Drawing on canvas

[JusJJ 0]

Hi,

Is there a way to prevent drawing outside the canvas?
If, for example, I have a rectangular shape on which I draw an ellipse and I want to limit the drawing to the area of the shape.

procedure TForm1.shapePaint(Sender: TObject; Canvas: TCanvas;
  const ARect: TRectF);
  var
  x,y :integer;
  circle : TRectF;
begin

    x:=round(shape.Width/2);
    y:=round(shape.Width/2);

    circle:=TRectF.Create(x-190,y-190,x+100,y+100);
    shape.Canvas.Stroke.Color:=TAlphaColors.Black;
    shape.Canvas.DrawEllipse(circle,50);
end;

Now part of it is also drawn outside the shape.

[PeaShooter_OMO 10]

Have a look at Clipping Regions.. Here is a little example (Obviously this for the Windows platform):

 

https://docwiki.embarcadero.com/CodeExamples/Sydney/en/ClipRect_(Delphi)

Edited May 10, 2023 by PeaShooter_OMO

[Remy Lebeau 1264]

8 hours ago, PeaShooter_OMO said:

Have a look at Clipping Regions.. Here is a little example (Obviously this for the Windows platform):

 

https://docwiki.embarcadero.com/CodeExamples/Sydney/en/ClipRect_(Delphi)

Clipping is the right solution.  But ClipRect() won't work for FMX.

 

In FMX, to clip a drawing to a rectangular area, use the TCanvas.IntersectClipRect() and TCanvas.ExcludeClipRect() methods.  To clip in a non-rectangular area, use TCanvas.DrawPath() and TCanvas.FillPath() instead.