Add the partial screen magnifier to Chrome OS.

ui/compositor/layer.cc

 // 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.
 
 #include "ui/compositor/layer.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 42 matching lines @@
       fills_bounds_opaquely_(true),
       layer_updated_externally_(false),
       opacity_(1.0f),
       background_blur_radius_(0),
       layer_saturation_(0.0f),
       layer_brightness_(0.0f),
       layer_grayscale_(0.0f),
       layer_inverted_(false),
       layer_mask_(NULL),
       layer_mask_back_link_(NULL),
+      zoom_x_offset_(0),
+      zoom_y_offset_(0),
+      zoom_(1),
       delegate_(NULL),
       web_layer_(NULL),
       scale_content_(true),
       device_scale_factor_(1.0f) {
   CreateWebLayer();
 }
 
 Layer::Layer(LayerType type)
     : type_(type),
       compositor_(NULL),
       parent_(NULL),
       visible_(true),
       force_render_surface_(false),
       fills_bounds_opaquely_(true),
       layer_updated_externally_(false),
       opacity_(1.0f),
       background_blur_radius_(0),
       layer_saturation_(0.0f),
       layer_brightness_(0.0f),
       layer_grayscale_(0.0f),
       layer_inverted_(false),
       layer_mask_(NULL),
       layer_mask_back_link_(NULL),
+      zoom_x_offset_(0),
+      zoom_y_offset_(0),
+      zoom_(1),
       delegate_(NULL),
       scale_content_(true),
       device_scale_factor_(1.0f) {
   CreateWebLayer();
 }
 
 Layer::~Layer() {
   // Destroying the animator may cause observers to use the layer (and
   // indirectly the WebLayer). Destroy the animator first so that the WebLayer
   // is still around.
@@ skipping 191 matching lines @@
     layer_mask_->layer_mask_back_link_ = NULL;
   layer_mask_ = layer_mask;
   web_layer_->setMaskLayer(
       layer_mask ? layer_mask->web_layer() : NULL);
   // We need to reference the linked object so that it can properly break the
   // link to us when it gets deleted.
   if (layer_mask)
     layer_mask->layer_mask_back_link_ = this;
 }
 
+void Layer::SetBackgroundZoom(float x_offset, float y_offset, float zoom) {
+  zoom_x_offset_ = x_offset;

[sky, 2012/09/07 16:06:59]

These values aren't used locally, only passed to webkit. Why do we need to cache
them in Layer too?

[Zachary Kuznia, 2012/09/13 11:49:02]

Done.

+  zoom_y_offset_ = y_offset;
+  zoom_ = zoom;
+
+  WebKit::WebFilterOperations filters;
+  if (zoom_ != 1) {
+    filters.append(WebKit::WebFilterOperation::createZoomFilter(
+        WebKit::WebRect(zoom_x_offset_, zoom_y_offset_,
+                        (bounds().width() / zoom_),

[piman, 2012/09/07 21:38:56]

is bounds() what you want, if the layer is animated? It feels like
GetTargetBounds() would be more appropriate.

[Zachary Kuznia, 2012/09/13 11:49:02]

Done.

+                        (bounds().height() / zoom_)), 16));

[piman, 2012/09/07 21:38:56]

16 looks very magic. Should it be passed as a parameter to SetBackgroundZoom?

[Zachary Kuznia, 2012/09/13 11:49:02]

Done.

+  }
+  web_layer_->setBackgroundFilters(filters);

[piman, 2012/09/07 21:38:56]

This overrides the SetBackgroundBlur setting and vice versa. Can we make sure to
keep this orthogonal? E.g. by recreating the background filter list when either
of them changes.

[Zachary Kuznia, 2012/09/13 11:49:02]

Done.

+}
+
 void Layer::SetLayerFilters() {
   WebKit::WebFilterOperations filters;
   if (layer_saturation_) {
     filters.append(WebKit::WebFilterOperation::createSaturateFilter(
         layer_saturation_));
   }
   if (layer_grayscale_) {
     filters.append(WebKit::WebFilterOperation::createGrayscaleFilter(
         layer_grayscale_));
   }
@@ skipping 459 matching lines @@
     return;
   unsigned int color = 0xFF000000;
   color |= web_layer_is_accelerated_ ? 0x0000FF00 : 0x00FF0000;
   bool opaque = fills_bounds_opaquely_ && (GetCombinedOpacity() == 1.f);
   if (!opaque)
     color |= 0xFF;
   web_layer_->setDebugBorderColor(color);
 }
 
 }  // namespace ui