color_provider.cc

// Copyright 2019 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 "ui/color/color_provider.h"

#include <map>
#include <set>
#include <utility>

#include "base/bind.h"
#include "base/logging.h"
#include "ui/color/color_mixer.h"
#include "ui/color/color_provider_utils.h"
#include "ui/color/color_recipe.h"
#include "ui/gfx/color_palette.h"

namespace ui {

ColorProvider::ColorProvider() = default;

ColorProvider::ColorProvider(ColorProvider&&) = default;

ColorProvider& ColorProvider::operator=(ColorProvider&&) = default;

ColorProvider::~ColorProvider() = default;

ColorMixer& ColorProvider::AddMixer() {
  DCHECK(!color_map_);

  mixers_.emplace_after(
      first_postprocessing_mixer_,
      base::BindRepeating([](const ColorMixer* mixer) { return mixer; },
                          GetLastNonPostprocessingMixer()),
      base::BindRepeating(&ColorProvider::GetLastNonPostprocessingMixer,
                          base::Unretained(this)));

  return *std::next(first_postprocessing_mixer_, 1);
}

ColorMixer& ColorProvider::AddPostprocessingMixer() {
  DCHECK(!color_map_);

  if (first_postprocessing_mixer_ == mixers_.before_begin()) {
    // The first postprocessing mixer points to the last regular mixer.
    auto previous_mixer_getter = base::BindRepeating(
        &ColorProvider::GetLastNonPostprocessingMixer, base::Unretained(this));
    mixers_.emplace_front(previous_mixer_getter, previous_mixer_getter);
    first_postprocessing_mixer_ = mixers_.begin();
  } else {
    // Other postprocessing mixers point to the next postprocessing mixer.
    auto previous_mixer_getter =
        base::BindRepeating([](const ColorMixer* mixer) { return mixer; },
                            base::Unretained(&mixers_.front()));
    mixers_.emplace_front(previous_mixer_getter, previous_mixer_getter);
  }
  return mixers_.front();
}

SkColor ColorProvider::GetColor(ColorId id) const {
  CHECK(color_map_);
  auto i = color_map_->find(id);
  return i == color_map_->end() ? gfx::kPlaceholderColor : i->second;
}

void ColorProvider::GenerateColorMap() {
  // This should only be called to generate the `color_map_` once.
  DCHECK(!color_map_);

  if (mixers_.empty())
    DVLOG(2) << "ColorProvider::GenerateColorMap: No mixers defined!";

  // Iterate over associated mixers and extract the ColorIds defined for this
  // provider.
  std::set<ColorId> color_ids;
  for (const auto& mixer : mixers_) {
    const auto mixer_color_ids = mixer.GetDefinedColorIds();
    color_ids.insert(mixer_color_ids.begin(), mixer_color_ids.end());
  }

  // Iterate through all defined ColorIds and seed the `color_map` with the
  // computed values. Use a std::map rather than a base::flat_map since it has
  // frequent inserts and could grow very large.
  std::map<ColorId, SkColor> color_map;
  for (const auto& color_id : color_ids)
    color_map.insert({color_id, mixers_.front().GetResultColor(color_id)});

  // Construct the color_map_.
  color_map_ = ColorMap(color_map.begin(), color_map.end());

  // Clear away all associated mixers as these are no longer needed.
  mixers_.clear();
  first_postprocessing_mixer_ = mixers_.before_begin();
}

void ColorProvider::SetColorForTesting(ColorId id, SkColor color) {
  if (color_map_) {
    (*color_map_)[id] = color;
  } else {
    if (mixers_.empty())
      AddMixer();
    (*std::next(first_postprocessing_mixer_, 1))[id] = {color};
  }
}

const ColorMixer* ColorProvider::GetLastNonPostprocessingMixer() const {
  const auto it = std::next(first_postprocessing_mixer_, 1);
  return (it == mixers_.cend()) ? nullptr : &(*it);
}

}  // namespace ui