Use LANCZOS3 resize algorithm to generate missing image reps for extension action icons.

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 "skia/ext/platform_canvas.h"
@@ skipping 302 matching lines @@
                skia::ImageOperations::ResizeMethod method,
                const Size& target_dip_size)
       : source_(source),
         resize_method_(method),
         target_dip_size_(target_dip_size) {
   }
   virtual ~ResizeSource() {}
 
   // gfx::ImageSkiaSource overrides:
   virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
-    const ImageSkiaRep& image_rep = source_.GetRepresentation(scale_factor);
-    if (image_rep.GetWidth() == target_dip_size_.width() &&
-        image_rep.GetHeight() == target_dip_size_.height())
-      return image_rep;
-
     const float scale = ui::GetScaleFactorScale(scale_factor);
     const Size target_pixel_size = gfx::ToFlooredSize(
         target_dip_size_.Scale(scale));
+
+    const ImageSkiaRep& image_rep = source_.GetRepresentation(scale_factor);
+
+    if (image_rep.pixel_width() == target_pixel_size.width() &&
+        image_rep.pixel_height() == target_pixel_size.height()) {
+      if (image_rep.scale_factor() == scale_factor)

[pkotwicz, 2012/10/17 18:42:20]

Nit: I think you can include this if as part of the outer if.

[tbarzic, 2012/10/17 19:00:46]

yeah, but in that case we could call skia::ImageOperations::Resize even if the
image_rep.sk_bitmap() had the correct size.
(e.g. situation where source has dip size 32x32 and contains rep for scale 1;
and we are looking for rep for scale 2 of image resized to 16x16)

[pkotwicz, 2012/10/17 19:13:29]

Sorry I should have seen that. You can if you want get rid of the inner if
altogether. ImageSkiaRep are cheap to create.

[tbarzic, 2012/10/17 19:15:42]

ok, Done.

+        return image_rep;
+      return ImageSkiaRep(image_rep.sk_bitmap(), scale_factor);
+    }
+
     const SkBitmap resized = skia::ImageOperations::Resize(
         image_rep.sk_bitmap(),
         resize_method_,
         target_pixel_size.width(),
         target_pixel_size.height());
     return ImageSkiaRep(resized, scale_factor);
   }
 
  private:
   const ImageSkia source_;
@@ skipping 101 matching lines @@
 // static
 ImageSkia ImageSkiaOperations::CreateResizedImage(
     const ImageSkia& source,
     skia::ImageOperations::ResizeMethod method,
     const Size& target_dip_size) {
   return ImageSkia(new ResizeSource(source, method, target_dip_size),
                    target_dip_size);
 }
 
 // static
+ImageSkia ImageSkiaOperations::SetFallbackResizeMethod(
+      const ImageSkia& source,
+      skia::ImageOperations::ResizeMethod method) {
+  return ImageSkia(new ResizeSource(source, method, source.size()),
+                   source.size());
+}
+
+// static
 ImageSkia ImageSkiaOperations::CreateImageWithDropShadow(
     const ImageSkia& source,
     const ShadowValues& shadows) {
   const gfx::Insets shadow_padding = -gfx::ShadowValue::GetMargin(shadows);
   gfx::Size shadow_image_size = source.size();
   shadow_image_size.Enlarge(shadow_padding.width(),
                             shadow_padding.height());
   return ImageSkia(new DropShadowSource(source, shadows), shadow_image_size);
 }
 
 }  // namespace gfx