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// 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 "chrome/browser/favicon/select_favicon_frames.h"
#include "skia/ext/image_operations.h"
#include "ui/gfx/image/image.h"
#include "ui/gfx/image/image_skia.h"
#include "third_party/skia/include/core/SkCanvas.h"
namespace {
size_t BiggestCandidate(const std::vector<SkBitmap>& bitmaps) {
size_t max_index = 0;
int max_area = bitmaps[0].width() * bitmaps[0].height();
for (size_t i = 1; i < bitmaps.size(); ++i) {
int area = bitmaps[i].width() * bitmaps[i].height();
if (area > max_area) {
max_area = area;
max_index = i;
}
}
return max_index;
}
SkBitmap PadWithBorder(const SkBitmap& contents,
int desired_size,
int source_size) {
SkBitmap bitmap;
bitmap.setConfig(
SkBitmap::kARGB_8888_Config, desired_size, desired_size);
bitmap.allocPixels();
bitmap.eraseARGB(0, 0, 0, 0);
{
SkCanvas canvas(bitmap);
int shift = (desired_size - source_size) / 2;
SkRect dest(SkRect::MakeXYWH(shift, shift, source_size, source_size));
canvas.drawBitmapRect(contents, NULL, dest);
}
return bitmap;
}
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;
}
SkBitmap SelectCandidate(const std::vector<SkBitmap>& bitmaps,
int desired_size,
ui::ScaleFactor scale_factor,
float* score) {
float scale = GetScaleFactorScale(scale_factor);
desired_size = static_cast<int>(desired_size * scale + 0.5f);
// Try to find an exact match.
for (size_t i = 0; i < bitmaps.size(); ++i) {
if (bitmaps[i].width() == desired_size &&
bitmaps[i].height() == desired_size) {
*score = 1;
return bitmaps[i];
}
}
// If that failed, the following special rules apply:
// 1. 17px-24px images are built from 16px images by adding
// a transparent border.
if (desired_size > 16 * scale && desired_size <= 24 * scale) {
int source_size = static_cast<int>(16 * scale + 0.5f);
for (size_t i = 0; i < bitmaps.size(); ++i) {
if (bitmaps[i].width() == source_size &&
bitmaps[i].height() == source_size) {
*score = 0.2f;
return PadWithBorder(bitmaps[i], desired_size, source_size);
}
}
// Try again, with upsizing the base variant.
for (size_t i = 0; i < bitmaps.size(); ++i) {
if (bitmaps[i].width() * scale == source_size &&
bitmaps[i].height() * scale == source_size) {
*score = 0.15f;
return PadWithBorder(bitmaps[i], desired_size, source_size);
}
}
}
// 2. Integer multiples are built using nearest neighbor sampling.
// 3. Else, use Lancosz scaling:
// b) If available, from the next bigger variant.
int candidate = -1;
int min_area = INT_MAX;
for (size_t i = 0; i < bitmaps.size(); ++i) {
int area = bitmaps[i].width() * bitmaps[i].height();
if (bitmaps[i].width() > desired_size &&
bitmaps[i].height() > desired_size &&
(candidate == -1 || area < min_area)) {
candidate = i;
min_area = area;
}
}
*score = 0.1f;
// c) Else, from the biggest smaller variant.
if (candidate == -1) {
*score = 0;
candidate = BiggestCandidate(bitmaps);
}
const SkBitmap& bitmap = bitmaps[candidate];
bool is_integer_multiple = desired_size % bitmap.width() == 0 &&
desired_size % bitmap.height() == 0;
if (is_integer_multiple)
return SampleNearestNeighbor(bitmap, desired_size);
return skia::ImageOperations::Resize(
bitmap, skia::ImageOperations::RESIZE_LANCZOS3,
desired_size, desired_size);
}
} // namespace
gfx::ImageSkia SelectFaviconFrames(
const std::vector<SkBitmap>& bitmaps,
const std::vector<ui::ScaleFactor>& scale_factors,
int desired_size,
float* match_score) {
gfx::ImageSkia multi_image;
if (bitmaps.empty())
return multi_image;
if (desired_size == 0) {
// Just return the biggest image available.
size_t max_index = BiggestCandidate(bitmaps);
multi_image.AddRepresentation(
gfx::ImageSkiaRep(bitmaps[max_index], ui::SCALE_FACTOR_100P));
if (match_score)
*match_score = 0.8f;
return multi_image;
}
float total_score = 0;
for (size_t i = 0; i < scale_factors.size(); ++i) {
float score;
multi_image.AddRepresentation(gfx::ImageSkiaRep(
SelectCandidate(bitmaps, desired_size, scale_factors[i], &score),
scale_factors[i]));
total_score += score;
}
if (match_score)
*match_score = total_score / scale_factors.size();
return multi_image;
}
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