shithub: rgbds

ref: a96aa1725f6d0760d3df39c5a1a44eb196f7c8c6
dir: /src/gfx/pal_sorting.cpp/

#include "gfx/pal_sorting.hpp"

#include <algorithm>
#include <png.h>
#include <vector>

#include "helpers.h"

#include "gfx/convert.hpp"
#include "gfx/main.hpp"

namespace sorting {

void indexed(std::vector<Palette> &palettes, int palSize, png_color const *palRGB,
             png_byte *palAlpha) {
	options.verbosePrint("Sorting palettes using embedded palette...\n");

	for (Palette &pal : palettes) {
		std::sort(pal.begin(), pal.end(), [&](uint16_t lhs, uint16_t rhs) {
			// Iterate through the PNG's palette, looking for either of the two
			for (int i = 0; i < palSize; ++i) {
				auto const &c = palRGB[i];
				Rgba color(c.red, c.green, c.blue, palAlpha ? palAlpha[i] : 0xFF);
				uint16_t cgbColor = color.cgbColor();
				if (cgbColor == Rgba::transparent) {
					continue;
				}
				// Return whether lhs < rhs
				if (cgbColor == rhs) {
					return false;
				}
				if (cgbColor == lhs) {
					return true;
				}
			}
			unreachable_(); // This should not be possible
		});
	}
}

void grayscale(std::vector<Palette> &palettes,
               std::array<std::optional<Rgba>, 0x8001> const &colors) {
	options.verbosePrint("Sorting grayscale-only palette...\n");

	// This method is only applicable if there are at most as many colors as colors per palette, so
	// we should only have a single palette.
	assert(palettes.size() == 1);

	Palette &palette = palettes[0];
	std::fill(palette.begin(), palette.end(), Rgba::transparent);
	for (auto const &slot : colors) {
		if (!slot.has_value() || slot->isTransparent()) {
			continue;
		}
		palette[slot->grayIndex()] = slot->cgbColor();
	}
}

static unsigned int legacyLuminance(uint16_t color) {
	uint8_t red = color & 0b11111;
	uint8_t green = color >> 5 & 0b11111;
	uint8_t blue = color >> 10;
	return 2126 * red + 7152 * green + 722 * blue;
}

void rgb(std::vector<Palette> &palettes) {
	options.verbosePrint("Sorting palettes by \"\"\"luminance\"\"\"...\n");

	for (Palette &pal : palettes) {
		std::sort(pal.begin(), pal.end(), [](uint16_t lhs, uint16_t rhs) {
			return legacyLuminance(lhs) < legacyLuminance(rhs);
		});
	}
}

} // namespace sorting