--- /dev/null
+/*
+ * jdatadst.c
+ *
+ * Copyright (C) 1994-1996, Thomas G. Lane.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains compression data destination routines for the case of
+ * emitting JPEG data to a file (or any stdio stream). While these routines
+ * are sufficient for most applications, some will want to use a different
+ * destination manager.
+ * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
+ * JOCTETs into 8-bit-wide elements on external storage. If char is wider
+ * than 8 bits on your machine, you may need to do some tweaking.
+ */
+
+/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
+#include "jinclude.h"
+#include "jpeglib.h"
+#include "jerror.h"
+
+
+/* Expanded data destination object for stdio output */
+
+typedef struct {
+ struct jpeg_destination_mgr pub; /* public fields */
+
+ FILE * outfile; /* target stream */
+ JOCTET * buffer; /* start of buffer */
+} my_destination_mgr;
+
+typedef my_destination_mgr * my_dest_ptr;
+
+#define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
+
+
+/*
+ * Initialize destination --- called by jpeg_start_compress
+ * before any data is actually written.
+ */
+
+METHODDEF(void)
+init_destination (j_compress_ptr cinfo)
+{
+ my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
+
+ /* Allocate the output buffer --- it will be released when done with image */
+ 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;
+}
+
+
+/*
+ * Empty the output buffer --- called whenever buffer fills up.
+ *
+ * In typical applications, this should write the entire output buffer
+ * (ignoring the current state of next_output_byte & free_in_buffer),
+ * reset the pointer & count to the start of the buffer, and return TRUE
+ * indicating that the buffer has been dumped.
+ *
+ * In applications that need to be able to suspend compression due to output
+ * overrun, a FALSE return indicates that the buffer cannot be emptied now.
+ * In this situation, the compressor will return to its caller (possibly with
+ * an indication that it has not accepted all the supplied scanlines). The
+ * application should resume compression after it has made more room in the
+ * output buffer. Note that there are substantial restrictions on the use of
+ * suspension --- see the documentation.
+ *
+ * When suspending, the compressor will back up to a convenient restart point
+ * (typically the start of the current MCU). next_output_byte & free_in_buffer
+ * indicate where the restart point will be if the current call returns FALSE.
+ * Data beyond this point will be regenerated after resumption, so do not
+ * write it out when emptying the buffer externally.
+ */
+
+METHODDEF(boolean)
+empty_output_buffer (j_compress_ptr cinfo)
+{
+ my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
+
+ if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
+ (size_t) 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;
+}
+
+
+/*
+ * Terminate destination --- called by jpeg_finish_compress
+ * after all data has been written. Usually needs to flush buffer.
+ *
+ * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
+ * application must deal with any cleanup that should happen even
+ * for error exit.
+ */
+
+METHODDEF(void)
+term_destination (j_compress_ptr cinfo)
+{
+ my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
+ size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
+
+ /* Write any data remaining in the buffer */
+ if (datacount > 0) {
+ if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
+ ERREXIT(cinfo, JERR_FILE_WRITE);
+ }
+ fflush(dest->outfile);
+ /* Make sure we wrote the output file OK */
+ if (ferror(dest->outfile))
+ ERREXIT(cinfo, JERR_FILE_WRITE);
+}
+
+
+/*
+ * Prepare for output to a stdio stream.
+ * The caller must have already opened the stream, and is responsible
+ * for closing it after finishing compression.
+ */
+
+GLOBAL(void)
+jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
+{
+ my_dest_ptr dest;
+
+ /* The destination object is made permanent so that multiple JPEG images
+ * can be written to the same file without re-executing jpeg_stdio_dest.
+ * This makes it dangerous to use this manager and a different destination
+ * manager serially with the same JPEG object, because their private object
+ * sizes may be different. Caveat programmer.
+ */
+ 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_mgr));
+ }
+
+ dest = (my_dest_ptr) cinfo->dest;
+ dest->pub.init_destination = init_destination;
+ dest->pub.empty_output_buffer = empty_output_buffer;
+ dest->pub.term_destination = term_destination;
+ dest->outfile = outfile;
+}
projects / opencv / blobdiff