src/cobalt/render_tree/color_rgba.h

/*
 * Copyright 2014 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef COBALT_RENDER_TREE_COLOR_RGBA_H_
#define COBALT_RENDER_TREE_COLOR_RGBA_H_

#include "base/logging.h"

namespace cobalt {
namespace render_tree {

// Used to specify a color in the RGB (plus alpha) space.
// This color format is referenced by many render_tree objects in order to
// specify a color.  It is expressed by a float for each component, and must
// be in the range [0.0, 1.0].
struct ColorRGBA {
 public:
  ColorRGBA() : r_(0), g_(0), b_(0), a_(0) {}

  ColorRGBA(float red, float green, float blue) {
    CheckRange(red);
    r_ = red;
    CheckRange(green);
    g_ = green;
    CheckRange(blue);
    b_ = blue;
    a_ = 1.0f;
  }

  ColorRGBA(float red, float green, float blue, float alpha) {
    CheckRange(red);
    r_ = red;
    CheckRange(green);
    g_ = green;
    CheckRange(blue);
    b_ = blue;
    CheckRange(alpha);
    a_ = alpha;
  }

  // Decodes the color value from 32-bit integer (4 channels, 8 bits each).
  // Note that alpha channel is mandatory, so opaque colors should be encoded
  // as 0xrrggbbff.
  explicit ColorRGBA(uint32_t rgba) {
    a_ = (rgba & 0xff) / 255.0f;
    rgba >>= 8;
    b_ = (rgba & 0xff) / 255.0f;
    rgba >>= 8;
    g_ = (rgba & 0xff) / 255.0f;
    rgba >>= 8;
    r_ = (rgba & 0xff) / 255.0f;
  }

  void set_r(float value) {
    CheckRange(value);
    r_ = value;
  }
  void set_g(float value) {
    CheckRange(value);
    g_ = value;
  }
  void set_b(float value) {
    CheckRange(value);
    b_ = value;
  }
  void set_a(float value) {
    CheckRange(value);
    a_ = value;
  }

  float r() const { return r_; }
  float g() const { return g_; }
  float b() const { return b_; }
  float a() const { return a_; }

 private:
  void CheckRange(float value) {
    DCHECK_LE(0.0f, value);
    DCHECK_GE(1.0f, value);
  }

  float r_, g_, b_, a_;
};

inline bool operator==(const ColorRGBA& lhs, const ColorRGBA& rhs) {
  return lhs.r() == rhs.r() && lhs.g() == rhs.g() && lhs.b() == rhs.b() &&
         lhs.a() == rhs.a();
}

// Used by tests.
inline std::ostream& operator<<(std::ostream& stream, const ColorRGBA& color) {
  return stream << "rgba(" << color.r() << ", " << color.g() << ", "
                << color.b() << ", " << color.a() << ")";
}

}  // namespace render_tree
}  // namespace cobalt

#endif  // COBALT_RENDER_TREE_COLOR_RGBA_H_