| /* |
| * 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 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 = 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->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; |
| dest->alloc = alloc; |
| |
| if (*outbuffer == NULL || *outsize == 0) { |
| if (alloc) { |
| /* 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; |
| } |
| else ERREXIT(cinfo, JERR_BUFFER_SIZE); |
| } |
| |
| dest->pub.next_output_byte = dest->buffer = *outbuffer; |
| dest->pub.free_in_buffer = dest->bufsize = *outsize; |
| } |