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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/safe_browsing/content/common/visual_utils.h"
#include <unordered_map>
#include <vector>
#include "base/check_op.h"
#include "base/feature_list.h"
#include "base/numerics/checked_math.h"
#include "base/trace_event/trace_event.h"
#include "build/build_config.h"
#include "components/safe_browsing/buildflags.h"
#include "components/safe_browsing/core/common/features.h"
#include "components/safe_browsing/core/common/proto/client_model.pb.h"
#include "components/safe_browsing/core/common/proto/csd.pb.h"
#include "skia/ext/image_operations.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColorSpace.h"
#include "third_party/skia/include/core/SkPixmap.h"
#include "third_party/skia/include/private/chromium/SkPMColor.h"
#include "ui/gfx/color_utils.h"
namespace safe_browsing::visual_utils {
namespace {
// WARNING: The following parameters are highly privacy and performance
// sensitive. These should not be changed without thorough review.
#if BUILDFLAG(IS_ANDROID)
const int kPHashDownsampleWidth = 108;
const int kPHashDownsampleHeight = 192;
const int kMinWidthForVisualFeatures = 258;
const int kMinHeightForVisualFeatures = 258;
#else
const int kPHashDownsampleWidth = 288;
const int kPHashDownsampleHeight = 288;
const int kMinWidthForVisualFeatures = 576;
const int kMinHeightForVisualFeatures = 576;
#endif
const int kPHashBlockSize = 6;
#if BUILDFLAG(FULL_SAFE_BROWSING)
// Parameters chosen to ensure privacy is preserved by visual features.
const float kMaxZoomForVisualFeatures = 2.0;
#endif // BUILDFLAG(FULL_SAFE_BROWSING)
int GetPHashDownsampleWidth() {
if (base::FeatureList::IsEnabled(kVisualFeaturesSizes)) {
return base::GetFieldTrialParamByFeatureAsInt(
kVisualFeaturesSizes, "phash_width", kPHashDownsampleWidth);
}
return kPHashDownsampleWidth;
}
int GetPHashDownsampleHeight() {
if (base::FeatureList::IsEnabled(kVisualFeaturesSizes)) {
return base::GetFieldTrialParamByFeatureAsInt(
kVisualFeaturesSizes, "phash_height", kPHashDownsampleHeight);
}
return kPHashDownsampleHeight;
}
int GetMinWidthForVisualFeatures() {
if (base::FeatureList::IsEnabled(kVisualFeaturesSizes)) {
return base::GetFieldTrialParamByFeatureAsInt(
kVisualFeaturesSizes, "min_width", kMinWidthForVisualFeatures);
}
return kMinWidthForVisualFeatures;
}
int GetMinHeightForVisualFeatures() {
if (base::FeatureList::IsEnabled(kVisualFeaturesSizes)) {
return base::GetFieldTrialParamByFeatureAsInt(
kVisualFeaturesSizes, "min_height", kMinHeightForVisualFeatures);
}
return kMinHeightForVisualFeatures;
}
} // namespace
bool GetBlurredImage(const SkBitmap& image,
VisualFeatures::BlurredImage* blurred_image) {
TRACE_EVENT0("safe_browsing", "GetBlurredImage");
if (image.drawsNothing())
return false;
// Use the Rec. 2020 color space, in case the user input is wide-gamut.
sk_sp<SkColorSpace> rec2020 = SkColorSpace::MakeRGB(
{2.22222f, 0.909672f, 0.0903276f, 0.222222f, 0.0812429f, 0, 0},
SkNamedGamut::kRec2020);
// We scale down twice, once with medium quality, then with a block mean
// average to be consistent with the backend.
// TODO(drubery): Investigate whether this is necessary for performance or
// not.
SkBitmap downsampled = skia::ImageOperations::Resize(
image, skia::ImageOperations::RESIZE_GOOD, GetPHashDownsampleWidth(),
GetPHashDownsampleHeight());
std::unique_ptr<SkBitmap> blurred =
BlockMeanAverage(downsampled, kPHashBlockSize);
blurred_image->set_width(blurred->width());
blurred_image->set_height(blurred->height());
const int data_size = blurred->width() * blurred->height();
blurred_image->mutable_data()->reserve(data_size);
for (int y = 0; y < blurred->height(); ++y) {
for (int x = 0; x < blurred->width(); ++x) {
SkColor color = blurred->getColor(x, y);
*blurred_image->mutable_data() += static_cast<char>(SkColorGetR(color));
*blurred_image->mutable_data() += static_cast<char>(SkColorGetG(color));
*blurred_image->mutable_data() += static_cast<char>(SkColorGetB(color));
}
}
return true;
}
std::unique_ptr<SkBitmap> BlockMeanAverage(const SkBitmap& image,
int block_size) {
// Compute the number of blocks in the target image, rounding up to account
// for partial blocks.
int num_blocks_high =
std::ceil(static_cast<float>(image.height()) / block_size);
int num_blocks_wide =
std::ceil(static_cast<float>(image.width()) / block_size);
SkImageInfo target_info = SkImageInfo::MakeN32(
num_blocks_wide, num_blocks_high, SkAlphaType::kUnpremul_SkAlphaType,
image.refColorSpace());
auto target = std::make_unique<SkBitmap>();
if (!target->tryAllocPixels(target_info))
return target;
for (int block_x = 0; block_x < num_blocks_wide; block_x++) {
for (int block_y = 0; block_y < num_blocks_high; block_y++) {
int r_total = 0, g_total = 0, b_total = 0, sample_count = 0;
// Compute boundary for the current block, taking into account the
// possibility of partial blocks near the edges.
int x_start = block_x * block_size;
int x_end = std::min(x_start + block_size, image.width());
int y_start = block_y * block_size;
int y_end = std::min(y_start + block_size, image.height());
for (int i = x_start; i < x_end; i++) {
for (int j = y_start; j < y_end; j++) {
const SkColor color = image.getColor(i, j);
r_total += SkColorGetR(color);
g_total += SkColorGetG(color);
b_total += SkColorGetB(color);
sample_count++;
}
}
int r_mean = r_total / sample_count;
int g_mean = g_total / sample_count;
int b_mean = b_total / sample_count;
*target->getAddr32(block_x, block_y) =
SkPMColorSetARGB(255, r_mean, g_mean, b_mean);
}
}
return target;
}
#if BUILDFLAG(IS_ANDROID)
CanExtractVisualFeaturesResult CanExtractVisualFeatures(bool is_user_opted_in,
bool is_off_the_record,
gfx::Size size) {
#else
CanExtractVisualFeaturesResult CanExtractVisualFeatures(bool is_user_opted_in,
bool is_off_the_record,
gfx::Size size,
double zoom_level) {
#endif
if (!is_user_opted_in) {
return CanExtractVisualFeaturesResult::kUserNotOptedIn;
}
if (is_off_the_record)
return CanExtractVisualFeaturesResult::kOffTheRecord;
if (size.width() < GetMinWidthForVisualFeatures() ||
size.height() < GetMinHeightForVisualFeatures())
return CanExtractVisualFeaturesResult::kBelowMinFrame;
#if !BUILDFLAG(IS_ANDROID)
if (zoom_level > kMaxZoomForVisualFeatures) {
return CanExtractVisualFeaturesResult::kAboveZoomLevel;
}
#endif
return CanExtractVisualFeaturesResult::kCanExtractVisualFeatures;
}
std::unique_ptr<VisualFeatures> ExtractVisualFeatures(
const SkBitmap& screenshot) {
auto features = std::make_unique<VisualFeatures>();
GetBlurredImage(screenshot, features->mutable_image());
return features;
}
} // namespace safe_browsing::visual_utils
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