Drawing degenerate QCanvasPolygon not working

[kalos80]

Hi there,

I have subclassed the QCanvasPolygon class and reimplemented the drawShape function in order to draw polygons with outlines (QCanvasPolygon class doesn't allows outlines for polygons).

class MyPolygon: public QCanvasPolygon
 {
....
   void drawShape(QPainter &){...}
};

class MyPolygon: public QCanvasPolygon
 {
....
   void drawShape(QPainter &){...}
};

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The drawShape in MyPolygon is working and I can see an outline for polygons that are in the canvas view.

The problem is that if a polygon is degenerate, that is if all verteces of the polygon are on a straight line (this implies that the area of the polygon is null), the drawShape of the polygon is not called when I update the canvas, so the polygon is not drawn.

Thanks in advance for your help!

[marcel]

Why didn't you create a custom pen for the outline and then set it with setPen?
The degenerate item isn't painted because Qt thinks it has nothing to draw.

Regards

[kalos80]

Is there a way to force the Qt to draw the item also if it is a degenerate polygon?

I had a look to the QCanvas code but I didn't find any clue.

[marcel]

Try setting an invisible ( transparency = 1.0 ) stroke for the polygon.

Regards