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{
This file is part of the Free Pascal run time library.
Copyright (c) 2003 by the Free Pascal development team
PNG reader/writer common code.
See the file COPYING.FPC, included in this distribution,
for details about the copyright.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
**********************************************************************}
{$mode objfpc}{$h+}
unit PNGcomn;
interface
uses SysUtils, FPImage, FPImgCmn;
type
PNGImageException = class (FPImageException);
TChunkTypes = (
ctIHDR, ctcHRM, ctgAMA, ctsBIT,
ctPLTE, ctbKGD, cthIST, cttRNS,
ctoFFs, ctpHYs, ctIDAT, cttIME,
ctsCAL, cttEXt, ctzTXt, ctIEND,
ctsRGB, ctiCCP, ctiTXt, ctsPLT,
ctUnknown
);
EightLong = array[0..7] of longword;
TChunkCode = array[0..3] of char;
TChunk = record
acapacity, alength, CRC : longword;
ReadType : TChunkCode;
data : PByteArray;
aType : TChunkTypes;
end;
TChunkHeader = record
CLength : longword;
CType : TChunkCode;
end;
THeaderChunk = record
Width, height : longword;
BitDepth, ColorType, Compression, Filter, Interlace : byte;
end;
const
Signature : Array[0..7] of Byte = ($89, $50, $4E, $47, $0D, $0A, $1A, $0A);
MaxChunkLength = $7FFFFFFF;
All1Bits : longword = $FFFFFFFF;
ChunkTypes : array[TChunkTypes] of TChunkCode = (
'IHDR', 'cHRM', 'gAMA', 'sBIT',
'PLTE', 'bKGD', 'hIST', 'tRNS',
'oFFs', 'pHYs', 'IDAT', 'tIME',
'sCAL', 'tEXt', 'zTXt', 'IEND',
'sRGB', 'iCCP', 'iTXt', 'sPLT',
'Unkn'
);
ChunkAncillary = $10000000;
ChunkPrivate = $00100000;
ChunkReserved = $00001000;
ChunkSafeCopy = $00000010;
StartRow : Array[0..7] of Integer = (0, 0, 0, 4, 0, 2, 0, 1);
StartCol : Array[0..7] of Integer = (0, 0, 4, 0, 2, 0, 1, 0);
RowInc : Array[0..7] of Integer = (1, 8, 8, 8, 4, 4, 2, 2);
ColInc : Array[0..7] of Integer = (1, 8, 8, 4, 4, 2, 2, 1);
BlockHght : Array[0..7] of Integer = (1, 8, 8, 4, 4, 2, 2, 1);
BlockWdth : Array[0..7] of Integer = (1, 8, 4, 4, 2, 2, 1, 1);
implementation
end.
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