src/jpeg/jdpostct.c

/*
 * jdpostct.c
 *
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * 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 the decompression postprocessing controller.
 * This controller manages the upsampling, color conversion, and color
 * quantization/reduction steps; specifically, it controls the buffering
 * between upsample/color conversion and color quantization/reduction.
 *
 * If no color quantization/reduction is required, then this module has no
 * work to do, and it just hands off to the upsample/color conversion code.
 * An integrated upsample/convert/quantize process would replace this module
 * entirely.
 */

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


/* Private buffer controller object */

typedef struct {
  struct jpeg_d_post_controller pub; /* public fields */

  /* Color quantization source buffer: this holds output data from
   * the upsample/color conversion step to be passed to the quantizer.
   * For two-pass color quantization, we need a full-image buffer;
   * for one-pass operation, a strip buffer is sufficient.
   */
  jvirt_sarray_ptr whole_image;	/* virtual array, or NULL if one-pass */
  JSAMPARRAY buffer;		/* strip buffer, or current strip of virtual */
  JDIMENSION strip_height;	/* buffer size in rows */
  /* for two-pass mode only: */
  JDIMENSION starting_row;	/* row # of first row in current strip */
  JDIMENSION next_row;		/* index of next row to fill/empty in strip */
} my_post_controller;

typedef my_post_controller * my_post_ptr;


/* Forward declarations */
METHODDEF(void) post_process_1pass
	JPP((j_decompress_ptr cinfo,
	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	     JDIMENSION in_row_groups_avail,
	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	     JDIMENSION out_rows_avail));
#ifdef QUANT_2PASS_SUPPORTED
METHODDEF(void) post_process_prepass
	JPP((j_decompress_ptr cinfo,
	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	     JDIMENSION in_row_groups_avail,
	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	     JDIMENSION out_rows_avail));
METHODDEF(void) post_process_2pass
	JPP((j_decompress_ptr cinfo,
	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	     JDIMENSION in_row_groups_avail,
	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	     JDIMENSION out_rows_avail));
#endif


/*
 * Initialize for a processing pass.
 */

METHODDEF(void)
start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
{
  my_post_ptr post = (my_post_ptr) cinfo->post;

  switch (pass_mode) {
  case JBUF_PASS_THRU:
    if (cinfo->quantize_colors) {
      /* Single-pass processing with color quantization. */
      post->pub.post_process_data = post_process_1pass;
      /* We could be doing buffered-image output before starting a 2-pass
       * color quantization; in that case, jinit_d_post_controller did not
       * allocate a strip buffer.  Use the virtual-array buffer as workspace.
       */
      if (post->buffer == NULL) {
	post->buffer = (*cinfo->mem->access_virt_sarray)
	  ((j_common_ptr) cinfo, post->whole_image,
	   (JDIMENSION) 0, post->strip_height, TRUE);
      }
    } else {
      /* For single-pass processing without color quantization,
       * I have no work to do; just call the upsampler directly.
       */
      post->pub.post_process_data = cinfo->upsample->upsample;
    }
    break;
#ifdef QUANT_2PASS_SUPPORTED
  case JBUF_SAVE_AND_PASS:
    /* First pass of 2-pass quantization */
    if (post->whole_image == NULL)
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    post->pub.post_process_data = post_process_prepass;
    break;
  case JBUF_CRANK_DEST:
    /* Second pass of 2-pass quantization */
    if (post->whole_image == NULL)
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    post->pub.post_process_data = post_process_2pass;
    break;
#endif /* QUANT_2PASS_SUPPORTED */
  default:
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    break;
  }
  post->starting_row = post->next_row = 0;
}


/*
 * Process some data in the one-pass (strip buffer) case.
 * This is used for color precision reduction as well as one-pass quantization.
 */

METHODDEF(void)
post_process_1pass (j_decompress_ptr cinfo,
		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
		    JDIMENSION in_row_groups_avail,
		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
		    JDIMENSION out_rows_avail)
{
  my_post_ptr post = (my_post_ptr) cinfo->post;
  JDIMENSION num_rows, max_rows;

  /* Fill the buffer, but not more than what we can dump out in one go. */
  /* Note we rely on the upsampler to detect bottom of image. */
  max_rows = out_rows_avail - *out_row_ctr;
  if (max_rows > post->strip_height)
    max_rows = post->strip_height;
  num_rows = 0;
  (*cinfo->upsample->upsample) (cinfo,
		input_buf, in_row_group_ctr, in_row_groups_avail,
		post->buffer, &num_rows, max_rows);
  /* Quantize and emit data. */
  (*cinfo->cquantize->color_quantize) (cinfo,
		post->buffer, output_buf + *out_row_ctr, (int) num_rows);
  *out_row_ctr += num_rows;
}


#ifdef QUANT_2PASS_SUPPORTED

/*
 * Process some data in the first pass of 2-pass quantization.
 */

METHODDEF(void)
post_process_prepass (j_decompress_ptr cinfo,
		      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
		      JDIMENSION in_row_groups_avail,
		      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
		      JDIMENSION out_rows_avail)
{
  my_post_ptr post = (my_post_ptr) cinfo->post;
  JDIMENSION old_next_row, num_rows;

  /* Reposition virtual buffer if at start of strip. */
  if (post->next_row == 0) {
    post->buffer = (*cinfo->mem->access_virt_sarray)
	((j_common_ptr) cinfo, post->whole_image,
	 post->starting_row, post->strip_height, TRUE);
  }

  /* Upsample some data (up to a strip height's worth). */
  old_next_row = post->next_row;
  (*cinfo->upsample->upsample) (cinfo,
		input_buf, in_row_group_ctr, in_row_groups_avail,
		post->buffer, &post->next_row, post->strip_height);

  /* Allow quantizer to scan new data.  No data is emitted, */
  /* but we advance out_row_ctr so outer loop can tell when we're done. */
  if (post->next_row > old_next_row) {
    num_rows = post->next_row - old_next_row;
    (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
					 (JSAMPARRAY) NULL, (int) num_rows);
    *out_row_ctr += num_rows;
  }

  /* Advance if we filled the strip. */
  if (post->next_row >= post->strip_height) {
    post->starting_row += post->strip_height;
    post->next_row = 0;
  }
}


/*
 * Process some data in the second pass of 2-pass quantization.
 */

METHODDEF(void)
post_process_2pass (j_decompress_ptr cinfo,
		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
		    JDIMENSION in_row_groups_avail,
		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
		    JDIMENSION out_rows_avail)
{
  my_post_ptr post = (my_post_ptr) cinfo->post;
  JDIMENSION num_rows, max_rows;

  /* Reposition virtual buffer if at start of strip. */
  if (post->next_row == 0) {
    post->buffer = (*cinfo->mem->access_virt_sarray)
	((j_common_ptr) cinfo, post->whole_image,
	 post->starting_row, post->strip_height, FALSE);
  }

  /* Determine number of rows to emit. */
  num_rows = post->strip_height - post->next_row; /* available in strip */
  max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
  if (num_rows > max_rows)
    num_rows = max_rows;
  /* We have to check bottom of image here, can't depend on upsampler. */
  max_rows = cinfo->output_height - post->starting_row;
  if (num_rows > max_rows)
    num_rows = max_rows;

  /* Quantize and emit data. */
  (*cinfo->cquantize->color_quantize) (cinfo,
		post->buffer + post->next_row, output_buf + *out_row_ctr,
		(int) num_rows);
  *out_row_ctr += num_rows;

  /* Advance if we filled the strip. */
  post->next_row += num_rows;
  if (post->next_row >= post->strip_height) {
    post->starting_row += post->strip_height;
    post->next_row = 0;
  }
}

#endif /* QUANT_2PASS_SUPPORTED */


/*
 * Initialize postprocessing controller.
 */

GLOBAL(void)
jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
{
  my_post_ptr post;

  post = (my_post_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				SIZEOF(my_post_controller));
  cinfo->post = (struct jpeg_d_post_controller *) post;
  post->pub.start_pass = start_pass_dpost;
  post->whole_image = NULL;	/* flag for no virtual arrays */
  post->buffer = NULL;		/* flag for no strip buffer */

  /* Create the quantization buffer, if needed */
  if (cinfo->quantize_colors) {
    /* The buffer strip height is max_v_samp_factor, which is typically
     * an efficient number of rows for upsampling to return.
     * (In the presence of output rescaling, we might want to be smarter?)
     */
    post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
    if (need_full_buffer) {
      /* Two-pass color quantization: need full-image storage. */
      /* We round up the number of rows to a multiple of the strip height. */
#ifdef QUANT_2PASS_SUPPORTED
      post->whole_image = (*cinfo->mem->request_virt_sarray)
	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
	 cinfo->output_width * cinfo->out_color_components,
	 (JDIMENSION) jround_up((long) cinfo->output_height,
				(long) post->strip_height),
	 post->strip_height);
#else
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
#endif /* QUANT_2PASS_SUPPORTED */
    } else {
      /* One-pass color quantization: just make a strip buffer. */
      post->buffer = (*cinfo->mem->alloc_sarray)
	((j_common_ptr) cinfo, JPOOL_IMAGE,
	 cinfo->output_width * cinfo->out_color_components,
	 post->strip_height);
    }
  }
}
Commit	Line	Data
	1	/*
	2	* jdpostct.c
	3	*
	4	* Copyright (C) 1994-1996, Thomas G. Lane.
	5	* This file is part of the Independent JPEG Group's software.
	6	* For conditions of distribution and use, see the accompanying README file.
	7	*
	8	* This file contains the decompression postprocessing controller.
	9	* This controller manages the upsampling, color conversion, and color
	10	* quantization/reduction steps; specifically, it controls the buffering
	11	* between upsample/color conversion and color quantization/reduction.
	12	*
	13	* If no color quantization/reduction is required, then this module has no
	14	* work to do, and it just hands off to the upsample/color conversion code.
	15	* An integrated upsample/convert/quantize process would replace this module
	16	* entirely.
	17	*/
	18
	19	#define JPEG_INTERNALS
	20	#include "jinclude.h"
	21	#include "jpeglib.h"
	22
	23
	24	/* Private buffer controller object */
	25
	26	typedef struct {
	27	struct jpeg_d_post_controller pub; /* public fields */
	28
	29	/* Color quantization source buffer: this holds output data from
	30	* the upsample/color conversion step to be passed to the quantizer.
	31	* For two-pass color quantization, we need a full-image buffer;
	32	* for one-pass operation, a strip buffer is sufficient.
	33	*/
	34	jvirt_sarray_ptr whole_image; /* virtual array, or NULL if one-pass */
	35	JSAMPARRAY buffer; /* strip buffer, or current strip of virtual */
	36	JDIMENSION strip_height; /* buffer size in rows */
	37	/* for two-pass mode only: */
	38	JDIMENSION starting_row; /* row # of first row in current strip */
	39	JDIMENSION next_row; /* index of next row to fill/empty in strip */
	40	} my_post_controller;
	41
	42	typedef my_post_controller * my_post_ptr;
	43
	44
	45	/* Forward declarations */
	46	METHODDEF(void) post_process_1pass
	47	JPP((j_decompress_ptr cinfo,
	48	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	49	JDIMENSION in_row_groups_avail,
	50	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	51	JDIMENSION out_rows_avail));
	52	#ifdef QUANT_2PASS_SUPPORTED
	53	METHODDEF(void) post_process_prepass
	54	JPP((j_decompress_ptr cinfo,
	55	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	56	JDIMENSION in_row_groups_avail,
	57	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	58	JDIMENSION out_rows_avail));
	59	METHODDEF(void) post_process_2pass
	60	JPP((j_decompress_ptr cinfo,
	61	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	62	JDIMENSION in_row_groups_avail,
	63	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	64	JDIMENSION out_rows_avail));
	65	#endif
	66
	67
	68	/*
	69	* Initialize for a processing pass.
	70	*/
	71
	72	METHODDEF(void)
	73	start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
	74	{
	75	my_post_ptr post = (my_post_ptr) cinfo->post;
	76
	77	switch (pass_mode) {
	78	case JBUF_PASS_THRU:
	79	if (cinfo->quantize_colors) {
	80	/* Single-pass processing with color quantization. */
	81	post->pub.post_process_data = post_process_1pass;
	82	/* We could be doing buffered-image output before starting a 2-pass
	83	* color quantization; in that case, jinit_d_post_controller did not
	84	* allocate a strip buffer. Use the virtual-array buffer as workspace.
	85	*/
	86	if (post->buffer == NULL) {
	87	post->buffer = (*cinfo->mem->access_virt_sarray)
	88	((j_common_ptr) cinfo, post->whole_image,
	89	(JDIMENSION) 0, post->strip_height, TRUE);
	90	}
	91	} else {
	92	/* For single-pass processing without color quantization,
	93	* I have no work to do; just call the upsampler directly.
	94	*/
	95	post->pub.post_process_data = cinfo->upsample->upsample;
	96	}
	97	break;
	98	#ifdef QUANT_2PASS_SUPPORTED
	99	case JBUF_SAVE_AND_PASS:
	100	/* First pass of 2-pass quantization */
	101	if (post->whole_image == NULL)
	102	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	103	post->pub.post_process_data = post_process_prepass;
	104	break;
	105	case JBUF_CRANK_DEST:
	106	/* Second pass of 2-pass quantization */
	107	if (post->whole_image == NULL)
	108	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	109	post->pub.post_process_data = post_process_2pass;
	110	break;
	111	#endif /* QUANT_2PASS_SUPPORTED */
	112	default:
	113	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	114	break;
	115	}
	116	post->starting_row = post->next_row = 0;
	117	}
	118
	119
	120	/*
	121	* Process some data in the one-pass (strip buffer) case.
	122	* This is used for color precision reduction as well as one-pass quantization.
	123	*/
	124
	125	METHODDEF(void)
	126	post_process_1pass (j_decompress_ptr cinfo,
	127	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	128	JDIMENSION in_row_groups_avail,
	129	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	130	JDIMENSION out_rows_avail)
	131	{
	132	my_post_ptr post = (my_post_ptr) cinfo->post;
	133	JDIMENSION num_rows, max_rows;
	134
	135	/* Fill the buffer, but not more than what we can dump out in one go. */
	136	/* Note we rely on the upsampler to detect bottom of image. */
	137	max_rows = out_rows_avail - *out_row_ctr;
	138	if (max_rows > post->strip_height)
	139	max_rows = post->strip_height;
	140	num_rows = 0;
	141	(*cinfo->upsample->upsample) (cinfo,
	142	input_buf, in_row_group_ctr, in_row_groups_avail,
	143	post->buffer, &num_rows, max_rows);
	144	/* Quantize and emit data. */
	145	(*cinfo->cquantize->color_quantize) (cinfo,
	146	post->buffer, output_buf + *out_row_ctr, (int) num_rows);
	147	*out_row_ctr += num_rows;
	148	}
	149
	150
	151	#ifdef QUANT_2PASS_SUPPORTED
	152
	153	/*
	154	* Process some data in the first pass of 2-pass quantization.
	155	*/
	156
	157	METHODDEF(void)
	158	post_process_prepass (j_decompress_ptr cinfo,
	159	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	160	JDIMENSION in_row_groups_avail,
	161	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	162	JDIMENSION out_rows_avail)
	163	{
	164	my_post_ptr post = (my_post_ptr) cinfo->post;
	165	JDIMENSION old_next_row, num_rows;
	166
	167	/* Reposition virtual buffer if at start of strip. */
	168	if (post->next_row == 0) {
	169	post->buffer = (*cinfo->mem->access_virt_sarray)
	170	((j_common_ptr) cinfo, post->whole_image,
	171	post->starting_row, post->strip_height, TRUE);
	172	}
	173
	174	/* Upsample some data (up to a strip height's worth). */
	175	old_next_row = post->next_row;
	176	(*cinfo->upsample->upsample) (cinfo,
	177	input_buf, in_row_group_ctr, in_row_groups_avail,
	178	post->buffer, &post->next_row, post->strip_height);
	179
	180	/* Allow quantizer to scan new data. No data is emitted, */
	181	/* but we advance out_row_ctr so outer loop can tell when we're done. */
	182	if (post->next_row > old_next_row) {
	183	num_rows = post->next_row - old_next_row;
	184	(*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
	185	(JSAMPARRAY) NULL, (int) num_rows);
	186	*out_row_ctr += num_rows;
	187	}
	188
	189	/* Advance if we filled the strip. */
	190	if (post->next_row >= post->strip_height) {
	191	post->starting_row += post->strip_height;
	192	post->next_row = 0;
	193	}
	194	}
	195
	196
	197	/*
	198	* Process some data in the second pass of 2-pass quantization.
	199	*/
	200
	201	METHODDEF(void)
	202	post_process_2pass (j_decompress_ptr cinfo,
	203	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	204	JDIMENSION in_row_groups_avail,
	205	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	206	JDIMENSION out_rows_avail)
	207	{
	208	my_post_ptr post = (my_post_ptr) cinfo->post;
	209	JDIMENSION num_rows, max_rows;
	210
	211	/* Reposition virtual buffer if at start of strip. */
	212	if (post->next_row == 0) {
	213	post->buffer = (*cinfo->mem->access_virt_sarray)
	214	((j_common_ptr) cinfo, post->whole_image,
	215	post->starting_row, post->strip_height, FALSE);
	216	}
	217
	218	/* Determine number of rows to emit. */
	219	num_rows = post->strip_height - post->next_row; /* available in strip */
	220	max_rows = out_rows_avail - out_row_ctr; / available in output area */
	221	if (num_rows > max_rows)
	222	num_rows = max_rows;
	223	/* We have to check bottom of image here, can't depend on upsampler. */
	224	max_rows = cinfo->output_height - post->starting_row;
	225	if (num_rows > max_rows)
	226	num_rows = max_rows;
	227
	228	/* Quantize and emit data. */
	229	(*cinfo->cquantize->color_quantize) (cinfo,
	230	post->buffer + post->next_row, output_buf + *out_row_ctr,
	231	(int) num_rows);
	232	*out_row_ctr += num_rows;
	233
	234	/* Advance if we filled the strip. */
	235	post->next_row += num_rows;
	236	if (post->next_row >= post->strip_height) {
	237	post->starting_row += post->strip_height;
	238	post->next_row = 0;
	239	}
	240	}
	241
	242	#endif /* QUANT_2PASS_SUPPORTED */
	243
	244
	245	/*
	246	* Initialize postprocessing controller.
	247	*/
	248
	249	GLOBAL(void)
	250	jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
	251	{
	252	my_post_ptr post;
	253
	254	post = (my_post_ptr)
	255	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	256	SIZEOF(my_post_controller));
	257	cinfo->post = (struct jpeg_d_post_controller *) post;
	258	post->pub.start_pass = start_pass_dpost;
	259	post->whole_image = NULL; /* flag for no virtual arrays */
	260	post->buffer = NULL; /* flag for no strip buffer */
	261
	262	/* Create the quantization buffer, if needed */
	263	if (cinfo->quantize_colors) {
	264	/* The buffer strip height is max_v_samp_factor, which is typically
	265	* an efficient number of rows for upsampling to return.
	266	* (In the presence of output rescaling, we might want to be smarter?)
	267	*/
	268	post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
	269	if (need_full_buffer) {
	270	/* Two-pass color quantization: need full-image storage. */
	271	/* We round up the number of rows to a multiple of the strip height. */
	272	#ifdef QUANT_2PASS_SUPPORTED
	273	post->whole_image = (*cinfo->mem->request_virt_sarray)
	274	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
	275	cinfo->output_width * cinfo->out_color_components,
	276	(JDIMENSION) jround_up((long) cinfo->output_height,
	277	(long) post->strip_height),
	278	post->strip_height);
	279	#else
	280	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	281	#endif /* QUANT_2PASS_SUPPORTED */
	282	} else {
	283	/* One-pass color quantization: just make a strip buffer. */
	284	post->buffer = (*cinfo->mem->alloc_sarray)
	285	((j_common_ptr) cinfo, JPOOL_IMAGE,
	286	cinfo->output_width * cinfo->out_color_components,
	287	post->strip_height);
	288	}
	289	}
	290	}