ref: f75b4fddb3bc6d242f65ac478b53bb62c75c9760
dir: /sys/src/cmd/gs/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); } } }