vc++编写 png转ico

的代码应该怎么写？

您可以使用第三方库，如libpng和libico，来编写PNG转ICO的代码。以下是一个简单的示例：

#include <stdio.h>
#include <stdlib.h>
#include <png.h>
#include <stdint.h>

#define ICO_HEADER_SIZE 6
#define ICO_ENTRY_SIZE 16

int main(int argc, char *argv[]) {
if (argc != 3) {
printf("Usage: %s input.png output.ico\n", argv[0]);
return 1;
}

FILE *input_file = fopen(argv[1], "rb");
if (!input_file) {
printf("Error: could not open input file %s\n", argv[1]);
return 1;
}

png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr) {
printf("Error: could not create PNG read struct\n");
fclose(input_file);
return 1;
}

png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
printf("Error: could not create PNG info struct\n");
png_destroy_read_struct(&png_ptr, NULL, NULL);
fclose(input_file);
return 1;
}

if (setjmp(png_jmpbuf(png_ptr))) {
printf("Error: could not read PNG file\n");
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
fclose(input_file);
return 1;
}

png_init_io(png_ptr, input_file);
png_read_info(png_ptr, info_ptr);

uint32_t width = png_get_image_width(png_ptr, info_ptr);
uint32_t height = png_get_image_height(png_ptr, info_ptr);
uint32_t bit_depth = png_get_bit_depth(png_ptr, info_ptr);
uint32_t color_type = png_get_color_type(png_ptr, info_ptr);

if (bit_depth != 8 || color_type != PNG_COLOR_TYPE_RGB_ALPHA) {
printf("Error: input PNG file must be 32-bit RGBA\n");
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
fclose(input_file);
return 1;
}

uint32_t row_bytes = png_get_rowbytes(png_ptr, info_ptr);
uint8_t *image_data = malloc(row_bytes * height);
png_bytepp row_pointers = png_get_rows(png_ptr, info_ptr);
for (uint32_t i = 0; i < height; i++) {
memcpy(image_data + i * row_bytes, row_pointers[i], row_bytes);
}

png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
fclose(input_file);

FILE *output_file = fopen(argv[2], "wb");
if (!output_file) {
printf("Error: could not open output file %s\n", argv[2]);
free(image_data);
return 1;
}

uint32_t image_size = row_bytes * height;
uint32_t file_size = ICO_HEADER_SIZE + ICO_ENTRY_SIZE + image_size;
uint8_t *file_data = malloc(file_size);
memset(file_data, 0, file_size);

file_data[0] = 0; // reserved
file_data[1] = 0; // reserved
file_data[2] = 1; // image type (1 = ICO)
file_data[3] = 0; // number of images (1)

// ICO entry
file_data[ICO_HEADER_SIZE + 0] = width; // width
file_data[ICO_HEADER_SIZE + 1] = height; // height
file_data[ICO_HEADER_SIZE + 2] = 0; // number of colors (0 = all)
file_data[ICO_HEADER_SIZE + 3] = 0; // reserved
file_data[ICO_HEADER_SIZE + 4] = 1; // number of color planes (1)
file_data[ICO_HEADER_SIZE + 5] = 32; // bits per pixel (32)

memcpy(file_data + ICO_HEADER_SIZE + ICO_ENTRY_SIZE, image_data, image_size);

fwrite(file_data, 1, file_size, output_file);

fclose(output_file);
free(image_data);
free(file_data);

return 0;
}