[Mac]Implement ViewID support. (third approach)

chrome/browser/cocoa/view_id_util.mm

+// Copyright (c) 2010 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.
+
+#import "chrome/browser/cocoa/view_id_util.h"
+
+#import <Cocoa/Cocoa.h>
+
+#include <map>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/singleton.h"
+#import "chrome/browser/cocoa/browser_window_controller.h"
+#import "chrome/browser/cocoa/tab_strip_controller.h"
+
+namespace {
+
+// TODO(suzhe): After migrating to Mac OS X 10.6, we may use Objective-C's new
+// "Associative References" feature to attach the ViewID to the view directly
+// rather than using a separated map.
+typedef std::map<NSView*, ViewID> ViewIDMap;
+
+// Returns the view's nearest descendant (including itself) with a specific
+// ViewID, or nil if no subview has that ViewID.
+NSView* FindViewWithID(NSView* view, ViewID viewID) {
+  if ([view viewID] == viewID)
+    return view;
+
+  for (NSView* subview in [view subviews]) {
+    NSView* result = FindViewWithID(subview, viewID);
+    if (result != nil)
+      return result;
+  }
+  return nil;
+}
+
+}  // anonymous namespace
+
+namespace view_id_util {
+
+void SetID(NSView* view, ViewID viewID) {
+  DCHECK(view);
+  DCHECK(viewID != VIEW_ID_NONE);
+  // We handle VIEW_ID_TAB_0 to VIEW_ID_TAB_LAST in GetView() function directly.
+  DCHECK(!((viewID >= VIEW_ID_TAB_0) && (viewID <= VIEW_ID_TAB_LAST)));
+  (*Singleton<ViewIDMap>::get())[view] = viewID;
+}
+
+void UnsetID(NSView* view) {
+  DCHECK(view);
+  Singleton<ViewIDMap>::get()->erase(view);
+}
+
+NSView* GetView(NSWindow* window, ViewID viewID) {
+  DCHECK(viewID != VIEW_ID_NONE);
+  DCHECK(window);
+
+  // As tabs can be created, destroyed or rearranged dynamically, we handle them
+  // here specially.
+  if (viewID >= VIEW_ID_TAB_0 && viewID <= VIEW_ID_TAB_LAST) {
+    BrowserWindowController* windowController = [window windowController];
+    DCHECK([windowController isKindOfClass:[BrowserWindowController class]]);
+    TabStripController* tabStripController =
+        [windowController tabStripController];
+    DCHECK(tabStripController);
+    NSUInteger count = [tabStripController viewsCount];
+    DCHECK(count);
+    NSUInteger index =
+        (viewID == VIEW_ID_TAB_LAST ? count - 1 : viewID - VIEW_ID_TAB_0);
+    return index < count ? [tabStripController viewAtIndex:index] : nil;
+  }
+
+  return FindViewWithID([[window contentView] superview], viewID);
+}
+
+}  // namespace view_id_util
+
+@implementation NSView (ViewID)
+
+- (ViewID)viewID {
+  ViewIDMap* map = Singleton<ViewIDMap>::get();
+  ViewIDMap::const_iterator iter = map->find(self);
+  return iter != map->end() ? iter->second : VIEW_ID_NONE;
+}
+
+@end