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// Copyright 2015 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/fallback_icon_style.h"
#include <algorithm>
#include "ui/gfx/color_analysis.h"
#include "ui/gfx/color_utils.h"
namespace favicon_base {
namespace {
// Luma threshold for background color determine whether to use dark or light
// text color.
const uint8_t kDarkTextLumaThreshold = 190;
// The maximum lightness of the background color to ensure light text is
// readable.
const double kMaxBackgroundColorLightness = 0.67;
const double kMinBackgroundColorLightness = 0.15;
// Default values for FallbackIconStyle.
const SkColor kDefaultBackgroundColor = SkColorSetRGB(0x78, 0x78, 0x78);
const SkColor kDefaultTextColorDark = SK_ColorBLACK;
const SkColor kDefaultTextColorLight = SK_ColorWHITE;
const double kDefaultFontSizeRatio = 0.44;
const double kDefaultRoundness = 0; // Square. Round corners are applied
// externally (Javascript or Java).
} // namespace
FallbackIconStyle::FallbackIconStyle()
: background_color(kDefaultBackgroundColor),
text_color(kDefaultTextColorLight),
font_size_ratio(kDefaultFontSizeRatio),
roundness(kDefaultRoundness) {
}
FallbackIconStyle::~FallbackIconStyle() {
}
bool FallbackIconStyle::operator==(const FallbackIconStyle& other) const {
return background_color == other.background_color &&
text_color == other.text_color &&
font_size_ratio == other.font_size_ratio &&
roundness == other.roundness;
}
void MatchFallbackIconTextColorAgainstBackgroundColor(
FallbackIconStyle* style) {
const uint8_t luma = color_utils::GetLuma(style->background_color);
style->text_color = (luma >= kDarkTextLumaThreshold) ?
kDefaultTextColorDark : kDefaultTextColorLight;
}
bool ValidateFallbackIconStyle(const FallbackIconStyle& style) {
return style.font_size_ratio >= 0.0 && style.font_size_ratio <= 1.0 &&
style.roundness >= 0.0 && style.roundness <= 1.0;
}
void SetDominantColorAsBackground(
const scoped_refptr<base::RefCountedMemory>& bitmap_data,
FallbackIconStyle* style) {
// Try to ensure color's lightness isn't too large so that light text is
// visible. Set an upper bound for the dominant color.
const color_utils::HSL lower_bound{-1.0, -1.0, kMinBackgroundColorLightness};
const color_utils::HSL upper_bound{-1.0, -1.0, kMaxBackgroundColorLightness};
color_utils::GridSampler sampler;
SkColor dominant_color = color_utils::CalculateKMeanColorOfPNG(
bitmap_data, lower_bound, upper_bound, &sampler);
// |CalculateKMeanColorOfPNG| will try to return a color that lies within the
// specified bounds if one exists in the image. If there's no such color, it
// will return the dominant color which may be lighter than our upper bound.
// Clamp lightness down to a reasonable maximum value so text is readable.
color_utils::HSL color_hsl;
color_utils::SkColorToHSL(dominant_color, &color_hsl);
color_hsl.l = std::min(color_hsl.l, kMaxBackgroundColorLightness);
style->background_color =
color_utils::HSLToSkColor(color_hsl, SK_AlphaOPAQUE);
}
} // namespace favicon_base
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