Animated Dashed Border in Android

Question

How do you create an animated dashed or dotted border of an arbitrary shape in Android? In XML (preferred) or programmatically.

See picture below for an example.

Answer 1

Have you seen the PathEffects API demo? http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/PathEffects.html

It produces precisely an animated line and you can just adjust the path to the edge of your view to create a border. For example:

Define a path by your view parameters / arbitrary shape:

Path path = new Path();
path.addRect(view.getLeft(), view.getTop(), view.getRight(), view.getBottom(), Path.Direction.CW);

Then create a dashed PathEffect with:

PathEffect pe = new DashPathEffect(new float[] {10, 5, 5, 5}, phase);

Then set the associate it with a Paint object and draw:

mPaint.setPathEffect(pe);
canvas.drawPath(path, mPaint);

EDIT: The animated effect comes from continuously changing the phase and redrawing. In the API demo it calls invalidate() in the onDraw() method (which triggers onDraw()...)