TJpegImage and compression 3

[towerbase]

I have never been able to get Delphi to compress a jpeg image. I set CompressionQuality to any value and then call Compress but the file is always saved with a length of zero bytes. Can someone tell me what I'm doing wrong? (It fails, for me, with Delphi 5 and Delphi 7).

uses jpeg;

procedure TForm1.GoClick(Sender: TObject);
const
  path = 'c:\';
var
  jpeg: TJpegImage;
begin
  jpeg := TJpegImage.Create;
  try
    jpeg.LoadFromFile( path + 'Old.jpg');
    jpeg.CompressionQuality := 50;
    jpeg.Compress;
    jpeg.SaveToFile ( path + 'New.jpg' );
  finally
    jpeg.Free;
  end;
end;

Andrew

 

[123rest]

Have a look at this site, they have Jpeg components with
compression

http://www.mwasoftware.co.uk

 

[halfyawn]

//--------------------------------------------
uses jpeg;

procedure TForm1.GoClick(Sender: TObject);
const
path = 'c:\';
var
jpeg: TJpegImage;
bmp: TBitmap;
begin
jpeg := TJpegImage.Create;
bmp := TBitmap.Create;
try
jpeg.LoadFromFile( path + 'Old.jpg');
bmp.Assign(jpeg);
jpeg.Assign(bmp);
jpeg.CompressionQuality := 50;
jpeg.Compress;
jpeg.SaveToFile ( path + 'New.jpg' );
finally
bmp.Free;
jpeg.Free;

end;
end;

 

[towerbase]

Now why didn't I try that?

Many thanks, halfyawn. Your code works. A star for you.

Andrew