libqrencode二维码放大

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <png.h>
#include <qrencode.h>

void save_png(const char *filename, unsigned char *data, int width, int height);

int main() {
    // 要编码成二维码的字符串
    const char *text = "https://example.com";

    // 生成二维码
    QRcode *qrcode = QRcode_encodeString(text, 0, QR_ECLEVEL_Q, QR_MODE_8, 1);

    // 将二维码放大到800x800
    int scale = 800 / qrcode->width;
    int size = qrcode->width * scale;
    unsigned char *buffer = (unsigned char *)malloc(size * size);
    for (int y = 0; y < size; y++) {
        for (int x = 0; x < size; x++) {
            buffer[y * size + x] = qrcode->data[y / scale * qrcode->width + x / scale] & 1 ? 0 : 255;
        }
    }

    // 保存为PNG文件
    save_png("qrcode.png", buffer, size, size);

    // 释放内存
    QRcode_free(qrcode);
    free(buffer);

    return 0;
}

void save_png(const char *filename, unsigned char *data, int width, int height) {
    FILE *fp;
    png_structp png_ptr;
    png_infop info_ptr;

    fp = fopen(filename, "wb");
    if (!fp) {
        fprintf(stderr, "Error: Unable to open file %s for writing\n", filename);
        return;
    }

    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
        fclose(fp);
        fprintf(stderr, "Error: Unable to create PNG write structure\n");
        return;
    }

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        png_destroy_write_struct(&png_ptr, NULL);
        fclose(fp);
        fprintf(stderr, "Error: Unable to create PNG info structure\n");
        return;
    }

    png_init_io(png_ptr, fp);

    png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_GRAY,
                 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

    png_write_info(png_ptr, info_ptr);

    for (int y = 0; y < height; y++) {
        png_write_row(png_ptr, data + y * width);
    }

    png_write_end(png_ptr, info_ptr);

    png_destroy_write_struct(&png_ptr, &info_ptr);
    fclose(fp);
}