Fix rounding rules for skia operations to work with non-integer scaling factors.

ui/gfx/image/image_skia_operations.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/gfx/image/image_skia_operations.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "skia/ext/image_operations.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/canvas_image_source.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_skia_rep.h"
 #include "ui/gfx/image/image_skia_source.h"
 #include "ui/gfx/insets.h"
+#include "ui/gfx/point.h"
+#include "ui/gfx/point_conversions.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/size.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/skbitmap_operations.h"
 #include "ui/gfx/skia_util.h"
 
 namespace gfx {
 namespace {
 
@@ skipping 20 matching lines @@
         second_(second),
         source_name_(source_name) {
   }
   virtual ~BinaryImageSource() {
   }
 
   // gfx::ImageSkiaSource overrides:
   virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
     ImageSkiaRep first_rep = first_.GetRepresentation(scale_factor);
     ImageSkiaRep second_rep = second_.GetRepresentation(scale_factor);
-    if (first_rep.pixel_size() != second_rep.pixel_size()) {
+    gfx::Size first_size = first_rep.pixel_size();
+    gfx::Size second_size = second_rep.pixel_size();
+    // Allow for maximum of 1 pixel mismatch due to rounding errors.
+    int dw = first_size.width() - second_size.width();
+    int dh = first_size.height() - second_size.height();
+    if (abs(dw) > 1 || abs(dh) > 1) {
       DCHECK_NE(first_rep.scale_factor(), second_rep.scale_factor());
       if (first_rep.scale_factor() == second_rep.scale_factor()) {
         LOG(ERROR) << "ImageSkiaRep size mismatch in " << source_name_;
         return GetErrorImageRep(first_rep.scale_factor(),
                                 first_rep.pixel_size());
       }
       first_rep = first_.GetRepresentation(ui::SCALE_FACTOR_100P);
       second_rep = second_.GetRepresentation(ui::SCALE_FACTOR_100P);
-      DCHECK_EQ(first_rep.pixel_width(), second_rep.pixel_width());
-      DCHECK_EQ(first_rep.pixel_height(), second_rep.pixel_height());
-      if (first_rep.pixel_size() != second_rep.pixel_size()) {
+      DCHECK_LE(abs(dw), 1);
+      DCHECK_LE(abs(dh), 1);
+      if (abs(dw) > 1 || abs(dh) > 1) {
         LOG(ERROR) << "ImageSkiaRep size mismatch in " << source_name_;
         return GetErrorImageRep(first_rep.scale_factor(),
                                 first_rep.pixel_size());
       }
     } else {
       DCHECK_EQ(first_rep.scale_factor(), second_rep.scale_factor());
     }
     return CreateImageSkiaRep(first_rep, second_rep);
   }
 
@@ skipping 130 matching lines @@
         dst_h_(dst_h) {
   }
 
   virtual ~TiledImageSource() {
   }
 
   // gfx::ImageSkiaSource overrides:
   virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
     ImageSkiaRep source_rep = source_.GetRepresentation(scale_factor);
     float scale = ui::GetScaleFactorScale(source_rep.scale_factor());
+    gfx::Point point = gfx::ToFlooredPoint(gfx::ScalePoint(

[pkotwicz, 2013/03/12 15:54:37]

You should create a generic method which does this logic at at the top of this
file.
ResizeSource and ExtractSubsetImageSource should get the same treatment.

[kevers, 2013/03/12 22:02:25]

Done.

+        gfx::Point(src_x_, src_y_), scale));
+    gfx::Size size = gfx::ToCeiledSize(gfx::ScaleSize(
+        gfx::Size(dst_w_, dst_h_), scale));
     return ImageSkiaRep(
         SkBitmapOperations::CreateTiledBitmap(
             source_rep.sk_bitmap(),
-            src_x_ * scale, src_y_ * scale, dst_w_ * scale, dst_h_ * scale),
+            point.x(), point.y(), size.width(), size.height()),
         source_rep.scale_factor());
   }
 
  private:
   const ImageSkia source_;
   const int src_x_;
   const int src_y_;
   const int dst_w_;
   const int dst_h_;
 
@@ skipping 20 matching lines @@
   }
 
  private:
   const gfx::ImageSkia image_;
   const color_utils::HSL hsl_shift_;
   DISALLOW_COPY_AND_ASSIGN(HSLImageSource);
 };
 
 // ImageSkiaSource which uses SkBitmapOperations::CreateButtonBackground
 // to generate image reps for the target image.
 class ButtonImageSource: public gfx::ImageSkiaSource {

[pkotwicz, 2013/03/12 15:54:37]

Nit: Switch this class to inherit from BinaryImageSource as well.

[kevers, 2013/03/12 22:02:25]

Done.

  public:
   ButtonImageSource(SkColor color,
                     const ImageSkia& image,
                     const ImageSkia& mask)
       : color_(color),
         image_(image),
         mask_(mask) {
   }
 
   virtual ~ButtonImageSource() {
@@ skipping 271 matching lines @@
     return ImageSkia();
 
   return ImageSkia(new RotatedSource(source, rotation),
       SkBitmapOperations::ROTATION_180_CW == rotation ?
           source.size() :
           gfx::Size(source.height(), source.width()));
 
 }
 
 }  // namespace gfx