color.h

// Copyright 2024 The Pigweed Authors
//
// 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
//
//     https://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.
#pragma once
 
#include <math.h>
#include <stdint.h>
 
#include <cinttypes>
#include <cstdint>
 
namespace pw::display {
 
using ColorRgba8888 = uint32_t;
 
using ColorRgb565 = uint16_t;
 
 
constexpr ColorRgb565 EncodeRgb565(uint8_t r, uint8_t g, uint8_t b) {
  return ((r & 0xF8) << 8) | ((g & 0xFC) << 3) | ((b & 0xF8) >> 3);
}
 
constexpr ColorRgb565 EncodeRgb565(ColorRgba8888 rgba8888) {
  uint8_t r = (rgba8888 & 0xFF);
  uint8_t g = (rgba8888 & 0xFF00) >> 8;
  uint8_t b = (rgba8888 & 0xFF0000) >> 16;
  // Alpha is ignored for RGB565.
  return EncodeRgb565(r, g, b);
}
 
constexpr ColorRgba8888 EncodeRgba8888(uint8_t r,
                                       uint8_t g,
                                       uint8_t b,
                                       uint8_t a) {
  return (a << 24) | (b << 16) | (g << 8) | r;
}
 
constexpr ColorRgba8888 EncodeRgba8888(ColorRgb565 rgb565) {
  uint8_t r = 255 * ((rgb565 & 0xF800) >> 11) / 31;
  uint8_t g = 255 * ((rgb565 & 0x7E0) >> 5) / 63;
  uint8_t b = 255 * (rgb565 & 0x1F) / 31;
  uint8_t a = 255;
  return EncodeRgba8888(r, g, b, a);
}
 
 
}  // namespace pw::display