Make the bookmark toolbar folders act like a menu bar....

chrome/browser/gtk/menu_bar_helper.cc

+// Copyright (c) 2009 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.
+
+#include "chrome/browser/gtk/menu_bar_helper.h"
+
+#include "base/logging.h"
+#include "chrome/common/gtk_util.h"
+
+namespace {
+
+// Recursively find all the GtkMenus that are attached to menu item |child|
+// and add them to |data|, which is a vector of GtkWidgets.
+void PopulateSubmenus(GtkWidget* child, gpointer data) {
+  std::vector<GtkWidget*>* submenus =
+      static_cast<std::vector<GtkWidget*>*>(data);
+  GtkWidget* submenu = gtk_menu_item_get_submenu(GTK_MENU_ITEM(child));
+  if (submenu) {
+    submenus->push_back(submenu);
+    gtk_container_foreach(GTK_CONTAINER(submenu), PopulateSubmenus, submenus);
+  }
+}
+
+// Is the cursor over |menu| or one of its parent menus?
+bool MotionIsOverMenu(GtkWidget* menu, GdkEventMotion* motion) {
+  if (motion->x >= 0 && motion->y >= 0 &&
+      motion->x < menu->allocation.width &&
+      motion->y < menu->allocation.height) {
+    return true;
+  }
+
+  while (menu) {
+    GtkWidget* menu_item = gtk_menu_get_attach_widget(GTK_MENU(menu));
+    if (!menu_item)
+      return false;
+    GtkWidget* parent = gtk_widget_get_parent(menu_item);
+
+    if (gtk_util::WidgetContainsCursor(parent))
+      return true;
+    menu = parent;
+  }
+
+  return false;
+}
+
+}  // namespace
+
+MenuBarHelper::MenuBarHelper(Delegate* delegate)
+    : button_showing_menu_(NULL),
+      showing_menu_(NULL),
+      delegate_(delegate) {
+  DCHECK(delegate_);
+}
+
+MenuBarHelper::~MenuBarHelper() {
+}
+
+void MenuBarHelper::Add(GtkWidget* button) {
+  buttons_.push_back(button);
+}
+
+void MenuBarHelper::Remove(GtkWidget* button) {
+  std::vector<GtkWidget*>::iterator iter =
+      find(buttons_.begin(), buttons_.end(), button);
+  if (iter == buttons_.end()) {
+    NOTREACHED();
+    return;
+  }
+  buttons_.erase(iter);
+}
+
+void MenuBarHelper::Clear() {
+  buttons_.clear();
+}
+
+void MenuBarHelper::MenuStartedShowing(GtkWidget* button, GtkWidget* menu) {
+  DCHECK(GTK_IS_MENU(menu));
+  button_showing_menu_ = button;
+  showing_menu_ = menu;
+  g_signal_connect(menu, "motion-notify-event",
+                   G_CALLBACK(OnMenuMotionNotifyThunk), this);
+  g_signal_connect(menu, "hide",
+                   G_CALLBACK(OnMenuHiddenThunk), this);
+  g_signal_connect(menu, "move-current",
+                   G_CALLBACK(OnMenuMoveCurrentThunk), this);
+  gtk_container_foreach(GTK_CONTAINER(menu), PopulateSubmenus, &submenus_);
+  for (size_t i = 0; i < submenus_.size(); ++i) {
+    g_signal_connect(submenus_[i], "motion-notify-event",
+                     G_CALLBACK(OnMenuMotionNotifyThunk), this);
+  }
+}
+
+gboolean MenuBarHelper::OnMenuMotionNotify(GtkWidget* menu,
+                                           GdkEventMotion* motion) {
+  // Don't do anything if pointer is in the menu.
+  if (MotionIsOverMenu(menu, motion))
+    return FALSE;
+  if (buttons_.empty())
+    return FALSE;
+
+  gint x = 0;
+  gint y = 0;
+  GtkWidget* last_button = NULL;
+
+  for (size_t i = 0; i < buttons_.size(); ++i) {
+    GtkWidget* button = buttons_[i];
+    // Figure out coordinates relative to this button. Avoid using
+    // gtk_widget_get_pointer() unnecessarily.
+    if (i == 0) {
+      // We have to make this call because the menu is a popup window, so it
+      // doesn't share a toplevel with the buttons and we can't just use
+      // gtk_widget_translate_coordinates().
+      gtk_widget_get_pointer(buttons_[0], &x, &y);
+    } else {
+      gint last_x = x;
+      gint last_y = y;
+      if (!gtk_widget_translate_coordinates(
+          last_button, button, last_x, last_y, &x, &y)) {
+        NOTREACHED();
+        return FALSE;
+      }
+    }
+
+    last_button = button;
+
+    if (x >= 0 && y >= 0 && x < button->allocation.width &&
+        y < button->allocation.height) {
+      if (button != button_showing_menu_)
+        delegate_->PopupForButton(button);
+      return TRUE;
+    }
+  }
+
+  return FALSE;
+}
+
+void MenuBarHelper::OnMenuHidden(GtkWidget* menu) {
+  DCHECK_EQ(showing_menu_, menu);
+  int matched = g_signal_handlers_disconnect_matched(showing_menu_,
+      G_SIGNAL_MATCH_DATA, 0, NULL, NULL, NULL, this);
+  DCHECK_EQ(3, matched);
+
+  for (size_t i = 0; i < submenus_.size(); ++i) {
+    g_signal_handlers_disconnect_by_func(submenus_[i],
+        reinterpret_cast<gpointer>(OnMenuMotionNotifyThunk), this);
+  }
+  showing_menu_ = NULL;
+  button_showing_menu_ = NULL;
+  submenus_.clear();
+}
+
+void MenuBarHelper::OnMenuMoveCurrent(GtkWidget* menu,
+                                      GtkMenuDirectionType dir) {
+  // The menu directions are triggered by the arrow keys as follows
+  //
+  //   PARENT   left
+  //   CHILD    right
+  //   NEXT     down
+  //   PREV     up
+  //
+  // We only care about left and right. Note that for RTL, they are swapped.
+  switch (dir) {
+    case GTK_MENU_DIR_CHILD: {
+      GtkWidget* active_item = GTK_MENU_SHELL(menu)->active_menu_item;
+      // The move is going to open a submenu; don't override default behavior.
+      if (active_item && gtk_menu_item_get_submenu(GTK_MENU_ITEM(active_item)))
+        return;
+      // Fall through.
+    }
+    case GTK_MENU_DIR_PARENT: {
+      delegate_->PopupForButtonNextTo(button_showing_menu_, dir);
+      break;
+    }
+    default:
+      return;
+  }
+
+  // This signal doesn't have a return value; we have to manually stop its
+  // propagation.
+  g_signal_stop_emission_by_name(menu, "move-current");
+}