ref: ca8693690ab7c0a1456348c733fbaf905754d73f
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 <cstdint> #include <stdint.h> struct Rgba { uint8_t red; uint8_t green; uint8_t blue; uint8_t alpha; constexpr 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 constexpr Rgba(uint32_t rgba = 0) : red(rgba >> 24), green(rgba >> 16), blue(rgba >> 8), alpha(rgba) {} static constexpr Rgba fromCGBColor(uint16_t cgbColor) { constexpr auto _5to8 = [](uint8_t fiveBpp) -> uint8_t { fiveBpp &= 0b11111; // For caller's convenience return fiveBpp << 3 | fiveBpp >> 2; }; return {_5to8(cgbColor), _5to8(cgbColor >> 5), _5to8(cgbColor >> 10), (uint8_t)(cgbColor & 0x8000 ? 0x00 : 0xFF)}; } /** * 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; static constexpr uint8_t transparency_threshold = 0x10; bool isTransparent() const { return alpha < transparency_threshold; } static constexpr uint8_t opacity_threshold = 0xF0; bool isOpaque() 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 */