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377 lines
12 KiB
377 lines
12 KiB
unit imjdapistd;
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{ Original : jdapistd.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 decompression 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-decompression 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_decompress, it will end up linking in the entire decompressor.
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We thus must separate this file from jdapimin.c to avoid linking the
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whole decompression 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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imjdmaster;
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{ Read some scanlines of data from the JPEG decompressor.
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The return value will be the number of lines actually read.
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This may be less than the number requested in several cases,
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including bottom of image, data source suspension, and operating
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modes that emit multiple scanlines at a time.
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Note: we warn about excess calls to jpeg_read_scanlines() since
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this likely signals an application programmer error. However,
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an oversize buffer (max_lines > scanlines remaining) is not an error. }
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{GLOBAL}
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function jpeg_read_scanlines (cinfo : j_decompress_ptr;
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scanlines : JSAMPARRAY;
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max_lines : JDIMENSION) : JDIMENSION;
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{ Alternate entry point to read 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_read_raw_data (cinfo : j_decompress_ptr;
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data : JSAMPIMAGE;
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max_lines : JDIMENSION) : JDIMENSION;
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{$ifdef D_MULTISCAN_FILES_SUPPORTED}
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{ Initialize for an output pass in buffered-image mode. }
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{GLOBAL}
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function jpeg_start_output (cinfo : j_decompress_ptr;
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scan_number : int) : boolean;
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{ Finish up after an output pass in buffered-image mode.
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Returns FALSE if suspended. The return value need be inspected only if
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a suspending data source is used. }
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{GLOBAL}
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function jpeg_finish_output (cinfo : j_decompress_ptr) : boolean;
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{$endif} { D_MULTISCAN_FILES_SUPPORTED }
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{ Decompression initialization.
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jpeg_read_header must be completed before calling this.
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If a multipass operating mode was selected, this will do all but the
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last pass, and thus may take a great deal of time.
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Returns FALSE if suspended. The return value need be inspected only if
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a suspending data source is used. }
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{GLOBAL}
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function jpeg_start_decompress (cinfo : j_decompress_ptr) : boolean;
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implementation
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{ Forward declarations }
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{LOCAL}
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function output_pass_setup (cinfo : j_decompress_ptr) : boolean; forward;
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{ Decompression initialization.
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jpeg_read_header must be completed before calling this.
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If a multipass operating mode was selected, this will do all but the
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last pass, and thus may take a great deal of time.
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Returns FALSE if suspended. The return value need be inspected only if
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a suspending data source is used. }
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{GLOBAL}
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function jpeg_start_decompress (cinfo : j_decompress_ptr) : boolean;
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var
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retcode : int;
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begin
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if (cinfo^.global_state = DSTATE_READY) then
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begin
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{ First call: initialize master control, select active modules }
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jinit_master_decompress(cinfo);
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if (cinfo^.buffered_image) then
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begin
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{ No more work here; expecting jpeg_start_output next }
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cinfo^.global_state := DSTATE_BUFIMAGE;
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jpeg_start_decompress := TRUE;
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exit;
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end;
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cinfo^.global_state := DSTATE_PRELOAD;
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end;
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if (cinfo^.global_state = DSTATE_PRELOAD) then
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begin
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{ If file has multiple scans, absorb them all into the coef buffer }
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if (cinfo^.inputctl^.has_multiple_scans) then
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begin
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{$ifdef D_MULTISCAN_FILES_SUPPORTED}
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while TRUE do
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begin
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{ Call progress monitor hook if present }
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if (cinfo^.progress <> NIL) then
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cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
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{ Absorb some more input }
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retcode := cinfo^.inputctl^.consume_input (cinfo);
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if (retcode = JPEG_SUSPENDED) then
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begin
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jpeg_start_decompress := FALSE;
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exit;
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end;
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if (retcode = JPEG_REACHED_EOI) then
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break;
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{ Advance progress counter if appropriate }
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if (cinfo^.progress <> NIL) and
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((retcode = JPEG_ROW_COMPLETED) or (retcode = JPEG_REACHED_SOS)) then
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begin
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Inc(cinfo^.progress^.pass_counter);
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if (cinfo^.progress^.pass_counter >= cinfo^.progress^.pass_limit) then
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begin
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{ jdmaster underestimated number of scans; ratchet up one scan }
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Inc(cinfo^.progress^.pass_limit, long(cinfo^.total_iMCU_rows));
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end;
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end;
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end;
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{$else}
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ERREXIT(j_common_ptr(cinfo), JERR_NOT_COMPILED);
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{$endif} { D_MULTISCAN_FILES_SUPPORTED }
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end;
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cinfo^.output_scan_number := cinfo^.input_scan_number;
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end
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else
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if (cinfo^.global_state <> DSTATE_PRESCAN) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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{ Perform any dummy output passes, and set up for the final pass }
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jpeg_start_decompress := output_pass_setup(cinfo);
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end;
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{ Set up for an output pass, and perform any dummy pass(es) needed.
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Common subroutine for jpeg_start_decompress and jpeg_start_output.
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Entry: global_state := DSTATE_PRESCAN only if previously suspended.
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Exit: If done, returns TRUE and sets global_state for proper output mode.
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If suspended, returns FALSE and sets global_state := DSTATE_PRESCAN. }
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{LOCAL}
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function output_pass_setup (cinfo : j_decompress_ptr) : boolean;
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var
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last_scanline : JDIMENSION;
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begin
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if (cinfo^.global_state <> DSTATE_PRESCAN) then
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begin
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{ First call: do pass setup }
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cinfo^.master^.prepare_for_output_pass (cinfo);
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cinfo^.output_scanline := 0;
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cinfo^.global_state := DSTATE_PRESCAN;
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end;
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{ Loop over any required dummy passes }
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while (cinfo^.master^.is_dummy_pass) do
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begin
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{$ifdef QUANT_2PASS_SUPPORTED}
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{ Crank through the dummy pass }
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while (cinfo^.output_scanline < cinfo^.output_height) do
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begin
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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^.output_scanline);
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cinfo^.progress^.pass_limit := long (cinfo^.output_height);
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cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
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end;
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{ Process some data }
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last_scanline := cinfo^.output_scanline;
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cinfo^.main^.process_data (cinfo, JSAMPARRAY(NIL),
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cinfo^.output_scanline, {var}
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JDIMENSION(0));
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if (cinfo^.output_scanline = last_scanline) then
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begin
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output_pass_setup := FALSE; { No progress made, must suspend }
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exit;
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end;
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end;
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{ Finish up dummy pass, and set up for another one }
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cinfo^.master^.finish_output_pass (cinfo);
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cinfo^.master^.prepare_for_output_pass (cinfo);
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cinfo^.output_scanline := 0;
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{$else}
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ERREXIT(j_common_ptr(cinfo), JERR_NOT_COMPILED);
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{$endif} { QUANT_2PASS_SUPPORTED }
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end;
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{ Ready for application to drive output pass through
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jpeg_read_scanlines or jpeg_read_raw_data. }
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if cinfo^.raw_data_out then
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cinfo^.global_state := DSTATE_RAW_OK
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else
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cinfo^.global_state := DSTATE_SCANNING;
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output_pass_setup := TRUE;
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end;
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{ Read some scanlines of data from the JPEG decompressor.
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The return value will be the number of lines actually read.
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This may be less than the number requested in several cases,
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including bottom of image, data source suspension, and operating
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modes that emit multiple scanlines at a time.
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Note: we warn about excess calls to jpeg_read_scanlines() since
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this likely signals an application programmer error. However,
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an oversize buffer (max_lines > scanlines remaining) is not an error. }
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{GLOBAL}
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function jpeg_read_scanlines (cinfo : j_decompress_ptr;
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scanlines : JSAMPARRAY;
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max_lines : JDIMENSION) : JDIMENSION;
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var
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row_ctr : JDIMENSION;
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begin
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if (cinfo^.global_state <> DSTATE_SCANNING) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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if (cinfo^.output_scanline >= cinfo^.output_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_read_scanlines := 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^.output_scanline);
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cinfo^.progress^.pass_limit := long (cinfo^.output_height);
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cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
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end;
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{ Process some data }
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row_ctr := 0;
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cinfo^.main^.process_data (cinfo, scanlines, {var}row_ctr, max_lines);
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Inc(cinfo^.output_scanline, row_ctr);
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jpeg_read_scanlines := row_ctr;
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end;
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{ Alternate entry point to read 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_read_raw_data (cinfo : j_decompress_ptr;
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data : JSAMPIMAGE;
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max_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 <> DSTATE_RAW_OK) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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if (cinfo^.output_scanline >= cinfo^.output_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_read_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^.output_scanline);
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cinfo^.progress^.pass_limit := long (cinfo^.output_height);
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cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
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end;
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{ Verify that at least one iMCU row can be returned. }
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lines_per_iMCU_row := cinfo^.max_v_samp_factor * cinfo^.min_DCT_scaled_size;
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if (max_lines < lines_per_iMCU_row) then
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ERREXIT(j_common_ptr(cinfo), JERR_BUFFER_SIZE);
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{ Decompress directly into user's buffer. }
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if (cinfo^.coef^.decompress_data (cinfo, data) = 0) then
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begin
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jpeg_read_raw_data := 0; { suspension forced, can do nothing more }
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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^.output_scanline, lines_per_iMCU_row);
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jpeg_read_raw_data := lines_per_iMCU_row;
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end;
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{ Additional entry points for buffered-image mode. }
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{$ifdef D_MULTISCAN_FILES_SUPPORTED}
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{ Initialize for an output pass in buffered-image mode. }
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{GLOBAL}
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function jpeg_start_output (cinfo : j_decompress_ptr;
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scan_number : int) : boolean;
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begin
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if (cinfo^.global_state <> DSTATE_BUFIMAGE) and
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(cinfo^.global_state <> DSTATE_PRESCAN) then
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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{ Limit scan number to valid range }
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if (scan_number <= 0) then
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scan_number := 1;
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if (cinfo^.inputctl^.eoi_reached) and
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(scan_number > cinfo^.input_scan_number) then
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scan_number := cinfo^.input_scan_number;
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cinfo^.output_scan_number := scan_number;
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{ Perform any dummy output passes, and set up for the real pass }
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jpeg_start_output := output_pass_setup(cinfo);
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end;
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{ Finish up after an output pass in buffered-image mode.
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Returns FALSE if suspended. The return value need be inspected only if
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a suspending data source is used. }
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{GLOBAL}
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function jpeg_finish_output (cinfo : j_decompress_ptr) : boolean;
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begin
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if ((cinfo^.global_state = DSTATE_SCANNING) or
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(cinfo^.global_state = DSTATE_RAW_OK) and cinfo^.buffered_image) then
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begin
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{ Terminate this pass. }
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{ We do not require the whole pass to have been completed. }
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cinfo^.master^.finish_output_pass (cinfo);
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cinfo^.global_state := DSTATE_BUFPOST;
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end
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else
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if (cinfo^.global_state <> DSTATE_BUFPOST) then
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begin
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{ BUFPOST := repeat call after a suspension, anything else is error }
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ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
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end;
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{ Read markers looking for SOS or EOI }
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while (cinfo^.input_scan_number <= cinfo^.output_scan_number) and
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(not cinfo^.inputctl^.eoi_reached) do
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begin
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if (cinfo^.inputctl^.consume_input (cinfo) = JPEG_SUSPENDED) then
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begin
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jpeg_finish_output := FALSE; { Suspend, come back later }
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exit;
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end;
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end;
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cinfo^.global_state := DSTATE_BUFIMAGE;
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jpeg_finish_output := TRUE;
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end;
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{$endif} { D_MULTISCAN_FILES_SUPPORTED }
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end.
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