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plugwash |
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{pngwrite.pas}
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{plugwashes png write code}
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{ Copyright (C) 2005 Bas Steendijk and Peter Green
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For conditions of distribution and use, see copyright notice in zlib_license.txt
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which is included in the package
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----------------------------------------------------------------------------- }
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unit pngwrite;
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interface
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uses
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zlib,zdeflate,zutil,classes,sysutils,pgtypes,
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{$ifdef win32}
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winsock;
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{$else}
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sockets;
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{$endif}
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{$i uint32.inc}
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type
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tcolortype=(ctgreyscale,ctpallette,ctbgr,ctrgb,ct8bp);
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// There are two types of color types
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//
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// native types result in direct output of the apps data to the png file
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// theese are
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// ctgreyscale : grey scale data all png supported depths should work
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// ctpallette : palletted data all png supported depths should work
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// ctrgb : currently 24 bit only
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//
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// Processed types are processed before data is output to the png file
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// ctbgr : truecolor data in bgr order usefull with tbitmap.
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// ct8bp : data from app is 8 bits per sample palletted but data is saved as
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// a lower depth palletted format (the app MUST only use the first
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// 2^bitdepth pallette entries
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tpngwrite=record
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destination : tstream;
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lines : integer;
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cols : integer;
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deflatestream : z_stream;
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chunkstart : integer; //used to fill in chunk length later
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chunkbytes : integer;
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chunkcrc : uint32;
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crc_table : array[byte] of uint32;
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colortype:tcolortype;
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colordepth : byte;
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bufferingchunkdata : boolean;
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bufferedchunkdata : tstringlist;
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end;
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procedure pngstart(var f : tpngwrite;destination : tstream;colordepth : integer;colortype:tcolortype;lines : integer;cols : integer);
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procedure pngwritescanline(var f : tpngwrite;scanline: pointer);
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procedure pngwritepal(var f : tpngwrite;p:pointer;entrys : integer);
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procedure pngstartdata(var f : tpngwrite);
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procedure pngfinishdata(var f : tpngwrite);
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procedure pngfinish(var f : tpngwrite);
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implementation
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procedure make_crc_table(var f:tpngwrite);
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var
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c: uint32;
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n,k : integer;
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begin
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with f do begin
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// unsigned long c;
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// int n, k;
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// for (n = 0; n < 256; n++)
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for n := 0 to 255 do begin
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// c = (unsigned long) n;
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c := n;
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// for (k = 0; k < 8; k++)
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for k := 0 to 7 do begin
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// if (c & 1)
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if (c and 1) <> 0 then begin
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// c = 0xedb88320L ^ (c >> 1);
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c := $edb88320 xor (c shr 1);
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// else
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end else begin
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// c = c >> 1;
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c := c shr 1;
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//
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end;
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end;
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// crc_table[n] = c;
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crc_table[n] := c;
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//
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end;
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// crc_table_computed = 1;
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end;
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end;
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(*
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unsigned long update_crc(unsigned long crc, unsigned char *buf,
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int len)
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{
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unsigned long c = crc;
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int n;
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if (!crc_table_computed)
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make_crc_table();
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for (n = 0; n < len; n++) {
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c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
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}
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return c;
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}
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*)
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procedure update_crc(var f : tpngwrite;buf : string);
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var
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n : integer;
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begin
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with f do begin
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for n := 1 to length(buf) do begin
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chunkcrc := crc_table[(chunkcrc xor byte(buf[n])) and $ff] xor (chunkcrc shr 8);
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end;
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end;
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end;
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procedure writetochunk(var f : tpngwrite;buf : string);
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begin
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if length(buf)=0 then raise exception.create('attempt to write zero length block to chunk');
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with f do begin
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if bufferingchunkdata then begin
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bufferedchunkdata.Add(buf);
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end else begin
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destination.Write(buf[1],length(buf));
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end;
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update_crc(f,buf);
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inc(chunkbytes,length(buf));
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end;
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end;
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procedure startchunk(var f : tpngwrite;chunktype : string);
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var
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outputdata : string;
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begin
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with f do begin
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try
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chunkstart := destination.Position;
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// 4 btye dummy for length we will insert this later.
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outputdata := ' ';
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destination.WriteBuffer(pchar(outputdata)^,4);
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except
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bufferingchunkdata := true;
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bufferedchunkdata := tstringlist.create;
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end;
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chunkbytes := -4;
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chunkcrc := $FFFFFFFF;
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writetochunk(f,chunktype);
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end;
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end;
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procedure stopchunk(var f:tpngwrite);
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var
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currentpos : integer;
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i : integer;
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begin
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with f do begin
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if not bufferingchunkdata then begin
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currentpos := destination.Position;
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destination.position := chunkstart;
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end;
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chunkbytes := htonl(chunkbytes);
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destination.WriteBuffer(chunkbytes,4);
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if bufferingchunkdata then begin
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// writeln('begin write of buffered chunk data');
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for i := 0 to bufferedchunkdata.Count-1 do begin
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destination.Write(bufferedchunkdata[i][1],length(bufferedchunkdata[i]));
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end;
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bufferedchunkdata.Free;
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// writeln('end write of buffered chunk data');
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end else begin
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destination.position := currentpos;
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end;
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chunkcrc := htonl(chunkcrc) ;
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chunkcrc := chunkcrc xor $FFFFFFFF;
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destination.WriteBuffer(chunkcrc,4);
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end;
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end;
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type
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tihdr=packed record
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width : uint32;
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height : uint32;
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Bitdepth : byte;
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Colortype : byte;
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Compressionmethod : byte;
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Filtermethod : byte;
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Interlacemethod : byte;
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end;
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pihdr=^tihdr;
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procedure pngstart(var f : tpngwrite;destination : tstream;colordepth : integer;colortype:tcolortype;lines : integer;cols : integer);
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var
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tempstring : string;
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ihdr : pihdr;
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begin
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fillchar(f,sizeof(f),#0);
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f.destination := destination;
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f.lines := lines;
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f.cols := cols;
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f.colortype := colortype;
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f.colordepth := colordepth;
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make_crc_table(f);
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with f do begin
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//file header
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destination.Write(pchar(#137'PNG'#13#10#26#10)^,8);
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startchunk(f,'IHDR');
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setlength(tempstring,sizeof(tihdr));
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ihdr := pihdr(tempstring);
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ihdr.width := htonl(cols);
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ihdr.height := htonl(lines);
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case colortype of
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ctgreyscale : begin
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ihdr.Bitdepth := colordepth;
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ihdr.Colortype := 0;
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end;
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ctpallette,ct8bp : begin
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ihdr.Bitdepth := colordepth;
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ihdr.Colortype := 3;
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end;
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ctrgb,ctbgr : begin
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ihdr.Bitdepth := 8;
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ihdr.Colortype := 2;
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end;
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end;
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ihdr.Compressionmethod := 0;
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ihdr.Filtermethod := 0;
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ihdr.Interlacemethod := 0;
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writetochunk(f,tempstring);
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stopchunk(f);
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end;
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end;
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procedure pngwritepal(var f : tpngwrite;p:pointer;entrys : integer);
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var
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tempstring : string;
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begin
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with f do begin
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startchunk(f,'PLTE');
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setlength(tempstring,entrys*3);
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move(p^,tempstring[1],entrys*3);
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writetochunk(f,tempstring);
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stopchunk(f);
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end;
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end;
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procedure pngstartdata(var f : tpngwrite);
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begin
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with f do begin
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startchunk(f,'IDAT');
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deflateInit(deflatestream,9);
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//writeln('test');
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end;
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end;
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type
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tlinedata = array[0..0] of byte;
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plinedata = ^tlinedata;
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function divup(a,b:integer):integer;
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begin
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result := (a div b)+ord((a mod b)<>0);
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end;
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procedure pngwritescanline(var f : tpngwrite;scanline: pointer);
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var
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outputstr : string;
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nullchar : char;
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scanlineb : plinedata absolute scanline;
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rearrangebuf : plinedata;
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counter : integer;
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pixelsperbyte : integer;
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samplevalue : byte;
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begin
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with f do begin
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//writeln('about to write starter byte');
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if cols > 127 then begin
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setlength(outputstr,cols*6);
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end else begin
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setlength(outputstr,768);
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end;
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deflatestream.next_out := pbytef(outputstr);
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deflatestream.avail_out := length(outputstr);
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// writeln(deflatestream.avail_out,' ',deflatestream.avail_in);
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nullchar := #0;
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deflatestream.next_in := @nullchar;
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deflatestream.avail_in :=1;
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//writeln('about to start deflation');
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deflate(deflatestream,0);
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//writeln('deflation complete deflatestream.avail_out=',deflatestream.avail_out);
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// writeln(deflatestream.avail_out,' ',deflatestream.avail_in);
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while deflatestream.avail_out = 0 do begin
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deflatestream.next_out := pbytef(taddrint(deflatestream.next_out) - taddrint(outputstr));
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deflatestream.avail_out := length(outputstr);
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setlength(outputstr,length(outputstr)*2);
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deflatestream.next_out := pbytef(taddrint(deflatestream.next_out) + taddrint(outputstr));
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deflate(deflatestream,0);
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end;
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//writeln('extra deflation done');
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if deflatestream.avail_in <> 0 then raise exception.create('compression problem');
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//writeln('about to write main data');
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case colortype of
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ctbgr : begin
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getmem(rearrangebuf,cols*3);
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for counter := 0 to cols-1 do begin
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rearrangebuf[(counter*3) ] := scanlineb[(counter*3)+2];
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rearrangebuf[(counter*3)+1] := scanlineb[(counter*3)+1];
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rearrangebuf[(counter*3)+2] := scanlineb[(counter*3) ];
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end;
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deflatestream.next_in := pointer(rearrangebuf);
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deflatestream.avail_in := cols*3;
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deflate(deflatestream,0);
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if deflatestream.avail_in <> 0 then raise exception.create('compression problem');
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freemem(rearrangebuf);
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end;
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ct8bp : begin
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rearrangebuf := allocmem(divup(cols* colordepth, 8));
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pixelsperbyte := 8 div colordepth;
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for counter := 0 to cols-1 do begin
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//shift sample value into most significant bits (which has the nice side effect of removing any garbage bits)
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samplevalue := scanlineb[counter] shl (8-colordepth);
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//shift sample value into correct place for pixel in question.
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samplevalue := samplevalue shr ((counter mod pixelsperbyte)*colordepth);
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rearrangebuf[counter div pixelsperbyte] := rearrangebuf[counter div pixelsperbyte] or samplevalue;
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end;
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deflatestream.next_in := pointer(rearrangebuf);
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deflatestream.avail_in := divup(cols* colordepth, 8);
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deflate(deflatestream,0);
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if deflatestream.avail_in <> 0 then raise exception.create('compression problem');
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freemem(rearrangebuf);
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end;
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else begin
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deflatestream.next_in := scanline;
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deflatestream.avail_in := divup(cols* colordepth, 8);
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deflate(deflatestream,0);
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while deflatestream.avail_out = 0 do begin
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369 |
|
|
deflatestream.next_out := pbytef(taddrint(deflatestream.next_out) - taddrint(outputstr));
|
370 |
|
|
deflatestream.avail_out := length(outputstr);
|
371 |
|
|
setlength(outputstr,length(outputstr)*2);
|
372 |
|
|
deflatestream.next_out := pbytef(taddrint(deflatestream.next_out) + taddrint(outputstr));
|
373 |
|
|
deflate(deflatestream,0);
|
374 |
|
|
end;
|
375 |
|
|
if deflatestream.avail_in <> 0 then raise exception.create('compression problem');
|
376 |
|
|
end;
|
377 |
|
|
end;
|
378 |
|
|
|
379 |
|
|
setlength(outputstr,length(outputstr)-deflatestream.avail_out);
|
380 |
|
|
//deflate doesn't always produce output when its given input, if this is the case no point pushing it any further
|
381 |
|
|
if length(outputstr) > 0 then writetochunk(f,outputstr);
|
382 |
|
|
// writeln;
|
383 |
|
|
end;
|
384 |
|
|
end;
|
385 |
|
|
|
386 |
|
|
procedure pngfinishdata(var f : tpngwrite);
|
387 |
|
|
var
|
388 |
|
|
outputstr : string;
|
389 |
|
|
deflateresult : integer;
|
390 |
|
|
begin
|
391 |
|
|
with f do begin
|
392 |
|
|
repeat
|
393 |
|
|
setlength(outputstr,512);
|
394 |
|
|
deflatestream.next_out := pbytef(outputstr);
|
395 |
|
|
deflatestream.avail_out := length(outputstr);
|
396 |
|
|
deflateresult := deflate(deflatestream,Z_FINISH);
|
397 |
|
|
setlength(outputstr,length(outputstr)-deflatestream.avail_out);
|
398 |
|
|
writetochunk(f,outputstr);
|
399 |
|
|
|
400 |
|
|
until deflateresult=Z_STREAM_END;
|
401 |
|
|
deflateEnd(deflatestream);
|
402 |
|
|
stopchunk(f);
|
403 |
|
|
|
404 |
|
|
end;
|
405 |
|
|
end;
|
406 |
|
|
|
407 |
|
|
|
408 |
|
|
procedure pngfinish(var f : tpngwrite);
|
409 |
|
|
|
410 |
|
|
begin
|
411 |
|
|
with f do begin
|
412 |
|
|
//setlength(outputstr,512);
|
413 |
|
|
startchunk(f,'IEND');
|
414 |
|
|
|
415 |
|
|
stopchunk(f);
|
416 |
|
|
end;
|
417 |
|
|
|
418 |
|
|
end;
|
419 |
|
|
|
420 |
|
|
|
421 |
|
|
|
422 |
|
|
|
423 |
|
|
end.
|