draw rotated path at particular point

Question

I'm working on a custom view (extends View) and working in the onDraw method.

I have made a path of an arrow:

    ARROW_PATH = new Path();
    ARROW_PATH.setLastPoint(20, 37);
    ARROW_PATH.lineTo(14, 25);
    ARROW_PATH.lineTo(18, 26);
    ARROW_PATH.lineTo(17, 4);
    ARROW_PATH.lineTo(23, 4);
    ARROW_PATH.lineTo(22, 26);
    ARROW_PATH.lineTo(26, 25);
    ARROW_PATH.close();

In different scenarios it needs to be rotated to depict a certain angle, and I need to draw it at a particular coordinate in the view. The coordinate also changes depending on the scenario.

I've tried playing around with Canvas.rotate however, it looks like the aspect of the path is skewed when the px and py values are not equal (the arrow gets narrower and taller when py > px.

I have also tried Canvas.rotate(angle, 0, 0); and then ARROW_PATH.moveTo(x, y); but it looks like the coords are rotated by the arbitrary angle making it very hard to calculate the required coordinate.

Ideally, I'd like to rotate the path and not the canvas but I don't think this operation is supported by the API.

Can someone suggest a better approach to this problem?

thanks, p.

Answer 1

This is a proper way to permanently rotate a path (it will stay like this until the next application of a matrix):

Matrix mMatrix = new Matrix();
RectF bounds = new RectF();
mPath.computeBounds(bounds, true);
mMatrix.postRotate(myAngle, bounds.centerX(), bounds.centerY());
mPath.transform(mMatrix);