/src/libjpeg-turbo.main/jdtrans.c

Source (jump to first uncovered line)
/*
 * jdtrans.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1995-1997, Thomas G. Lane.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2020, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains library routines for transcoding decompression,
 * that is, reading raw DCT coefficient arrays from an input JPEG file.
 * The routines in jdapimin.c will also be needed by a transcoder.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jpegcomp.h"


/* Forward declarations */
LOCAL(void) transdecode_master_selection(j_decompress_ptr cinfo);


/*
 * Read the coefficient arrays from a JPEG file.
 * jpeg_read_header must be completed before calling this.
 *
 * The entire image is read into a set of virtual coefficient-block arrays,
 * one per component.  The return value is a pointer to the array of
 * virtual-array descriptors.  These can be manipulated directly via the
 * JPEG memory manager, or handed off to jpeg_write_coefficients().
 * To release the memory occupied by the virtual arrays, call
 * jpeg_finish_decompress() when done with the data.
 *
 * An alternative usage is to simply obtain access to the coefficient arrays
 * during a buffered-image-mode decompression operation.  This is allowed
 * after any jpeg_finish_output() call.  The arrays can be accessed until
 * jpeg_finish_decompress() is called.  (Note that any call to the library
 * may reposition the arrays, so don't rely on access_virt_barray() results
 * to stay valid across library calls.)
 *
 * Returns NULL if suspended.  This case need be checked only if
 * a suspending data source is used.
 */

GLOBAL(jvirt_barray_ptr *)
jpeg_read_coefficients(j_decompress_ptr cinfo)
{
  if (cinfo->global_state == DSTATE_READY) {
    /* First call: initialize active modules */
    transdecode_master_selection(cinfo);
    cinfo->global_state = DSTATE_RDCOEFS;
  }
  if (cinfo->global_state == DSTATE_RDCOEFS) {
    /* Absorb whole file into the coef buffer */
    for (;;) {
      int retcode;
      /* Call progress monitor hook if present */
      if (cinfo->progress != NULL)
        (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
      /* Absorb some more input */
      retcode = (*cinfo->inputctl->consume_input) (cinfo);
      if (retcode == JPEG_SUSPENDED)
        return NULL;
      if (retcode == JPEG_REACHED_EOI)
        break;
      /* Advance progress counter if appropriate */
      if (cinfo->progress != NULL &&
          (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
        if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
          /* startup underestimated number of scans; ratchet up one scan */
          cinfo->progress->pass_limit += (long)cinfo->total_iMCU_rows;
        }
      }
    }
    /* Set state so that jpeg_finish_decompress does the right thing */
    cinfo->global_state = DSTATE_STOPPING;
  }
  /* At this point we should be in state DSTATE_STOPPING if being used
   * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
   * to the coefficients during a full buffered-image-mode decompression.
   */
  if ((cinfo->global_state == DSTATE_STOPPING ||
       cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
    return cinfo->coef->coef_arrays;
  }
  /* Oops, improper usage */
  ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  return NULL;                  /* keep compiler happy */
}


/*
 * Master selection of decompression modules for transcoding.
 * This substitutes for jdmaster.c's initialization of the full decompressor.
 */

LOCAL(void)
transdecode_master_selection(j_decompress_ptr cinfo)
{
  /* This is effectively a buffered-image operation. */
  cinfo->buffered_image = TRUE;

#if JPEG_LIB_VERSION >= 80
  /* Compute output image dimensions and related values. */
  jpeg_core_output_dimensions(cinfo);
#endif

  /* Entropy decoding: either Huffman or arithmetic coding. */
  if (cinfo->arith_code) {
#ifdef D_ARITH_CODING_SUPPORTED
    jinit_arith_decoder(cinfo);
#else
    ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
  } else {
    if (cinfo->progressive_mode) {
#ifdef D_PROGRESSIVE_SUPPORTED
      jinit_phuff_decoder(cinfo);
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
    } else
      jinit_huff_decoder(cinfo);
  }

  /* Always get a full-image coefficient buffer. */
  jinit_d_coef_controller(cinfo, TRUE);

  /* We can now tell the memory manager to allocate virtual arrays. */
  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);

  /* Initialize input side of decompressor to consume first scan. */
  (*cinfo->inputctl->start_input_pass) (cinfo);

  /* Initialize progress monitoring. */
  if (cinfo->progress != NULL) {
    int nscans;
    /* Estimate number of scans to set pass_limit. */
    if (cinfo->progressive_mode) {
      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
      nscans = 2 + 3 * cinfo->num_components;
    } else if (cinfo->inputctl->has_multiple_scans) {
      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
      nscans = cinfo->num_components;
    } else {
      nscans = 1;
    }
    cinfo->progress->pass_counter = 0L;
    cinfo->progress->pass_limit = (long)cinfo->total_iMCU_rows * nscans;
    cinfo->progress->completed_passes = 0;
    cinfo->progress->total_passes = 1;
  }
}

Line	Count	Source (jump to first uncovered line)
1		/*
2		* jdtrans.c
3		*
4		* This file was part of the Independent JPEG Group's software:
5		* Copyright (C) 1995-1997, Thomas G. Lane.
6		* libjpeg-turbo Modifications:
7		* Copyright (C) 2020, D. R. Commander.
8		* For conditions of distribution and use, see the accompanying README.ijg
9		* file.
10		*
11		* This file contains library routines for transcoding decompression,
12		* that is, reading raw DCT coefficient arrays from an input JPEG file.
13		* The routines in jdapimin.c will also be needed by a transcoder.
14		*/
15
16		#define JPEG_INTERNALS
17		#include "jinclude.h"
18		#include "jpeglib.h"
19		#include "jpegcomp.h"
20
21
22		/* Forward declarations */
23		LOCAL(void) transdecode_master_selection(j_decompress_ptr cinfo);
24
25
26		/*
27		* Read the coefficient arrays from a JPEG file.
28		* jpeg_read_header must be completed before calling this.
29		*
30		* The entire image is read into a set of virtual coefficient-block arrays,
31		* one per component. The return value is a pointer to the array of
32		* virtual-array descriptors. These can be manipulated directly via the
33		* JPEG memory manager, or handed off to jpeg_write_coefficients().
34		* To release the memory occupied by the virtual arrays, call
35		* jpeg_finish_decompress() when done with the data.
36		*
37		* An alternative usage is to simply obtain access to the coefficient arrays
38		* during a buffered-image-mode decompression operation. This is allowed
39		* after any jpeg_finish_output() call. The arrays can be accessed until
40		* jpeg_finish_decompress() is called. (Note that any call to the library
41		* may reposition the arrays, so don't rely on access_virt_barray() results
42		* to stay valid across library calls.)
43		*
44		* Returns NULL if suspended. This case need be checked only if
45		* a suspending data source is used.
46		*/
47
48		GLOBAL(jvirt_barray_ptr *)
49		jpeg_read_coefficients(j_decompress_ptr cinfo)
50	0	{
51	0	if (cinfo->global_state == DSTATE_READY) {
52		/* First call: initialize active modules */
53	0	transdecode_master_selection(cinfo);
54	0	cinfo->global_state = DSTATE_RDCOEFS;
55	0	}
56	0	if (cinfo->global_state == DSTATE_RDCOEFS) {
57		/* Absorb whole file into the coef buffer */
58	0	for (;;) {
59	0	int retcode;
60		/* Call progress monitor hook if present */
61	0	if (cinfo->progress != NULL)
62	0	(*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
63		/* Absorb some more input */
64	0	retcode = (*cinfo->inputctl->consume_input) (cinfo);
65	0	if (retcode == JPEG_SUSPENDED)
66	0	return NULL;
67	0	if (retcode == JPEG_REACHED_EOI)
68	0	break;
69		/* Advance progress counter if appropriate */
70	0	if (cinfo->progress != NULL &&
71	0	(retcode == JPEG_ROW_COMPLETED \|\| retcode == JPEG_REACHED_SOS)) {
72	0	if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
73		/* startup underestimated number of scans; ratchet up one scan */
74	0	cinfo->progress->pass_limit += (long)cinfo->total_iMCU_rows;
75	0	}
76	0	}
77	0	}
78		/* Set state so that jpeg_finish_decompress does the right thing */
79	0	cinfo->global_state = DSTATE_STOPPING;
80	0	}
81		/* At this point we should be in state DSTATE_STOPPING if being used
82		* standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
83		* to the coefficients during a full buffered-image-mode decompression.
84		*/
85	0	if ((cinfo->global_state == DSTATE_STOPPING \|\|
86	0	cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
87	0	return cinfo->coef->coef_arrays;
88	0	}
89		/* Oops, improper usage */
90	0	ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
91	0	return NULL; /* keep compiler happy */
92	0	}
93
94
95		/*
96		* Master selection of decompression modules for transcoding.
97		* This substitutes for jdmaster.c's initialization of the full decompressor.
98		*/
99
100		LOCAL(void)
101		transdecode_master_selection(j_decompress_ptr cinfo)
102	0	{
103		/* This is effectively a buffered-image operation. */
104	0	cinfo->buffered_image = TRUE;
105
106		#if JPEG_LIB_VERSION >= 80
107		/* Compute output image dimensions and related values. */
108		jpeg_core_output_dimensions(cinfo);
109		#endif
110
111		/* Entropy decoding: either Huffman or arithmetic coding. */
112	0	if (cinfo->arith_code) {
113	0	#ifdef D_ARITH_CODING_SUPPORTED
114	0	jinit_arith_decoder(cinfo);
115		#else
116		ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
117		#endif
118	0	} else {
119	0	if (cinfo->progressive_mode) {
120	0	#ifdef D_PROGRESSIVE_SUPPORTED
121	0	jinit_phuff_decoder(cinfo);
122		#else
123		ERREXIT(cinfo, JERR_NOT_COMPILED);
124		#endif
125	0	} else
126	0	jinit_huff_decoder(cinfo);
127	0	}
128
129		/* Always get a full-image coefficient buffer. */
130	0	jinit_d_coef_controller(cinfo, TRUE);
131
132		/* We can now tell the memory manager to allocate virtual arrays. */
133	0	(*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
134
135		/* Initialize input side of decompressor to consume first scan. */
136	0	(*cinfo->inputctl->start_input_pass) (cinfo);
137
138		/* Initialize progress monitoring. */
139	0	if (cinfo->progress != NULL) {
140	0	int nscans;
141		/* Estimate number of scans to set pass_limit. */
142	0	if (cinfo->progressive_mode) {
143		/* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
144	0	nscans = 2 + 3 * cinfo->num_components;
145	0	} else if (cinfo->inputctl->has_multiple_scans) {
146		/* For a nonprogressive multiscan file, estimate 1 scan per component. */
147	0	nscans = cinfo->num_components;
148	0	} else {
149	0	nscans = 1;
150	0	}
151	0	cinfo->progress->pass_counter = 0L;
152	0	cinfo->progress->pass_limit = (long)cinfo->total_iMCU_rows * nscans;
153	0	cinfo->progress->completed_passes = 0;
154	0	cinfo->progress->total_passes = 1;
155	0	}
156	0	}

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Created: 2024-05-18 12:36