Update panel layout immediately after the user has finished resizing a panel.

chrome/browser/ui/views/panels/x11_panel_resizer.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_VIEWS_PANELS_X11_PANEL_RESIZER_H_
+#define CHROME_BROWSER_UI_VIEWS_PANELS_X11_PANEL_RESIZER_H_
+
+#include "ui/events/event_handler.h"
+#include "ui/gfx/point.h"
+
+namespace aura {
+class Window;
+}
+
+class Panel;
+
+// EventHandler which implements special handling for resizing panels. Panels
+// should use X11PanelResizer instead of X11WindowEventFilter.
+// When resizing a panel:
+// - The panel bounds should update in sync with the user's mouse movement
+//   during the resize operation.
+// - The layout of all of the panels should be updated once the resize operation
+//   completes.
+// X11PanelResizer does not hand off resizing to the window manager because it
+// is not possible to determine when the window manager has finished resizing.
+class X11PanelResizer : public ui::EventHandler {
+ public:
+  X11PanelResizer(Panel* panel, aura::Window* window);
+  virtual ~X11PanelResizer();
+
+ private:
+  enum ResizeState {
+    NOT_RESIZING,
+
+    // The user has clicked on one of the panel's edges.
+    RESIZE_CAN_START,
+
+    // The user has dragged one of the panel's edges far enough for resizing to
+    // begin.
+    RESIZE_IN_PROGRESS
+  };
+
+  // Called as a result of ET_MOUSE_PRESSED.
+  void OnMousePressed(ui::MouseEvent* event);
+
+  // Called as a result of ET_MOUSE_DRAGGED.
+  void OnMouseDragged(ui::MouseEvent* event);
+
+  // Stops the resize operation if one is in progress. Consumes |event| if it
+  // is not NULL and the resize operation was stopped.
+  void StopResizing(ui::MouseEvent* event, bool canceled);
+
+  // ui::EventHandler:
+  virtual void OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
+
+  // The panel being resized.
+  Panel* panel_;
+
+  // |panel|'s window.
+  aura::Window* window_;
+
+  ResizeState resize_state_;
+
+  // The edge that the user is resizing.
+  int resize_component_;
+
+  // The location of the mouse click on the window border.
+  gfx::Point initial_press_location_in_screen_;
+
+  DISALLOW_COPY_AND_ASSIGN(X11PanelResizer);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_PANELS_X11_PANEL_RESIZER_H_