Zoom Extension API (chrome)

chrome/browser/ui/zoom/zoom_controller.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_ZOOM_ZOOM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ZOOM_ZOOM_CONTROLLER_H_
 
+#include <queue>

[Devlin, 2014/06/19 21:15:30]

Do we still need this?

[wjmaclean, 2014/06/20 22:01:34]

Good catch, no. Removed.

+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/prefs/pref_member.h"
 #include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 class ZoomObserver;
 
 namespace content {
 class WebContents;
 }
 
-// Per-tab class to manage the Omnibox zoom icon.
+namespace extensions {
+class Extension;
+}  // namespace extensions
+
+// Per-tab class to manage zoom changes and the Omnibox zoom icon.
 class ZoomController : public content::WebContentsObserver,
                        public content::WebContentsUserData<ZoomController> {
  public:
+  // Defines how zoom changes are handled.
+  // |kZoomModeDefault| results in default zoom behavior, i.e. zoom changes are
+  //     handled automatically and on a per-origin basis, meaning that other
+  //     tabs navigated to the same origin will also zoom.
+  // |kZoomModeIsolated| results in zoom changes being handled automatically,
+  //     but on a per-tab basis. Tabs in this zoom mode will not be affected by
+  //     zoom changes in other tabs, and vice versa.
+  // |kZoomModeManual| overrides the automatic handling of zoom changes. The
+  //     |onZoomChange| event will still be dispatched, but the page will not
+  //     actually be zoomed. These zoom changes can be handled manually by
+  //     listening for the |onZoomChange| event. Zooming in this mode is also on
+  //     a per-tab basis.
+  // |kZoomModeDisabled| disables all zooming in this tab. The tab will revert
+  //     to default (100%) zoom, and all attempted zoom changes will be ignored.
+  enum ZoomMode {
+    kZoomModeDefault,
+    kZoomModeIsolated,
+    kZoomModeManual,
+    kZoomModeDisabled,
+  };
+
   virtual ~ZoomController();
 
-  int zoom_percent() const { return zoom_percent_; }
+  ZoomMode zoom_mode() const { return zoom_mode_; }
 
   // Convenience method to quickly check if the tab's at default zoom.
   bool IsAtDefaultZoom() const;
 
   // Returns which image should be loaded for the current zoom level.
   int GetResourceForZoomLevel() const;
 
-  void set_observer(ZoomObserver* observer) { observer_ = observer; }
+  const extensions::Extension* last_extension() const {
+    return last_extension_.get();
+  }
+
+  void AddObserver(ZoomObserver* observer) { observers_.push_back(observer); }

[Devlin, 2014/06/19 21:15:30]

A "remove observer" would also be good :)

[wjmaclean, 2014/06/20 22:01:34]

OK, I don't mind adding that. The reason I haven't added it before now is that
there are no callers for it at present, and I've generally been told not to add
unused interface in the past.

Done.

+
+  double GetZoomLevel() const;
+  int GetZoomPercent() const;
+
+  // Sets the zoom level through HostZoomMap.
+  // Returns true on success.
+  bool SetZoomLevel(double zoom_level);
+
+  // Sets the zoom level through WebContents::SetZoomLevel(), and attributes the
+  // zoom to |extension|. Returns a boolean flag indicating success (true) or
+  // failure (false).
+  bool SetZoomLevelByExtension(
+      double zoom_level,
+      scoped_refptr<const extensions::Extension> extension);
+
+  // Sets the zoom mode, which defines zoom behavior (see enum ZoomMode).
+  void SetZoomMode(ZoomMode zoom_mode);
 
   // content::WebContentsObserver overrides:
   virtual void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) OVERRIDE;
 
  private:
   explicit ZoomController(content::WebContents* web_contents);
   friend class content::WebContentsUserData<ZoomController>;
   friend class ZoomControllerTest;
 
   void OnZoomLevelChanged(const content::HostZoomMap::ZoomLevelChange& change);
 
   // Updates the zoom icon and zoom percentage based on current values and
   // notifies the observer if changes have occurred. |host| may be empty,
   // meaning the change should apply to ~all sites. If it is not empty, the
   // change only affects sites with the given host.
   void UpdateState(const std::string& host);
+  void UpdateStateIncludingTemporary(const std::string& host,

[Devlin, 2014/06/19 21:15:30]

Document the difference between this and UpdateState() (i.e., say what a
"temporary zoom" is in this context).

[wjmaclean, 2014/06/20 22:01:34]

Done.

+                                     bool is_temporary_zoom);
 
-  // The current zoom percentage.
-  int zoom_percent_;
+  // The current zoom mode.
+  ZoomMode zoom_mode_;
+
+  // Current zoom level.
+  double zoom_level_;
 
   // Used to access the default zoom level preference.
   DoublePrefMember default_zoom_level_;
 
+  // Keeps track of the extension (if any) that initiated the last zoom change
+  // that took effect.
+  scoped_refptr<const extensions::Extension> last_extension_;
+
   // Observer receiving notifications on state changes.
-  ZoomObserver* observer_;
+  std::vector<ZoomObserver*> observers_;

[Devlin, 2014/06/19 21:15:30]

Take a look at ObserverList (base/observer_list.h)

[wjmaclean, 2014/06/20 22:01:34]

Done.

 
   content::BrowserContext* browser_context_;
 
   scoped_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
 
   DISALLOW_COPY_AND_ASSIGN(ZoomController);
 };
 
 #endif  // CHROME_BROWSER_UI_ZOOM_ZOOM_CONTROLLER_H_