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jdatadst.c

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00001 #include <stdio.h>
00002 #include <stdlib.h>
00003 #include "jpeg.h"
00004 #include "jpegwrapper.h"
00005 #include "jerror.h"
00006 #include "filemov.h"
00007 
00008 /* Expanded data destination object for stdio output */
00009 
00010 typedef struct {
00011   struct jpeg_destination_mgr pub; /* public fields */
00012 
00013   JOCTET *buffer;               // Pointer to buffer
00014   thread_struct *buffer_struct;
00015 } bcast_destination_mgr;
00016 
00017 typedef bcast_destination_mgr *bcast_dest_ptr;
00018 
00019 
00020 /*
00021  * Initialize destination --- called by jpeg_start_compress
00022  * before any data is actually written.
00023  */
00024 
00025 METHODDEF(void)
00026 bcast_init_destination (j_compress_ptr cinfo)
00027 {
00028   bcast_dest_ptr dest = (bcast_dest_ptr) cinfo->dest;
00029 
00030 // Set the pointer to the preallocated buffer
00031   dest->buffer = dest->buffer_struct->output_buffer;
00032 
00033   dest->pub.next_output_byte = dest->buffer;
00034   dest->pub.free_in_buffer = dest->buffer_struct->output_allocated;
00035 }
00036 
00037 
00038 /*
00039  * Empty the output buffer --- called whenever buffer fills up.
00040  *
00041  * In typical applications, this should write the entire output buffer
00042  * (ignoring the current state of next_output_byte & free_in_buffer),
00043  * reset the pointer & count to the start of the buffer, and return TRUE
00044  * indicating that the buffer has been dumped.
00045  *
00046  * In applications that need to be able to suspend compression due to output
00047  * overrun, a FALSE return indicates that the buffer cannot be emptied now.
00048  * In this situation, the compressor will return to its caller (possibly with
00049  * an indication that it has not accepted all the supplied scanlines).  The
00050  * application should resume compression after it has made more room in the
00051  * output buffer.  Note that there are substantial restrictions on the use of
00052  * suspension --- see the documentation.
00053  *
00054  * When suspending, the compressor will back up to a convenient restart point
00055  * (typically the start of the current MCU). next_output_byte & free_in_buffer
00056  * indicate where the restart point will be if the current call returns FALSE.
00057  * Data beyond this point will be regenerated after resumption, so do not
00058  * write it out when emptying the buffer externally.
00059  */
00060 
00061 METHODDEF(boolean)
00062 bcast_empty_output_buffer (j_compress_ptr cinfo)
00063 {
00064 // Allocate a bigger buffer.
00065         bcast_dest_ptr dest = (bcast_dest_ptr) cinfo->dest;
00066         unsigned char *new_buffer;
00067         int new_size, i;
00068         int offset = dest->buffer_struct->output_allocated;
00069 
00070         new_size = dest->buffer_struct->output_allocated * 2;
00071         new_buffer = (unsigned char*)malloc(new_size);
00072         for(i = 0; i < offset; i++)
00073                 new_buffer[i] = dest->buffer_struct->output_buffer[i];
00074         free(dest->buffer_struct->output_buffer);
00075         dest->buffer_struct->output_buffer = new_buffer;
00076         dest->buffer_struct->output_allocated = new_size;
00077         dest->buffer = dest->buffer_struct->output_buffer;
00078 
00079         dest->pub.next_output_byte = dest->buffer + offset;
00080         dest->pub.free_in_buffer = dest->buffer_struct->output_allocated - offset;
00081 
00082         return TRUE;
00083 }
00084 
00085 
00086 /*
00087  * Terminate destination --- called by jpeg_finish_compress
00088  * after all data has been written.  Usually needs to flush buffer.
00089  *
00090  * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
00091  * application must deal with any cleanup that should happen even
00092  * for error exit.
00093  */
00094 
00095 METHODDEF(void)
00096 bcast_term_destination (j_compress_ptr cinfo)
00097 {
00098 // Just get the length
00099         bcast_dest_ptr dest = (bcast_dest_ptr) cinfo->dest;
00100         dest->buffer_struct->output_size = dest->buffer_struct->output_allocated - dest->pub.free_in_buffer;
00101 }
00102 
00103 
00104 /*
00105  * Prepare for output to a stdio stream.
00106  * The caller must have already opened the stream, and is responsible
00107  * for closing it after finishing compression.
00108  */
00109 
00110 GLOBAL(void)
00111 bcast_jpeg_buffer_dest (j_compress_ptr cinfo, thread_struct *buffer_struct)
00112 {
00113   bcast_dest_ptr dest;
00114 
00115   /* The destination object is made permanent so that multiple JPEG images
00116    * can be written to the same file without re-executing jpeg_stdio_dest.
00117    * This makes it dangerous to use this manager and a different destination
00118    * manager serially with the same JPEG object, because their private object
00119    * sizes may be different.  Caveat programmer.
00120    */
00121   if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
00122     cinfo->dest = (struct jpeg_destination_mgr *)
00123       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
00124                                   sizeof(bcast_destination_mgr));
00125   }
00126 
00127   dest = (bcast_dest_ptr) cinfo->dest;
00128   dest->pub.init_destination = bcast_init_destination;
00129   dest->pub.empty_output_buffer = bcast_empty_output_buffer;
00130   dest->pub.term_destination = bcast_term_destination;
00131   dest->buffer_struct = buffer_struct;
00132 }

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