content/public/browser/host_zoom_map.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 CONTENT_PUBLIC_BROWSER_HOST_ZOOM_MAP_H_
#define CONTENT_PUBLIC_BROWSER_HOST_ZOOM_MAP_H_

#include <map>
#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/callback.h"
#include "base/callback_list.h"
#include "content/common/content_export.h"

namespace content {

class BrowserContext;
class ResourceContext;

// Maps hostnames to custom zoom levels.  Written on the UI thread and read on
// any thread.  One instance per browser context. Must be created on the UI
// thread, and it'll delete itself on the UI thread as well.
// Zoom can be defined at three levels: default zoom, zoom for host, and zoom
// for host with specific scheme. Setting any of the levels leaves settings
// for other settings intact. Getting the zoom level starts at the most
// specific setting and progresses to the less specific: first the zoom for the
// host and scheme pair is checked, secondly the zoom for the host only and
// lastly default zoom.

class HostZoomMap {
 public:
  // Enum that indicates what was the scope of zoom level change.
  enum ZoomLevelChangeMode {
    ZOOM_CHANGED_FOR_HOST,            // Zoom level changed for host.
    ZOOM_CHANGED_FOR_SCHEME_AND_HOST, // Zoom level changed for scheme/host
                                      // pair.
    ZOOM_CHANGED_TEMPORARY_ZOOM,      // Temporary zoom change for specific
                                      // renderer, no scheme/host is specified.
  };

  // Structure used to notify about zoom changes. Host and/or scheme are empty
  // if not applicable to |mode|.
  struct ZoomLevelChange {
    ZoomLevelChangeMode mode;
    std::string host;
    std::string scheme;
    double zoom_level;
  };

  CONTENT_EXPORT static HostZoomMap* GetForBrowserContext(
      BrowserContext* browser_context);

  // Copy the zoom levels from the given map. Can only be called on the UI
  // thread.
  virtual void CopyFrom(HostZoomMap* copy) = 0;

  // Here |host| is the host portion of URL, or (in the absence of a host)
  // the complete spec of the URL.
  // Returns the zoom for the specified |scheme| and |host|. See class
  // description for details.
  //
  // This may be called on any thread.
  virtual double GetZoomLevelForHostAndScheme(
      const std::string& scheme,
      const std::string& host) const = 0;

  // Here |host| is the host portion of URL, or (in the absence of a host)
  // the complete spec of the URL.
  // Sets the zoom level for the |host| to |level|.  If the level matches the
  // current default zoom level, the host is erased from the saved preferences;
  // otherwise the new value is written out.
  // Zoom levels specified for both scheme and host are not affected.
  //
  // This should only be called on the UI thread.
  virtual void SetZoomLevelForHost(const std::string& host, double level) = 0;

  // Here |host| is the host portion of URL, or (in the absence of a host)
  // the complete spec of the URL.
  // Sets the zoom level for the |scheme|/|host| pair to |level|. No values
  // will be erased during this operation, and this value will not be stored in
  // the preferences.
  //
  // This should only be called on the UI thread.
  virtual void SetZoomLevelForHostAndScheme(const std::string& scheme,
                                            const std::string& host,
                                            double level) = 0;

  // Get/Set the default zoom level for pages that don't override it.
  virtual double GetDefaultZoomLevel() const = 0;
  virtual void SetDefaultZoomLevel(double level) = 0;;

  typedef base::Callback<void(const ZoomLevelChange&)> ZoomLevelChangedCallback;
  typedef base::CallbackList<void(const ZoomLevelChange&)>::Subscription
      Subscription;
  // Add and remove zoom level changed callbacks.
  virtual scoped_ptr<Subscription> AddZoomLevelChangedCallback(
      const ZoomLevelChangedCallback& callback) = 0;

 protected:
  virtual ~HostZoomMap() {}
};

}  // namespace content

#endif  // CONTENT_PUBLIC_BROWSER_HOST_ZOOM_MAP_H_