前面写了《批量下载网络图片到本地》及《将多张图片合并成大图》，所以综合一下，完整的从电子地图网站把电子地图生成到本地的程序：

#include <vector>

#include <urlmon.h>

#include <string>

#include <iostream>

#include "loadpng.h"

using namespace std;

#pragma comment(lib, "urlmon.lib")



#define ROW	12

#define COL	9

#define PIC_WIDTH	256

#define PIC_HEIGHT	256



void decodeOneStep()

{

	std::vector<unsigned char> image_ret(ROW*COL*PIC_WIDTH*PIC_HEIGHT*4);

	std::vector<unsigned char> image[ROW][COL];

	unsigned width = 0; 

	unsigned height = 0;

	unsigned error = 0;

	unsigned int idx_row;

	unsigned int idx_col;

	char filename[100];

	unsigned int idx_row_tmp;

	unsigned int idx_col_tmp;

	unsigned int x;

	unsigned int y;

	unsigned int pos;

	const char *out = "out.png";



	for (idx_row = 0; idx_row < ROW; idx_row++) {

		for (idx_col = 0; idx_col < COL; idx_col++) {

			sprintf(filename, "map/%d_%d.png", idx_col, (ROW-idx_row-1));

			error = lodepng::decode(image[idx_row][idx_col], width, height, filename);

			printf("file:%s  w:%d h:%d\n", filename, width, height);

			if (error) {

				printf("decoder error:%d  %s\n", error, lodepng_error_text(error));

			}

			if (width != PIC_WIDTH || height != PIC_HEIGHT) {

				printf(" error size of pic \n");

			}



			pos = 0;

			for (idx_row_tmp = 0; idx_row_tmp < height; idx_row_tmp++) {

				for (idx_col_tmp = 0; idx_col_tmp < width; idx_col_tmp++) {

					x = idx_col * PIC_WIDTH + idx_col_tmp;

					y = idx_row * PIC_HEIGHT + idx_row_tmp;

					image_ret[(y * PIC_WIDTH * COL + x) * 4] = image[idx_row][idx_col][(pos*4)];

					image_ret[(y * PIC_WIDTH * COL + x) * 4 + 1] = image[idx_row][idx_col][(pos * 4 + 1)];

					image_ret[(y * PIC_WIDTH * COL + x) * 4 + 2] = image[idx_row][idx_col][(pos * 4 + 2)];

					image_ret[(y * PIC_WIDTH * COL + x) * 4 + 3] = image[idx_row][idx_col][(pos * 4 + 3)];

					pos++;

				}

			}





		}

	}

	printf("image ******* len:%u\n", image_ret.size());

	lodepng::encode(out, image_ret, PIC_WIDTH * COL, PIC_HEIGHT * ROW);



}



int main(int argc, char* argv[])

{

	int i, j;

	string url;

	string file;

	char tmp_url[1024];

	char tmp_file[100];

	wchar_t *buffer_url;

	wchar_t *buffer_file;

	size_t len;

	int nmlen;



	for (i = 0; i < COL; i++) {

		for (j = 0; j < ROW; j++) {

			sprintf(tmp_url, "http://img.wikia.nocookie.net/intmap_tile_set_5360/4/%d/%d.png", i,j);

			sprintf(tmp_file, "map/%d_%d.png", i, j);

			url = tmp_url;

			file = tmp_file;



			len = url.length();

			nmlen = MultiByteToWideChar(CP_ACP, 0, url.c_str(), len + 1, NULL, 0);

			buffer_url = new wchar_t[nmlen];

			MultiByteToWideChar(CP_ACP, 0, url.c_str(), len + 1, buffer_url, nmlen);



			len = file.length();

			nmlen = MultiByteToWideChar(CP_ACP, 0, file.c_str(), len + 1, NULL, 0);

			buffer_file = new wchar_t[nmlen];

			MultiByteToWideChar(CP_ACP, 0, file.c_str(), len + 1, buffer_file, nmlen);



			URLDownloadToFile(NULL, buffer_url, buffer_file, 0, 0);

			delete[]buffer_url;

			delete[]buffer_file;

			cout << url << "  ->>>" << file << endl;

		}

	}



	decodeOneStep();

	system("pause");

	return 0;

}