Resize support for detached GTK Panels.

chrome/browser/ui/panels/panel_drag_gtk.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 CHROME_BROWSER_UI_PANELS_PANEL_DRAG_GTK_H_
+#define CHROME_BROWSER_UI_PANELS_PANEL_DRAG_GTK_H_
+#pragma once
+
+#include <gtk/gtk.h>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "ui/base/gtk/gtk_signal.h"
+
+class Panel;
+class PanelDragDelegate;
+
+// Class for GTK handling of move-drag and resize-drag on a panel.
+// Only one type of drag may be active at any time.
+// Dragging only begins if the mouse is moved beyond the drag threshold.
+// If mouse is released without exceeding the drag threshold, the mouse
+// press and release is treated as a mouse click.
+class PanelDragGtk {

[dcheng, 2012/04/12 00:12:45]

Given that this is named drag_helper_ in PanelBrowserWindowGtk, I think it's
appropriate to call this PanelDragHelper. But I don't have a strong opinion
about this.

+ public:
+  explicit PanelDragGtk(Panel* panel);
+  ~PanelDragGtk();
+
+  GtkWidget* widget() const { return drag_widget_; }
+
+  // Sets up mouse and keyboard events processing while the mouse
+  // is pressed on a window edge.
+  // |event| is the mouse press event.
+  // |cursor| is the cursor to display during the drag.
+  // |edge| is the window edge from which to resize the panel.
+  void InitialWindowEdgeMousePress(GdkEventButton* event, GdkCursor* cursor,
+                                   GdkWindowEdge& edge);
+
+  // Sets up mouse and keyboard events processing while the mouse is
+  // pressed on the titlebar.
+  // |event| is the mouse press event.
+  // |titlebar_widget| should handle the mouse release event if the mouse
+  // is released without exceeding the drag threshold (a mouse click).
+  void InitialTitlebarMousePress(GdkEventButton* event,
+                                 GtkWidget* titlebar_widget);
+
+ private:
+  enum DragState {
+    NOT_DRAGGING,
+    DRAG_IN_PROGRESS
+  };
+
+  // Callbacks for GTK mouse and key events.
+  CHROMEGTK_CALLBACK_1(PanelDragGtk, gboolean, OnMouseMoveEvent,
+                       GdkEventMotion*);
+  CHROMEGTK_CALLBACK_1(PanelDragGtk, gboolean, OnButtonPressEvent,
+                       GdkEventButton*);
+  CHROMEGTK_CALLBACK_1(PanelDragGtk, gboolean, OnButtonReleaseEvent,
+                       GdkEventButton*);
+  CHROMEGTK_CALLBACK_1(PanelDragGtk, gboolean, OnKeyPressEvent,
+                       GdkEventKey*);
+  CHROMEGTK_CALLBACK_1(PanelDragGtk, gboolean, OnKeyReleaseEvent,
+                       GdkEventKey*);
+  CHROMEGTK_CALLBACK_1(PanelDragGtk, gboolean, OnGrabBrokenEvent,
+                       GdkEventGrabBroken*);
+
+  // Utility to dcheck a bunch of state to ensure a clean slate.
+  // Returns true only if all the dchecks pass.
+  bool AssertCleanState();
+
+  void GrabPointerAndKeyboard(GdkEventButton* event,
+                              GdkCursor* cursor);
+
+  // Ends any drag that is currently in progress (if any).
+  // Also resets all drag state.
+  void EndDrag(bool canceled);
+
+  // Weak pointer to the panel being dragged.
+  Panel* panel_;
+
+  // Invisible event box to receive mouse and key events.
+  GtkWidget* drag_widget_;
+
+  DragState drag_state_;
+
+  // A copy of the initial button press event.
+  GdkEvent* initial_mouse_down_;
+
+  // Widget that should process the mouse click if mouse is released
+  // without exceeding the drag threshold. May be NULL if no click
+  // handling is necessary.
+  GtkWidget* click_handler_;
+
+  // Delegate for processing drag depends on actual type of drag.
+  PanelDragDelegate* drag_delegate_;

[dcheng, 2012/04/12 00:12:45]

Nit: DISABLE_COPY_AND_ASSIGN

[jennb, 2012/04/12 18:00:24]

Done.

+};
+
+#endif  // CHROME_BROWSER_UI_PANELS_PANEL_DRAG_GTK_H_