window.cc
+++ b/ui/ozone/platform/dri/dri_window.cc
@@ -74,9 +74,13 @@ gfx::Rect DriWindow::GetBounds() {
   return bounds_;
 }
 
-void DriWindow::SetCapture() {}
+void DriWindow::SetCapture() {
+  window_manager_->GrabMouseEvents(widget_);
+}
 
-void DriWindow::ReleaseCapture() {}
+void DriWindow::ReleaseCapture() {
+  window_manager_->UngrabMouseEvents(widget_);
+}
 
 void DriWindow::ToggleFullscreen() {}
 
@@ -103,13 +107,32 @@ void DriWindow::MoveCursorTo(const gfx::Point& location) {
 bool DriWindow::CanDispatchEvent(const PlatformEvent& ne) {
   DCHECK(ne);
   Event* event = static_cast<Event*>(ne);
-  if (event->IsMouseEvent() || event->IsScrollEvent())
+  if (event->IsMouseEvent() || event->IsScrollEvent()) {
+    // Bail out if there is a grab on mouse events.
+    gfx::AcceleratedWidget grabber = window_manager_->mouse_events_grabber();
+    if (grabber != gfx::kNullAcceleratedWidget)
+      return grabber == widget_;
+
+    // Otherwise, just consider the position of the cursor.
     return window_manager_->cursor()->GetCursorWindow() == widget_;
+  }
 
   return true;
 }
 
 uint32_t DriWindow::DispatchEvent(const PlatformEvent& native_event) {
+  // Implement implicit mouse grab on button press
+  Event* event = static_cast<Event*>(native_event);
+  if (event->IsMouseEvent() || event->IsScrollEvent()) {
+    // We need to convert the cursor's position into coordinates
+    // relative to the window in case of an implicit grab.
+    if (window_manager_->cursor()->GetCursorWindow() != widget_) {
+      LocatedEvent* located_event = static_cast<LocatedEvent*>(event);
+      gfx::PointF location = located_event->root_location();
+      location.Offset(-bounds_.origin().x(), -bounds_.origin().y());
+      located_event->set_location(location);
+    }
+  }
   DispatchEventFromNativeUiEvent(
       native_event, base::Bind(&PlatformWindowDelegate::DispatchEvent,
                                base::Unretained(delegate_)));