Make HasRepresentation() work better for vector images.

ui/gfx/image/image_skia.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.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 74 matching lines @@
   bool CanModify() const;
 
   // Checks if the current thread can safely read the storage.
   bool CanRead() const;
 
   // Add a new representation. This checks if the scale of the added image
   // is not 1.0f, and mark the existing rep as scaled to make
   // the image high DPI aware.
   void AddRepresentation(const ImageSkiaRep& image);
 
+  // Returns whether the underlying image source can provide a representation at
+  // any scale.  In this case, the caller is guaranteed that
+  // FindRepresentation(..., true) will always succeed.
+  bool HasRepresentationAtAllScales() const;
+
   // Returns the iterator of the image rep whose density best matches
   // |scale|. If the image for the |scale| doesn't exist in the storage and
   // |storage| is set, it fetches new image by calling
   // |ImageSkiaSource::GetImageForScale|. There are two modes to deal with
   // arbitrary scale factors.
   // 1: Invoke GetImageForScale with requested scale and if the source
   //   returns the image with different scale (if the image doesn't exist in
   //   resource, for example), it will fallback to closest image rep.
   // 2: Invoke GetImageForScale with the closest known scale to the requested
   //   one and rescale the image.
@@ skipping 48 matching lines @@
 
 bool ImageSkiaStorage::CanModify() const {
   return !read_only_ && CalledOnValidThread();
 }
 
 bool ImageSkiaStorage::CanRead() const {
   return (read_only_ && !source_) || CalledOnValidThread();
 }
 
 void ImageSkiaStorage::AddRepresentation(const ImageSkiaRep& image) {
+  // Explicitly adding a representation makes no sense for images that
+  // inherently have representations at all scales already.
+  DCHECK(!HasRepresentationAtAllScales());
+
   if (image.scale() != 1.0f) {
     for (ImageSkia::ImageSkiaReps::iterator it = image_reps_.begin();
          it < image_reps_.end(); ++it) {
       if (it->unscaled()) {
         DCHECK_EQ(1.0f, it->scale());
         it->SetScaled();
         break;
       }
     }
   }
   image_reps_.push_back(image);
 }
 
+bool ImageSkiaStorage::HasRepresentationAtAllScales() const {
+  return source_ && source_->HasRepresentationAtAllScales();
+}
+
 std::vector<ImageSkiaRep>::iterator ImageSkiaStorage::FindRepresentation(
     float scale,
     bool fetch_new_image) const {
   ImageSkiaStorage* non_const = const_cast<ImageSkiaStorage*>(this);
 
   ImageSkia::ImageSkiaReps::iterator closest_iter =
       non_const->image_reps().end();
   ImageSkia::ImageSkiaReps::iterator exact_iter = non_const->image_reps().end();
   float smallest_diff = std::numeric_limits<float>::max();
   for (ImageSkia::ImageSkiaReps::iterator it = non_const->image_reps().begin();
@@ skipping 186 matching lines @@
       storage_->FindRepresentation(scale, false);
   if (it != image_reps.end() && it->scale() == scale)
     image_reps.erase(it);
 }
 
 bool ImageSkia::HasRepresentation(float scale) const {
   if (isNull())
     return false;
   CHECK(CanRead());
 
+  // This check is not only faster than FindRepresentation(), it's important for
+  // getting the right answer in cases of image types that are not based on
+  // discrete preset underlying representations, which otherwise might report
+  // "false" for this if GetRepresentation() has not yet been called for this
+  // |scale|.
+  if (storage_->HasRepresentationAtAllScales())
+    return true;
+
   ImageSkiaReps::iterator it = storage_->FindRepresentation(scale, false);
   return (it != storage_->image_reps().end() && it->scale() == scale);
 }
 
 const ImageSkiaRep& ImageSkia::GetRepresentation(float scale) const {
   if (isNull())
     return NullImageRep();
 
   CHECK(CanRead());
 
@@ skipping 104 matching lines @@
 bool ImageSkia::CanModify() const {
   return !storage_.get() || storage_->CanModify();
 }
 
 void ImageSkia::DetachStorageFromThread() {
   if (storage_.get())
     storage_->DetachFromThread();
 }
 
 }  // namespace gfx