Function main

imagequant-sys/example.c:27–108

#include "libimagequant.h"

int main(int argc, char *argv[]) {
    if (argc < 2) {
        fprintf(stderr, "Please specify a path to a PNG file\n");
        return EXIT_FAILURE;
    }

    const char *input_png_file_path = argv[1];

    // Load PNG file and decode it as raw RGBA pixels
    // This uses lodepng library for PNG reading (not part of libimagequant)

    unsigned int width, height;
    unsigned char *raw_rgba_pixels;
    unsigned int status = lodepng_decode32_file(&raw_rgba_pixels, &width, &height, input_png_file_path);
    if (status) {
        fprintf(stderr, "Can't load %s: %s\n", input_png_file_path, lodepng_error_text(status));
        return EXIT_FAILURE;
    }

    // Use libimagequant to make a palette for the RGBA pixels

    liq_attr *handle = liq_attr_create();
    liq_image *input_image = liq_image_create_rgba(handle, raw_rgba_pixels, width, height, 0);
    // You could set more options here, like liq_set_quality
    liq_result *quantization_result;
    if (liq_image_quantize(input_image, handle, &quantization_result) != LIQ_OK) {
        fprintf(stderr, "Quantization failed\n");
        return EXIT_FAILURE;
    }

    // Use libimagequant to make new image pixels from the palette

    size_t pixels_size = width * height;
    unsigned char *raw_8bit_pixels = malloc(pixels_size);
    liq_set_dithering_level(quantization_result, 1.0);

    liq_write_remapped_image(quantization_result, input_image, raw_8bit_pixels, pixels_size);
    const liq_palette *palette = liq_get_palette(quantization_result);

    // Save converted pixels as a PNG file
    // This uses lodepng library for PNG writing (not part of libimagequant)

    LodePNGState state;
    lodepng_state_init(&state);
    state.info_raw.colortype = LCT_PALETTE;
    state.info_raw.bitdepth = 8;
    state.info_png.color.colortype = LCT_PALETTE;
    state.info_png.color.bitdepth = 8;

    for(int i=0; i < palette->count; i++) {
        lodepng_palette_add(&state.info_png.color, palette->entries[i].r, palette->entries[i].g, palette->entries[i].b, palette->entries[i].a);
        lodepng_palette_add(&state.info_raw, palette->entries[i].r, palette->entries[i].g, palette->entries[i].b, palette->entries[i].a);
    }

    unsigned char *output_file_data;
    size_t output_file_size;
    unsigned int out_status = lodepng_encode(&output_file_data, &output_file_size, raw_8bit_pixels, width, height, &state);
    if (out_status) {