Question Error Saving a JPegImage

Once I modify a JPEG image I can't save it to a stream or file.  Always gets "File not open." error message.  No errors with PNG or BITMAP images. 

basic code example:

Procedure Tform1.ButtonLoadImageClick(Sender : Tobject);
Var
  AFileName : TFileName;
  AJPeg : TJPegImage;
  AStream : TMemoryStream;
Begin
  If GetFileName(AFileName, 'JPEG Images (*.jpg)|*.jpg') Then  //  Just a dialog box to select a jpeg image
  Begin
    AJPeg := TJPegImage.Create;
    Try
      AJPeg.LoadFromFile(AFileName);
      ResizeJPeg(AJpeg, 200, 200);
      Image1.Picture.Assign(AJPeg);  //  resized image displays fine here
      AStream := TMemoryStream.Create;
      Try
        AJPeg.SaveToStream(AStream);  //  Here is the error "File not open."
      Finally
        FreeAndNil(AStream);
      End;
    Finally
      FreeAndNil(AJPeg);
    End;
  End;
End;     

Thanks

Robert

Forgot to let you know

Typhon 7.5 x64 version
Windows 10 x64 with all updates

Robert

If I do not modify the JPEG it seems to be fine.  If I just load and save all works.  But when loading a PNG and converting to a JPEG it gives the error.  And when resizing a JPEG it gives that error.  No errors doing same things with PNG.  I can load JPEG and convert to PNG just fine.  I can resize a PNG just fine.  It is only when modifying a JPEG and then trying to save it.  It appears to be an issue in the SaveToStream procedure but I tried to trace through with the debugger and could not figure it out. 

Here is the code I have been using to resize a JPEG.  If you just change the data type to a PNG it works for a PNG fine.


Procedure ResizeJPeg(Const AJPegImage: TJPegImage; Const AWidth, AHeight: Integer);
Var
  ARect:    TRect;
  ATempJPeg: TJPegImage;
  X, Y:     Integer;
Begin
  If (AJPegImage.Width = AWidth) And (AJPegImage.Height = AHeight) Then Exit;

  FillChar(ARect, SizeOf(TRect), 0);
  If (AJPegImage.Width > AJPegImage.Height) Then
  Begin
    ARect.Right := AWidth;
    ARect.Bottom := ((AWidth * AJPegImage.Height) Div AJPegImage.Width);
    X := 0;
    Y := (AHeight Div 2) - (ARect.Bottom Div 2);
  End
  Else
  Begin
    ARect.Right := ((AHeight * AJPegImage.Width) Div AJPegImage.Height);
    ARect.Bottom := AHeight;
    X := (AWidth Div 2) - (ARect.Right Div 2);
    Y := 0;
  End;

  ATempJPeg := TJPegImage.Create;
  Try
    ATempJPeg.PixelFormat := AJPegImage.PixelFormat;
    ATempJPeg.Transparent := AJPegImage.Transparent;
    ATempJPeg.TransparentMode := AJPegImage.TransparentMode;
    ATempJPeg.TransparentColor := AJPegImage.TransparentColor;
    ATempJPeg.SetSize(AWidth, AHeight);
    ATempJPeg.Canvas.FillRect(ATempJPeg.Canvas.ClipRect);
    ATempJPeg.Canvas.StretchDraw(ARect, AJPegImage);

    AJPegImage.SetSize(AWidth, AHeight);
    AJPegImage.Canvas.FillRect(AJPegImage.Canvas.ClipRect);
    AJPegImage.Canvas.Draw(X, Y, ATempJPeg);
  Finally
    FreeAndNil(ATempJPeg);
  End;
End;

If you suggest a better routine to resize a JPEG that would be fine as well.  Speed is not so important for what I am doing.

Here is my routine for loading a PNG and converting it to a JPEG.  The routine seems to work but when I attempt to save the resulting JPEG I get the same error.  It does display correctly in a TImage.

Function PngToJPeg(Const APng: TPngImage; Const AJPeg: TJPegImage): Boolean;
Begin
  Result := False;
  Try
    AJPeg.Clear;
    AJPeg.Transparent := APng.Transparent;
    If (AJPeg.Transparent) Then
    Begin
      AJPeg.TransparentColor := APng.TransparentColor;
      AJPeg.TransparentMode := APng.TransparentMode;
    End;
    AJPeg.Width := APng.Width;
    AJPeg.Height := APng.Height;
    AJPeg.PixelFormat := APng.PixelFormat;
    AJPeg.Canvas.Draw(0, 0, APng);
    Result := True;
  Except
    Result := False;
  End;
End;
 

Robert

Thanks for looking into this.  I will either reinstall current release or upgrade to latest development version and try again.  I did add a patch to fix an issue with QR code generation but outside of that I have not modified any core code. 

Robert

I used CT Center to download "LAB Development Version (Experimental)".  After everything downloaded and compiled there are no errors with JPEG.  I also double checked my QR Code generation tool and it also compiled and ran fine with no error. 

Thank you VERY much for you help on this issue and EVERYTHING you do with CodeTyhpon!!!  CodeTyphon is my favorite development tool!!

Robert