用IJG的jpeglib压缩文件，目标都设成个FILE * outfile; 压缩完了就写到文件里去了，而且只有个压缩质量的参数，不知道根据那个参数压出来的文件尺寸会多大； 我弄个办法解决鸭的，不过比较傻； 这是个基本用法，用这个函数把RGB buffer压缩成个jpeg文件存起来,而我只需要他压缩到一个buffer里给我就行了，我不想要文件存储IO开销； BOOL RGBToJpegFile(const char * fileName, BYTE *dataBuf, UINT widthPix, UINT height, BOOL color, int quality)
{
if (dataBuf==NULL)
return FALSE;
if (widthPix==0)
return FALSE;
if (height==0)
return FALSE; LPBYTE tmp;
if (!color) {//处理黑白图像
tmp = (BYTE*)new BYTE[widthPix*height];
if (tmp==NULL) {
return FALSE;
} UINT row,col;
for (row=0;row for (col=0;col LPBYTE pRed, pGrn, pBlu;
pRed = dataBuf + row * widthPix * 3 + col * 3;
pGrn = dataBuf + row * widthPix * 3 + col * 3 + 1;
pBlu = dataBuf + row * widthPix * 3 + col * 3 + 2; // luminance
int lum = (int)(.299 * (double)(*pRed) + .587 * (double)(*pGrn) + .114 * (double)(*pBlu));
LPBYTE pGray;
pGray = tmp + row * widthPix + col;
*pGray = (BYTE)lum;
}
}
} struct jpeg_compress_struct cinfo;
FILE * outfile=NULL; /* 目标文件 */
int row_stride; /* 行宽*/ struct my_error_mgr jerr; /* Step 1: 分配对象*/
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_error_exit; if (setjmp(jerr.setjmp_buffer)) {
/* 出错了 */ jpeg_destroy_compress(&cinfo); if (outfile!=NULL)
fclose(outfile); if (!color) {
delete [] tmp;
}
return FALSE;
} /* 初始化. */
jpeg_create_compress(&cinfo); /* Step 2: 指定目标 */
if ((outfile = fopen(fileName, "wb")) == NULL) {
return FALSE;
} jpeg_stdio_dest(&cinfo, outfile); /* Step 3: 设参数*/
cinfo.image_width = widthPix; /* 宽度*/
cinfo.image_height = height;/* 高度*/
if (color) {
cinfo.input_components = 3; /* # of color components per pixel */
cinfo.in_color_space = JCS_RGB; /* colorspace of input image */
} else {
cinfo.input_components = 1; /* # of color components per pixel */
cinfo.in_color_space = JCS_GRAYSCALE; /* colorspace of input image */
} jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, quality, TRUE ); /*设参数*/ /* Step 4: 开始压缩*/ jpeg_start_compress(&cinfo, TRUE); /* Step 5: 逐行写入 */
row_stride = widthPix * 3; /* 行宽*/ while (cinfo.next_scanline < cinfo.image_height) {
/* 逐行写入 */
LPBYTE outRow;
if (color) {
outRow = dataBuf + (cinfo.next_scanline * widthPix * 3);
} else {
outRow = tmp + (cinfo.next_scanline * widthPix);
} (void) jpeg_write_scanlines(&cinfo, &outRow, 1);
} /* Step 6: 完成压缩*/ jpeg_finish_compress(&cinfo); /* 关闭文件. */
fclose(outfile); /* Step 7: 释放对象*/
jpeg_destroy_compress(&cinfo); if (!color)
delete [] tmp;
/* 完成*/ return TRUE;
} =========================================================================== 解决起来挺傻的，不知道有没有人有更好的办法，反正我是一直没再花心思琢磨它，有个用就好了； 定义了一个这样的结构 typedef struct {
unsigned char * buff;
long buffsize;
long next_byte_to_write; }XXX_JPEG_FILE_BUFFER; XXX_JPEG_FILE_BUFFER filebuffer; jpeg_stdio_destf(&cinfo, &filebuffer); //把结构替代输出文件作为目标设进去就行了；这样压缩完成的图片就在buffer里了 不过jpeg_stdio_destf这个函数是不一样的，我自己对jpeglib做了修改，增加了这么一个函数；具体内容下面详述； #define JPEG_BUFFERSIZE 0x100000 long RGBToJpegBuffer( char ** filebuffer, BYTE *dataBuf, UINT widthPix, UINT height, BOOL color, int quality)
{
if (dataBuf==NULL)
return -1;
if (widthPix==0)
return -1;
if (height==0)
return -1; LPBYTE tmp;
if (!color) {//处理黑白图像
tmp = (BYTE*)new BYTE[widthPix*height];
if (tmp==NULL) {
return -1;
} UINT row,col;
for (row=0;row for (col=0;col LPBYTE pRed, pGrn, pBlu;
pRed = dataBuf + row * widthPix * 3 + col * 3;
pGrn = dataBuf + row * widthPix * 3 + col * 3 + 1;
pBlu = dataBuf + row * widthPix * 3 + col * 3 + 2; // luminance
int lum = (int)(.299 * (double)(*pRed) + .587 * (double)(*pGrn) + .114 * (double)(*pBlu));
LPBYTE pGray;
pGray = tmp + row * widthPix + col;
*pGray = (BYTE)lum;
}
}
} struct jpeg_compress_struct cinfo;
int row_stride; /* 行宽*/ struct my_error_mgr jerr; /* Step 1: 分配对象*/
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_error_exit; if (setjmp(jerr.setjmp_buffer)) {
/* 出错了 */ jpeg_destroy_compress(&cinfo); if (!color) {
delete [] tmp;
}
return -1;
} /* 初始化. */
jpeg_create_compress(&cinfo); /* Step 2: 指定目标 */
XXX_JPEG_FILE_BUFFER filebuffer;
filebuffer.buff = (unsigned char *)malloc(JPEG_BUFFERSIZE );
filebuffer.next_byte_to_write = 0;
if (filebuffer.buff == NULL) {
return 0;
} jpeg_stdio_destf(&cinfo, &filebuffer); /* Step 3: 设参数*/
cinfo.image_width = widthPix; /* 宽度*/
cinfo.image_height = height;/* 高度*/
if (color) {
cinfo.input_components = 3; /* # of color components per pixel */
cinfo.in_color_space = JCS_RGB; /* colorspace of input image */
} else {
cinfo.input_components = 1; /* # of color components per pixel */
cinfo.in_color_space = JCS_GRAYSCALE; /* colorspace of input image */
} jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, quality, TRUE ); /*设参数*/ /* Step 4: 开始压缩*/ jpeg_start_compress(&cinfo, TRUE); /* Step 5: 逐行写入 */
row_stride = widthPix * 3; /* 行宽*/ while (cinfo.next_scanline < cinfo.image_height) {
/* 逐行写入 */
LPBYTE outRow;
if (color) {
outRow = dataBuf + (cinfo.next_scanline * widthPix * 3);
} else {
outRow = tmp + (cinfo.next_scanline * widthPix);
} (void) jpeg_write_scanlines(&cinfo, &outRow, 1);
} /* Step 6: 完成压缩*/ jpeg_finish_compress(&cinfo); /* Step 7: 释放对象*/
jpeg_destroy_compress(&cinfo); if (!color)
delete [] tmp;
/* 完成*/ * filebuffer = filebuffer.buff return filebuffer.next_byte_to_write;
} //============================================================================== 下面说如何扩展jpeglib的流管理器，jpeglib有文档专门说如何做自己的流管理器，我就是看完了那个然后拿原来的库改的； 在jdatadstf.c这个文件里做文章,这个文件是我把jdatadst.c做了一份拷贝改了个名字加到jpeglib工程里的； 定义自己的管理器结构 typedef struct {
struct jpeg_destination_mgr pub; /* public fields */ XXX_JPEG_FILE_BUFFER * outfile; /* target stream */
JOCTET * buffer; /* start of buffer */
} my_destination_mgrf; typedef my_destination_mgrf * my_dest_ptrf; #define OUTPUT_BUF_SIZE 4096 /* 缓冲区块大小*/ //------------------------------------------自己的初始化函数--------------------------- METHODDEF(void)
init_destination (j_compress_ptr cinfo) //
{
my_dest_ptrf dest = (my_dest_ptrf) cinfo->dest; dest->buffer = (JOCTET *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
OUTPUT_BUF_SIZE * SIZEOF(JOCTET)); dest->pub.next_output_byte = dest->buffer;
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
} //-----------------------------------清空函数------------------------------------------------------ METHODDEF(boolean)
empty_output_buffer (j_compress_ptr cinfo)
{
my_dest_ptrf dest = (my_dest_ptrf) cinfo->dest;
unsigned char * destbuff = dest->outfile->buff + dest->outfile->next_byte_to_write;
memcpy(destbuff, dest->buffer, OUTPUT_BUF_SIZE);
dest->outfile->next_byte_to_write += OUTPUT_BUF_SIZE;
// ERREXIT(cinfo, JERR_FILE_WRITE); dest->pub.next_output_byte = dest->buffer;
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE; return TRUE;
} //-------------------------------------这个函数干啥的忘了-------------------------------------------------- METHODDEF(void)
term_destination (j_compress_ptr cinfo)
{
my_dest_ptrf dest = (my_dest_ptrf) cinfo->dest;
size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
unsigned char * destbuff = dest->outfile->buff + dest->outfile->next_byte_to_write;
/* Write any data remaining in the buffer */
if (datacount > 0) {
memcpy(destbuff, dest->buffer, datacount);
dest->outfile->next_byte_to_write += datacount;
}
//fflush(dest->outfile);
/* Make sure we wrote the output file OK */
//if (ferror(dest->outfile))
// ERREXIT(cinfo, JERR_FILE_WRITE);
}
//--------------------------------------------这个就是最关键的，公开的那个------------------------------- GLOBAL(void)
jpeg_stdio_destf (j_compress_ptr cinfo, XXX_JPEG_FILE_BUFFER * outbuffer)
{
my_dest_ptrf dest; if (cinfo->dest == NULL) { /* first time for this JPEG object? */
cinfo->dest = (struct jpeg_destination_mgr *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
SIZEOF(my_destination_mgrf));
} dest = (my_dest_ptrf) cinfo->dest;
dest->pub.init_destination = init_destination;
dest->pub.empty_output_buffer = empty_output_buffer;
dest->pub.term_destination = term_destination;
dest->outfile = outbuffer;
} 后面还有工作要做 在jpeglib.h文件中加入这一行#define jpeg_stdio_destf jStdDestf 还有这一行 EXTERN(void) jpeg_stdio_destf JPP((j_compress_ptr cinfo, XXX_JPEG_FILE_BUFFER * outbuffer)); 重新编译jpeglib以后自己用就可以了； |
