android - Why is canvas not clipped in onDraw? -


in example, try invalidate rectangle of custom view, canvas passed ondraw not clipped. output shows clip bounds contain whole canvas. what's reason this?

public class clippingactivity extends activity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(new clippingview(this));     } }  class clippingview extends view {      rect r = new rect();      public clippingview(context context) {         super(context);     }      @override     protected void ondraw(canvas canvas) {         canvas.getclipbounds(r);         log.d("clippingview","ondraw: " + r);     }      @override     public boolean ontouchevent(motionevent event) {         invalidate(0,0,400,400);         return true;     } }

i found closely related question: partial invalidation in custom android view hardware acceleration

romain guy answered it:

partial redraw works fine, specified region of screen redrawn. won't change clip bounds on canvas. drawing operations recorded ones intersecting dirty region executed.


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