c++读写BMP JPG 和png 的图像文件（linux）

#include <png.h> #include"png.h" CPNGHandler::CPNGHandler() { } CPNGHandler::~CPNGHandler() { } int CPNGHandler::ReadPNGfile(const char* filename, CImageInfo* img) {/* 用于解码png图片 */ FILE *pic_fp; pic_fp = fopen(filename, "rb"); if(pic_fp == NULL) /* 文件打开失败 */ { perror("fopen"); return -1; } /* 初始化各种结构 */ png_structp png_ptr; png_infop info_ptr; char buf[PNG_BYTES_TO_CHECK]; int temp; png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0); info_ptr = png_create_info_struct(png_ptr); setjmp(png_jmpbuf(png_ptr)); // 这句很重要 temp = fread(buf,1,PNG_BYTES_TO_CHECK,pic_fp); temp = png_sig_cmp((png_bytep)buf, (png_size_t)0, PNG_BYTES_TO_CHECK); /*检测是否为png文件*/ if (temp!=0) { fclose(pic_fp); return -1; } rewind(pic_fp); /*开始读文件*/ png_init_io(png_ptr, pic_fp); // 读文件 png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_EXPAND, 0); /*获取宽度，高度，位深，颜色类型*/ int channels = png_get_channels(png_ptr, info_ptr); /*获取通道数*/ int color_type = png_get_color_type(png_ptr, info_ptr); /*颜色类型*/ int bit_depth = png_get_bit_depth(png_ptr, info_ptr); /* 获取位深 */ /* row_pointers里边就是rgba数据 */ png_bytep* row_pointers; row_pointers = png_get_rows(png_ptr, info_ptr); int width = png_get_image_width(png_ptr, info_ptr); int height = png_get_image_height(png_ptr, info_ptr); int size = width *channels; size+=size%4;//4字节对齐 size *= height; unsigned char* data = new unsigned char[size]; int pos = 0; int stride=channels; for(int i = height-1; i >= 0; i--)//png上下颠倒 { for(int j = 0; j <stride*width; j += stride) {/* 一个字节一个字节的赋值 */ data[pos++] = row_pointers[i][j]; // red data[pos++] = row_pointers[i][j+1]; // green data[pos++] = row_pointers[i][j+2]; // blue if(stride==4) { data[pos++] = row_pointers[i][j+3]; // alpha } } pos+=(stride*width)%4; } CImageInfo newImg(width,height,channels,size,data); *img=newImg; /* 撤销数据占用的内存 */ png_destroy_read_struct(&png_ptr, &info_ptr, 0); fclose(pic_fp); return 0; } int CPNGHandler::WritePNGfile(const char *filename , CImageInfo &img) { png_byte color_type; png_structp png_ptr; png_infop info_ptr; /* create file */ FILE *fp = fopen(filename, "wb"); if (!fp) { perror("fopen"); return -1; } /* initialize stuff */ png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); if (!png_ptr) { printf("[write_png_file] png_create_write_struct failed"); return -1; } info_ptr = png_create_info_struct(png_ptr); if (!info_ptr) { printf("[write_png_file] png_create_info_struct failed"); return -1; } if (setjmp(png_jmpbuf(png_ptr))) { printf("[write_png_file] Error during init_io"); return -1; } png_init_io(png_ptr, fp); /* write header */ if (setjmp(png_jmpbuf(png_ptr))) { printf("[write_png_file] Error during writing header"); return -1; } /* 判断要写入至文件的图片数据是否有透明度，来选择色彩类型 */ if(img.GetChannels()==4) { color_type = PNG_COLOR_TYPE_RGB_ALPHA; } else if(img.GetChannels()==3) { color_type = PNG_COLOR_TYPE_RGB; } else { return -1; } png_set_IHDR(png_ptr, info_ptr, img.GetWidth(), img.GetHeight(), 8, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);//位深暂时默认8 png_write_info(png_ptr, info_ptr); /* write bytes */ if (setjmp(png_jmpbuf(png_ptr))) { printf("[write_png_file] Error during writing bytes"); return -1; } int pos = 0; png_bytep * row_pointers = new png_bytep[img.GetHeight()]; int SizeEachLine=img.GetChannels() * img.GetWidth(); unsigned char*data=img.GetData();//获取图像数据 for(int i = img.GetHeight()-1; i >=0; i--) { row_pointers[i] =new png_byte[SizeEachLine]; for(int j = 0; j < SizeEachLine; j += img.GetChannels()) { row_pointers[i][j] = data[pos++]; // red row_pointers[i][j+1] = data[pos++]; // green row_pointers[i][j+2] = data[pos++]; // blue if(img.GetChannels()==4) row_pointers[i][j+3] = data[pos++]; // alpha } pos+=SizeEachLine%4; } png_write_image(png_ptr, row_pointers); /* end write */ if (setjmp(png_jmpbuf(png_ptr))) { printf("[write_png_file] Error during end of write"); return -1; } png_write_end(png_ptr, NULL); /* cleanup heap allocation */ for (int j=0; j<img.GetHeight(); j++) delete []row_pointers[j]; delete []row_pointers; fclose(fp); return 0; }