+
+bool gdcm_write_JPEG_file (std::ofstream *fp, void *im_buf,
+ int image_width, int image_height, int quality)
+{
+
+ JSAMPLE *image_buffer = (JSAMPLE*) im_buf;
+
+ /* This struct contains the JPEG compression parameters and pointers to
+ * working space (which is allocated as needed by the JPEG library).
+ * It is possible to have several such structures, representing multiple
+ * compression/decompression processes, in existence at once. We refer
+ * to any one struct (and its associated working data) as a "JPEG object".
+ */
+ struct jpeg_compress_struct cinfo;
+ /* This struct represents a JPEG error handler. It is declared separately
+ * because applications often want to supply a specialized error handler
+ * (see the second half of this file for an example). But here we just
+ * take the easy way out and use the standard error handler, which will
+ * print a message on stderr and call exit() if compression fails.
+ * Note that this struct must live as long as the main JPEG parameter
+ * struct, to avoid dangling-pointer problems.
+ */
+ struct jpeg_error_mgr jerr;
+ /* More stuff */
+ //FILE* outfile; /* target FILE* /
+ JSAMPROW row_pointer[1]; /* pointer to JSAMPLE row[s] */
+ int row_stride; /* physical row width in image buffer */
+
+ /* Step 1: allocate and initialize JPEG compression object */
+
+ /* We have to set up the error handler first, in case the initialization
+ * step fails. (Unlikely, but it could happen if you are out of memory.)
+ * This routine fills in the contents of struct jerr, and returns jerr's
+ * address which we place into the link field in cinfo.
+ */
+ cinfo.err = jpeg_std_error(&jerr);
+ /* Now we can initialize the JPEG compression object. */
+ jpeg_create_compress(&cinfo);
+
+ /* Step 2: specify data destination (eg, a file) */
+ /* Note: steps 2 and 3 can be done in either order. */
+
+ /* Here we use the library-supplied code to send compressed data to a
+ * stdio stream. You can also write your own code to do something else.
+ * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
+ * requires it in order to write binary files.
+ */
+ // if ((outfile = fopen(filename, "wb")) == NULL) {
+ // fprintf(stderr, "can't open %s\n", filename);
+ // exit(1);
+ //
+ // }
+ jpeg_stdio_dest(&cinfo, fp);
+
+ /* Step 3: set parameters for compression */
+
+ /* First we supply a description of the input image.
+ * Four fields of the cinfo struct must be filled in:
+ */
+ cinfo.image_width = image_width;/* image width and height, in pixels */
+ cinfo.image_height = image_height;
+ cinfo.input_components = 3; /* # of color components per pixel */
+ cinfo.in_color_space = JCS_RGB; /* colorspace of input image */
+ /* Now use the library's routine to set default compression parameters.
+ * (You must set at least cinfo.in_color_space before calling this,
+ * since the defaults depend on the source color space.)
+ */
+ jpeg_set_defaults(&cinfo);
+ /* Now you can set any non-default parameters you wish to.
+ * Here we just illustrate the use of quality (quantization table) scaling:
+ */
+ jpeg_set_quality(&cinfo, quality, TRUE /* limit to baseline-JPEG values */);
+
+ /* Step 4: Start compressor */
+
+ /* TRUE ensures that we will write a complete interchange-JPEG file.
+ * Pass TRUE unless you are very sure of what you're doing.
+ */
+ jpeg_start_compress(&cinfo, TRUE);
+
+ /* Step 5: while (scan lines remain to be written) */
+ /* jpeg_write_scanlines(...); */
+
+ /* Here we use the library's state variable cinfo.next_scanline as the
+ * loop counter, so that we don't have to keep track ourselves.
+ * To keep things simple, we pass one scanline per call; you can pass
+ * more if you wish, though.
+ */
+ row_stride = 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] = & image_buffer[cinfo.next_scanline * row_stride];