Add the partial screen magnifier to Chrome OS.

ui/compositor/layer.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_COMPOSITOR_LAYER_H_
 #define UI_COMPOSITOR_LAYER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 150 matching lines @@
   // Change the grayscale of all pixels from this layer by this amount.
   // This effect will get "combined" with the inverted, saturate
   // and brightness setting.
   float layer_grayscale() const { return layer_grayscale_; }
   void SetLayerGrayscale(float grayscale);
 
   // Return the target grayscale if animator is running, or the current
   // grayscale otherwise.
   float GetTargetGrayscale() const;
 
+  // Zoom the background by this amount.

[sky, 2012/10/11 17:00:49]

Its not obvious what 'inset' is, document it.

[Zachary Kuznia, 2012/10/12 08:41:35]

Done.

+  void SetBackgroundZoom(float x_offset, float y_offset, float zoom, int inset);
+
   // Invert the layer.
   bool layer_inverted() const { return layer_inverted_; }
   void SetLayerInverted(bool inverted);
 
   // Return the target opacity if animator is running, or the current opacity
   // otherwise.
   float GetTargetOpacity() const;
 
   // Set a layer mask for a layer.
   // Note the provided layer mask can neither have a layer mask itself nor can
@@ skipping 138 matching lines @@
   virtual float GetGrayscaleForAnimation() const OVERRIDE;
 
   void CreateWebLayer();
   void RecomputeTransform();
   void RecomputeDrawsContentAndUVRect();
   void RecomputeDebugBorderColor();
 
   // Set all filters which got applied to the layer.
   void SetLayerFilters();
 
+  // Set all filters which got applied to the layer background.
+  void SetLayerBackgroundFilters();
+
   const LayerType type_;
 
   Compositor* compositor_;
 
   scoped_refptr<ui::Texture> texture_;
 
   Layer* parent_;
 
   // This layer's children, in bottom-to-top stacking order.
   std::vector<Layer*> children_;
@@ skipping 26 matching lines @@
   float layer_grayscale_;
   bool layer_inverted_;
 
   // The associated mask layer with this layer.
   Layer* layer_mask_;
   // The back link from the mask layer to it's associated masked layer.
   // We keep this reference for the case that if the mask layer gets deleted
   // while attached to the main layer before the main layer is deleted.
   Layer* layer_mask_back_link_;
 
+  // When the layer is zoomed, this is the offset to the upper left corner of
+  // the area in the layer that is zoomed.
+  float zoom_x_offset_;
+  float zoom_y_offset_;
+
+  // The zoom factor to scale the layer by.  Zooming is disabled when this is
+  // set to 1.
+  float zoom_;
+
+  // Width of the border in pixels, where the scaling is blended.
+  int zoom_inset_;
+
   std::string name_;
 
   LayerDelegate* delegate_;
 
   scoped_refptr<LayerAnimator> animator_;
 
   // Ownership of the layer is held through one of the strongly typed layer
   // pointers, depending on which sort of layer this is.
   scoped_ptr<WebKit::WebContentLayer> content_layer_;
   scoped_ptr<WebKit::WebExternalTextureLayer> texture_layer_;
   scoped_ptr<WebKit::WebSolidColorLayer> solid_color_layer_;
   WebKit::WebLayer* web_layer_;
   bool web_layer_is_accelerated_;
   bool show_debug_borders_;
 
   // If true, the layer scales the canvas and the texture with the device scale
   // factor as appropriate. When true, the texture size is in DIP.
   bool scale_content_;
 
   // A cached copy of |Compositor::device_scale_factor()|.
   float device_scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_H_