vs2013 C++ ：将多张png小图 拼接成一张大图，新手求教

[drouin]

基于zlib库和libpng库在vs2013平台下用c++编写：


将多张同样大小的 png小图 ，拼接组成一张大的png图，比如12张小图，256*256的，拼接成大图，可以是三行四列，那么大图的长256*4 ，高256*3 ；
12张小图的名字可以 是00.png 01.png ....

鄙人是个刚培训完的新手，到新公司给的任务，做了一天，实现了2张拼接的，但转成多张，遇到各种问题，所以请各位大神指导，周一要交，不然难保，否则就自己钻研了，求教！！！

以下是自网上下载某位高手的，自己修改的：

[drouin]

#define _CRT_SECURE_NO_WARNINGS #include <tchar.h> #include <vector> #include "png.h" #include "pnginfo.h" #define LOG printf #define tmin(a, b) ((a)>(b) ? (b):(a)) #define tmax(a,b) ((a) > (b)?(a):(b)) //!1不要将这三个宏同时打开 //需要互斥 #define USE_PREMULTIPLY_APLHA (0)//使用预乘 #define USE_RGBA (1)//使用 r g b a #define USE_ABGR (0)//使用 a b g r //预乘 aplha #define CC_RGB_PREMULTIPLY_APLHA(vr, vg, vb, va) \ (unsigned)(((unsigned)((unsigned char)(vr) * ((unsigned char)(va) + 1)) >> 8) | \ ((unsigned)((unsigned char)(vg) * ((unsigned char)(va) + 1) >> 8) << 8) | \ ((unsigned)((unsigned char)(vb) * ((unsigned char)(va) + 1) >> 8) << 16) | \ ((unsigned)(unsigned char)(va) << 24)) //r g b a #define CC_RGB_PREMULTIPLY_APLHA_RGBA(vr, vg, vb, va)\ ( (unsigned)(vr))|\ ( (unsigned)(vg) << 8)|\ ( (unsigned)(vb) << 16)|\ ((unsigned)(va) << 24) //a b g r //使用该宏的时候 write png时需要调用函数 png_set_swap_alpha #define CC_RGB_PREMULTIPLY_APLHA_ABGR(vr, vg, vb, va)\ ( (unsigned)(vr) << 8)|\ ( (unsigned)(vg) << 16)|\ ( (unsigned)(vb) << 24)|\ ((unsigned)(va)) //helper struct typedef struct _ImageData { char* m_data; int m_size; int m_offset; }ImageData; //Image struct typedef struct _Image { char* m_pRawData; int m_width; int m_height; int m_bytesPerLine; }Image; //declare static bool TestWritePng(unsigned char* pData, int dataLen); //read data cakk back static void customerReadDataCallBack(png_structp png_ptr, png_bytep data, png_size_t length) { ImageData* pImageData = (ImageData*)png_get_io_ptr(png_ptr); if ((int)(pImageData->m_offset + length) <= pImageData->m_size) { memcpy(data, pImageData->m_data + pImageData->m_offset, length); pImageData->m_offset += length; } else { LOG("customerReadDataCallBack failed"); } }

[drouin]

//read png static bool TestReadPng(char* pData, int dataLeng, Image* image) { bool ret = false; png_structp png_ptr = NULL; png_infop info_ptr = NULL; do { //check png header's length png_byte header[8] = { 0 }; if (dataLeng < 8) { break; } //check header memcpy(header, pData, 8); if (0 != png_sig_cmp(header, 0, 8)) { break; } //create png_struct png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); if (!png_ptr) { break; } //create png info struct info_ptr = png_create_info_struct(png_ptr); if (!info_ptr) { break; } //set i/o ImageData imageData; imageData.m_data = pData; imageData.m_size = dataLeng; imageData.m_offset = 0; png_set_read_fn(png_ptr, (void*)&imageData, customerReadDataCallBack); //start to read png // read png //set transfer // PNG_TRANSFORM_EXPAND: perform set_expand() // PNG_TRANSFORM_PACKING: expand 1, 2 and 4-bit samples to bytes // PNG_TRANSFORM_STRIP_16: strip 16-bit samples to 8 bits // PNG_TRANSFORM_GRAY_TO_RGB: expand grayscale samples to RGB (or GA to RGBA) png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_EXPAND | PNG_TRANSFORM_PACKING | PNG_TRANSFORM_STRIP_16 | PNG_TRANSFORM_GRAY_TO_RGB, 0); //get ihdr int color_type = 0; png_uint_32 nWidth = 0; png_uint_32 nHeight = 0; int nBitsPerComponent = 0; png_get_IHDR(png_ptr, info_ptr, &nWidth, &nHeight, &nBitsPerComponent, &color_type, NULL, NULL, NULL); // int bytesPerComponent = 3; bool bhasAplha = false; if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA) { bhasAplha = true; } if (bhasAplha) { bytesPerComponent = 4; } //allocate memory unsigned char* pImateRawData = new unsigned char[nHeight * nWidth * bytesPerComponent]; //get row pointers png_bytep * rowPointers = png_get_rows(png_ptr, info_ptr); int bytesPerRow = nWidth * bytesPerComponent; //read data if (bhasAplha) { unsigned int *tmp = (unsigned int *)pImateRawData; for (unsigned int i = 0; i < nHeight; i++) { for (int j = 0; j < bytesPerRow; j += 4) { #if USE_PREMULTIPLY_APLHA *tmp++ = CC_RGB_PREMULTIPLY_APLHA(rowPointers[i][j], rowPointers[i][j + 1], rowPointers[i][j + 2], rowPointers[i][j + 3]); #elif USE_RGBA *tmp++ = CC_RGB_PREMULTIPLY_APLHA_RGBA(rowPointers[i][j], rowPointers[i][j + 1], rowPointers[i][j + 2], rowPointers[i][j + 3]); #elif USE_ABGR *tmp++ = CC_RGB_PREMULTIPLY_APLHA_ABGR(rowPointers[i][j], rowPointers[i][j + 1], rowPointers[i][j + 2], rowPointers[i][j + 3]); #endif } } } else { for (unsigned int j = 0; j < nHeight; ++j) { memcpy(pImateRawData + j * bytesPerRow, rowPointers[j], bytesPerRow); } } // image->m_pRawData = (char*)pImateRawData; image->m_width = nWidth; image->m_height = nHeight; image->m_bytesPerLine = bytesPerRow; ret = true; } while (0); //destory read struct if (png_ptr) { png_destroy_read_struct(&png_ptr, (info_ptr) ? &info_ptr : 0, 0); } return ret; }

[drouin]

//write png static bool TestWritePng(Image* pImage) { bool ret = false; if (pImage) { FILE *fp; png_structp png_ptr; png_infop info_ptr; /* Open the file */ fp = fopen("test.png", "wb"); if (fp) { png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); info_ptr = png_create_info_struct(png_ptr); png_init_io(png_ptr, fp); png_set_IHDR(png_ptr, info_ptr, pImage->m_width, pImage->m_height, 8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); png_write_info(png_ptr, info_ptr); png_set_packing(png_ptr); #if USE_ABGR png_set_swap_alpha(png_ptr); #endif //png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); png_bytepp row_pointers = new png_bytep[pImage->m_height]; memset(row_pointers, 0, pImage->m_height * sizeof(png_byte)); png_bytep pData = (png_bytep)pImage->m_pRawData; for (int k = 0; k < pImage->m_height; k++) row_pointers[k] = pData + k * pImage->m_bytesPerLine; png_write_image(png_ptr, row_pointers); png_write_end(png_ptr, info_ptr); png_destroy_write_struct(&png_ptr, &info_ptr); fclose(fp); ret = true; } } return ret; }

[jiht594]

既然2张可以成功, 可以每次合成2张啊, 多合几次而已. 可以以后再改啊

[fly_dragon_fly]

也就是调试的问题了，你先生成最终大小的png，然后每次把小块拷到目标位置，每次存出来看看对不对

[flyrack]

还有png的格式是从下往上的 大概是这样 5 6 7 8 9 0 1 2 3 4