www.pudn.com > imgport.rar > jcmainct.c, change:2008-11-05,size:9557b


/* 
 * jcmainct.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 main buffer controller for compression. 
 * The main buffer lies between the pre-processor and the JPEG 
 * compressor proper; it holds downsampled data in the JPEG colorspace. 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
 
 
/* Note: currently, there is no operating mode in which a full-image buffer 
 * is needed at this step.  If there were, that mode could not be used with 
 * "raw data" input, since this module is bypassed in that case.  However, 
 * we've left the code here for possible use in special applications. 
 */ 
#undef FULL_MAIN_BUFFER_SUPPORTED 
 
 
/* Private buffer controller object */ 
 
typedef struct { 
  struct jpeg_c_main_controller pub; /* public fields */ 
 
  JDIMENSION cur_iMCU_row;	/* number of current iMCU row */ 
  JDIMENSION rowgroup_ctr;	/* counts row groups received in iMCU row */ 
  boolean suspended;		/* remember if we suspended output */ 
  J_BUF_MODE pass_mode;		/* current operating mode */ 
 
  /* If using just a strip buffer, this points to the entire set of buffers 
   * (we allocate one for each component).  In the full-image case, this 
   * points to the currently accessible strips of the virtual arrays. 
   */ 
  JSAMPARRAY buffer[MAX_COMPONENTS]; 
 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
  /* If using full-image storage, this array holds pointers to virtual-array 
   * control blocks for each component.  Unused if not full-image storage. 
   */ 
  jvirt_sarray_ptr whole_image[MAX_COMPONENTS]; 
#endif 
} my_main_controller; 
 
typedef my_main_controller * my_main_ptr; 
 
 
/* Forward declarations */ 
METHODDEF(void) process_data_simple_main 
	JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf, 
	     JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail)); 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
METHODDEF(void) process_data_buffer_main 
	JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf, 
	     JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail)); 
#endif 
 
 
/* 
 * Initialize for a processing pass. 
 */ 
 
METHODDEF(void) 
start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode) 
{ 
  my_main_ptr mymain = (my_main_ptr) cinfo->main; 
 
  /* Do nothing in raw-data mode. */ 
  if (cinfo->raw_data_in) 
    return; 
 
  mymain->cur_iMCU_row = 0;	/* initialize counters */ 
  mymain->rowgroup_ctr = 0; 
  mymain->suspended = FALSE; 
  mymain->pass_mode = pass_mode;	/* save mode for use by process_data */ 
 
  switch (pass_mode) { 
  case JBUF_PASS_THRU: 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
    if (mymain->whole_image[0] != NULL) 
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
#endif 
    mymain->pub.process_data = process_data_simple_main; 
    break; 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
  case JBUF_SAVE_SOURCE: 
  case JBUF_CRANK_DEST: 
  case JBUF_SAVE_AND_PASS: 
    if (mymain->whole_image[0] == NULL) 
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
    mymain->pub.process_data = process_data_buffer_main; 
    break; 
#endif 
  default: 
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
    break; 
  } 
} 
 
 
/* 
 * Process some data. 
 * This routine handles the simple pass-through mode, 
 * where we have only a strip buffer. 
 */ 
 
METHODDEF(void) 
process_data_simple_main (j_compress_ptr cinfo, 
			  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, 
			  JDIMENSION in_rows_avail) 
{ 
  my_main_ptr mymain = (my_main_ptr) cinfo->main; 
 
  while (mymain->cur_iMCU_row < cinfo->total_iMCU_rows) { 
    /* Read input data if we haven't filled the main buffer yet */ 
    if (mymain->rowgroup_ctr < DCTSIZE) 
      (*cinfo->prep->pre_process_data) (cinfo, 
					input_buf, in_row_ctr, in_rows_avail, 
					mymain->buffer, &mymain->rowgroup_ctr, 
					(JDIMENSION) DCTSIZE); 
 
    /* If we don't have a full iMCU row buffered, return to application for 
     * more data.  Note that preprocessor will always pad to fill the iMCU row 
     * at the bottom of the image. 
     */ 
    if (mymain->rowgroup_ctr != DCTSIZE) 
      return; 
 
    /* Send the completed row to the compressor */ 
    if (! (*cinfo->coef->compress_data) (cinfo, mymain->buffer)) { 
      /* If compressor did not consume the whole row, then we must need to 
       * suspend processing and return to the application.  In this situation 
       * we pretend we didn't yet consume the last input row; otherwise, if 
       * it happened to be the last row of the image, the application would 
       * think we were done. 
       */ 
      if (! mymain->suspended) { 
	(*in_row_ctr)--; 
	mymain->suspended = TRUE; 
      } 
      return; 
    } 
    /* We did finish the row.  Undo our little suspension hack if a previous 
     * call suspended; then mark the main buffer empty. 
     */ 
    if (mymain->suspended) { 
      (*in_row_ctr)++; 
      mymain->suspended = FALSE; 
    } 
    mymain->rowgroup_ctr = 0; 
    mymain->cur_iMCU_row++; 
  } 
} 
 
 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
 
/* 
 * Process some data. 
 * This routine handles all of the modes that use a full-size buffer. 
 */ 
 
METHODDEF(void) 
process_data_buffer_main (j_compress_ptr cinfo, 
			  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, 
			  JDIMENSION in_rows_avail) 
{ 
  my_main_ptr mymain = (my_main_ptr) cinfo->main; 
  int ci; 
  jpeg_component_info *compptr; 
  boolean writing = (mymain->pass_mode != JBUF_CRANK_DEST); 
 
  while (mymain->cur_iMCU_row < cinfo->total_iMCU_rows) { 
    /* Realign the virtual buffers if at the start of an iMCU row. */ 
    if (mymain->rowgroup_ctr == 0) { 
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
	   ci++, compptr++) { 
	mymain->buffer[ci] = (*cinfo->mem->access_virt_sarray) 
	  ((j_common_ptr) cinfo, mymain->whole_image[ci], 
	   mymain->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE), 
	   (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing); 
      } 
      /* In a read pass, pretend we just read some source data. */ 
      if (! writing) { 
	*in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE; 
	mymain->rowgroup_ctr = DCTSIZE; 
      } 
    } 
 
    /* If a write pass, read input data until the current iMCU row is full. */ 
    /* Note: preprocessor will pad if necessary to fill the last iMCU row. */ 
    if (writing) { 
      (*cinfo->prep->pre_process_data) (cinfo, 
					input_buf, in_row_ctr, in_rows_avail, 
					mymain->buffer, &mymain->rowgroup_ctr, 
					(JDIMENSION) DCTSIZE); 
      /* Return to application if we need more data to fill the iMCU row. */ 
      if (mymain->rowgroup_ctr < DCTSIZE) 
	return; 
    } 
 
    /* Emit data, unless this is a sink-only pass. */ 
    if (mymain->pass_mode != JBUF_SAVE_SOURCE) { 
      if (! (*cinfo->coef->compress_data) (cinfo, mymain->buffer)) { 
	/* If compressor did not consume the whole row, then we must need to 
	 * suspend processing and return to the application.  In this situation 
	 * we pretend we didn't yet consume the last input row; otherwise, if 
	 * it happened to be the last row of the image, the application would 
	 * think we were done. 
	 */ 
	if (! mymain->suspended) { 
	  (*in_row_ctr)--; 
	  mymain->suspended = TRUE; 
	} 
	return; 
      } 
      /* We did finish the row.  Undo our little suspension hack if a previous 
       * call suspended; then mark the main buffer empty. 
       */ 
      if (mymain->suspended) { 
	(*in_row_ctr)++; 
	mymain->suspended = FALSE; 
      } 
    } 
 
    /* If get here, we are done with this iMCU row.  Mark buffer empty. */ 
    mymain->rowgroup_ctr = 0; 
    mymain->cur_iMCU_row++; 
  } 
} 
 
#endif /* FULL_MAIN_BUFFER_SUPPORTED */ 
 
 
/* 
 * Initialize main buffer controller. 
 */ 
 
GLOBAL(void) 
jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer) 
{ 
  my_main_ptr mymain; 
  int ci; 
  jpeg_component_info *compptr; 
 
  mymain = (my_main_ptr) 
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 
				SIZEOF(my_main_controller)); 
  cinfo->main = (struct jpeg_c_main_controller *) mymain; 
  mymain->pub.start_pass = start_pass_main; 
 
  /* We don't need to create a buffer in raw-data mode. */ 
  if (cinfo->raw_data_in) 
    return; 
 
  /* Create the buffer.  It holds downsampled data, so each component 
   * may be of a different size. 
   */ 
  if (need_full_buffer) { 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
    /* Allocate a full-image virtual array for each component */ 
    /* Note we pad the bottom to a multiple of the iMCU height */ 
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
	 ci++, compptr++) { 
      mymain->whole_image[ci] = (*cinfo->mem->request_virt_sarray) 
	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE, 
	 compptr->width_in_blocks * DCTSIZE, 
	 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 
				(long) compptr->v_samp_factor) * DCTSIZE, 
	 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE)); 
    } 
#else 
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
#endif 
  } else { 
#ifdef FULL_MAIN_BUFFER_SUPPORTED 
    mymain->whole_image[0] = NULL; /* flag for no virtual arrays */ 
#endif 
    /* Allocate a strip buffer for each component */ 
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
	 ci++, compptr++) { 
      mymain->buffer[ci] = (*cinfo->mem->alloc_sarray) 
	((j_common_ptr) cinfo, JPOOL_IMAGE, 
	 compptr->width_in_blocks * DCTSIZE, 
	 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE)); 
    } 
  } 
}