///////////////////////////////////////////////////////////////////////////////////////////
//行压缩函数
//该函数是内部调用函数,如果你想要引用它,必须保证
//cinfo->inbuf填满有效数据 ,否则将不能得到正确的压缩数据
void jint_process_rows(jpeg_compress_info *cinfo)
{
int mn; //当前缓冲里的MCU
JSAMPLE *mcu_start;
int mcu_delta;
JSAMPLE *pdata;
//颜色转换选择调用(这里只做RGB到YCrCb的转换)
if(cinfo->in_color_space==JCS_RGB)
jutl_cc_rgb2ycc(cinfo->inbuf,cinfo->inbuf_width*cinfo->inbuf_height);
//处理每个MCU数据,分割inbuf的数据到每个元件的dct表中,并降低每个元件的采样率
mcu_start=&cinfo->inbuf[0];
mcu_delta=cinfo->mcu_width*cinfo->num_comp*sizeof(JSAMPLE);
for(mn=0;mn<cinfo->mcu_per_row;mn++)
{
//对于每个元件,降低采样率并保存到各个元件中
int cn;//元件计数器
for(cn=0;cn<cinfo->num_comp;cn++)
{
JSAMPLE *comp_start=(JSAMPLE*)(mcu_start+cn);
//初始化采样间隔(sampledelta)数据指针
int h_samp_delta=cinfo->max_h_factor/cinfo->comp[cn].h_factor*cinfo->num_comp*sizeof(JSAMPLE);
int v_samp_delta=cinfo->max_v_factor/cinfo->comp[cn].v_factor*cinfo->num_comp*sizeof(JSAMPLE)*cinfo->inbuf_width;
//对于每个块(block)
int bn;//块计数器
int pn;//数据指针
for(bn=0;bn<cinfo->comp[cn].num_dct_table;bn++)
{
//初始化块开始地址
JSAMPLE *block_start=(JSAMPLE*)(comp_start+(bn%cinfo->comp[cn].h_factor)*DCTSIZE*h_samp_delta+(bn/cinfo->comp[cn].v_factor)*DCTSIZE*v_samp_delta);
DCTVAL *dct=(DCTVAL*)&cinfo->comp[cn].dct_table[bn];//dct表元素
for(pn=0;pn<DCTSIZE2;pn++)//对于每个元素
{
if(pn%DCTSIZE==0)pdata=(JSAMPLE*)(pn/DCTSIZE*v_samp_delta+block_start);
dct[pn]=*pdata;
pdata+=h_samp_delta;
}
}
}//颜色元件处理循环结束
mcu_start+=mcu_delta;
jint_process_mcu(cinfo);//处理当前MCU数据
}
}
void jint_process_rows(jpeg_compress_info *cinfo)
{
int mn; /* current mcu in buffer */
JSAMPLE *mcu_start; //jsample 压缩样本
int mcu_delta;
JSAMPLE *pdata; //
// JSAMPLE *pdata;
/* Color convertion invoke select.
* Note: We just implemente RGB -> YCrCb converte.
*/ //如果颜色空间为RGB格式，则通过加权平均值法转换为YUV格式
if(cinfo->in_color_space==JCS_RGB)//RGB到YUV的变换
jutl_cc_rgb2ycc(cinfo->inbuf,cinfo->inbuf_width*cinfo->inbuf_height);
/* Process each of MCU data.
* Separate the 'inbuf' data to each color component's dct table,
* and 'Make' down sample for every component.
*/
mcu_start=&cinfo->inbuf[0];
mcu_delta=cinfo->mcu_width*cinfo->num_comp*sizeof(JSAMPLE);
for(mn=0;mn<cinfo->mcu_per_row;mn++)
{
/* For every color component.
* Down sample and save to each color component.
*/
int cn; /* component counter */
for (cn=0; cn<cinfo->num_comp; cn++)
{
JSAMPLE *comp_start = (JSAMPLE *)(mcu_start + cn);
/* init data-point sample delta */
int h_samp_delta = cinfo->max_h_factor / cinfo->comp[cn].h_factor
* cinfo->num_comp * sizeof(JSAMPLE);
int v_samp_delta = cinfo->max_v_factor / cinfo->comp[cn].v_factor
* cinfo->num_comp * sizeof(JSAMPLE)
* cinfo->inbuf_width;
/* for every block */
int bn; /* block counter */
int pn; /* point of data */
for (bn=0; bn<cinfo->comp[cn].num_dct_table; bn++)
{
/* init block start address */
JSAMPLE *block_start = (JSAMPLE *)(comp_start
+ (bn%cinfo->comp[cn].h_factor)*DCTSIZE*h_samp_delta
+ (bn/cinfo->comp[cn].v_factor)*DCTSIZE*v_samp_delta);
/* dct table element */
DCTVAL *dct = (DCTVAL *)&cinfo->comp[cn].dct_table[bn];
/* for each element */
for (pn=0; pn<DCTSIZE2; pn++)
{
if (pn % DCTSIZE == 0)
{
pdata = (JSAMPLE *)(pn/DCTSIZE * v_samp_delta + block_start);
}
dct[pn] = *pdata;
pdata += h_samp_delta;
}
}
} /* End of color component loop */
mcu_start += mcu_delta;
/* Process current MCU data.
*/
jint_process_mcu(cinfo);
/* for example : call jint_process_mcu(cinfo) */
}
}