223 lines
8.1 KiB
Plaintext
223 lines
8.1 KiB
Plaintext
unit imjcapistd;
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{ Original : jcapistd.c ; Copyright (C) 1994-1996, 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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This file contains application interface code for the compression half
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of the JPEG library. These are the "standard" API routines that are
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used in the normal full-compression case. They are not used by a
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transcoding-only application. Note that if an application links in
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jpeg_start_compress, it will end up linking in the entire compressor.
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We thus must separate this file from jcapimin.c to avoid linking the
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whole compression library into a transcoder. }
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interface
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{$I imjconfig.inc}
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uses
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imjmorecfg,
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imjinclude,
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imjdeferr,
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imjerror,
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imjpeglib,
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imjcapimin, imjcinit;
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{ Compression initialization.
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Before calling this, all parameters and a data destination must be set up.
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We require a write_all_tables parameter as a failsafe check when writing
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multiple datastreams from the same compression object. Since prior runs
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will have left all the tables marked sent_table=TRUE, a subsequent run
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would emit an abbreviated stream (no tables) by default. This may be what
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is wanted, but for safety's sake it should not be the default behavior:
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programmers should have to make a deliberate choice to emit abbreviated
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images. Therefore the documentation and examples should encourage people
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to pass write_all_tables=TRUE; then it will take active thought to do the
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wrong thing. }
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{GLOBAL}
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procedure jpeg_start_compress (cinfo : j_compress_ptr;
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write_all_tables : boolean);
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{ Write some scanlines of data to the JPEG compressor.
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The return value will be the number of lines actually written.
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This should be less than the supplied num_lines only in case that
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the data destination module has requested suspension of the compressor,
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or if more than image_height scanlines are passed in.
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Note: we warn about excess calls to jpeg_write_scanlines() since
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this likely signals an application programmer error. However,
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excess scanlines passed in the last valid call are *silently* ignored,
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so that the application need not adjust num_lines for end-of-image
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when using a multiple-scanline buffer. }
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{GLOBAL}
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function jpeg_write_scanlines (cinfo : j_compress_ptr;
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scanlines : JSAMPARRAY;
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num_lines : JDIMENSION) : JDIMENSION;
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{ Alternate entry point to write raw data.
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Processes exactly one iMCU row per call, unless suspended. }
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{GLOBAL}
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function jpeg_write_raw_data (cinfo : j_compress_ptr;
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data : JSAMPIMAGE;
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num_lines : JDIMENSION) : JDIMENSION;
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implementation
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{ Compression initialization.
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Before calling this, all parameters and a data destination must be set up.
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We require a write_all_tables parameter as a failsafe check when writing
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multiple datastreams from the same compression object. Since prior runs
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will have left all the tables marked sent_table=TRUE, a subsequent run
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would emit an abbreviated stream (no tables) by default. This may be what
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is wanted, but for safety's sake it should not be the default behavior:
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programmers should have to make a deliberate choice to emit abbreviated
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images. Therefore the documentation and examples should encourage people
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to pass write_all_tables=TRUE; then it will take active thought to do the
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wrong thing. }
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{GLOBAL}
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procedure jpeg_start_compress (cinfo : j_compress_ptr;
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write_all_tables : boolean);
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begin
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if (cinfo^.global_state <> CSTATE_START) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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if (write_all_tables) then
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jpeg_suppress_tables(cinfo, FALSE); { mark all tables to be written }
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{ (Re)initialize error mgr and destination modules }
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cinfo^.err^.reset_error_mgr (j_common_ptr(cinfo));
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cinfo^.dest^.init_destination (cinfo);
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{ Perform master selection of active modules }
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jinit_compress_master(cinfo);
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{ Set up for the first pass }
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cinfo^.master^.prepare_for_pass (cinfo);
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{ Ready for application to drive first pass through jpeg_write_scanlines
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or jpeg_write_raw_data. }
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cinfo^.next_scanline := 0;
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if cinfo^.raw_data_in then
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cinfo^.global_state := CSTATE_RAW_OK
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else
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cinfo^.global_state := CSTATE_SCANNING;
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end;
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{ Write some scanlines of data to the JPEG compressor.
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The return value will be the number of lines actually written.
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This should be less than the supplied num_lines only in case that
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the data destination module has requested suspension of the compressor,
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or if more than image_height scanlines are passed in.
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Note: we warn about excess calls to jpeg_write_scanlines() since
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this likely signals an application programmer error. However,
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excess scanlines passed in the last valid call are *silently* ignored,
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so that the application need not adjust num_lines for end-of-image
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when using a multiple-scanline buffer. }
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{GLOBAL}
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function jpeg_write_scanlines (cinfo : j_compress_ptr;
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scanlines : JSAMPARRAY;
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num_lines : JDIMENSION) : JDIMENSION;
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var
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row_ctr, rows_left : JDIMENSION;
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begin
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if (cinfo^.global_state <> CSTATE_SCANNING) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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if (cinfo^.next_scanline >= cinfo^.image_height) then
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WARNMS(j_common_ptr(cinfo), JWRN_TOO_MUCH_DATA);
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{ Call progress monitor hook if present }
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if (cinfo^.progress <> NIL) then
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begin
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cinfo^.progress^.pass_counter := long (cinfo^.next_scanline);
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cinfo^.progress^.pass_limit := long (cinfo^.image_height);
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cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
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end;
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{ Give master control module another chance if this is first call to
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jpeg_write_scanlines. This lets output of the frame/scan headers be
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delayed so that application can write COM, etc, markers between
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jpeg_start_compress and jpeg_write_scanlines. }
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if (cinfo^.master^.call_pass_startup) then
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cinfo^.master^.pass_startup (cinfo);
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{ Ignore any extra scanlines at bottom of image. }
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rows_left := cinfo^.image_height - cinfo^.next_scanline;
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if (num_lines > rows_left) then
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num_lines := rows_left;
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row_ctr := 0;
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cinfo^.main^.process_data (cinfo, scanlines, {var}row_ctr, num_lines);
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Inc(cinfo^.next_scanline, row_ctr);
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jpeg_write_scanlines := row_ctr;
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end;
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{ Alternate entry point to write raw data.
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Processes exactly one iMCU row per call, unless suspended. }
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{GLOBAL}
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function jpeg_write_raw_data (cinfo : j_compress_ptr;
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data : JSAMPIMAGE;
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num_lines : JDIMENSION) : JDIMENSION;
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var
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lines_per_iMCU_row : JDIMENSION;
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begin
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if (cinfo^.global_state <> CSTATE_RAW_OK) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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if (cinfo^.next_scanline >= cinfo^.image_height) then
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begin
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WARNMS(j_common_ptr(cinfo), JWRN_TOO_MUCH_DATA);
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jpeg_write_raw_data := 0;
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exit;
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end;
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{ Call progress monitor hook if present }
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if (cinfo^.progress <> NIL) then
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begin
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cinfo^.progress^.pass_counter := long(cinfo^.next_scanline);
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cinfo^.progress^.pass_limit := long(cinfo^.image_height);
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cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
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end;
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{ Give master control module another chance if this is first call to
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jpeg_write_raw_data. This lets output of the frame/scan headers be
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delayed so that application can write COM, etc, markers between
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jpeg_start_compress and jpeg_write_raw_data. }
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if (cinfo^.master^.call_pass_startup) then
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cinfo^.master^.pass_startup (cinfo);
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{ Verify that at least one iMCU row has been passed. }
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lines_per_iMCU_row := cinfo^.max_v_samp_factor * DCTSIZE;
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if (num_lines < lines_per_iMCU_row) then
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ERREXIT(j_common_ptr(cinfo), JERR_BUFFER_SIZE);
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{ Directly compress the row. }
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if (not cinfo^.coef^.compress_data (cinfo, data)) then
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begin
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{ If compressor did not consume the whole row, suspend processing. }
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jpeg_write_raw_data := 0;
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exit;
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end;
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{ OK, we processed one iMCU row. }
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Inc(cinfo^.next_scanline, lines_per_iMCU_row);
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jpeg_write_raw_data := lines_per_iMCU_row;
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end;
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end.
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