Drawing dynamic polygons in WPF

Question

I am not sure if this is the right place to ask for such concept information advice, so I apologise if it's unrelated or off-topic to ask in Stack Overflow.

I want to develop an application in WPF which has the ability to draw polygons with the functionality of a regular control, they may change shape by adding, removing or moving vertices, change brushes all by run-time, from data-binding or perhaps direct manipulating from C# code (still not sure about that).

What I am trying to achieve is an application which draws a map and the shapes on it are the entities with the dynamic borders over the map (for instance say political borders). The polygons also have to be clickable controls with collision test (not just a bounding box, but exactly by the shape of the entity on the map). I can expect the shapes to be very detailed because of borders which found by rivers and mountains or other natural objects which not just a straight line of two vertices, so it's performance should be an important factor here because one polygon may contain hundreds of vertices).

What I've concluded that it is possible to achieve via WPF such an application. But my uncertainty is on the most efficient way to implement the map drawing, perhaps I should implement D3D hosting like SharpDX but I don't want it, it would make things even more complicated and difficult.

I prefer everything in this map to be functional as a regular WPF control with it's data-binding and stylising abilities. I've developed with WPF some several small test projects for months to learn the basics and its main concept. But now comes the main interest of mine to develop with WPF. I need some advice please, because drawing complicated and dynamic shapes is still not really clear to me to just go on and start develop it.

Answer 1

I would use WPF, indeed I would say WPF is perfect for this, though there will be considerable amount to learn. WPF uses DirectX so is preformant enough I imagine (provided you have the hardware).

You will need to become familiar with:

• UserControl
• DependencyProperties
• Polygon
• Canvas

However if you are not already familiar with Dependency Properties, they can be a headache to learn, so rather than creating your own UserControl with them, you can get away with a Canvas in your Window and build things programmatically or at design time in XAML.

As for actually drawing shapes; if you know ahead of time what the shapes will look like you can draw them ahead of time using tool like Blend (or by yourself in XAML - you will need to become familiar with the Path Markup Syntax) then you can use transforms such as a ScaleTransform to transform them at run-time, or if you want to build them at run-time you can do so programmatically adding points to a Polygon

e.g. from (Polygon)

//Add the Polygon Element
myPolygon = new Polygon();
myPolygon.Stroke = System.Windows.Media.Brushes.Black;
myPolygon.Fill = System.Windows.Media.Brushes.LightSeaGreen;
myPolygon.StrokeThickness = 2;
myPolygon.HorizontalAlignment = HorizontalAlignment.Left;
myPolygon.VerticalAlignment = VerticalAlignment.Center;
System.Windows.Point Point1 = new System.Windows.Point(1, 50);
System.Windows.Point Point2 = new System.Windows.Point(10,80);
System.Windows.Point Point3 = new System.Windows.Point(50,50);
PointCollection myPointCollection = new PointCollection();
myPointCollection.Add(Point1);
myPointCollection.Add(Point2);
myPointCollection.Add(Point3);
myPolygon.Points = myPointCollection;
myGrid.Children.Add(myPolygon);