BGRAGraphicControl turns transparent onredraw

[MaartenJB]

Hi,

I've got an issue with the with the TBGRAGraphicControl component. When I reposition for example a button on the form from within the onredraw, the canvas turns transparent for a moment, before painting it. This does not happen with the TBGRAVirtualScreen. This is the test code I use:

procedure TForm1.FormCreate(Sender: TObject);
begin
  with BGRAGraphicControl1
  do begin
    Align:=alLeft;
    BevelOuter := bvNone;
    Color := clYellow;
    ColorOpacity:=255;
    Caption := '';
  end;

  with BGRAVirtualScreen1
  do begin
    Align:=alRight;
    Caption := '';
  end;
end;

procedure TForm1.FormResize(Sender: TObject);
begin
  BGRAGraphicControl1.Width := (Form1.Width div 2);
  BGRAVirtualScreen1.Width := Form1.Width - BGRAGraphicControl1.Width-10;
end;

procedure TForm1.BGRAGraphicControl1Redraw(Sender: TObject; Bitmap: TBGRABitmap);
begin
  Bitmap.FillRect(0, 0, Bitmap.Width, Bitmap.Height, clLime);
  sleep(10); // To make it a little bit more visible
  Button1.Left := (Form1.Width div 2); // <--- enable this and the screen flickers
end;

procedure TForm1.BGRAVirtualScreen1Redraw(Sender: TObject; Bitmap: TBGRABitmap);
begin
  Bitmap.FillRect(0, 0, Bitmap.Width, Bitmap.Height, clRed);
  sleep(10); // To make it a little bit more visible
  //Button1.Left := (Form1.Width div 2); // <--- enable this and the screen won't flicker  (and disable the above)
end; 

Is this fixable? I've looked into the onredraw source, but can't find a problem there.

Best regards, Maarten

[circular17]

Hi

That's kind of normal. The thing is you need to decide where the button is before redrawing the content. What is supposed to trigger the button to move? Surely not the update of the graphic control.

[MaartenJB]

Hi, ah ok, that makes sense. I have a grid menu of buttons that need to be center on the graphic control. (even if you resize the application)

I've moved the positioning of the buttons to the onresize of the form, and that works fine.

Thanks for the fast response.

Maarten

[MaartenJB]

user error corrected ;-)

[circular17]

Happy you found your way :-)