Delphi image canvas... paint an area (triangle, rectangle, polygons) - delphi

Question

I have a variable number of points on a canvas.
Sometime its four other times 3 points, or 6.
Is there a function that can paint the area inside?
Thank you for your help.

Answer 1

Use the TCanvas.Polygon function. Declare an array of TPoint, set its length to the count of your points, specify each point's coordinates (optionally modify canvas pen and/or brush) and pass this array to the TCanvas.Polygon function. Like in this boring example:
procedure TForm1.Button1Click(Sender: TObject);
var
Points: array of TPoint;
begin
SetLength(Points, 3);
Points[0] := Point(5, 5);
Points[1] := Point(55, 5);
Points[2] := Point(30, 30);
Canvas.Pen.Width := 2;
Canvas.Pen.Color := clRed;
Canvas.Brush.Color := clYellow;
Canvas.Polygon(Points);
end;
Here's how it looks like:

Answer 2

As a complement to TLama's excellent answer, this is a case where you can obtain pretty convenient syntax using the open array construct. Consider the helper function
procedure DrawPolygon(Canvas: TCanvas; const Points: array of integer);
var
arr: array of TPoint;
i: Integer;
begin
SetLength(arr, Length(Points) div 2);
for i := 0 to High(arr) do
arr[i] := Point(Points[2*i], Points[2*i+1]);
Canvas.Polygon(arr);
end;
defined and implemented once and for all. Now you can do simply
Canvas.Pen.Width := 2;
Canvas.Pen.Color := clRed;
Canvas.Brush.Color := clYellow;
DrawPolygon(Canvas, [5, 5, 55, 5, 30, 30]);
to draw the same figure as in TLama's example.

Answer 3

As a complement to both TLama's and Andreas answer, here's another alternative :
procedure TForm1.Button1Click(Sender: TObject);
begin
Canvas.Pen.Color := clRed;
Canvas.Brush.Color := clYellow;
Self.Canvas.Polygon( [Point(5,5), Point(55,5), Point(30,30)]);
end;
Utilizing open array construct and Point record.