/* * 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_SUPPORTEDMETHODDEF(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);    }  }}