jpeg 交叉编译以及接口的使用, RGB->jpg

使用jpeg版本：jpegsrc.v9a.tar.gz

configure参数：./configure --prefix=/usr/local/jpeglib_arm/ --host=arm-none-linux-gnueabi

之后make； make install

调用jpeg接口

/*
    将bgr数据转换为jpg图像存储
    filename: 生成的jpg文件名
    width height:    传入bmp file 的宽和高
    pBGRBuffer:    传入bgr数据
*/
int convert_to_jpg(char *filename, int width, int height, unsigned char *pBGRBuffer)
{
    FILE *fJpg;
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;
    JSAMPROW row_pointer[1];
    int row_stride;

    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);
    fJpg = fopen(filename, "wb");
    if(fJpg == NULL){
        debugE("Cannot open file %s\n", filename);
        return -1;
    }
    jpeg_stdio_dest(&cinfo, fJpg);
    cinfo.image_width = width;
    cinfo.image_height = height;
    cinfo.input_components = 3;
    cinfo.in_color_space = JCS_RGB;
    jpeg_set_defaults(&cinfo);
    jpeg_set_quality(&cinfo, 30, TRUE);
    jpeg_start_compress(&cinfo, TRUE);
    row_stride = cinfo.image_width * 3;    /* JSAMPLEs per row in image_buffer */
    while (cinfo.next_scanline < cinfo.image_height) {
        /* jpeg_write_scanlines expects an array of pointers to scanlines.
         * Here the array is only one element long, but you could pass
         * more than one scanline at a time if that's more convenient.
         */
        //row_pointer[0] = & pBMPBuffer[cinfo.next_scanline * row_stride];
        row_pointer[0] = &pBGRBuffer[row_stride*(cinfo.image_height - cinfo.next_scanline - 1)];
        (void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
    }

    jpeg_finish_compress(&cinfo);
    jpeg_destroy_compress(&cinfo);
    fclose(fJpg);

    return 0;
}