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// 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 "extensions/common/image_util.h"
#include <stddef.h>
#include <stdint.h>
#include <vector>
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "third_party/re2/src/re2/re2.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkColor.h"
#include "third_party/skia/include/core/SkImage.h"
#include "third_party/skia/include/utils/SkParse.h"
#include "ui/gfx/codec/png_codec.h"
#include "ui/gfx/color_utils.h"
namespace extensions {
namespace image_util {
bool ParseCssColorString(const std::string& color_string, SkColor* result) {
if (color_string.empty())
return false;
if (color_string[0] == '#')
return ParseHexColorString(color_string, result);
if (base::StartsWith(color_string, "hsl", base::CompareCase::SENSITIVE))
return ParseHslColorString(color_string, result);
if (base::StartsWith(color_string, "rgb", base::CompareCase::SENSITIVE)) {
return ParseRgbColorString(color_string, result);
}
if (SkParse::FindNamedColor(color_string.c_str(), color_string.size(),
result) != nullptr) {
return true;
}
return false;
}
bool ParseHexColorString(const std::string& color_string, SkColor* result) {
std::string formatted_color;
// Save a memory allocation -- we never need more than 8 chars.
formatted_color.reserve(8);
// Check the string for incorrect formatting.
if (color_string.empty() || color_string[0] != '#')
return false;
// Convert the string from #FFF format to #FFFFFF format.
if (color_string.length() == 4 || color_string.length() == 5) {
for (size_t i = 1; i < color_string.length(); ++i) {
formatted_color += color_string[i];
formatted_color += color_string[i];
}
} else if (color_string.length() == 7) {
formatted_color = color_string.substr(1, 6);
} else if (color_string.length() == 9) {
formatted_color = color_string.substr(1, 8);
} else {
return false;
}
// Add an alpha if one was not set.
if (formatted_color.length() == 6) {
formatted_color += "FF";
}
// Convert the string to an integer and make sure it is in the correct value
// range.
std::vector<uint8_t> color_bytes;
if (!base::HexStringToBytes(formatted_color, &color_bytes))
return false;
*result = SkColorSetARGB(color_bytes[3], color_bytes[0], color_bytes[1],
color_bytes[2]);
return true;
}
std::string GenerateHexColorString(SkColor color) {
return base::StringPrintf("#%02X%02X%02X", SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
}
bool ParseRgbColorString(const std::string& color_string, SkColor* result) {
// https://www.w3.org/wiki/CSS/Properties/color/RGB#The_format_of_the_RGB_Value
// The CSS3 specification defines the format of a RGB color as
// rgb(<number>, <number>, <number>) or
// rgb(<percent>, <percent>, <percent>) or
// and with alpha, the format is
// rgb(<number>, <number>, <number>, <alphavalue>) or
// rgba(<percent>, <percent>, <percent>, <alphavalue>)
// Whitespace is arbitrary.
// e.g.: rgb(120, 100, 50), rgba(120, 100, 50, 0.5);
int r = 0;
int g = 0;
int b = 0;
// 'rgb()' has '1' alpha value implicitly.
double alpha = 1.0;
// Percentage rgb values are not supported.
if (color_string.find('%') != std::string::npos) {
NOTIMPLEMENTED();
return false;
}
if (!re2::RE2::FullMatch(color_string,
"rgb\\(([\\d]+),\\s*([\\d]+),\\s*([\\d]+)\\)", &r,
&g, &b) &&
!re2::RE2::FullMatch(
color_string,
"rgba\\(([\\d]+),\\s*([\\d]+),\\s*([\\d]+),\\s*([\\d.]+)\\)", &r, &g,
&b, &alpha)) {
return false;
}
if (alpha < 0 || alpha > 1.0 || r < 0 || r > 255 || g < 0 || g > 255 ||
b < 0 || b > 255) {
return false;
}
SkAlpha sk_alpha = alpha * 255;
*result = SkColorSetARGB(sk_alpha, r, g, b);
return true;
}
bool ParseHslColorString(const std::string& color_string, SkColor* result) {
// http://www.w3.org/wiki/CSS/Properties/color/HSL#The_format_of_the_HSL_Value
// The CSS3 specification defines the format of a HSL color as
// hsl(<number>, <percent>, <percent>)
// and with alpha, the format is
// hsla(<number>, <percent>, <percent>, <number>)
// e.g.: hsl(120, 100%, 50%), hsla(120, 100%, 50%, 0.5);
double hue = 0.0;
double saturation = 0.0;
double lightness = 0.0;
// 'hsl()' has '1' alpha value implicitly.
double alpha = 1.0;
if (!re2::RE2::FullMatch(color_string,
"hsl\\((-?[\\d.]+),\\s*([\\d.]+)%,\\s*([\\d.]+)%\\)",
&hue, &saturation, &lightness) &&
!re2::RE2::FullMatch(
color_string,
"hsla\\((-?[\\d.]+),\\s*([\\d.]+)%,\\s*([\\d.]+)%,\\s*([\\d.]+)\\)",
&hue, &saturation, &lightness, &alpha)) {
return false;
}
color_utils::HSL hsl;
// Normalize the value between 0.0 and 1.0.
hsl.h = (((static_cast<int>(hue) % 360) + 360) % 360) / 360.0;
hsl.s = std::max(0.0, std::min(100.0, saturation)) / 100.0;
hsl.l = std::max(0.0, std::min(100.0, lightness)) / 100.0;
SkAlpha sk_alpha = std::max(0.0, std::min(1.0, alpha)) * 255;
*result = color_utils::HSLToSkColor(hsl, sk_alpha);
return true;
}
bool IsIconSufficientlyVisible(const SkBitmap& bitmap) {
// TODO(crbug.com/805600): Currently, we only consider if there are enough
// visible pixels that it won't be difficult for the user to see. Future
// revisions will consider the background color of the display context.
// If the alpha value of any pixel is greater than kAlphaThreshold, the
// pixmap is not transparent. These values will likely be adjusted, based
// on stats and research into visibility thresholds.
constexpr unsigned int kAlphaThreshold = 10;
// The minimum "percent" of pixels that must be visible for the icon to be
// considered OK.
constexpr double kMinPercentVisiblePixels = 0.05;
const unsigned int total_pixels = bitmap.height() * bitmap.width();
unsigned int visible_pixels = 0;
for (int y = 0; y < bitmap.height(); ++y) {
for (int x = 0; x < bitmap.width(); ++x) {
if (SkColorGetA(bitmap.getColor(x, y)) >= kAlphaThreshold) {
++visible_pixels;
}
}
}
// TODO(crbug.com/805600): Add UMA stats when we move to a more
// sophisticated analysis of the image and the background display
// color.
return static_cast<double>(visible_pixels) / total_pixels >=
kMinPercentVisiblePixels;
}
bool IsIconAtPathSufficientlyVisible(const base::FilePath& path) {
SkBitmap icon;
if (!LoadPngFromFile(path, &icon)) {
return false;
}
return IsIconSufficientlyVisible(icon);
}
bool IsRenderedIconSufficientlyVisible(const SkBitmap& icon,
SkColor background_color) {
// If any of a pixel's RGB values is greater than this number, the pixel is
// considered visible.
constexpr unsigned int kThreshold = 15;
// The minimum "percent" of pixels that must be visible for the icon to be
// considered OK.
constexpr double kMinPercentVisiblePixels = 0.05;
const int total_pixels = icon.height() * icon.width();
// Draw the icon onto a canvas, then draw the background color onto the
// resulting bitmap, using SkBlendMode::kDifference. Then, check the RGB
// values against the threshold. Any pixel with a value greater than the
// threshold is considered visible.
SkBitmap bitmap;
bitmap.allocN32Pixels(icon.width(), icon.height());
bitmap.eraseColor(background_color);
SkCanvas offscreen(bitmap);
offscreen.drawImage(SkImage::MakeFromBitmap(icon), 0, 0);
offscreen.drawColor(background_color, SkBlendMode::kDifference);
int visible_pixels = 0;
for (int x = 0; x < icon.width(); ++x) {
for (int y = 0; y < icon.height(); ++y) {
SkColor pixel = bitmap.getColor(x, y);
if (SkColorGetR(pixel) > kThreshold || SkColorGetB(pixel) > kThreshold ||
SkColorGetG(pixel) > kThreshold) {
++visible_pixels;
}
}
}
return static_cast<double>(visible_pixels) / total_pixels >=
kMinPercentVisiblePixels;
}
bool IsRenderedIconAtPathSufficientlyVisible(const base::FilePath& path,
SkColor background_color) {
SkBitmap icon;
if (!LoadPngFromFile(path, &icon)) {
return false;
}
return IsRenderedIconSufficientlyVisible(icon, background_color);
}
bool LoadPngFromFile(const base::FilePath& path, SkBitmap* dst) {
std::string png_bytes;
if (!base::ReadFileToString(path, &png_bytes)) {
return false;
}
return gfx::PNGCodec::Decode(
reinterpret_cast<const unsigned char*>(png_bytes.data()),
png_bytes.length(), dst);
}
} // namespace image_util
} // namespace extensions