Makes ImageView do a bit more checking before assuming images equal

ui/views/controls/image_view.cc

Index: ui/views/controls/image_view.cc
diff --git a/ui/views/controls/image_view.cc b/ui/views/controls/image_view.cc
index fc44a84cfbffba6eb0b8b640e2208315ab25b649..c86cf2875884c411881ee3707b7da0361202fe88 100644
--- a/ui/views/controls/image_view.cc
+++ b/ui/views/controls/image_view.cc
@@ -17,16 +17,19 @@ ImageView::ImageView()
     : image_size_set_(false),
       horiz_alignment_(CENTER),
       vert_alignment_(CENTER),
-      interactive_(true) {
+      interactive_(true),
+      last_paint_scale_(0.f),
+      last_painted_image_(NULL) {
 }
 
 ImageView::~ImageView() {
 }
 
 void ImageView::SetImage(const gfx::ImageSkia& img) {
-  if (image_.BackedBySameObjectAs(img))
+  if (IsImageEqual(img))

[pkotwicz, 2013/11/15 20:57:09]

Can you please add a comment (in the code) as to why IsImageEqual() works the
way it does. (Which bug / suboptimality IsImageEqual() is working around)

[sky, 2013/11/15 22:19:13]

I placed the comment in IsImageEqual.

     return;
 
+  last_painted_image_ = NULL;
   gfx::Size pref_size(GetPreferredSize());
   image_ = img;
   if (pref_size != GetPreferredSize())
@@ -82,6 +85,13 @@ gfx::Size ImageView::GetPreferredSize() {
                    image_.height() + insets.height());
 }
 
+bool ImageView::IsImageEqual(const gfx::ImageSkia& img) const {
+  return image_.BackedBySameObjectAs(img) &&
+      last_paint_scale_ != 0.0f &&
+      last_painted_image_ ==
+      img.GetRepresentation(last_paint_scale_).sk_bitmap().getPixels();
+}
+
 gfx::Point ImageView::ComputeImageOrigin(const gfx::Size& image_size) const {
   gfx::Insets insets = GetInsets();
 
@@ -114,6 +124,9 @@ gfx::Point ImageView::ComputeImageOrigin(const gfx::Size& image_size) const {
 void ImageView::OnPaint(gfx::Canvas* canvas) {
   View::OnPaint(canvas);
 
+  last_paint_scale_ = canvas->image_scale();
+  last_painted_image_ = NULL;
+
   if (image_.isNull())
     return;
 
@@ -131,6 +144,8 @@ void ImageView::OnPaint(gfx::Canvas* canvas) {
   } else {
     canvas->DrawImageInt(image_, image_bounds.x(), image_bounds.y());
   }
+  last_painted_image_ =
+      image_.GetRepresentation(last_paint_scale_).sk_bitmap().getPixels();
 }
 
 void ImageView::GetAccessibleState(ui::AccessibleViewState* state) {