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[sir.dev.a.lot]

[TRUCO DELPHI] Comprimir y Descomprimir un Stream.

 

Hay que adicionar esta Unidad.

delphi

Uses ZLib;

delphi

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;
 
 
 
	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;

Ejemplo de uso:

delphi

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;
 
 
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;

Saludos!