#if !defined(_FX_JPEG_TURBO_) | |
/* | |
* jcprepct.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 compression preprocessing controller. | |
* This controller manages the color conversion, downsampling, | |
* and edge expansion steps. | |
* | |
* Most of the complexity here is associated with buffering input rows | |
* as required by the downsampler. See the comments at the head of | |
* jcsample.c for the downsampler's needs. | |
*/ | |
#define JPEG_INTERNALS | |
#include "jinclude.h" | |
#include "jpeglib.h" | |
/* At present, jcsample.c can request context rows only for smoothing. | |
* In the future, we might also need context rows for CCIR601 sampling | |
* or other more-complex downsampling procedures. The code to support | |
* context rows should be compiled only if needed. | |
*/ | |
#ifdef INPUT_SMOOTHING_SUPPORTED | |
#define CONTEXT_ROWS_SUPPORTED | |
#endif | |
/* | |
* For the simple (no-context-row) case, we just need to buffer one | |
* row group's worth of pixels for the downsampling step. At the bottom of | |
* the image, we pad to a full row group by replicating the last pixel row. | |
* The downsampler's last output row is then replicated if needed to pad | |
* out to a full iMCU row. | |
* | |
* When providing context rows, we must buffer three row groups' worth of | |
* pixels. Three row groups are physically allocated, but the row pointer | |
* arrays are made five row groups high, with the extra pointers above and | |
* below "wrapping around" to point to the last and first real row groups. | |
* This allows the downsampler to access the proper context rows. | |
* At the top and bottom of the image, we create dummy context rows by | |
* copying the first or last real pixel row. This copying could be avoided | |
* by pointer hacking as is done in jdmainct.c, but it doesn't seem worth the | |
* trouble on the compression side. | |
*/ | |
/* Private buffer controller object */ | |
typedef struct { | |
struct jpeg_c_prep_controller pub; /* public fields */ | |
/* Downsampling input buffer. This buffer holds color-converted data | |
* until we have enough to do a downsample step. | |
*/ | |
JSAMPARRAY color_buf[MAX_COMPONENTS]; | |
JDIMENSION rows_to_go; /* counts rows remaining in source image */ | |
int next_buf_row; /* index of next row to store in color_buf */ | |
#ifdef CONTEXT_ROWS_SUPPORTED /* only needed for context case */ | |
int this_row_group; /* starting row index of group to process */ | |
int next_buf_stop; /* downsample when we reach this index */ | |
#endif | |
} my_prep_controller; | |
typedef my_prep_controller * my_prep_ptr; | |
/* | |
* Initialize for a processing pass. | |
*/ | |
METHODDEF(void) | |
start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode) | |
{ | |
my_prep_ptr prep = (my_prep_ptr) cinfo->prep; | |
if (pass_mode != JBUF_PASS_THRU) | |
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); | |
/* Initialize total-height counter for detecting bottom of image */ | |
prep->rows_to_go = cinfo->image_height; | |
/* Mark the conversion buffer empty */ | |
prep->next_buf_row = 0; | |
#ifdef CONTEXT_ROWS_SUPPORTED | |
/* Preset additional state variables for context mode. | |
* These aren't used in non-context mode, so we needn't test which mode. | |
*/ | |
prep->this_row_group = 0; | |
/* Set next_buf_stop to stop after two row groups have been read in. */ | |
prep->next_buf_stop = 2 * cinfo->max_v_samp_factor; | |
#endif | |
} | |
/* | |
* Expand an image vertically from height input_rows to height output_rows, | |
* by duplicating the bottom row. | |
*/ | |
LOCAL(void) | |
expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols, | |
int input_rows, int output_rows) | |
{ | |
register int row; | |
for (row = input_rows; row < output_rows; row++) { | |
jcopy_sample_rows(image_data, input_rows-1, image_data, row, | |
1, num_cols); | |
} | |
} | |
/* | |
* Process some data in the simple no-context case. | |
* | |
* Preprocessor output data is counted in "row groups". A row group | |
* is defined to be v_samp_factor sample rows of each component. | |
* Downsampling will produce this much data from each max_v_samp_factor | |
* input rows. | |
*/ | |
METHODDEF(void) | |
pre_process_data (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, | |
JDIMENSION in_rows_avail, | |
JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr, | |
JDIMENSION out_row_groups_avail) | |
{ | |
my_prep_ptr prep = (my_prep_ptr) cinfo->prep; | |
int numrows, ci; | |
JDIMENSION inrows; | |
jpeg_component_info * compptr; | |
while (*in_row_ctr < in_rows_avail && | |
*out_row_group_ctr < out_row_groups_avail) { | |
/* Do color conversion to fill the conversion buffer. */ | |
inrows = in_rows_avail - *in_row_ctr; | |
numrows = cinfo->max_v_samp_factor - prep->next_buf_row; | |
numrows = (int) MIN((JDIMENSION) numrows, inrows); | |
(*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr, | |
prep->color_buf, | |
(JDIMENSION) prep->next_buf_row, | |
numrows); | |
*in_row_ctr += numrows; | |
prep->next_buf_row += numrows; | |
prep->rows_to_go -= numrows; | |
/* If at bottom of image, pad to fill the conversion buffer. */ | |
if (prep->rows_to_go == 0 && | |
prep->next_buf_row < cinfo->max_v_samp_factor) { | |
for (ci = 0; ci < cinfo->num_components; ci++) { | |
expand_bottom_edge(prep->color_buf[ci], cinfo->image_width, | |
prep->next_buf_row, cinfo->max_v_samp_factor); | |
} | |
prep->next_buf_row = cinfo->max_v_samp_factor; | |
} | |
/* If we've filled the conversion buffer, empty it. */ | |
if (prep->next_buf_row == cinfo->max_v_samp_factor) { | |
(*cinfo->downsample->downsample) (cinfo, | |
prep->color_buf, (JDIMENSION) 0, | |
output_buf, *out_row_group_ctr); | |
prep->next_buf_row = 0; | |
(*out_row_group_ctr)++; | |
} | |
/* If at bottom of image, pad the output to a full iMCU height. | |
* Note we assume the caller is providing a one-iMCU-height output buffer! | |
*/ | |
if (prep->rows_to_go == 0 && | |
*out_row_group_ctr < out_row_groups_avail) { | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
expand_bottom_edge(output_buf[ci], | |
compptr->width_in_blocks * DCTSIZE, | |
(int) (*out_row_group_ctr * compptr->v_samp_factor), | |
(int) (out_row_groups_avail * compptr->v_samp_factor)); | |
} | |
*out_row_group_ctr = out_row_groups_avail; | |
break; /* can exit outer loop without test */ | |
} | |
} | |
} | |
#ifdef CONTEXT_ROWS_SUPPORTED | |
/* | |
* Process some data in the context case. | |
*/ | |
METHODDEF(void) | |
pre_process_context (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, | |
JDIMENSION in_rows_avail, | |
JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr, | |
JDIMENSION out_row_groups_avail) | |
{ | |
my_prep_ptr prep = (my_prep_ptr) cinfo->prep; | |
int numrows, ci; | |
int buf_height = cinfo->max_v_samp_factor * 3; | |
JDIMENSION inrows; | |
while (*out_row_group_ctr < out_row_groups_avail) { | |
if (*in_row_ctr < in_rows_avail) { | |
/* Do color conversion to fill the conversion buffer. */ | |
inrows = in_rows_avail - *in_row_ctr; | |
numrows = prep->next_buf_stop - prep->next_buf_row; | |
numrows = (int) MIN((JDIMENSION) numrows, inrows); | |
(*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr, | |
prep->color_buf, | |
(JDIMENSION) prep->next_buf_row, | |
numrows); | |
/* Pad at top of image, if first time through */ | |
if (prep->rows_to_go == cinfo->image_height) { | |
for (ci = 0; ci < cinfo->num_components; ci++) { | |
int row; | |
for (row = 1; row <= cinfo->max_v_samp_factor; row++) { | |
jcopy_sample_rows(prep->color_buf[ci], 0, | |
prep->color_buf[ci], -row, | |
1, cinfo->image_width); | |
} | |
} | |
} | |
*in_row_ctr += numrows; | |
prep->next_buf_row += numrows; | |
prep->rows_to_go -= numrows; | |
} else { | |
/* Return for more data, unless we are at the bottom of the image. */ | |
if (prep->rows_to_go != 0) | |
break; | |
/* When at bottom of image, pad to fill the conversion buffer. */ | |
if (prep->next_buf_row < prep->next_buf_stop) { | |
for (ci = 0; ci < cinfo->num_components; ci++) { | |
expand_bottom_edge(prep->color_buf[ci], cinfo->image_width, | |
prep->next_buf_row, prep->next_buf_stop); | |
} | |
prep->next_buf_row = prep->next_buf_stop; | |
} | |
} | |
/* If we've gotten enough data, downsample a row group. */ | |
if (prep->next_buf_row == prep->next_buf_stop) { | |
(*cinfo->downsample->downsample) (cinfo, | |
prep->color_buf, | |
(JDIMENSION) prep->this_row_group, | |
output_buf, *out_row_group_ctr); | |
(*out_row_group_ctr)++; | |
/* Advance pointers with wraparound as necessary. */ | |
prep->this_row_group += cinfo->max_v_samp_factor; | |
if (prep->this_row_group >= buf_height) | |
prep->this_row_group = 0; | |
if (prep->next_buf_row >= buf_height) | |
prep->next_buf_row = 0; | |
prep->next_buf_stop = prep->next_buf_row + cinfo->max_v_samp_factor; | |
} | |
} | |
} | |
/* | |
* Create the wrapped-around downsampling input buffer needed for context mode. | |
*/ | |
LOCAL(void) | |
create_context_buffer (j_compress_ptr cinfo) | |
{ | |
my_prep_ptr prep = (my_prep_ptr) cinfo->prep; | |
int rgroup_height = cinfo->max_v_samp_factor; | |
int ci, i; | |
jpeg_component_info * compptr; | |
JSAMPARRAY true_buffer, fake_buffer; | |
/* Grab enough space for fake row pointers for all the components; | |
* we need five row groups' worth of pointers for each component. | |
*/ | |
fake_buffer = (JSAMPARRAY) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
(cinfo->num_components * 5 * rgroup_height) * | |
SIZEOF(JSAMPROW)); | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
/* Allocate the actual buffer space (3 row groups) for this component. | |
* We make the buffer wide enough to allow the downsampler to edge-expand | |
* horizontally within the buffer, if it so chooses. | |
*/ | |
true_buffer = (*cinfo->mem->alloc_sarray) | |
((j_common_ptr) cinfo, JPOOL_IMAGE, | |
(JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE * | |
cinfo->max_h_samp_factor) / compptr->h_samp_factor), | |
(JDIMENSION) (3 * rgroup_height)); | |
/* Copy true buffer row pointers into the middle of the fake row array */ | |
MEMCOPY(fake_buffer + rgroup_height, true_buffer, | |
3 * rgroup_height * SIZEOF(JSAMPROW)); | |
/* Fill in the above and below wraparound pointers */ | |
for (i = 0; i < rgroup_height; i++) { | |
fake_buffer[i] = true_buffer[2 * rgroup_height + i]; | |
fake_buffer[4 * rgroup_height + i] = true_buffer[i]; | |
} | |
prep->color_buf[ci] = fake_buffer + rgroup_height; | |
fake_buffer += 5 * rgroup_height; /* point to space for next component */ | |
} | |
} | |
#endif /* CONTEXT_ROWS_SUPPORTED */ | |
/* | |
* Initialize preprocessing controller. | |
*/ | |
GLOBAL(void) | |
jinit_c_prep_controller (j_compress_ptr cinfo, boolean need_full_buffer) | |
{ | |
my_prep_ptr prep; | |
int ci; | |
jpeg_component_info * compptr; | |
if (need_full_buffer) /* safety check */ | |
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); | |
prep = (my_prep_ptr) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
SIZEOF(my_prep_controller)); | |
cinfo->prep = (struct jpeg_c_prep_controller *) prep; | |
prep->pub.start_pass = start_pass_prep; | |
/* Allocate the color conversion buffer. | |
* We make the buffer wide enough to allow the downsampler to edge-expand | |
* horizontally within the buffer, if it so chooses. | |
*/ | |
if (cinfo->downsample->need_context_rows) { | |
/* Set up to provide context rows */ | |
#ifdef CONTEXT_ROWS_SUPPORTED | |
prep->pub.pre_process_data = pre_process_context; | |
create_context_buffer(cinfo); | |
#else | |
ERREXIT(cinfo, JERR_NOT_COMPILED); | |
#endif | |
} else { | |
/* No context, just make it tall enough for one row group */ | |
prep->pub.pre_process_data = pre_process_data; | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
prep->color_buf[ci] = (*cinfo->mem->alloc_sarray) | |
((j_common_ptr) cinfo, JPOOL_IMAGE, | |
(JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE * | |
cinfo->max_h_samp_factor) / compptr->h_samp_factor), | |
(JDIMENSION) cinfo->max_v_samp_factor); | |
} | |
} | |
} | |
#endif //_FX_JPEG_TURBO_ |