Allow upgrading to 2x DSF for lower UI scale when 2x resoruces are available.

ash/display/display_info.h

 // Copyright (c) 2013 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 ASH_DISPLAY_DISPLAY_INFO_H_
 #define ASH_DISPLAY_DISPLAY_INFO_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 63 matching lines @@
   static DisplayInfo CreateFromSpec(const std::string& spec);
 
   // Creates a DisplayInfo from string spec using given |id|.
   static DisplayInfo CreateFromSpecWithID(const std::string& spec,
                                           int64 id);
 
   DisplayInfo();
   DisplayInfo(int64 id, const std::string& name, bool has_overscan);
   ~DisplayInfo();
 
+  // When this is set to true, Chrome switches High DPI when lower UI scale
+  // (<1.0f) is specificed on 1x device to make UI sharp, e.g, upgrade 0.6

[Jun Mukai, 2014/04/09 18:16:40]

typo: specified?

[oshima, 2014/04/10 14:22:22]

Done.

+  // scale on 1x DSF to 1.2 scale on 2x DSF.
+  static void SetAllowUpgradeToHighDPI(bool enable);
+
   int64 id() const { return id_; }
 
   // The name of the display.
   const std::string& name() const { return name_; }
 
   // True if the display EDID has the overscan flag. This does not create the
   // actual overscan automatically, but used in the message.
   bool has_overscan() const { return has_overscan_; }
 
   void set_rotation(gfx::Display::Rotation rotation) { rotation_ = rotation; }
@@ skipping 22 matching lines @@
   const gfx::Insets& overscan_insets_in_dip() const {
     return overscan_insets_in_dip_;
   }
 
   // Sets/gets configured ui scale. This can be different from the ui
   // scale actually used when the scale is 2.0 and DSF is 2.0.
   // (the effective ui scale is 1.0 in this case).
   float configured_ui_scale() const { return configured_ui_scale_; }
   void set_configured_ui_scale(float scale) { configured_ui_scale_ = scale; }
 
-  // Returns the ui scale used for the device scale factor. This
-  // return 1.0f if the ui scale and dsf are both set to 2.0.
+  // Returns the ui scale and device scale factor actually used to create
+  // display that chrome sees. This can be different from one obtained
+  // from dispaly or one specified by a user in following situation.
+  // 1) DSF is 2.0f and UI scale is 2.0f. (Returns 1.0f and 1.0f respectiely)
+  // 2) Lower UI scale (< 1.0) is specified on 1.0f DSF
+  // when 2x resources is available. (Returns 2.0f + 1.2f for 1.0DSF + 0.6
+  // ui scale) so that chrome can use 2x resoruces.
   float GetEffectiveUIScale() const;
+  float GetEffectiveDeviceScaleFactor() const;

[Jun Mukai, 2014/04/09 18:16:40]

a bit confused because the order of declaration of UIScale() and
DeviceScaleFactor() is different from the comment (the comment is saying
DSF->UIScale).

[oshima, 2014/04/10 14:22:22]

Fixed the comment.

 
   // Copy the display info except for fields that can be modified by a
   // user (|rotation_| and |configured_ui_scale_|). |rotation_| and
   // |configured_ui_scale_| are copied when the |another_info| isn't native one.
   void Copy(const DisplayInfo& another_info);
 
   // Update the |bounds_in_native_| and |size_in_pixel_| using
   // given |bounds_in_native|.
   void SetBounds(const gfx::Rect& bounds_in_native);
 
@@ skipping 81 matching lines @@
   // The current profile of the color calibration.
   ui::ColorCalibrationProfile color_profile_;
 
   // The list of available variations for the color calibration.
   std::vector<ui::ColorCalibrationProfile> available_color_profiles_;
 };
 
 }  // namespace ash
 
 #endif  //  ASH_DISPLAY_DISPLAY_INFO_H_