Hi there,

I have some shape nodes and for I do not know what reason the method ContainsPoint(diagramPoint) return false for some situations when the mouse is inside the node.
Here are some images displayingthe situations: ContainsPoint method returns false:

ContainsPoint method returns true:


When the ContainsPoint method returns true the mouse cursor is changed.

Can anybody point me to a solution.

Dexter

I am using custom behavior and in the method SetMouseCursor I am searching for a node at the point using Diagram.GetItemAt(point, exclLocked). If i find a node I set the diagramView.PointerCursor to a custom cursor (the one in the second picture) and return the CursorHint.Pointer.

I must say that this is visible only with a large zoom (500 and more) and on shapes that have some kinds of rounded corners (round rectangles, or ellipse shapes).

I hope this helps.

Dexter

Hi,

I can see a margin of couple of pixels in or out where hit-testing is not correct  at zoom level 500, but not as much as in your image.

Hit-testing for ShapeNodes is implemented by calling GraphicsPath.IsVisible(), and so we can't think of anything to make it better.

If you need better precision at large zoom levels that much, you might try overriding ContainsPoint and use the ellipse's equation to determine if a point is inside. That could still lead to differences with what's shown on screen, because the shapes are rendered as GraphicsPaths, and GDI+ paths are implemented as a series of straight line segments and Bezier splines - there will be no trace of the ellipse there.

For even better precision you might override Draw to call DrawEllipse instead of using GraphicsPaths, but then it's still not clear if there will be much improvement because ellipses are rendered using the Bresenham's algorithm and not through the ellipse equation.

Of course you can draw ellipses point by point using the equation, but then rendering will be very slow. All in all, we would not invest time in this, but you have some options to try if you wish to.

Stoyan