JCAPIMIN.PAS

Unit JcAPImin;
{$N+}
{  This file contains application interface code for the compression half
  of the JPEG library.  These are the "minimum" API routines that may be
  needed in either the normal full-compression case or the transcoding-only
  case.

  Most of the routines intended to be called directly by an application
  are in this file or in jcapistd.c.  But also see jcparam.c for
  parameter-setup helper routines, jcomapi.c for routines shared by
  compression and decompression, and jctrans.c for the transcoding case. }

{ jcapimin.c ;  Copyright (C) 1994-1996, Thomas G. Lane. }


interface

{$I jconfig.inc}

uses
  jmorecfg,
  jinclude,
  jdeferr,
  jerror,
  jpeglib,
  jcomapi,
  jmemmgr,
  jcmarker;

{ Initialization of JPEG compression objects.
  Nomssi: This is a macro in the original code.

  jpeg_create_compress() and jpeg_create_decompress() are the exported
  names that applications should call.  These expand to calls on
  jpeg_CreateCompress and jpeg_CreateDecompress with additional information
  passed for version mismatch checking.
  NB: you must set up the error-manager BEFORE calling jpeg_create_xxx. }

procedure jpeg_create_compress(cinfo : j_compress_ptr);


{ Initialization of a JPEG compression object.
  The error manager must already be set up (in case memory manager fails). }

{GLOBAL}
procedure jpeg_CreateCompress (cinfo : j_compress_ptr;
                               version : int;
                               structsize : size_t);

{ Destruction of a JPEG compression object }

{GLOBAL}
procedure jpeg_destroy_compress (cinfo : j_compress_ptr);


{ Abort processing of a JPEG compression operation,
  but don't destroy the object itself. }

{GLOBAL}
procedure jpeg_abort_compress (cinfo : j_compress_ptr);


{ Forcibly suppress or un-suppress all quantization and Huffman tables.
  Marks all currently defined tables as already written (if suppress)
  or not written (if !suppress).  This will control whether they get emitted
  by a subsequent jpeg_start_compress call.

  This routine is exported for use by applications that want to produce
  abbreviated JPEG datastreams.  It logically belongs in jcparam.c, but
  since it is called by jpeg_start_compress, we put it here --- otherwise
  jcparam.o would be linked whether the application used it or not. }

{GLOBAL}
procedure jpeg_suppress_tables (cinfo : j_compress_ptr;
                                suppress : boolean);


{ Finish JPEG compression.

  If a multipass operating mode was selected, this may do a great deal of
  work including most of the actual output. }

{GLOBAL}
procedure jpeg_finish_compress (cinfo : j_compress_ptr);

{ Write a special marker.
  This is only recommended for writing COM or APPn markers.
  Must be called after jpeg_start_compress() and before
  first call to jpeg_write_scanlines() or jpeg_write_raw_data(). }

{GLOBAL}
procedure jpeg_write_marker (cinfo : j_compress_ptr;
                             marker : int;
		             const dataptr : JOCTETptr;
                             datalen : uInt);

{ Alternate compression function: just write an abbreviated table file.
  Before calling this, all parameters and a data destination must be set up.

  To produce a pair of files containing abbreviated tables and abbreviated
  image data, one would proceed as follows:

 		initialize JPEG object
 		set JPEG parameters
 		set destination to table file
 		jpeg_write_tables(cinfo);
 		set destination to image file
 		jpeg_start_compress(cinfo, FALSE);
 		write data...
 		jpeg_finish_compress(cinfo);

  jpeg_write_tables has the side effect of marking all tables written
  (same as jpeg_suppress_tables(..., TRUE)).  Thus a subsequent start_compress
  will not re-emit the tables unless it is passed write_all_tables=TRUE. }

{GLOBAL}
procedure jpeg_write_tables (cinfo : j_compress_ptr);

implementation

procedure jpeg_create_compress(cinfo : j_compress_ptr);
begin
  jpeg_CreateCompress(cinfo, JPEG_LIB_VERSION,
                      size_t(sizeof(jpeg_compress_struct)));
end;

{ Initialization of a JPEG compression object.
  The error manager must already be set up (in case memory manager fails). }

{GLOBAL}
procedure jpeg_CreateCompress (cinfo : j_compress_ptr;
                               version : int;
                               structsize : size_t);
var
  i : int;
var
  err : jpeg_error_mgr_ptr;
begin

  { Guard against version mismatches between library and caller. }
  cinfo^.mem := NIL;		{ so jpeg_destroy knows mem mgr not called }
  if (version <> JPEG_LIB_VERSION) then
    ERREXIT2(j_common_ptr(cinfo), JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
  if (structsize <> SIZEOF(jpeg_compress_struct)) then
    ERREXIT2(j_common_ptr(cinfo), JERR_BAD_STRUCT_SIZE,
	     int(SIZEOF(jpeg_compress_struct)), int(structsize));

  { For debugging purposes, zero the whole master structure.
    But error manager pointer is already there, so save and restore it. }


  err := cinfo^.err;
  MEMZERO(cinfo, SIZEOF(jpeg_compress_struct));
  cinfo^.err := err;
  cinfo^.is_decompressor := FALSE;

  { Initialize a memory manager instance for this object }
  jinit_memory_mgr(j_common_ptr(cinfo));

  { Zero out pointers to permanent structures. }
  cinfo^.progress := NIL;
  cinfo^.dest := NIL;

  cinfo^.comp_info := NIL;

  for i := 0 to pred(NUM_QUANT_TBLS) do
    cinfo^.quant_tbl_ptrs[i] := NIL;

  for i := 0 to pred(NUM_HUFF_TBLS) do
  begin
    cinfo^.dc_huff_tbl_ptrs[i] := NIL;
    cinfo^.ac_huff_tbl_ptrs[i] := NIL;
  end;

  cinfo^.input_gamma := 1.0;	{ in case application forgets }

  { OK, I'm ready }
  cinfo^.global_state := CSTATE_START;
end;


{ Destruction of a JPEG compression object }

{GLOBAL}
procedure jpeg_destroy_compress (cinfo : j_compress_ptr);
begin
  jpeg_destroy(j_common_ptr(cinfo)); { use common routine }
end;


{ Abort processing of a JPEG compression operation,
  but don't destroy the object itself. }

{GLOBAL}
procedure jpeg_abort_compress (cinfo : j_compress_ptr);
begin
  jpeg_abort(j_common_ptr(cinfo)); { use common routine }
end;


{ Forcibly suppress or un-suppress all quantization and Huffman tables.
  Marks all currently defined tables as already written (if suppress)
  or not written (if !suppress).  This will control whether they get emitted
  by a subsequent jpeg_start_compress call.

  This routine is exported for use by applications that want to produce
  abbreviated JPEG datastreams.  It logically belongs in jcparam.c, but
  since it is called by jpeg_start_compress, we put it here --- otherwise
  jcparam.o would be linked whether the application used it or not. }

{GLOBAL}
procedure jpeg_suppress_tables (cinfo : j_compress_ptr;
                                suppress : boolean);
var
  i : int;
  qtbl : JQUANT_TBL_PTR;
  htbl : JHUFF_TBL_PTR;
begin
  for i := 0 to pred(NUM_QUANT_TBLS) do
  begin
    qtbl := cinfo^.quant_tbl_ptrs[i];
    if (qtbl <> NIL) then
      qtbl^.sent_table := suppress;
  end;

  for i := 0 to pred(NUM_HUFF_TBLS) do
  begin
    htbl := cinfo^.dc_huff_tbl_ptrs[i];
    if (htbl <> NIL) then
      htbl^.sent_table := suppress;
    htbl := cinfo^.ac_huff_tbl_ptrs[i];
    if (htbl <> NIL) then
      htbl^.sent_table := suppress;
  end;
end;


{ Finish JPEG compression.

  If a multipass operating mode was selected, this may do a great deal of
  work including most of the actual output. }

{GLOBAL}
procedure jpeg_finish_compress (cinfo : j_compress_ptr);
var
  iMCU_row : JDIMENSION;
begin
  if (cinfo^.global_state = CSTATE_SCANNING) or
     (cinfo^.global_state = CSTATE_RAW_OK) then
  begin
    { Terminate first pass }
    if (cinfo^.next_scanline < cinfo^.image_height) then
      ERREXIT(j_common_ptr(cinfo), JERR_TOO_LITTLE_DATA);
    cinfo^.master^.finish_pass (cinfo);
  end
  else
    if (cinfo^.global_state <> CSTATE_WRCOEFS) then
      ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);
  { Perform any remaining passes }
  while (not cinfo^.master^.is_last_pass) do
  begin
    cinfo^.master^.prepare_for_pass (cinfo);
    for iMCU_row := 0 to pred(cinfo^.total_iMCU_rows) do
    begin
      if (cinfo^.progress <> NIL) then
      begin
	cinfo^.progress^.pass_counter := long (iMCU_row);
	cinfo^.progress^.pass_limit := long (cinfo^.total_iMCU_rows);
	cinfo^.progress^.progress_monitor (j_common_ptr(cinfo));
      end;
      { We bypass the main controller and invoke coef controller directly;
        all work is being done from the coefficient buffer. }

      if (not cinfo^.coef^.compress_data (cinfo, JSAMPIMAGE(NIL))) then
	ERREXIT(j_common_ptr(cinfo), JERR_CANT_SUSPEND);
    end;
    cinfo^.master^.finish_pass (cinfo);
  end;
  { Write EOI, do final cleanup }
  cinfo^.marker^.write_file_trailer (cinfo);
  cinfo^.dest^.term_destination (cinfo);
  { We can use jpeg_abort to release memory and reset global_state }
  jpeg_abort(j_common_ptr(cinfo));
end;


{ Write a special marker.
  This is only recommended for writing COM or APPn markers.
  Must be called after jpeg_start_compress() and before
  first call to jpeg_write_scanlines() or jpeg_write_raw_data(). }

{GLOBAL}
procedure jpeg_write_marker (cinfo : j_compress_ptr;
                             marker : int;
		             const dataptr : JOCTETptr;
                             datalen : uInt);
begin
  if (cinfo^.next_scanline <> 0) or
     ((cinfo^.global_state <> CSTATE_SCANNING) and
      (cinfo^.global_state <> CSTATE_RAW_OK) and
      (cinfo^.global_state <> CSTATE_WRCOEFS)) then
    ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);

  cinfo^.marker^.write_any_marker (cinfo, marker, dataptr, datalen);
end;


{ Alternate compression function: just write an abbreviated table file.
  Before calling this, all parameters and a data destination must be set up.

  To produce a pair of files containing abbreviated tables and abbreviated
  image data, one would proceed as follows:

 		initialize JPEG object
 		set JPEG parameters
 		set destination to table file
 		jpeg_write_tables(cinfo);
 		set destination to image file
 		jpeg_start_compress(cinfo, FALSE);
 		write data...
 		jpeg_finish_compress(cinfo);

  jpeg_write_tables has the side effect of marking all tables written
  (same as jpeg_suppress_tables(..., TRUE)).  Thus a subsequent start_compress
  will not re-emit the tables unless it is passed write_all_tables=TRUE. }

{GLOBAL}
procedure jpeg_write_tables (cinfo : j_compress_ptr);
begin
  if (cinfo^.global_state <> CSTATE_START) then
    ERREXIT1(j_common_ptr(cinfo), JERR_BAD_STATE, cinfo^.global_state);

  { (Re)initialize error mgr and destination modules }
  cinfo^.err^.reset_error_mgr (j_common_ptr(cinfo));
  cinfo^.dest^.init_destination (cinfo);
  { Initialize the marker writer ... bit of a crock to do it here. }
  jinit_marker_writer(cinfo);
  { Write them tables! }
  cinfo^.marker^.write_tables_only (cinfo);
  { And clean up. }
  cinfo^.dest^.term_destination (cinfo);
  { We can use jpeg_abort to release memory. }
  jpeg_abort(j_common_ptr(cinfo));
end;

end.