MacViews: Implement event monitoring for a specific window

ui/views/event_monitor_mac.mm

 // Copyright 2014 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 "ui/views/event_monitor_mac.h"
 
 #include "base/logging.h"
 #include "ui/events/event.h"
 #include "ui/events/event_handler.h"
 #include "ui/events/event_utils.h"
 
 namespace views {
 
 // static
 EventMonitor* EventMonitor::Create(ui::EventHandler* event_handler) {
-  return new EventMonitorMac(event_handler);
+  return new EventMonitorMac(event_handler, nullptr);
 }
 
 // static
+EventMonitor* EventMonitor::Create(ui::EventHandler* event_handler,
+                                   gfx::NativeWindow target_window) {
+  return new EventMonitorMac(event_handler, target_window);
+}
+
+// static
 gfx::Point EventMonitor::GetLastMouseLocation() {
   NSPoint mouseLocation = [NSEvent mouseLocation];
   // Flip coordinates to gfx (0,0 in top-left corner) using primary screen.
   NSScreen* screen = [[NSScreen screens] objectAtIndex:0];
   mouseLocation.y = NSMaxY([screen frame]) - mouseLocation.y;
   return gfx::Point(mouseLocation.x, mouseLocation.y);

[tapted, 2014/11/20 22:39:02]

also orthogonal, but we probably should move this snippet to
ui/gfx/mac/coordinate_conversion.h at some point

[Andre, 2014/11/21 00:28:28]

Yeah, we should add ScreenPointFromNSPoint there.

 }
 
-EventMonitorMac::EventMonitorMac(ui::EventHandler* event_handler) {
+EventMonitorMac::EventMonitorMac(ui::EventHandler* event_handler,
+                                 gfx::NativeWindow target_window) {
   DCHECK(event_handler);
   monitor_ = [NSEvent addLocalMonitorForEventsMatchingMask:NSAnyEventMask
       handler:^NSEvent*(NSEvent* event){
-                  scoped_ptr<ui::Event> ui_event = ui::EventFromNative(event);
-                  event_handler->OnEvent(ui_event.get());
+                  if (!target_window || [event window] == target_window) {

[tapted, 2014/11/20 22:39:02]

Can the EventMonitorMac outlive this NSWindow?

(Maybe this is something to plonk on BridgedNativeWidget, which is kinda like
our aura::Window)

[Andre, 2014/11/21 00:28:28]

There is that risk, same with EventMonitorAura as well.
We can use something like NativeWindowTracker, I suppose.
Which part are you thinking to plonk on BridgedNativeWidget?
I see you are adding GetBridgeForNativeWindow, but how will that help is the
window is already destroyed?

[tapted, 2014/11/21 00:57:34]

WidgetObserver might be nicer, in which case these Create functions could take a
Widget* instead.

GetBridgeForNativeWindow would allow you to call a function like
BridgedNativeWidget::AddPreTargetHandler


If you make it clear on the added Create method (i.e. comment) that the
EventMonitor must be destroyed before |target_window|, it might be fine as-is.
No point over-engineering if the callers are already doing this (and getting a
Widget* from webcontents might be tricky)

[Andre, 2014/12/10 00:18:13]

Done.
Added the comment.

+                    scoped_ptr<ui::Event> ui_event = ui::EventFromNative(event);
+                    event_handler->OnEvent(ui_event.get());
+                  }
                   return event;
               }];
 }
 
 EventMonitorMac::~EventMonitorMac() {
   [NSEvent removeMonitor:monitor_];
 }
 
 }  // namespace views