Make info button appear only when mouse is over the panel or the panel has focus.

chrome/browser/ui/panels/panel_browser_frame_view.h

 // Copyright (c) 2011 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 CHROME_BROWSER_UI_PANELS_PANEL_BROWSER_FRAME_VIEW_H_
 #define CHROME_BROWSER_UI_PANELS_PANEL_BROWSER_FRAME_VIEW_H_
 #pragma once
 
 #include "base/gtest_prod_util.h"
+#include "base/message_loop.h"
 #include "base/scoped_ptr.h"
 #include "chrome/browser/ui/views/frame/browser_non_client_frame_view.h"
 #include "chrome/browser/ui/views/tab_icon_view.h"
 #include "views/controls/button/button.h"
 
 class PanelBrowserView;
 namespace views {
 class ImageButton;
 class Label;
 }
@@ skipping 39 matching lines @@
   virtual void ButtonPressed(views::Button* sender, const views::Event& event)
       OVERRIDE;
 
   // Overridden from TabIconView::TabIconViewModel:
   virtual bool ShouldTabIconViewAnimate() const OVERRIDE;
   virtual SkBitmap GetFaviconForTabIconView() OVERRIDE;
 
  private:
   friend class PanelBrowserViewTest;
   FRIEND_TEST_ALL_PREFIXES(PanelBrowserViewTest, CreatePanel);
+  FRIEND_TEST_ALL_PREFIXES(PanelBrowserViewTest, ShowOrHideInfoButton);
 
   enum PaintState {
     NOT_PAINTED,
     PAINT_AS_INACTIVE,
     PAINT_AS_ACTIVE
   };
 
+  class MouseWatcher : public MessageLoopForUI::Observer {
+   public:
+    explicit MouseWatcher(PanelBrowserFrameView* view);
+    virtual ~MouseWatcher();
+
+    virtual bool IsCursorInViewBounds() const;
+
+  #if defined(OS_WIN)
+    virtual void WillProcessMessage(const MSG& msg) OVERRIDE { }
+    virtual void DidProcessMessage(const MSG& msg) OVERRIDE;
+  #else
+    virtual void WillProcessEvent(GdkEvent* event) OVERRIDE { }
+    virtual void DidProcessEvent(GdkEvent* event) OVERRIDE;
+  #endif
+
+   private:
+    void HandleGlobalMouseMoveEvent();
+
+    PanelBrowserFrameView* view_;
+    bool in_view_;

[Dmitry Titov, 2011/05/24 20:21:56]

I saw often in the past the suggestion to keep names of this kind of variables
with the "Is" in them, like: is_mouse_within_

[jianli, 2011/05/24 21:58:56]

Done.

+
+    DISALLOW_COPY_AND_ASSIGN(MouseWatcher);
+  };
+
   // Returns the thickness of the entire nonclient left, right, and bottom
   // borders, including both the window frame and any client edge.
   int NonClientBorderThickness() const;
 
   // Returns the height of the entire nonclient top border, including the window
   // frame, any title area, and any connected client edge.
   int NonClientTopBorderHeight() const;
 
   // Update control styles to indicate if the title bar is active or not.
   void UpdateControlStyles(PaintState paint_state);
 
   // Custom draw the frame.
   void PaintFrameBorder(gfx::Canvas* canvas);
   void PaintClientEdge(gfx::Canvas* canvas);
 
+  // Called by MouseWatcher to notify if the mouse enters or leaves the window.
+  void OnMouseEnterOrLeaveWindow(bool mouse_entered);
+
+  // Make info button visible if either of the conditions is met:
+  // 1) The panel is active, i.e. having focus.
+  // 2) The mouse is over the panel.
+  void UpdateInfoButtonVisibility(bool active, bool cursor_in_view);
+
+#ifdef UNIT_TEST
+  void set_mouse_watcher(MouseWatcher* mouse_watcher) {
+    mouse_watcher_.reset(mouse_watcher);
+  }
+#endif
+
   // The frame that hosts this view. This is a weak reference such that frame_
   // will always be valid in the lifetime of this view.
   BrowserFrame* frame_;
 
   // The client view hosted within this non-client frame view that is
   // guaranteed to be freed before the client view.
   // (see comments about view hierarchies in non_client_view.h)
   PanelBrowserView* browser_view_;
 
   PaintState paint_state_;
   views::ImageButton* info_button_;
   views::ImageButton* close_button_;
   TabIconView* title_icon_;
   views::Label* title_label_;
   gfx::Rect client_view_bounds_;
+  scoped_ptr<MouseWatcher> mouse_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(PanelBrowserFrameView);
 };
 
 #endif  // CHROME_BROWSER_UI_PANELS_PANEL_BROWSER_FRAME_VIEW_H_