jdatadst-tj.c 6.6 KB

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  1. /*
  2. * jdatadst-tj.c
  3. *
  4. * This file was part of the Independent JPEG Group's software:
  5. * Copyright (C) 1994-1996, Thomas G. Lane.
  6. * Modified 2009-2012 by Guido Vollbeding.
  7. * libjpeg-turbo Modifications:
  8. * Copyright (C) 2011, 2014, 2016, D. R. Commander.
  9. * For conditions of distribution and use, see the accompanying README.ijg
  10. * file.
  11. *
  12. * This file contains compression data destination routines for the case of
  13. * emitting JPEG data to memory or to a file (or any stdio stream).
  14. * While these routines are sufficient for most applications,
  15. * some will want to use a different destination manager.
  16. * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
  17. * JOCTETs into 8-bit-wide elements on external storage. If char is wider
  18. * than 8 bits on your machine, you may need to do some tweaking.
  19. */
  20. /* this is not a core library module, so it doesn't define JPEG_INTERNALS */
  21. #include "jinclude.h"
  22. #include "jpeglib.h"
  23. #include "jerror.h"
  24. #ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
  25. extern void *malloc(size_t size);
  26. extern void free(void *ptr);
  27. #endif
  28. #define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
  29. /* Expanded data destination object for memory output */
  30. typedef struct {
  31. struct jpeg_destination_mgr pub; /* public fields */
  32. unsigned char **outbuffer; /* target buffer */
  33. unsigned long *outsize;
  34. unsigned char *newbuffer; /* newly allocated buffer */
  35. JOCTET *buffer; /* start of buffer */
  36. size_t bufsize;
  37. boolean alloc;
  38. } my_mem_destination_mgr;
  39. typedef my_mem_destination_mgr *my_mem_dest_ptr;
  40. /*
  41. * Initialize destination --- called by jpeg_start_compress
  42. * before any data is actually written.
  43. */
  44. METHODDEF(void)
  45. init_mem_destination(j_compress_ptr cinfo)
  46. {
  47. /* no work necessary here */
  48. }
  49. /*
  50. * Empty the output buffer --- called whenever buffer fills up.
  51. *
  52. * In typical applications, this should write the entire output buffer
  53. * (ignoring the current state of next_output_byte & free_in_buffer),
  54. * reset the pointer & count to the start of the buffer, and return TRUE
  55. * indicating that the buffer has been dumped.
  56. *
  57. * In applications that need to be able to suspend compression due to output
  58. * overrun, a FALSE return indicates that the buffer cannot be emptied now.
  59. * In this situation, the compressor will return to its caller (possibly with
  60. * an indication that it has not accepted all the supplied scanlines). The
  61. * application should resume compression after it has made more room in the
  62. * output buffer. Note that there are substantial restrictions on the use of
  63. * suspension --- see the documentation.
  64. *
  65. * When suspending, the compressor will back up to a convenient restart point
  66. * (typically the start of the current MCU). next_output_byte & free_in_buffer
  67. * indicate where the restart point will be if the current call returns FALSE.
  68. * Data beyond this point will be regenerated after resumption, so do not
  69. * write it out when emptying the buffer externally.
  70. */
  71. METHODDEF(boolean)
  72. empty_mem_output_buffer(j_compress_ptr cinfo)
  73. {
  74. size_t nextsize;
  75. JOCTET *nextbuffer;
  76. my_mem_dest_ptr dest = (my_mem_dest_ptr)cinfo->dest;
  77. if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE);
  78. /* Try to allocate new buffer with double size */
  79. nextsize = dest->bufsize * 2;
  80. nextbuffer = (JOCTET *)malloc(nextsize);
  81. if (nextbuffer == NULL)
  82. ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
  83. MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
  84. if (dest->newbuffer != NULL)
  85. free(dest->newbuffer);
  86. dest->newbuffer = nextbuffer;
  87. dest->pub.next_output_byte = nextbuffer + dest->bufsize;
  88. dest->pub.free_in_buffer = dest->bufsize;
  89. dest->buffer = nextbuffer;
  90. dest->bufsize = nextsize;
  91. return TRUE;
  92. }
  93. /*
  94. * Terminate destination --- called by jpeg_finish_compress
  95. * after all data has been written. Usually needs to flush buffer.
  96. *
  97. * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
  98. * application must deal with any cleanup that should happen even
  99. * for error exit.
  100. */
  101. METHODDEF(void)
  102. term_mem_destination(j_compress_ptr cinfo)
  103. {
  104. my_mem_dest_ptr dest = (my_mem_dest_ptr)cinfo->dest;
  105. if (dest->alloc) *dest->outbuffer = dest->buffer;
  106. *dest->outsize = (unsigned long)(dest->bufsize - dest->pub.free_in_buffer);
  107. }
  108. /*
  109. * Prepare for output to a memory buffer.
  110. * The caller may supply an own initial buffer with appropriate size.
  111. * Otherwise, or when the actual data output exceeds the given size,
  112. * the library adapts the buffer size as necessary.
  113. * The standard library functions malloc/free are used for allocating
  114. * larger memory, so the buffer is available to the application after
  115. * finishing compression, and then the application is responsible for
  116. * freeing the requested memory.
  117. */
  118. GLOBAL(void)
  119. jpeg_mem_dest_tj(j_compress_ptr cinfo, unsigned char **outbuffer,
  120. unsigned long *outsize, boolean alloc)
  121. {
  122. boolean reused = FALSE;
  123. my_mem_dest_ptr dest;
  124. if (outbuffer == NULL || outsize == NULL) /* sanity check */
  125. ERREXIT(cinfo, JERR_BUFFER_SIZE);
  126. /* The destination object is made permanent so that multiple JPEG images
  127. * can be written to the same buffer without re-executing jpeg_mem_dest.
  128. */
  129. if (cinfo->dest == NULL) { /* first time for this JPEG object? */
  130. cinfo->dest = (struct jpeg_destination_mgr *)
  131. (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
  132. sizeof(my_mem_destination_mgr));
  133. dest = (my_mem_dest_ptr)cinfo->dest;
  134. dest->newbuffer = NULL;
  135. dest->buffer = NULL;
  136. } else if (cinfo->dest->init_destination != init_mem_destination) {
  137. /* It is unsafe to reuse the existing destination manager unless it was
  138. * created by this function.
  139. */
  140. ERREXIT(cinfo, JERR_BUFFER_SIZE);
  141. }
  142. dest = (my_mem_dest_ptr)cinfo->dest;
  143. dest->pub.init_destination = init_mem_destination;
  144. dest->pub.empty_output_buffer = empty_mem_output_buffer;
  145. dest->pub.term_destination = term_mem_destination;
  146. if (dest->buffer == *outbuffer && *outbuffer != NULL && alloc)
  147. reused = TRUE;
  148. dest->outbuffer = outbuffer;
  149. dest->outsize = outsize;
  150. dest->alloc = alloc;
  151. if (*outbuffer == NULL || *outsize == 0) {
  152. if (alloc) {
  153. /* Allocate initial buffer */
  154. dest->newbuffer = *outbuffer = (unsigned char *)malloc(OUTPUT_BUF_SIZE);
  155. if (dest->newbuffer == NULL)
  156. ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
  157. *outsize = OUTPUT_BUF_SIZE;
  158. } else
  159. ERREXIT(cinfo, JERR_BUFFER_SIZE);
  160. }
  161. dest->pub.next_output_byte = dest->buffer = *outbuffer;
  162. if (!reused)
  163. dest->bufsize = *outsize;
  164. dest->pub.free_in_buffer = dest->bufsize;
  165. }