ref: 3fa1854332735f4817bd43eee748b44cdc811c06
dir: /include/gfx/rgba.hpp/
/*
* This file is part of RGBDS.
*
* Copyright (c) 2022, Eldred Habert and RGBDS contributors.
*
* SPDX-License-Identifier: MIT
*/
#ifndef RGBDS_GFX_RGBA_HPP
#define RGBDS_GFX_RGBA_HPP
#include <stdint.h>
struct Rgba {
uint8_t red;
uint8_t green;
uint8_t blue;
uint8_t alpha;
Rgba(uint8_t r, uint8_t g, uint8_t b, uint8_t a) : red(r), green(g), blue(b), alpha(a) {}
/**
* Constructs the color from a "packed" RGBA representation (0xRRGGBBAA)
*/
explicit Rgba(uint32_t rgba = 0)
: red(rgba >> 24), green(rgba >> 16), blue(rgba >> 8), alpha(rgba) {}
/**
* Returns this RGBA as a 32-bit number that can be printed in hex (`%08x`) to yield its CSS
* representation
*/
uint32_t toCSS() const {
auto shl = [](uint8_t val, unsigned shift) { return static_cast<uint32_t>(val) << shift; };
return shl(red, 24) | shl(green, 16) | shl(blue, 8) | shl(alpha, 0);
}
friend bool operator!=(Rgba const &lhs, Rgba const &rhs) { return lhs.toCSS() != rhs.toCSS(); }
/**
* CGB colors are RGB555, so we use bit 15 to signify that the color is transparent instead
* Since the rest of the bits don't matter then, we return 0x8000 exactly.
*/
static constexpr uint16_t transparent = 0b1'00000'00000'00000;
/**
* All alpha values strictly below this will be considered transparent
*/
static constexpr uint8_t opacity_threshold = 0xF0; // TODO: adjust this
// TODO: also a transparency threshold, and error out on "middle" values
bool isTransparent() const { return alpha < opacity_threshold; }
/**
* Computes the equivalent CGB color, respects the color curve depending on options
*/
uint16_t cgbColor() const;
bool isGray() const { return red == green && green == blue; }
uint8_t grayIndex() const;
};
#endif /* RGBDS_GFX_RGBA_HPP */