ash: Add a heads-up display to track touch-point states and positions.

ash/touch/touch_observer_hud.h

+// Copyright (c) 2012 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.
+
+#ifndef ASH_TOUCH_TOUCH_OBSERVER_HUD_H_
+#define ASH_TOUCH_TOUCH_OBSERVER_HUD_H_
+#pragma once
+
+#include "ash/shell.h"
+#include "ui/aura/event_filter.h"
+#include "ui/gfx/point.h"
+
+namespace aura {
+class MouseEvent;
+class KeyEvent;
+class Window;
+}
+
+namespace views {
+class Label;
+class Widget;
+}
+
+namespace ash {
+namespace internal {
+
+// An event filter which handles system level gesture events.
+class TouchObserverHUD : public aura::EventFilter {
+ public:
+  TouchObserverHUD();
+  virtual ~TouchObserverHUD();
+
+ private:
+  void UpdateTouchPointLabel(int index);
+
+  // Overriden from aura::EventFilter:
+  virtual bool PreHandleKeyEvent(aura::Window* target,
+                                 aura::KeyEvent* event) OVERRIDE;
+  virtual bool PreHandleMouseEvent(aura::Window* target,
+                                   aura::MouseEvent* event) OVERRIDE;
+  virtual ui::TouchStatus PreHandleTouchEvent(aura::Window* target,
+                                              aura::TouchEvent* event) OVERRIDE;
+  virtual ui::GestureStatus PreHandleGestureEvent(
+      aura::Window* target,
+      aura::GestureEvent* event) OVERRIDE;
+
+  static const int kMaxTouchPoints = 32;
+  scoped_ptr<views::Widget> widget_;
+  views::Label* touch_labels_[kMaxTouchPoints];
+  gfx::Point touch_positions_[kMaxTouchPoints];
+  ui::EventType touch_status_[kMaxTouchPoints];
+
+  DISALLOW_COPY_AND_ASSIGN(TouchObserverHUD);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_TOUCH_TOUCH_OBSERVER_HUD_H_