michael@0: /*
michael@0:  * jcapistd.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 application interface code for the compression half
michael@0:  * of the JPEG library.  These are the "standard" API routines that are
michael@0:  * used in the normal full-compression case.  They are not used by a
michael@0:  * transcoding-only application.  Note that if an application links in
michael@0:  * jpeg_start_compress, it will end up linking in the entire compressor.
michael@0:  * We thus must separate this file from jcapimin.c to avoid linking the
michael@0:  * whole compression library into a transcoder.
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: /*
michael@0:  * Compression initialization.
michael@0:  * Before calling this, all parameters and a data destination must be set up.
michael@0:  *
michael@0:  * We require a write_all_tables parameter as a failsafe check when writing
michael@0:  * multiple datastreams from the same compression object.  Since prior runs
michael@0:  * will have left all the tables marked sent_table=TRUE, a subsequent run
michael@0:  * would emit an abbreviated stream (no tables) by default.  This may be what
michael@0:  * is wanted, but for safety's sake it should not be the default behavior:
michael@0:  * programmers should have to make a deliberate choice to emit abbreviated
michael@0:  * images.  Therefore the documentation and examples should encourage people
michael@0:  * to pass write_all_tables=TRUE; then it will take active thought to do the
michael@0:  * wrong thing.
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
michael@0: {
michael@0:   if (cinfo->global_state != CSTATE_START)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0: 
michael@0:   if (write_all_tables)
michael@0:     jpeg_suppress_tables(cinfo, FALSE);	/* mark all tables to be written */
michael@0: 
michael@0:   /* (Re)initialize error mgr and destination modules */
michael@0:   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
michael@0:   (*cinfo->dest->init_destination) (cinfo);
michael@0:   /* Perform master selection of active modules */
michael@0:   jinit_compress_master(cinfo);
michael@0:   /* Set up for the first pass */
michael@0:   (*cinfo->master->prepare_for_pass) (cinfo);
michael@0:   /* Ready for application to drive first pass through jpeg_write_scanlines
michael@0:    * or jpeg_write_raw_data.
michael@0:    */
michael@0:   cinfo->next_scanline = 0;
michael@0:   cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Write some scanlines of data to the JPEG compressor.
michael@0:  *
michael@0:  * The return value will be the number of lines actually written.
michael@0:  * This should be less than the supplied num_lines only in case that
michael@0:  * the data destination module has requested suspension of the compressor,
michael@0:  * or if more than image_height scanlines are passed in.
michael@0:  *
michael@0:  * Note: we warn about excess calls to jpeg_write_scanlines() since
michael@0:  * this likely signals an application programmer error.  However,
michael@0:  * excess scanlines passed in the last valid call are *silently* ignored,
michael@0:  * so that the application need not adjust num_lines for end-of-image
michael@0:  * when using a multiple-scanline buffer.
michael@0:  */
michael@0: 
michael@0: GLOBAL(JDIMENSION)
michael@0: jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
michael@0: 		      JDIMENSION num_lines)
michael@0: {
michael@0:   JDIMENSION row_ctr, rows_left;
michael@0: 
michael@0:   if (cinfo->global_state != CSTATE_SCANNING)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0:   if (cinfo->next_scanline >= cinfo->image_height)
michael@0:     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
michael@0: 
michael@0:   /* Call progress monitor hook if present */
michael@0:   if (cinfo->progress != NULL) {
michael@0:     cinfo->progress->pass_counter = (long) cinfo->next_scanline;
michael@0:     cinfo->progress->pass_limit = (long) cinfo->image_height;
michael@0:     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
michael@0:   }
michael@0: 
michael@0:   /* Give master control module another chance if this is first call to
michael@0:    * jpeg_write_scanlines.  This lets output of the frame/scan headers be
michael@0:    * delayed so that application can write COM, etc, markers between
michael@0:    * jpeg_start_compress and jpeg_write_scanlines.
michael@0:    */
michael@0:   if (cinfo->master->call_pass_startup)
michael@0:     (*cinfo->master->pass_startup) (cinfo);
michael@0: 
michael@0:   /* Ignore any extra scanlines at bottom of image. */
michael@0:   rows_left = cinfo->image_height - cinfo->next_scanline;
michael@0:   if (num_lines > rows_left)
michael@0:     num_lines = rows_left;
michael@0: 
michael@0:   row_ctr = 0;
michael@0:   (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
michael@0:   cinfo->next_scanline += row_ctr;
michael@0:   return row_ctr;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Alternate entry point to write raw data.
michael@0:  * Processes exactly one iMCU row per call, unless suspended.
michael@0:  */
michael@0: 
michael@0: GLOBAL(JDIMENSION)
michael@0: jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,
michael@0: 		     JDIMENSION num_lines)
michael@0: {
michael@0:   JDIMENSION lines_per_iMCU_row;
michael@0: 
michael@0:   if (cinfo->global_state != CSTATE_RAW_OK)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0:   if (cinfo->next_scanline >= cinfo->image_height) {
michael@0:     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
michael@0:     return 0;
michael@0:   }
michael@0: 
michael@0:   /* Call progress monitor hook if present */
michael@0:   if (cinfo->progress != NULL) {
michael@0:     cinfo->progress->pass_counter = (long) cinfo->next_scanline;
michael@0:     cinfo->progress->pass_limit = (long) cinfo->image_height;
michael@0:     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
michael@0:   }
michael@0: 
michael@0:   /* Give master control module another chance if this is first call to
michael@0:    * jpeg_write_raw_data.  This lets output of the frame/scan headers be
michael@0:    * delayed so that application can write COM, etc, markers between
michael@0:    * jpeg_start_compress and jpeg_write_raw_data.
michael@0:    */
michael@0:   if (cinfo->master->call_pass_startup)
michael@0:     (*cinfo->master->pass_startup) (cinfo);
michael@0: 
michael@0:   /* Verify that at least one iMCU row has been passed. */
michael@0:   lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE;
michael@0:   if (num_lines < lines_per_iMCU_row)
michael@0:     ERREXIT(cinfo, JERR_BUFFER_SIZE);
michael@0: 
michael@0:   /* Directly compress the row. */
michael@0:   if (! (*cinfo->coef->compress_data) (cinfo, data)) {
michael@0:     /* If compressor did not consume the whole row, suspend processing. */
michael@0:     return 0;
michael@0:   }
michael@0: 
michael@0:   /* OK, we processed one iMCU row. */
michael@0:   cinfo->next_scanline += lines_per_iMCU_row;
michael@0:   return lines_per_iMCU_row;
michael@0: }