android - How to Draw a TextView into a Canvas then change the text later -

i have canvas , write textview canvas. problem is: later need change text in textview don't know how update canvas (erase previous text , insert new one). can't clear using setcolor(color.black) because have image in canvas.

code:

       linearlayout layout = new linearlayout(context);          textview textview = new textview(context);         textview.setvisibility(view.visible);         textview.settext("hello world");         layout.addview(textview);          layout.measure(canvas.getwidth(), canvas.getheight());         layout.layout(0, 0, canvas.getwidth(), canvas.getheight());          layout.draw(mcanvas);          textview.settext("abc");          textview.invalidate();         textview.postinvalidate();         layout.invalidate();         layout.postinvalidate(); 

use setter in custom view.

public synchronized void settext(string text) {     this.text = text;     postinvalidate(); } 

if didn't use custom view, should call view.postinvalidate()