/*+
−
 * 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);+
−
    }+
−
  }+
−
}+
−