的很好的解决方案在这里描述:http://www.christian-etter.de/?cat=48
typedef struct _jpeg_destination_mem_mgr
{
jpeg_destination_mgr mgr;
std::vector<unsigned char> data;
} jpeg_destination_mem_mgr;
初始化:
static void mem_init_destination(j_compress_ptr cinfo)
{
jpeg_destination_mem_mgr* dst = (jpeg_destination_mem_mgr*)cinfo->dest;
dst->data.resize(JPEG_MEM_DST_MGR_BUFFER_SIZE);
cinfo->dest->next_output_byte = dst->data.data();
cinfo->dest->free_in_buffer = dst->data.size();
}
当我们完成那么我们需要将缓冲区大小调整为实际大小:
static void mem_term_destination(j_compress_ptr cinfo)
{
jpeg_destination_mem_mgr* dst = (jpeg_destination_mem_mgr*)cinfo->dest;
dst->data.resize(dst->data.size() - cinfo->dest->free_in_buffer);
}
当缓冲区大小太小,那么我们需要增加它:
static boolean mem_empty_output_buffer(j_compress_ptr cinfo)
{
jpeg_destination_mem_mgr* dst = (jpeg_destination_mem_mgr*)cinfo->dest;
size_t oldsize = dst->data.size();
dst->data.resize(oldsize + JPEG_MEM_DST_MGR_BUFFER_SIZE);
cinfo->dest->next_output_byte = dst->data.data() + oldsize;
cinfo->dest->free_in_buffer = JPEG_MEM_DST_MGR_BUFFER_SIZE;
return true;
}
回调配置:
static void jpeg_mem_dest(j_compress_ptr cinfo, jpeg_destination_mem_mgr * dst)
{
cinfo->dest = (jpeg_destination_mgr*)dst;
cinfo->dest->init_destination = mem_init_destination;
cinfo->dest->term_destination = mem_term_destination;
cinfo->dest->empty_output_buffer = mem_empty_output_buffer;
}
而且样品用量:
jpeg_destination_mem_mgr dst_mem;
jpeg_compress_struct_wrapper cinfo;
j_compress_ptr pcinfo = cinfo;
jpeg_mem_dest(cinfo, &dst_mem);
可能重复[写入内存缓冲区而不是使用libjpeg的文件?] (http://stackoverflow.com/questions/4559648/write-to-memory-buffer-instead-of-file-with-libjpeg) – 2014-10-01 14:48:59
我发现这篇文章,但有一个全局向量,因此它不安全并行程序。 – AdamF 2014-10-01 14:50:32
你看过其他答案吗? – 2014-10-01 14:53:29