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* Simulate position

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This commit is contained in:
Michaël Van Canneyt 2022-11-23 21:50:03 +01:00
parent dbd87a3cfc
commit 5288194d3c
1 changed files with 29 additions and 2 deletions
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31
packages/fcl-base/src/lzwstream.pp
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@ -88,6 +88,7 @@ Type
FOutSize : Cardinal;
FOutRead : Cardinal;
FFirstRead : Boolean;
FPosition : Int64;
procedure MoveFromBuffer(Dest: PByte; aCount: Integer);
Protected
function ReadByte(out aByte: Byte): Boolean;
@ -98,8 +99,11 @@ Type
procedure WriteStringFromCode(aCode: integer; AddFirstChar: boolean = false);
Procedure FillInBuffer;
Procedure FillOutBuffer;
function GetPosition: Int64; override;
procedure SetPosition(const Pos: Int64); override;
Public
Constructor Create(aSource : TStream; aOptions : TLZWStreamOptions; InitialBufsize : Word = LZWDefaultBufSize); overload;
function Seek(const Offset: Int64; Origin: TSeekOrigin): Int64; override;
function Read(var Buffer; Count: Longint): Longint; override;
end;
@ -278,7 +282,7 @@ end;
procedure TLZWDecompressionStream.WriteStringFromCode(aCode: integer; AddFirstChar: boolean = false);
var
s: TLZWString;
i : Integer;
// i : Integer;
begin
// WriteLn('WriteStringFromCode Code=',aCode,' AddFirstChar=',AddFirstChar);
@ -378,6 +382,18 @@ begin
until FOutSize>=FillCapacity;
end;
function TLZWDecompressionStream.GetPosition: Int64;
begin
Result:=FPosition;
end;
procedure TLZWDecompressionStream.SetPosition(const Pos: Int64);
begin
if Pos=FPosition then
exit;
inherited SetPosition(Pos);
end;
constructor TLZWDecompressionStream.Create(aSource: TStream;
aOptions: TLZWStreamOptions; InitialBufsize: Word);
begin
@ -386,6 +402,16 @@ begin
FOutSize:=0;
FOutRead:=0;
FFirstRead:=True;
FPosition:=0;
end;
function TLZWDecompressionStream.Seek(const Offset: Int64; Origin: TSeekOrigin
): Int64;
begin
if (Offset=0) and (Origin=soCurrent) then
Result:=FPosition
else
Result:=inherited Seek(Offset, Origin);
end;
procedure TLZWDecompressionStream.MoveFromBuffer(Dest : PByte; aCount : Integer);
@ -395,7 +421,7 @@ begin
Inc(FOutRead,aCount);
end;
Procedure TLZWDecompressionStream.FillInBuffer;
procedure TLZWDecompressionStream.FillInBuffer;
begin
FInSize:=Source.Read(FInBuffer,SizeOf(FInBuffer));
@ -439,6 +465,7 @@ begin
if Count>0 then // we need more data
FillOutBuffer;
end;
Inc(FPosition,Result);
end;