276 lines
9.4 KiB
C++
276 lines
9.4 KiB
C++
// * jdpostct.c
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// *
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// * Copyright (C) 1994-1995, Thomas G. Lane.
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// * This file is part of the Independent JPEG Group's software.
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// * For conditions of distribution and use, see the accompanying README file.
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// *
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// * This file contains the decompression postprocessing controller.
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// * This controller manages the upsampling, color conversion, and color
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// * quantization/reduction steps; specifically, it controls the buffering
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// * between upsample/color conversion and color quantization/reduction.
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// *
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// * If no color quantization/reduction is required, then this module has no
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// * work to do, and it just hands off to the upsample/color conversion code.
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// * An integrated upsample/convert/quantize process would replace this module
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// * entirely.
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#define JPEG_INTERNALS
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#include "JINCLUDE.h"
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#include "JPEGLIB.h"
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// Private buffer controller object
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typedef struct {
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struct jpeg_d_post_controller pub; // public fields
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// Color quantization source buffer: this holds output data from
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// * the upsample/color conversion step to be passed to the quantizer.
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// * For two-pass color quantization, we need a full-image buffer;
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// * for one-pass operation, a strip buffer is sufficient.
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jvirt_sarray_ptr whole_image; // virtual array, or NULL if one-pass
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JSAMPARRAY buffer; // strip buffer, or current strip of virtual
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JDIMENSION strip_height; // buffer size in rows
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// for two-pass mode only:
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JDIMENSION starting_row; // row # of first row in current strip
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JDIMENSION next_row; // index of next row to fill/empty in strip
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} my_post_controller;
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typedef my_post_controller * my_post_ptr;
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// Forward declarations
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METHODDEF void post_process_1pass
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JPP((j_decompress_ptr cinfo,
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
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JDIMENSION in_row_groups_avail,
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
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JDIMENSION out_rows_avail));
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#ifdef QUANT_2PASS_SUPPORTED
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METHODDEF void post_process_prepass
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JPP((j_decompress_ptr cinfo,
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
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JDIMENSION in_row_groups_avail,
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
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JDIMENSION out_rows_avail));
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METHODDEF void post_process_2pass
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JPP((j_decompress_ptr cinfo,
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
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JDIMENSION in_row_groups_avail,
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
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JDIMENSION out_rows_avail));
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#endif
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// * Initialize for a processing pass.
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METHODDEF void
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start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
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{
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my_post_ptr post = (my_post_ptr) cinfo->post;
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switch (pass_mode) {
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case JBUF_PASS_THRU:
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if (cinfo->quantize_colors) {
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// Single-pass processing with color quantization.
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post->pub.post_process_data = post_process_1pass;
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// We could be doing buffered-image output before starting a 2-pass
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// * color quantization; in that case, jinit_d_post_controller did not
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// * allocate a strip buffer. Use the virtual-array buffer as workspace.
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if (post->buffer == NULL) {
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post->buffer = (*cinfo->mem->access_virt_sarray)
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((j_common_ptr) cinfo, post->whole_image,
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(JDIMENSION) 0, post->strip_height, TRUE);
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}
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} else {
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// For single-pass processing without color quantization,
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// * I have no work to do; just call the upsampler directly.
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post->pub.post_process_data = cinfo->upsample->upsample;
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}
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break;
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#ifdef QUANT_2PASS_SUPPORTED
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case JBUF_SAVE_AND_PASS:
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// First pass of 2-pass quantization
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if (post->whole_image == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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post->pub.post_process_data = post_process_prepass;
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break;
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case JBUF_CRANK_DEST:
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// Second pass of 2-pass quantization
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if (post->whole_image == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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post->pub.post_process_data = post_process_2pass;
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break;
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#endif // QUANT_2PASS_SUPPORTED
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default:
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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break;
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}
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post->starting_row = post->next_row = 0;
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}
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// * Process some data in the one-pass (strip buffer) case.
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// * This is used for color precision reduction as well as one-pass quantization.
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METHODDEF void
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post_process_1pass (j_decompress_ptr cinfo,
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
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JDIMENSION in_row_groups_avail,
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
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JDIMENSION out_rows_avail)
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{
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my_post_ptr post = (my_post_ptr) cinfo->post;
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JDIMENSION num_rows, max_rows;
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// Fill the buffer, but not more than what we can dump out in one go.
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// Note we rely on the upsampler to detect bottom of image.
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max_rows = out_rows_avail - *out_row_ctr;
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if (max_rows > post->strip_height)
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max_rows = post->strip_height;
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num_rows = 0;
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(*cinfo->upsample->upsample) (cinfo,
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input_buf, in_row_group_ctr, in_row_groups_avail,
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post->buffer, &num_rows, max_rows);
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// Quantize and emit data.
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(*cinfo->cquantize->color_quantize) (cinfo,
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post->buffer, output_buf + *out_row_ctr, (int) num_rows);
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*out_row_ctr += num_rows;
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}
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#ifdef QUANT_2PASS_SUPPORTED
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// * Process some data in the first pass of 2-pass quantization.
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METHODDEF void
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post_process_prepass (j_decompress_ptr cinfo,
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
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JDIMENSION in_row_groups_avail,
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
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JDIMENSION out_rows_avail)
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{
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my_post_ptr post = (my_post_ptr) cinfo->post;
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JDIMENSION old_next_row, num_rows;
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// Reposition virtual buffer if at start of strip.
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if (post->next_row == 0) {
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post->buffer = (*cinfo->mem->access_virt_sarray)
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((j_common_ptr) cinfo, post->whole_image,
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post->starting_row, post->strip_height, TRUE);
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}
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// Upsample some data (up to a strip height's worth).
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old_next_row = post->next_row;
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(*cinfo->upsample->upsample) (cinfo,
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input_buf, in_row_group_ctr, in_row_groups_avail,
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post->buffer, &post->next_row, post->strip_height);
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// Allow quantizer to scan new data. No data is emitted,
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// but we advance out_row_ctr so outer loop can tell when we're done.
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if (post->next_row > old_next_row) {
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num_rows = post->next_row - old_next_row;
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(*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
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(JSAMPARRAY) NULL, (int) num_rows);
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*out_row_ctr += num_rows;
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}
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// Advance if we filled the strip.
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if (post->next_row >= post->strip_height) {
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post->starting_row += post->strip_height;
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post->next_row = 0;
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}
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}
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// * Process some data in the second pass of 2-pass quantization.
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METHODDEF void
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post_process_2pass (j_decompress_ptr cinfo,
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
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JDIMENSION in_row_groups_avail,
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
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JDIMENSION out_rows_avail)
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{
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my_post_ptr post = (my_post_ptr) cinfo->post;
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JDIMENSION num_rows, max_rows;
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// Reposition virtual buffer if at start of strip.
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if (post->next_row == 0) {
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post->buffer = (*cinfo->mem->access_virt_sarray)
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((j_common_ptr) cinfo, post->whole_image,
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post->starting_row, post->strip_height, FALSE);
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}
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// Determine number of rows to emit.
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num_rows = post->strip_height - post->next_row; // available in strip
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max_rows = out_rows_avail - *out_row_ctr; // available in output area
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if (num_rows > max_rows)
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num_rows = max_rows;
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// We have to check bottom of image here, can't depend on upsampler.
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max_rows = cinfo->output_height - post->starting_row;
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if (num_rows > max_rows)
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num_rows = max_rows;
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// Quantize and emit data.
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(*cinfo->cquantize->color_quantize) (cinfo,
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post->buffer + post->next_row, output_buf + *out_row_ctr,
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(int) num_rows);
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*out_row_ctr += num_rows;
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// Advance if we filled the strip.
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post->next_row += num_rows;
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if (post->next_row >= post->strip_height) {
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post->starting_row += post->strip_height;
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post->next_row = 0;
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}
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}
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#endif // QUANT_2PASS_SUPPORTED
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// * Initialize postprocessing controller.
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GLOBAL void
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jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
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{
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my_post_ptr post;
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post = (my_post_ptr)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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SIZEOF(my_post_controller));
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cinfo->post = (struct jpeg_d_post_controller *) post;
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post->pub.start_pass = start_pass_dpost;
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post->whole_image = NULL; // flag for no virtual arrays
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post->buffer = NULL; // flag for no strip buffer
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// Create the quantization buffer, if needed
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if (cinfo->quantize_colors) {
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// The buffer strip height is max_v_samp_factor, which is typically
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// * an efficient number of rows for upsampling to return.
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// * (In the presence of output rescaling, we might want to be smarter?)
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post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
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if (need_full_buffer) {
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// Two-pass color quantization: need full-image storage.
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// We round up the number of rows to a multiple of the strip height.
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#ifdef QUANT_2PASS_SUPPORTED
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post->whole_image = (*cinfo->mem->request_virt_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
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cinfo->output_width * cinfo->out_color_components,
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(JDIMENSION) jround_up((LONG) cinfo->output_height,
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(LONG) post->strip_height),
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post->strip_height);
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#else
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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#endif // QUANT_2PASS_SUPPORTED
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} else {
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// One-pass color quantization: just make a strip buffer.
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post->buffer = (*cinfo->mem->alloc_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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cinfo->output_width * cinfo->out_color_components,
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post->strip_height);
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}
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}
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}
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