MakeScreenshot for dynamically created control

Question

I need to dynamically draw created control to bitmap.

But it does not work, it does not draw anything.

procedure TForm2.Button1Click(Sender: TObject);
var
  cb: TCheckBox;
  BMP: TBitmap;
begin
  BMP:= nil;

  cb:= TCheckBox.Create(nil);
  try
    cb.IsChecked:= true;
    cb.Repaint;
    BMP:= cb.MakeScreenshot;
    BMP.SaveToFile('C:\bmp.bmp');
  finally
    FreeAndNil(cb);
    FreeAndNil(BMP);
  end;
end;

I have tried also directly PaintTo - but the same effect. I have tried also setting parent but this is still not enough.

If i do same for control placed by hand on the form it is working, but dynamically created not.

How to do this. This control should not be visible anywhere i need to paint it only and free it.

Answer 1

Two issues. First, you do need the control to be parented for it to be paintable.

Second, you're saving as a BMP which does not support the transparency used in FMX to generate the screenshot (and is platform specific besides). Save it as a PNG instead.

procedure TForm1.FormCreate(Sender: TObject);
var
  cb: TCheckBox;
  BMP: TBitmap;
begin
  BMP:= nil;
  cb:= TCheckBox.Create(nil);
  try
    cb.Parent := self;
    cb.Text := 'testing';      
    cb.IsChecked:= true;
    bmp := cb.MakeScreenshot;
    BMP.SaveToFile('C:\bmp.png');
  finally
    cb.Free;
    BMP.Free;
  end;
end;