Add scale factor tag to data packs

ui/base/resource/resource_handle.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 UI_BASE_RESOURCE_RESOURCE_HANDLE_H_
 #define UI_BASE_RESOURCE_RESOURCE_HANDLE_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/string_piece.h"
 #include "ui/base/ui_export.h"
 
 namespace base {
 class RefCountedStaticMemory;
 }
 
 namespace ui {
 
 class UI_EXPORT ResourceHandle {
  public:
   // What type of encoding the text resources use.
   enum TextEncodingType {
     BINARY,
     UTF8,
     UTF16
   };
 
+  // The scale factors for image resources.
+  static const float kScaleFactor1x;

[Jói, 2012/04/26 11:02:05]

Idea:  Using percentage-based naming might make for better constant names for
various non-integral scale factors, since we can't put a . in identifiers.  That
would name these constants as kScaleFactor100 and kScaleFactor200.

[sail, 2012/05/01 04:16:02]

Done.

+  static const float kScaleFactor2x;

[oshima, 2012/04/26 15:32:10]

I *think* you can just do static const float kScaleFactor2x = 1.0f;

[sail, 2012/05/01 04:16:02]

Unfortunately this only works for ints. For floats you need to put it in the CC
file.

+
   virtual ~ResourceHandle() {}
 
   // Get resource by id |resource_id|, filling in |data|.
   // The data is owned by the DataPack object and should not be modified.
   // Returns false if the resource id isn't found.
   virtual bool GetStringPiece(uint16 resource_id,
                               base::StringPiece* data) const = 0;
 
   // Like GetStringPiece(), but returns a reference to memory.
   // Caller owns the returned object.
   virtual base::RefCountedStaticMemory* GetStaticMemory(
       uint16 resource_id) const = 0;
 
   // Get the encoding type of text resources.
   virtual TextEncodingType GetTextEncodingType() const = 0;
+
+  // The scale of images in this resource pack relative to images in the 1x
+  // resource pak.
+  virtual float GetScaleFactor() const = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_RESOURCE_RESOURCE_HANDLE_H_