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Diffstat (limited to 'jdatadst-tj.c')
-rw-r--r-- | jdatadst-tj.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/jdatadst-tj.c b/jdatadst-tj.c new file mode 100644 index 0000000..8551495 --- /dev/null +++ b/jdatadst-tj.c @@ -0,0 +1,190 @@ +/* + * jdatadst-tj.c + * + * This file was part of the Independent JPEG Group's software: + * Copyright (C) 1994-1996, Thomas G. Lane. + * Modified 2009-2012 by Guido Vollbeding. + * Modifications: + * Copyright (C) 2011, D. R. Commander. + * 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 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. + */ + +/* this is not a core library module, so it doesn't define JPEG_INTERNALS */ +#include "jinclude.h" +#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 + + +#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; + boolean alloc; +} 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. + */ + +METHODDEF(void) +init_mem_destination (j_compress_ptr cinfo) +{ + /* no work necessary here */ +} + + +/* + * 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_mem_output_buffer (j_compress_ptr cinfo) +{ + size_t nextsize; + JOCTET * nextbuffer; + my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest; + + if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE); + + /* Try to allocate new buffer with double size */ + nextsize = dest->bufsize * 2; + nextbuffer = (JOCTET *) 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 + * 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_mem_destination (j_compress_ptr cinfo) +{ + my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest; + + if(dest->alloc) *dest->outbuffer = dest->buffer; + *dest->outsize = (unsigned long)(dest->bufsize - dest->pub.free_in_buffer); +} + + +/* + * 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_tj (j_compress_ptr cinfo, + unsigned char ** outbuffer, unsigned long * outsize, + boolean alloc) +{ + 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->newbuffer = NULL; + } + + 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->alloc = alloc; + + if (*outbuffer == NULL || *outsize == 0) { + if (alloc) { + /* Allocate initial buffer */ + dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE); + if (dest->newbuffer == NULL) + ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10); + *outsize = OUTPUT_BUF_SIZE; + } + else ERREXIT(cinfo, JERR_BUFFER_SIZE); + } + + dest->pub.next_output_byte = dest->buffer = *outbuffer; + dest->pub.free_in_buffer = dest->bufsize = *outsize; +} |