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

ui/gfx/image/image_skia_operations.cc

Index: ui/gfx/image/image_skia_operations.cc
diff --git a/ui/gfx/image/image_skia_operations.cc b/ui/gfx/image/image_skia_operations.cc
index 4b5612ea063bc1376556b58dee5e03e80b9ffe23..07784f06687ad4073d9934fa896d461f053c5dcb 100644
--- a/ui/gfx/image/image_skia_operations.cc
+++ b/ui/gfx/image/image_skia_operations.cc
@@ -14,6 +14,8 @@
 #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"
@@ -54,7 +56,12 @@ class BinaryImageSource : public gfx::ImageSkiaSource {
   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_;
@@ -63,9 +70,9 @@ class BinaryImageSource : public gfx::ImageSkiaSource {
       }
       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());
@@ -216,10 +223,14 @@ class TiledImageSource : public gfx::ImageSkiaSource {
   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());
   }