The Independent JPEG Group's JPEG software v8
diff --git a/jdatadst.c b/jdatadst.c
index a8f6fb0..472d5f3 100644
--- a/jdatadst.c
+++ b/jdatadst.c
@@ -2,13 +2,14 @@
* jdatadst.c
*
* Copyright (C) 1994-1996, Thomas G. Lane.
+ * Modified 2009 by Guido Vollbeding.
* 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.
+ * emitting JPEG data to memory or 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.
@@ -19,6 +20,11 @@
#include "jpeglib.h"
#include "jerror.h"
+#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
+extern void * malloc JPP((size_t size));
+extern void free JPP((void *ptr));
+#endif
+
/* Expanded data destination object for stdio output */
@@ -34,6 +40,21 @@
#define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
+/* Expanded data destination object for memory output */
+
+typedef struct {
+ struct jpeg_destination_mgr pub; /* public fields */
+
+ unsigned char ** outbuffer; /* target buffer */
+ unsigned long * outsize;
+ unsigned char * newbuffer; /* newly allocated buffer */
+ JOCTET * buffer; /* start of buffer */
+ size_t bufsize;
+} my_mem_destination_mgr;
+
+typedef my_mem_destination_mgr * my_mem_dest_ptr;
+
+
/*
* Initialize destination --- called by jpeg_start_compress
* before any data is actually written.
@@ -53,6 +74,12 @@
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
}
+METHODDEF(void)
+init_mem_destination (j_compress_ptr cinfo)
+{
+ /* no work necessary here */
+}
+
/*
* Empty the output buffer --- called whenever buffer fills up.
@@ -92,6 +119,36 @@
return TRUE;
}
+METHODDEF(boolean)
+empty_mem_output_buffer (j_compress_ptr cinfo)
+{
+ size_t nextsize;
+ JOCTET * nextbuffer;
+ my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
+
+ /* Try to allocate new buffer with double size */
+ nextsize = dest->bufsize * 2;
+ nextbuffer = malloc(nextsize);
+
+ if (nextbuffer == NULL)
+ ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
+
+ MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
+
+ if (dest->newbuffer != NULL)
+ free(dest->newbuffer);
+
+ dest->newbuffer = nextbuffer;
+
+ dest->pub.next_output_byte = nextbuffer + dest->bufsize;
+ dest->pub.free_in_buffer = dest->bufsize;
+
+ dest->buffer = nextbuffer;
+ dest->bufsize = nextsize;
+
+ return TRUE;
+}
+
/*
* Terminate destination --- called by jpeg_finish_compress
@@ -119,6 +176,15 @@
ERREXIT(cinfo, JERR_FILE_WRITE);
}
+METHODDEF(void)
+term_mem_destination (j_compress_ptr cinfo)
+{
+ my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
+
+ *dest->outbuffer = dest->buffer;
+ *dest->outsize = dest->bufsize - dest->pub.free_in_buffer;
+}
+
/*
* Prepare for output to a stdio stream.
@@ -149,3 +215,53 @@
dest->pub.term_destination = term_destination;
dest->outfile = outfile;
}
+
+
+/*
+ * Prepare for output to a memory buffer.
+ * The caller may supply an own initial buffer with appropriate size.
+ * Otherwise, or when the actual data output exceeds the given size,
+ * the library adapts the buffer size as necessary.
+ * The standard library functions malloc/free are used for allocating
+ * larger memory, so the buffer is available to the application after
+ * finishing compression, and then the application is responsible for
+ * freeing the requested memory.
+ */
+
+GLOBAL(void)
+jpeg_mem_dest (j_compress_ptr cinfo,
+ unsigned char ** outbuffer, unsigned long * outsize)
+{
+ my_mem_dest_ptr dest;
+
+ if (outbuffer == NULL || outsize == NULL) /* sanity check */
+ ERREXIT(cinfo, JERR_BUFFER_SIZE);
+
+ /* The destination object is made permanent so that multiple JPEG images
+ * can be written to the same buffer without re-executing jpeg_mem_dest.
+ */
+ 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_mem_destination_mgr));
+ }
+
+ dest = (my_mem_dest_ptr) cinfo->dest;
+ dest->pub.init_destination = init_mem_destination;
+ dest->pub.empty_output_buffer = empty_mem_output_buffer;
+ dest->pub.term_destination = term_mem_destination;
+ dest->outbuffer = outbuffer;
+ dest->outsize = outsize;
+ dest->newbuffer = NULL;
+
+ if (*outbuffer == NULL || *outsize == 0) {
+ /* Allocate initial buffer */
+ dest->newbuffer = *outbuffer = malloc(OUTPUT_BUF_SIZE);
+ if (dest->newbuffer == NULL)
+ ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
+ *outsize = OUTPUT_BUF_SIZE;
+ }
+
+ dest->pub.next_output_byte = dest->buffer = *outbuffer;
+ dest->pub.free_in_buffer = dest->bufsize = *outsize;
+}