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authordeva <deva>2006-03-04 14:53:17 +0000
committerdeva <deva>2006-03-04 14:53:17 +0000
commitf02095ee5ceb78f1781a9e250693b8866ca42181 (patch)
tree7953c6b5f004f31ee9b340d7cdff5e85890594fc /lib/jpeg_mem_dest.cc
parent71c713dce2b5128862b293aa7fcc1d7ee89ffaf1 (diff)
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ * jpeg_mem_dest.cc
+ *
+ * Thu Jul 28 16:40:08 CEST 2005
+ * Copyright 2005 Bent Bisballe
+ * deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ * This file is part of MIaV.
+ *
+ * MIaV is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * MIaV is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with MIaV; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+#include <config.h>
+#include "jpeg_mem_dest.h"
+
+#define OUTPUT_BUF_SIZE 4096 /* choose an efficiently ?? size */
+
+/* Expanded data destination object for stdio output */
+typedef struct {
+ struct jpeg_destination_mgr pub; /* public fields */
+
+ JOCTET * outbuff; /* target buffer */
+ size_t * size;
+} mem_destination_mgr;
+
+typedef mem_destination_mgr * mem_dest_ptr;
+
+/*
+ * Initialize destination --- called by jpeg_start_compress
+ * before any data is actually written.
+ */
+void init_destination (j_compress_ptr cinfo)
+{
+ mem_dest_ptr dest = (mem_dest_ptr) cinfo->dest;
+
+ *dest->size = 0;
+ dest->pub.next_output_byte = dest->outbuff;
+ dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
+}
+
+/*
+ * 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.
+ */
+void term_destination (j_compress_ptr cinfo)
+{
+ mem_dest_ptr dest = (mem_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) {
+ dest->outbuff+=datacount;
+ *dest->size+=datacount;
+ }
+}
+
+/*
+ * 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.
+ */
+boolean empty_output_buffer (j_compress_ptr cinfo)
+{
+ mem_dest_ptr dest = (mem_dest_ptr) cinfo->dest;
+
+ dest->outbuff+=OUTPUT_BUF_SIZE;
+ *dest->size+=OUTPUT_BUF_SIZE;
+
+ dest->pub.next_output_byte = dest->outbuff;
+ dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
+
+ return TRUE;
+}
+
+/*
+ * Prepare for output to a memory buffer.
+ . The caller must have already allocated the buffer, and is responsible
+ * for closing it after finishing compression.
+ */
+void jpeg_mem_dest (j_compress_ptr cinfo, char * outbuff, size_t * size)
+{
+ mem_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(mem_destination_mgr));
+ }
+
+ dest = (mem_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->outbuff = (JOCTET *)outbuff;
+ dest->size = (size_t *)size;
+}