TUniCanvas Polygon Floodfill Issue

[andyhill]

Using UniCanvas I build many polygons and flood fill some.

I am having issues with this polygon and FloodFill (not others) - please advise - Thanks

387/134
385/133
380/132
375/133
373/135
371/139
371/144
373/150
377/161
383/171
385/175
385/176
385/177
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386/187
390/194
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398/185
396/178
394/169
391/159
387/134

    // I suspect the winding direction of the polygon points

    // Right, Down
    p.X:= PlyArray[0].X+1; // PlyArray[0].X+2; PlyArray[0].X-1; PlyArray[0].X-2;
    p.Y:= PlyArray[0].Y + 1; // PlyArray[0].Y + 2; PlyArray[0].Y - 1; PlyArray[0].Y - 2;
    //p.X:= PlyArray[n].X+1; // PlyArray[n].X+2; PlyArray[n].X-1; PlyArray[n].X-2;
    //p.Y:= PlyArray[n].Y + 1; // PlyArray[n].Y + 2; PlyArray[n].Y - 1; PlyArray[n].Y - 2;

    // My Point "p" Is Inside the Polygon by a few pixels, if I make sure "p" has say 10px margin from the edges then in it fills, 2px margin it does not   
    if PointInPolygon(p, PlyArray) = True then begin
      cArea.MoveTo(p.X, p.Y);
      HoldColour:= cArea.Brush.Color;
      HoldOpacity:= cArea.Brush.Opacity;
      cArea.Brush.Color:= FillColour;
      cArea.Brush.Opacity:= 0.25;
      cArea.FloodFill(p.X, p.Y);
      cArea.Brush.Color:= HoldColour;
      cArea.Brush.Opacity:= HoldOpacity;

 

[andyhill]

As I expected it is related winding and Anti-Aliasing.

[andyhill]

Please see image below, you will notice each polygon center has a small red circle indicator.

Note the polygon that will not Flood Fill even though we are in the center of the polygon.

As mentioned earlier it is an anti-aliasing issue.

Please advise how to turn off anti-aliasing -or- better still how to resolve (set edge proximity) ?