Makes the maximize/restore button handling

ash/wm/workspace/frame_maximize_button.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_WM_WORKSPACE_FRAME_MAXIMIZE_BUTTON_H_
+#define ASH_WM_WORKSPACE_FRAME_MAXIMIZE_BUTTON_H_
+
+#include "ash/ash_export.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/views/controls/button/image_button.h"
+
+namespace views {
+class MouseEvent;

[tfarina, 2012/03/14 16:38:42]

nit: no need to forward declare this, it comes from ui/views/view.h

+}
+
+namespace ash {
+
+namespace internal {
+class PhantomWindowController;
+}
+
+// Button used for the maximize control on the frame. Handles snapping logic.
+class ASH_EXPORT FrameMaximizeButton : public views::ImageButton {
+ public:
+  explicit FrameMaximizeButton(views::ButtonListener* listener);
+  virtual ~FrameMaximizeButton();
+
+  // ImageButton overrides:
+  virtual bool OnMousePressed(const views::MouseEvent& event) OVERRIDE;
+  virtual void OnMouseEntered(const views::MouseEvent& event) OVERRIDE;
+  virtual void OnMouseExited(const views::MouseEvent& event) OVERRIDE;
+  virtual bool OnMouseDragged(const views::MouseEvent& event) OVERRIDE;
+  virtual void OnMouseReleased(const views::MouseEvent& event) OVERRIDE;
+  virtual void OnMouseCaptureLost() OVERRIDE;
+
+ protected:
+  // ImageButton overrides:
+  virtual SkBitmap GetImageToPaint() OVERRIDE;
+
+ private:
+  // Where to snap to.
+  enum SnapType {
+    SNAP_LEFT,
+    SNAP_RIGHT,
+    SNAP_MAXIMIZE,
+    SNAP_MINIMIZE,
+    SNAP_NONE
+  };
+
+  // Updates |snap_type_| based on a mouse drag. The parameters are relative to
+  // the mouse pressed location.
+  void UpdateSnap(int delta_x, int delta_y);
+
+  // Returns the type of snap based on the specified coordaintes (relative to
+  // the press location).
+  SnapType SnapTypeForDelta(int delta_x, int delta_y) const;
+
+  // Returns the bounds of the resulting window for the specified type.
+  gfx::Rect BoundsForType(SnapType type) const;
+
+  // Snaps the window to the current snap position.
+  void Snap();
+
+  // Renders the snap position.
+  scoped_ptr<internal::PhantomWindowController> phantom_window_;
+
+  // Is snapping enabled? Set on press so that in drag we know whether we
+  // should show the snap locations.
+  bool is_snap_enabled_;
+
+  // Did the user drag far enough to trigger snapping?
+  bool exceeded_drag_threshold_;
+
+  // Location of the press.
+  gfx::Point press_location_;
+
+  // Current snap type.
+  SnapType snap_type_;
+
+  DISALLOW_COPY_AND_ASSIGN(FrameMaximizeButton);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_WORKSPACE_FRAME_MAXIMIZE_BUTTON_H_