components/favicon_base/fallback_icon_style.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/favicon_base/fallback_icon_style.h"
   6
   7 #include <algorithm>
   8
   9 #include "ui/gfx/color_analysis.h"
  10 #include "ui/gfx/color_utils.h"
  11
  12 namespace favicon_base {
  13
  14 namespace {
  15
  16 // Luminance threshold for background color determine whether to use dark or
  17 // light text color.
  18 const int kDarkTextLuminanceThreshold = 190;
  19
  20 // The maximum luminance of the background color to ensure light text is
  21 // readable.
  22 const double kMaxBackgroundColorLuminance = 0.67;
  23
  24 // Default values for FallbackIconStyle.
  25 const SkColor kDefaultBackgroundColor = SkColorSetRGB(0x78, 0x78, 0x78);
  26 const SkColor kDefaultTextColorDark = SK_ColorBLACK;
  27 const SkColor kDefaultTextColorLight = SK_ColorWHITE;
  28 const double kDefaultFontSizeRatio = 0.44;
  29 const double kDefaultRoundness = 0;  // Square. Round corners are applied
  30                                      // externally (Javascript or Java).
  31
  32 }  // namespace
  33
  34 FallbackIconStyle::FallbackIconStyle()
  35     : background_color(kDefaultBackgroundColor),
  36       text_color(kDefaultTextColorLight),
  37       font_size_ratio(kDefaultFontSizeRatio),
  38       roundness(kDefaultRoundness) {
  39 }
  40
  41 FallbackIconStyle::~FallbackIconStyle() {
  42 }
  43
  44 void MatchFallbackIconTextColorAgainstBackgroundColor(
  45     FallbackIconStyle* style) {
  46   int luminance = color_utils::GetLuminanceForColor(style->background_color);
  47   style->text_color = (luminance >= kDarkTextLuminanceThreshold ?
  48       kDefaultTextColorDark : kDefaultTextColorLight);
  49 }
  50
  51 bool ValidateFallbackIconStyle(const FallbackIconStyle& style) {
  52   return style.font_size_ratio >= 0.0 && style.font_size_ratio <= 1.0 &&
  53       style.roundness >= 0.0 && style.roundness <= 1.0;
  54 }
  55
  56 void SetDominantColorAsBackground(
  57     const scoped_refptr<base::RefCountedMemory>& bitmap_data,
  58     FallbackIconStyle* style) {
  59   SkColor dominant_color =
  60       color_utils::CalculateKMeanColorOfPNG(bitmap_data);
  61   // Assumes |style.text_color| is light, and clamps luminance down to a
  62   // reasonable maximum value so text is readable.
  63   color_utils::HSL color_hsl;
  64   color_utils::SkColorToHSL(dominant_color, &color_hsl);
  65   color_hsl.l = std::min(color_hsl.l, kMaxBackgroundColorLuminance);
  66   style->background_color =
  67       color_utils::HSLToSkColor(color_hsl, SK_AlphaOPAQUE);
  68 }
  69
  70 }  // namespace favicon_base