苗火 Nicholas

[C++]将多张图片合并成大图

2016-11-18 萧 写技术

在《批量下载网络图片到本地》里写到了批量下载图片，其实那些图片是电子地图的散片，我想把这些图片合成一张大图，以便做成可以直接打开查看的地图甚至把印成纸质地图。当然这一切可以用图片处理软件一张一张地拼接，但地图散片动不动就是成百上千片，手动处理会很累，于是我选择了C++，代码很简单，同时这也得益于lodepng库的引入:

#include <vector>
#include <urlmon.h>
#include <string>
#include <iostream>
#include "loadpng.h"
using namespace std;
#pragma comment(lib, "urlmon.lib")

#define ROW	10
#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[])
{
	decodeOneStep();
	system("pause");
}

标签: C++