mus: Let clients set the cursor of their window.

components/mus/ws/event_dispatcher.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/mus/ws/event_dispatcher.h"
 
 #include <set>
 
 #include "cc/surfaces/surface_hittest.h"
 #include "components/mus/surfaces/surfaces_state.h"
@@ skipping 121 matching lines @@
   mojom::EventType event_type_;
   mojom::EventFlags event_flags_;
   mojom::KeyboardCode keyboard_code_;
   mojom::PointerKind pointer_kind_;
   gfx::RectF pointer_region_;
 };
 
 ////////////////////////////////////////////////////////////////////////////////
 
 EventDispatcher::EventDispatcher(EventDispatcherDelegate* delegate)
-    : delegate_(delegate), root_(nullptr) {}
+    : delegate_(delegate),
+      root_(nullptr),
+      mouse_button_down_(false),
+      mouse_cursor_source_window_(nullptr) {}
 
 EventDispatcher::~EventDispatcher() {
   std::set<ServerWindow*> pointer_targets;
   for (const auto& pair : pointer_targets_) {
     if (pair.second.window &&
         pointer_targets.insert(pair.second.window).second) {
       pair.second.window->RemoveObserver(this);
     }
   }
 }
@@ skipping 61 matching lines @@
       gfx::Point location(EventLocationToPoint(*event));
       pointer_target.window =
           FindDeepestVisibleWindowForEvents(root_, surface_id_, &location);
     }
     DispatchToPointerTarget(pointer_target, event.Pass());
     return;
   }
 
   // Pointer down implicitly captures.
   if (pointer_targets_.count(pointer_id) == 0) {
     DCHECK(event->action == mojom::EVENT_TYPE_POINTER_DOWN);

[sky, 2015/12/03 03:23:18]

This should be the place you add the logic for the down. For a mouse this is
only entered on the first mouse button down, which is what you want.

     const bool is_first_pointer_down = pointer_targets_.empty();
     gfx::Point location(EventLocationToPoint(*event));
     ServerWindow* target =
         FindDeepestVisibleWindowForEvents(root_, surface_id_, &location);
     DCHECK(target);
     if (!IsObservingWindow(target))
       target->AddObserver(this);
 
     pointer_targets_[pointer_id].window = target;
     pointer_targets_[pointer_id].in_nonclient_area =
         IsLocationInNonclientArea(target, location);
 
     if (is_first_pointer_down)
       delegate_->SetFocusedWindowFromEventDispatcher(target);
   }
 
   // Release capture on pointer up. For mouse we only release if there are
   // no buttons down.
   const bool should_reset_target =
       (event->action == mojom::EVENT_TYPE_POINTER_UP ||
        event->action == mojom::EVENT_TYPE_POINTER_CANCEL) &&
       (event->pointer_data->kind != mojom::POINTER_KIND_MOUSE ||
        IsOnlyOneMouseButtonDown(event->flags));
 
   DispatchToPointerTarget(pointer_targets_[pointer_id], event.Pass());
 
   if (should_reset_target) {
     ServerWindow* target = pointer_targets_[pointer_id].window;

[sky, 2015/12/03 03:23:18]

And this should be the place you add logic for the up. This block is hit for
both touch and mouse, so you'll need to add a check to make sure the pointer
corresponds to a mouse.

     pointer_targets_.erase(pointer_id);
     if (target && !IsObservingWindow(target))
       target->RemoveObserver(this);
   }
 }
 
 void EventDispatcher::DispatchToPointerTarget(const PointerTarget& target,
                                               mojom::EventPtr event) {
   if (!target.window)
     return;
 
+  if (event->pointer_data->kind == mojom::PointerKind::POINTER_KIND_MOUSE) {
+    if (event->action == mojom::EventType::EVENT_TYPE_POINTER_MOVE) {
+      // Only change the last targeted window when we are moving without
+      // dragging.
+      if (!mouse_button_down_)
+        mouse_cursor_source_window_ = target.window;
+    } else if (event->action == mojom::EventType::EVENT_TYPE_POINTER_UP ||
+               event->action == mojom::EventType::EVENT_TYPE_POINTER_CANCEL) {
+      mouse_button_down_ = false;
+
+      // When we release the mouse button, we want the cursor to be sourced
+      // from the window under the mouse pointer, even though we're sending the
+      // button up event to the window that had implicit capture.
+      gfx::Point location(EventLocationToPoint(*event));
+      mouse_cursor_source_window_ =
+          FindDeepestVisibleWindowForEvents(root_, surface_id_, &location);
+    } else if (event->action == mojom::EventType::EVENT_TYPE_POINTER_DOWN) {
+      mouse_button_down_ = true;
+      mouse_cursor_source_window_ = target.window;
+    }
+  }
+
   gfx::Point location(EventLocationToPoint(*event));
   gfx::Transform transform(GetTransformToWindow(surface_id_, target.window));
   transform.TransformPoint(&location);
   event->pointer_data->location->x = location.x();
   event->pointer_data->location->y = location.y();
   delegate_->DispatchInputEventToWindow(target.window, target.in_nonclient_area,
                                         event.Pass());
 }
 
 void EventDispatcher::CancelPointerEventsToTarget(ServerWindow* window) {
@@ skipping 30 matching lines @@
                                                   ServerWindow* old_parent) {
   CancelPointerEventsToTarget(window);
 }
 
 void EventDispatcher::OnWindowVisibilityChanged(ServerWindow* window) {
   CancelPointerEventsToTarget(window);
 }
 
 void EventDispatcher::OnWindowDestroyed(ServerWindow* window) {
   CancelPointerEventsToTarget(window);
+
+  if (mouse_cursor_source_window_ == window)
+    mouse_cursor_source_window_ = nullptr;
 }
 
 }  // namespace ws
 }  // namespace mus