Mega Code Archive
Compress, decompress a stream
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uses
ZLib;
{ Compress a stream }
procedure CompressStream(inpStream, outStream: TStream);
var
InpBuf, OutBuf: Pointer;
InpBytes, OutBytes: Integer;
begin
InpBuf := nil;
OutBuf := nil;
try
GetMem(InpBuf, inpStream.Size);
inpStream.Position := 0;
InpBytes := inpStream.Read(InpBuf^, inpStream.Size);
CompressBuf(InpBuf, InpBytes, OutBuf, OutBytes);
outStream.Write(OutBuf^, OutBytes);
finally
if InpBuf <> nil then FreeMem(InpBuf);
if OutBuf <> nil then FreeMem(OutBuf);
end;
end;
{ Decompress a stream }
procedure DecompressStream(inpStream, outStream: TStream);
var
InpBuf, OutBuf: Pointer;
OutBytes, sz: Integer;
begin
InpBuf := nil;
OutBuf := nil;
sz := inpStream.Size - inpStream.Position;
if sz > 0 then
try
GetMem(InpBuf, sz);
inpStream.Read(InpBuf^, sz);
DecompressBuf(InpBuf, sz, 0, OutBuf, OutBytes);
outStream.Write(OutBuf^, OutBytes);
finally
if InpBuf <> nil then FreeMem(InpBuf);
if OutBuf <> nil then FreeMem(OutBuf);
end;
outStream.Position := 0;
end;
{
Example:
Compress the contents of RichEdit1 and
calculate the compression rate.
Then save the stream to a file (ms2.dat)
Beispiel:
Komprimiert den Inhalt von RichEdit1 und
berechnet die Kompressionsrate.
Dann wird der Stream in eine Datei (ms2.dat) gespeichert.
}
procedure TForm1.Button1Click(Sender: TObject);
var
ms1, ms2: TMemoryStream;
begin
ms1 := TMemoryStream.Create;
try
ms2 := TMemoryStream.Create;
try
RichEdit1.Lines.SaveToStream(ms1);
CompressStream(ms1, ms2);
ShowMessage(Format('Stream Compression Rate: %d %%',
[round(100 / ms1.Size * ms2.Size)]));
ms2.SaveToFile('C:\ms2.dat');
finally
ms1.Free;
end;
finally
ms2.Free;
end;
end;
{
Loads the stream from a file (ms2.dat)
and decompresses it.
Then loads the Stream to RichEdit1.
Lädt den komprimierten Stream von einer Datei (ms2.dat)
und dekomprimiert ihn.
Dann wird der Stream wieder in RichEdit1 geladen.
}
procedure TForm1.Button2Click(Sender: TObject);
var
ms1, ms2: TMemoryStream;
begin
ms1 := TMemoryStream.Create;
try
ms2 := TMemoryStream.Create;
try
ms1.LoadFromFile('C:\ms2.dat');
DecompressStream(ms1, ms2);
RichEdit1.Lines.LoadFromStream(ms2);
finally
ms1.Free;
end;
finally
ms2.Free;
end;
end;
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