michael@0: /*
michael@0:  * jdpostct.c
michael@0:  *
michael@0:  * Copyright (C) 1994-1996, Thomas G. Lane.
michael@0:  * This file is part of the Independent JPEG Group's software.
michael@0:  * For conditions of distribution and use, see the accompanying README file.
michael@0:  *
michael@0:  * This file contains the decompression postprocessing controller.
michael@0:  * This controller manages the upsampling, color conversion, and color
michael@0:  * quantization/reduction steps; specifically, it controls the buffering
michael@0:  * between upsample/color conversion and color quantization/reduction.
michael@0:  *
michael@0:  * If no color quantization/reduction is required, then this module has no
michael@0:  * work to do, and it just hands off to the upsample/color conversion code.
michael@0:  * An integrated upsample/convert/quantize process would replace this module
michael@0:  * entirely.
michael@0:  */
michael@0: 
michael@0: #define JPEG_INTERNALS
michael@0: #include "jinclude.h"
michael@0: #include "jpeglib.h"
michael@0: 
michael@0: 
michael@0: /* Private buffer controller object */
michael@0: 
michael@0: typedef struct {
michael@0:   struct jpeg_d_post_controller pub; /* public fields */
michael@0: 
michael@0:   /* Color quantization source buffer: this holds output data from
michael@0:    * the upsample/color conversion step to be passed to the quantizer.
michael@0:    * For two-pass color quantization, we need a full-image buffer;
michael@0:    * for one-pass operation, a strip buffer is sufficient.
michael@0:    */
michael@0:   jvirt_sarray_ptr whole_image;	/* virtual array, or NULL if one-pass */
michael@0:   JSAMPARRAY buffer;		/* strip buffer, or current strip of virtual */
michael@0:   JDIMENSION strip_height;	/* buffer size in rows */
michael@0:   /* for two-pass mode only: */
michael@0:   JDIMENSION starting_row;	/* row # of first row in current strip */
michael@0:   JDIMENSION next_row;		/* index of next row to fill/empty in strip */
michael@0: } my_post_controller;
michael@0: 
michael@0: typedef my_post_controller * my_post_ptr;
michael@0: 
michael@0: 
michael@0: /* Forward declarations */
michael@0: METHODDEF(void) post_process_1pass
michael@0: 	JPP((j_decompress_ptr cinfo,
michael@0: 	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
michael@0: 	     JDIMENSION in_row_groups_avail,
michael@0: 	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
michael@0: 	     JDIMENSION out_rows_avail));
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0: METHODDEF(void) post_process_prepass
michael@0: 	JPP((j_decompress_ptr cinfo,
michael@0: 	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
michael@0: 	     JDIMENSION in_row_groups_avail,
michael@0: 	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
michael@0: 	     JDIMENSION out_rows_avail));
michael@0: METHODDEF(void) post_process_2pass
michael@0: 	JPP((j_decompress_ptr cinfo,
michael@0: 	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
michael@0: 	     JDIMENSION in_row_groups_avail,
michael@0: 	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
michael@0: 	     JDIMENSION out_rows_avail));
michael@0: #endif
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Initialize for a processing pass.
michael@0:  */
michael@0: 
michael@0: METHODDEF(void)
michael@0: start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
michael@0: {
michael@0:   my_post_ptr post = (my_post_ptr) cinfo->post;
michael@0: 
michael@0:   switch (pass_mode) {
michael@0:   case JBUF_PASS_THRU:
michael@0:     if (cinfo->quantize_colors) {
michael@0:       /* Single-pass processing with color quantization. */
michael@0:       post->pub.post_process_data = post_process_1pass;
michael@0:       /* We could be doing buffered-image output before starting a 2-pass
michael@0:        * color quantization; in that case, jinit_d_post_controller did not
michael@0:        * allocate a strip buffer.  Use the virtual-array buffer as workspace.
michael@0:        */
michael@0:       if (post->buffer == NULL) {
michael@0: 	post->buffer = (*cinfo->mem->access_virt_sarray)
michael@0: 	  ((j_common_ptr) cinfo, post->whole_image,
michael@0: 	   (JDIMENSION) 0, post->strip_height, TRUE);
michael@0:       }
michael@0:     } else {
michael@0:       /* For single-pass processing without color quantization,
michael@0:        * I have no work to do; just call the upsampler directly.
michael@0:        */
michael@0:       post->pub.post_process_data = cinfo->upsample->upsample;
michael@0:     }
michael@0:     break;
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0:   case JBUF_SAVE_AND_PASS:
michael@0:     /* First pass of 2-pass quantization */
michael@0:     if (post->whole_image == NULL)
michael@0:       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
michael@0:     post->pub.post_process_data = post_process_prepass;
michael@0:     break;
michael@0:   case JBUF_CRANK_DEST:
michael@0:     /* Second pass of 2-pass quantization */
michael@0:     if (post->whole_image == NULL)
michael@0:       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
michael@0:     post->pub.post_process_data = post_process_2pass;
michael@0:     break;
michael@0: #endif /* QUANT_2PASS_SUPPORTED */
michael@0:   default:
michael@0:     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
michael@0:     break;
michael@0:   }
michael@0:   post->starting_row = post->next_row = 0;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Process some data in the one-pass (strip buffer) case.
michael@0:  * This is used for color precision reduction as well as one-pass quantization.
michael@0:  */
michael@0: 
michael@0: METHODDEF(void)
michael@0: post_process_1pass (j_decompress_ptr cinfo,
michael@0: 		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
michael@0: 		    JDIMENSION in_row_groups_avail,
michael@0: 		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
michael@0: 		    JDIMENSION out_rows_avail)
michael@0: {
michael@0:   my_post_ptr post = (my_post_ptr) cinfo->post;
michael@0:   JDIMENSION num_rows, max_rows;
michael@0: 
michael@0:   /* Fill the buffer, but not more than what we can dump out in one go. */
michael@0:   /* Note we rely on the upsampler to detect bottom of image. */
michael@0:   max_rows = out_rows_avail - *out_row_ctr;
michael@0:   if (max_rows > post->strip_height)
michael@0:     max_rows = post->strip_height;
michael@0:   num_rows = 0;
michael@0:   (*cinfo->upsample->upsample) (cinfo,
michael@0: 		input_buf, in_row_group_ctr, in_row_groups_avail,
michael@0: 		post->buffer, &num_rows, max_rows);
michael@0:   /* Quantize and emit data. */
michael@0:   (*cinfo->cquantize->color_quantize) (cinfo,
michael@0: 		post->buffer, output_buf + *out_row_ctr, (int) num_rows);
michael@0:   *out_row_ctr += num_rows;
michael@0: }
michael@0: 
michael@0: 
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0: 
michael@0: /*
michael@0:  * Process some data in the first pass of 2-pass quantization.
michael@0:  */
michael@0: 
michael@0: METHODDEF(void)
michael@0: post_process_prepass (j_decompress_ptr cinfo,
michael@0: 		      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
michael@0: 		      JDIMENSION in_row_groups_avail,
michael@0: 		      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
michael@0: 		      JDIMENSION out_rows_avail)
michael@0: {
michael@0:   my_post_ptr post = (my_post_ptr) cinfo->post;
michael@0:   JDIMENSION old_next_row, num_rows;
michael@0: 
michael@0:   /* Reposition virtual buffer if at start of strip. */
michael@0:   if (post->next_row == 0) {
michael@0:     post->buffer = (*cinfo->mem->access_virt_sarray)
michael@0: 	((j_common_ptr) cinfo, post->whole_image,
michael@0: 	 post->starting_row, post->strip_height, TRUE);
michael@0:   }
michael@0: 
michael@0:   /* Upsample some data (up to a strip height's worth). */
michael@0:   old_next_row = post->next_row;
michael@0:   (*cinfo->upsample->upsample) (cinfo,
michael@0: 		input_buf, in_row_group_ctr, in_row_groups_avail,
michael@0: 		post->buffer, &post->next_row, post->strip_height);
michael@0: 
michael@0:   /* Allow quantizer to scan new data.  No data is emitted, */
michael@0:   /* but we advance out_row_ctr so outer loop can tell when we're done. */
michael@0:   if (post->next_row > old_next_row) {
michael@0:     num_rows = post->next_row - old_next_row;
michael@0:     (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
michael@0: 					 (JSAMPARRAY) NULL, (int) num_rows);
michael@0:     *out_row_ctr += num_rows;
michael@0:   }
michael@0: 
michael@0:   /* Advance if we filled the strip. */
michael@0:   if (post->next_row >= post->strip_height) {
michael@0:     post->starting_row += post->strip_height;
michael@0:     post->next_row = 0;
michael@0:   }
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Process some data in the second pass of 2-pass quantization.
michael@0:  */
michael@0: 
michael@0: METHODDEF(void)
michael@0: post_process_2pass (j_decompress_ptr cinfo,
michael@0: 		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
michael@0: 		    JDIMENSION in_row_groups_avail,
michael@0: 		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
michael@0: 		    JDIMENSION out_rows_avail)
michael@0: {
michael@0:   my_post_ptr post = (my_post_ptr) cinfo->post;
michael@0:   JDIMENSION num_rows, max_rows;
michael@0: 
michael@0:   /* Reposition virtual buffer if at start of strip. */
michael@0:   if (post->next_row == 0) {
michael@0:     post->buffer = (*cinfo->mem->access_virt_sarray)
michael@0: 	((j_common_ptr) cinfo, post->whole_image,
michael@0: 	 post->starting_row, post->strip_height, FALSE);
michael@0:   }
michael@0: 
michael@0:   /* Determine number of rows to emit. */
michael@0:   num_rows = post->strip_height - post->next_row; /* available in strip */
michael@0:   max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
michael@0:   if (num_rows > max_rows)
michael@0:     num_rows = max_rows;
michael@0:   /* We have to check bottom of image here, can't depend on upsampler. */
michael@0:   max_rows = cinfo->output_height - post->starting_row;
michael@0:   if (num_rows > max_rows)
michael@0:     num_rows = max_rows;
michael@0: 
michael@0:   /* Quantize and emit data. */
michael@0:   (*cinfo->cquantize->color_quantize) (cinfo,
michael@0: 		post->buffer + post->next_row, output_buf + *out_row_ctr,
michael@0: 		(int) num_rows);
michael@0:   *out_row_ctr += num_rows;
michael@0: 
michael@0:   /* Advance if we filled the strip. */
michael@0:   post->next_row += num_rows;
michael@0:   if (post->next_row >= post->strip_height) {
michael@0:     post->starting_row += post->strip_height;
michael@0:     post->next_row = 0;
michael@0:   }
michael@0: }
michael@0: 
michael@0: #endif /* QUANT_2PASS_SUPPORTED */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Initialize postprocessing controller.
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
michael@0: {
michael@0:   my_post_ptr post;
michael@0: 
michael@0:   post = (my_post_ptr)
michael@0:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
michael@0: 				SIZEOF(my_post_controller));
michael@0:   cinfo->post = (struct jpeg_d_post_controller *) post;
michael@0:   post->pub.start_pass = start_pass_dpost;
michael@0:   post->whole_image = NULL;	/* flag for no virtual arrays */
michael@0:   post->buffer = NULL;		/* flag for no strip buffer */
michael@0: 
michael@0:   /* Create the quantization buffer, if needed */
michael@0:   if (cinfo->quantize_colors) {
michael@0:     /* The buffer strip height is max_v_samp_factor, which is typically
michael@0:      * an efficient number of rows for upsampling to return.
michael@0:      * (In the presence of output rescaling, we might want to be smarter?)
michael@0:      */
michael@0:     post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
michael@0:     if (need_full_buffer) {
michael@0:       /* Two-pass color quantization: need full-image storage. */
michael@0:       /* We round up the number of rows to a multiple of the strip height. */
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0:       post->whole_image = (*cinfo->mem->request_virt_sarray)
michael@0: 	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
michael@0: 	 cinfo->output_width * cinfo->out_color_components,
michael@0: 	 (JDIMENSION) jround_up((long) cinfo->output_height,
michael@0: 				(long) post->strip_height),
michael@0: 	 post->strip_height);
michael@0: #else
michael@0:       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
michael@0: #endif /* QUANT_2PASS_SUPPORTED */
michael@0:     } else {
michael@0:       /* One-pass color quantization: just make a strip buffer. */
michael@0:       post->buffer = (*cinfo->mem->alloc_sarray)
michael@0: 	((j_common_ptr) cinfo, JPOOL_IMAGE,
michael@0: 	 cinfo->output_width * cinfo->out_color_components,
michael@0: 	 post->strip_height);
michael@0:     }
michael@0:   }
michael@0: }