Hi,

Is it possible to, within a Diagram, autosnap nodes if they are within a certain amount of distance (WpfPoint) of each other?

I first want to try snapping them to the bottom of each other. I have a startnode that has a certain height (75) and a set position (Point start = new Point(270, 20)). So the position where I want the next node is Point destination = new Point(x, 95); 75 + 20. But I still want to be able to move the node around. Only if it comes within, let's say 10 WpfPoints, should it snap to that destination point. How can I do this?

Thanks in advance!

Vincent

That works, thanks!

I have another question:
I'm using the Factory to create a node in the diagram. The method for a ShapeNode requires 4 parameters of which the first 2 are the coordinates to where the node should be placed. I tried to do this dynamically by getting the width and height of the parent element. But when I run it the node doesn't appear. And when I show the width in a MessageBox I get a NaN value. What am I doing wrong?

Thanks in advance!

Vincent

Ah ok. What I want is to place the node based on the width of the diagram. I tried to achieve that by calling the parent property but its width is NaN. Is there another way I can get the width?

It works!
ActualWidth gives back 0 but the Bounds.Width returns the width that I was searching for.

Thanks Stoyan!

Vincent

Hi,

There is no built-in support for aligning nodes by their geometries. You will have to implement that yourself, by overriding either UpdateModify in a custom node type, or AlignPointToGrid in a derived Diagram class. For example, this aligns the dragged node's top-middle point to a target node's interior point (X at center, Y at 2/3 height):

protected override void UpdateModify(Point current, InteractionState ist)
{
	base.UpdateModify(current, ist);
	Align(current, ist);
}

protected override void CompleteModify(Point end, InteractionState ist)
{
	base.CompleteModify(end, ist);
	Align(end, ist);
}

private void Align(Point current, InteractionState ist)
{
	if (ist.AdjustmentHandle == 8 /* move */)
	{
		var nearbyNode = Parent.GetNearestNode(current, 60, this);
		if (nearbyNode != null)
		{
			var r1 = nearbyNode.Bounds;
			var targetPoint = new Point(r1.X + r1.Width / 2, r1.Bottom - r1.Height / 3);

			var r2 = this.Bounds;
			var pointToSnap = new Point(r2.X + r2.Width / 2, r2.Y);

			double dx = targetPoint.X - pointToSnap.X;
			double dy = targetPoint.Y - pointToSnap.Y;

			r2.Offset(dx, dy);
			SetBounds(r2, true, true);
		}
	}
} 

If you use only a few node types, your could keep potential pointToSnap / targetPoint lists for each pair of node types. Otherwise you could loop over points of both nodes' geometries, in sequences of 3, and check whether the current 3 points of the dragged node are at the same offset from the current 3 points of the target node; in such case, use the middle points of the sequences as snap / target points.

I hope that helps,
Stoyan

It should be possible, you'll need to loop over all potential target points, check their distance to the source snap points, and finally snap between the nearest points:

Point[] sourcePoints = ...;
Point[] targetPoints = ...;
double minDistance = double.MaxValue;
foreach (var s in sourcePoints)
{
    foreach (var t in targetPoints)
    {
        double d = Utilities.Distance(s, t);
        if (d < minDistance)
        {
            minDistance = d;
            targetPoint = t;
            snapPoint = s;
        }
    }
}

// proceed with alignment from snapPoint to targetPoint
 

I hope that helps,
Stoyan

Hi Vincent,

You cannot use LineTemplates in that case, they specify coordinates as percent and can resize only proportionally to the node's dimensions. Instead, you could either draw the shape from a Draw override, or use Shape(CreatePathDelegate) or Shape(formula) constructors.

I hope that helps,
Stoyan

Hi,

The C shape could be defined like that:

new Shape(@"
	LineTo(Width, 0);
	LineTo(Width, 20);
	LineTo(20, 20);
	LineTo(20, Height - 20);
	LineTo(Width, Height - 20);
	LineTo(Width, Height);
	LineTo(0, Height);
	LineTo(0, 0);
	", "C"); 

Min returns the smaller of its two arguments, as usual E.g. you might want to apply Min if you are letting users resize the shape, to make sure some elements don't start sticking outside when the node gets small. If you only allow moving these nodes and are setting their size from code, you can safely use fixed values such as the 20 above.

I hope that helps,
Stoyan