Custom InkCanvas (MSDN Code Sample not working properly)

Answer 1

Why this is happening: The WPF InkCanvas control has a limited number of inputs per second when using a mouse; meaning that your stylus inputs will have greater and greater distances between them as you move the mouse faster and faster. The sample itself appears to draw elipses at every stylus input point, not in-between the points.

How to solve this: use a Tablet PC - a digitizer such as on a Tablet PC has a much higher number of inputs per second so it is more difficult to encounter, or fill in the blanks - essentially estimate based on previous points, perhaps a bezier curve.

Answer 2

Why this is happening

The custom InkCanvas in the example draws an ellipse at every collected StrokePoint but makes no attempt to draw lines between them. The standard InkCanvas control is implemented by drawing lines between the points it is given. This is why the custom InkCanvas implementation from the example leaves gaps and the built-in one doesn't.

How to "fix" it

The custom code could easily be extended to not leave gaps: In addition to drawing ellipses at each point, it could draw lines between each pair of points.

Code to draw connecting lines might be added before the code to draw the ellipses, like this:

// Draw connecting lines
var geo = new StreamGeometry();
using(geoContext = geo.Open())
{
  geoContext.StartFigure(stylusPoints[0], false, false);
  geoContext.PolyLineTo(stylusPoints.Skip(1).Cast<Point>(), true, false);
}
drawingContext.DrawGeometry(null, connectingLinePen, geo);

// Draw ellipses
for(int i = 1; i < stylusPoints.Count; i++)
{
  ... etc ...

This code works by constructing a polyline StreamGeometry and then drawing it to the context. Using a StreamGeometry in this context is generally more efficient than creating a PathGeometry with a Polyline or doing a bunch of DrawLine calls directly on the drawingCanvas.

Note: Using a better digitizer won't solve the underlying problem, which is that the custom InkCanvas is actually designed to only show data at the sampled points and not in between.

Answer 3

ReDAeR Look this http://msdn.microsoft.com/en-us/library/bb531278.aspx