Question

I am using stylus input to draw lines in a canvas. I want to change the color of the stroke with the pen pressure. so I used:

DrawingAttributes dattribute = new DrawingAttributes();
inkcan.EditingMode = InkCanvasEditingMode.Ink;

if (stylusInput.pressureFactor < 0.5)
dattribute.Color = Colors.Red;
else
dattribute.Color = Colors.Blue;

inkcan.DefaultDrawingAttributes = dattribute;

but I have found that the color changes only when I lift off and retouch the pen to tablet surface. I am not sure how to fix that problem.

Any help would be greatly appreciated.

Answer 1

Look at this question: InkCanvas Eraser

In the MSDN it states:

If you change the EraserShape, the cursor rendered on the InkCanvas is
not updated until the next EditingMode change.

The effect you are experiencing might be caused by the EditingMode being changed when you pull the pen off the canvas and put it back down.

If so, you could toggle the EditingMode property as I suggested in the linked answer.

EDIT

Have a look at this a 3rd down it says:

Off course, life is never as simple as that, so there is one more
little issue to handle. Apparently, the InkCanvas uses different
renderers for the final result compared to while the strokes are being
drawn. To show a transparency based on the pressure while the
drawing action is still in progress, we need to use the protected
property called DyamicRenderer which gets/sets the object used to
render the strokes on a drawing context while the stroke is being
drawn. This rendering object must be a descendent of DynamicRenderer.
All you need to do here is override the OnDraw method and change the
brush that is used. When you assign a new value to this property, the
InkCanvas actually changes an internal ‘PlugIn list’ which is called
whenever data is entered using the stylus.

This might be it.