1 files changed, 253 insertions, 0 deletions
diff --git a/components/favicon_base/select_favicon_frames.cc b/components/favicon_base/select_favicon_frames.cc
new file mode 100644
index 0000000..32f7094
--- /dev/null
+++ b/components/favicon_base/select_favicon_frames.cc
@@ -0,0 +1,253 @@
+// Copyright 2014 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 "components/favicon_base/select_favicon_frames.h"
+
+#include <limits>
+#include <set>
+
+#include "skia/ext/image_operations.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "ui/gfx/image/image.h"
+#include "ui/gfx/image/image_skia.h"
+#include "ui/gfx/size.h"
+
+namespace {
+
+size_t BiggestCandidate(const std::vector<gfx::Size>& candidate_sizes) {
+  size_t max_index = 0;
+  int max_area = candidate_sizes[0].GetArea();
+  for (size_t i = 1; i < candidate_sizes.size(); ++i) {
+    int area = candidate_sizes[i].GetArea();
+    if (area > max_area) {
+      max_area = area;
+      max_index = i;
+    }
+  }
+  return max_index;
+}
+
+SkBitmap SampleNearestNeighbor(const SkBitmap& contents, int desired_size) {
+  SkBitmap bitmap;
+  bitmap.setConfig(SkBitmap::kARGB_8888_Config, desired_size, desired_size);
+  bitmap.allocPixels();
+  if (!contents.isOpaque())
+    bitmap.eraseARGB(0, 0, 0, 0);
+
+  {
+    SkCanvas canvas(bitmap);
+    SkRect dest(SkRect::MakeWH(desired_size, desired_size));
+    canvas.drawBitmapRect(contents, NULL, dest);
+  }
+
+  return bitmap;
+}
+
+enum ResizeMethod { NONE, SAMPLE_NEAREST_NEIGHBOUR, LANCZOS };
+
+size_t GetCandidateIndexWithBestScore(
+    const std::vector<gfx::Size>& candidate_sizes_in_pixel,
+    ui::ScaleFactor scale_factor,
+    int desired_size_in_dip,
+    float* score,
+    ResizeMethod* resize_method) {
+  DCHECK_NE(desired_size_in_dip, 0);
+
+  float scale = ui::GetImageScale(scale_factor);
+  int desired_size_in_pixel =
+      static_cast<int>(desired_size_in_dip * scale + 0.5f);
+
+  // Try to find an exact match.
+  for (size_t i = 0; i < candidate_sizes_in_pixel.size(); ++i) {
+    if (candidate_sizes_in_pixel[i].width() == desired_size_in_pixel &&
+        candidate_sizes_in_pixel[i].height() == desired_size_in_pixel) {
+      *score = 1;
+      *resize_method = NONE;
+      return i;
+    }
+  }
+
+  // Huge favicon bitmaps often have a completely different visual style from
+  // smaller favicon bitmaps. Avoid these favicon bitmaps when a favicon of
+  // gfx::kFaviconSize DIP is requested.
+  const int kHugeEdgeSizeInPixel = desired_size_in_pixel * 8;
+
+  // Order of preference:
+  // 1) Bitmaps with width and height smaller than |kHugeEdgeSizeInPixel|.
+  // 2) Bitmaps which need to be scaled down instead of up.
+  // 3) Bitmaps which do not need to be scaled as much.
+  size_t candidate_index = std::numeric_limits<size_t>::max();
+  float candidate_score = 0;
+  for (size_t i = 0; i < candidate_sizes_in_pixel.size(); ++i) {
+    float average_edge_in_pixel = (candidate_sizes_in_pixel[i].width() +
+                                   candidate_sizes_in_pixel[i].height()) /
+                                  2.0f;
+
+    float score = 0;
+    if (candidate_sizes_in_pixel[i].width() >= kHugeEdgeSizeInPixel ||
+        candidate_sizes_in_pixel[i].height() >= kHugeEdgeSizeInPixel) {
+      score =
+          std::min(1.0f, desired_size_in_pixel / average_edge_in_pixel) * 0.01f;
+    } else if (candidate_sizes_in_pixel[i].width() >= desired_size_in_pixel &&
+               candidate_sizes_in_pixel[i].height() >= desired_size_in_pixel) {
+      score = desired_size_in_pixel / average_edge_in_pixel * 0.01f + 0.15f;
+    } else {
+      score = std::min(1.0f, average_edge_in_pixel / desired_size_in_pixel) *
+                  0.01f +
+              0.1f;
+    }
+
+    if (candidate_index == std::numeric_limits<size_t>::max() ||
+        score > candidate_score) {
+      candidate_index = i;
+      candidate_score = score;
+    }
+  }
+  *score = candidate_score;
+
+  // Integer multiples are built using nearest neighbor sampling. Otherwise,
+  // Lanczos scaling is used.
+  const gfx::Size& candidate_size_in_pixel =
+      candidate_sizes_in_pixel[candidate_index];
+  if (candidate_size_in_pixel.IsEmpty()) {
+    *resize_method = NONE;
+  } else if (desired_size_in_pixel % candidate_size_in_pixel.width() == 0 &&
+             desired_size_in_pixel % candidate_size_in_pixel.height() == 0) {
+    *resize_method = SAMPLE_NEAREST_NEIGHBOUR;
+  } else {
+    *resize_method = LANCZOS;
+  }
+  return candidate_index;
+}
+
+// Represents the index of the best candidate for a |scale_factor| from the
+// |candidate_sizes| passed into GetCandidateIndicesWithBestScores().
+struct SelectionResult {
+  // index in |candidate_sizes| of the best candidate.
+  size_t index;
+
+  // The ScaleFactor for which |index| is the best candidate.
+  ui::ScaleFactor scale_factor;
+
+  // How the bitmap data that the bitmap with |candidate_sizes[index]| should
+  // be resized for displaying in the UI.
+  ResizeMethod resize_method;
+};
+
+void GetCandidateIndicesWithBestScores(
+    const std::vector<gfx::Size>& candidate_sizes,
+    const std::vector<ui::ScaleFactor>& scale_factors,
+    int desired_size,
+    float* match_score,
+    std::vector<SelectionResult>* results) {
+  if (candidate_sizes.empty()) {
+    if (match_score)
+      *match_score = 0.0f;
+    return;
+  }
+
+  if (desired_size == 0) {
+    // Just return the biggest image available.
+    SelectionResult result;
+    result.index = BiggestCandidate(candidate_sizes);
+    result.scale_factor = ui::SCALE_FACTOR_100P;
+    result.resize_method = NONE;
+    results->push_back(result);
+    if (match_score)
+      *match_score = 1.0f;
+    return;
+  }
+
+  float total_score = 0;
+  for (size_t i = 0; i < scale_factors.size(); ++i) {
+    float score;
+    SelectionResult result;
+    result.scale_factor = scale_factors[i];
+    result.index = GetCandidateIndexWithBestScore(candidate_sizes,
+                                                  result.scale_factor,
+                                                  desired_size,
+                                                  &score,
+                                                  &result.resize_method);
+    results->push_back(result);
+    total_score += score;
+  }
+
+  if (match_score)
+    *match_score = total_score / scale_factors.size();
+}
+
+// Resize |source_bitmap| using |resize_method|.
+SkBitmap GetResizedBitmap(const SkBitmap& source_bitmap,
+                          int desired_size_in_dip,
+                          ui::ScaleFactor scale_factor,
+                          ResizeMethod resize_method) {
+  float scale = ui::GetImageScale(scale_factor);
+  int desired_size_in_pixel =
+      static_cast<int>(desired_size_in_dip * scale + 0.5f);
+
+  switch (resize_method) {
+    case NONE:
+      return source_bitmap;
+    case SAMPLE_NEAREST_NEIGHBOUR:
+      return SampleNearestNeighbor(source_bitmap, desired_size_in_pixel);
+    case LANCZOS:
+      return skia::ImageOperations::Resize(
+          source_bitmap,
+          skia::ImageOperations::RESIZE_LANCZOS3,
+          desired_size_in_pixel,
+          desired_size_in_pixel);
+  }
+  return source_bitmap;
+}
+
+}  // namespace
+
+const float kSelectFaviconFramesInvalidScore = -1.0f;
+
+gfx::ImageSkia SelectFaviconFrames(
+    const std::vector<SkBitmap>& bitmaps,
+    const std::vector<gfx::Size>& original_sizes,
+    const std::vector<ui::ScaleFactor>& scale_factors,
+    int desired_size,
+    float* match_score) {
+  std::vector<SelectionResult> results;
+  GetCandidateIndicesWithBestScores(
+      original_sizes, scale_factors, desired_size, match_score, &results);
+
+  gfx::ImageSkia multi_image;
+  for (size_t i = 0; i < results.size(); ++i) {
+    const SelectionResult& result = results[i];
+    SkBitmap resized_bitmap = GetResizedBitmap(bitmaps[result.index],
+                                               desired_size,
+                                               result.scale_factor,
+                                               result.resize_method);
+    multi_image.AddRepresentation(gfx::ImageSkiaRep(
+        resized_bitmap, ui::GetImageScale(result.scale_factor)));
+  }
+  return multi_image;
+}
+
+void SelectFaviconFrameIndices(
+    const std::vector<gfx::Size>& frame_pixel_sizes,
+    const std::vector<ui::ScaleFactor>& scale_factors,
+    int desired_size,
+    std::vector<size_t>* best_indices,
+    float* match_score) {
+  std::vector<SelectionResult> results;
+  GetCandidateIndicesWithBestScores(
+      frame_pixel_sizes, scale_factors, desired_size, match_score, &results);
+
+  std::set<size_t> already_added;
+  for (size_t i = 0; i < results.size(); ++i) {
+    size_t index = results[i].index;
+    // GetCandidateIndicesWithBestScores() will return duplicate indices if the
+    // bitmap data with |frame_pixel_sizes[index]| should be used for multiple
+    // scale factors. Remove duplicates here such that |best_indices| contains
+    // no duplicates.
+    if (already_added.find(index) == already_added.end()) {
+      already_added.insert(index);
+      best_indices->push_back(index);
+    }
+  }
+}