mus: Server-side implementation of modal windows

components/mus/ws/event_dispatcher.cc

Index: components/mus/ws/event_dispatcher.cc
diff --git a/components/mus/ws/event_dispatcher.cc b/components/mus/ws/event_dispatcher.cc
index 71dea6063039e8877df57d356e8f2ba37b6b7f36..368567b2f9a091b58477d01ef74fa5f8cc3bc744 100644
--- a/components/mus/ws/event_dispatcher.cc
+++ b/components/mus/ws/event_dispatcher.cc
@@ -52,6 +52,23 @@ bool IsLocationInNonclientArea(const ServerWindow* target,
   return true;
 }
 
+ServerWindow* GetClosestModalTargetForWindow(ServerWindow* target) {

[sky, 2016/03/08 17:07:53]

Add description as closest isn't clear in this context. I think ancestor is
better, but I'm ok with closest and a description.

[mohsen, 2016/03/09 08:26:48]

Renamed to GetModalChildForWindowAncestor() (also changed to return nullptr when
nothing is found to match the new name better).

I moved these functions to server_window.cc to make the functionality accessible
to other codes.

+  for (ServerWindow* window = target; window; window = window->parent()) {
+    for (const auto& transient_child : window->transient_children()) {
+      if (transient_child->is_modal() && transient_child->IsDrawn())
+        return transient_child;
+    }
+  }
+  return target;
+}
+
+ServerWindow* GetModalTargetForWindow(ServerWindow* target) {
+  ServerWindow* closest_target = GetClosestModalTargetForWindow(target);
+  if (closest_target == target)
+    return target;
+  return GetModalTargetForWindow(closest_target);
+}
+
 }  // namespace
 
 class EventMatcher {
@@ -216,14 +233,18 @@ EventDispatcher::~EventDispatcher() {
   pointer_targets_.clear();
 }
 
-void EventDispatcher::SetCaptureWindow(ServerWindow* window,
+bool EventDispatcher::SetCaptureWindow(ServerWindow* window,
                                        bool in_nonclient_area) {
   if (window == capture_window_)
-    return;
+    return true;
+
+  // A window that is blocked by a modal window cannot gain capture.
+  if (window && GetClosestModalTargetForWindow(window) != window)
+    return false;
 
   if (capture_window_) {
     // Stop observing old capture window. |pointer_targets_| are cleared on
-    // intial setting of a capture window.
+    // initial setting of a capture window.
     delegate_->OnServerWindowCaptureLost(capture_window_);
     capture_window_->RemoveObserver(this);
   } else {
@@ -245,7 +266,7 @@ void EventDispatcher::SetCaptureWindow(ServerWindow* window,
           pair.second.is_mouse_event ? ui::EventPointerType::POINTER_TYPE_MOUSE
                                      : ui::EventPointerType::POINTER_TYPE_TOUCH;
       // TODO(jonross): Track previous location in PointerTarget for sending
-      // cancels
+      // cancels.
       ui::PointerEvent event(event_type, pointer_type, gfx::Point(),
                              gfx::Point(), ui::EF_NONE, pair.first,
                              ui::EventTimeForNow());
@@ -267,6 +288,7 @@ void EventDispatcher::SetCaptureWindow(ServerWindow* window,
 
   capture_window_ = window;
   capture_window_in_nonclient_area_ = in_nonclient_area;
+  return true;
 }
 
 void EventDispatcher::UpdateCursorProviderByLastKnownLocation() {
@@ -451,10 +473,12 @@ EventDispatcher::PointerTarget EventDispatcher::PointerTargetForEvent(
     const ui::PointerEvent& event) const {
   PointerTarget pointer_target;
   gfx::Point location(event.location());
-  pointer_target.window =
+  ServerWindow* target_window =
       FindDeepestVisibleWindowForEvents(root_, surface_id_, &location);
+  pointer_target.window = GetModalTargetForWindow(target_window);
   pointer_target.is_mouse_event = event.IsMousePointerEvent();
   pointer_target.in_nonclient_area =
+      target_window != pointer_target.window ||
       IsLocationInNonclientArea(pointer_target.window, location);
   pointer_target.is_pointer_down = event.type() == ui::ET_POINTER_DOWN;
   return pointer_target;