Как обработать нажатие на drawText?

private void onTouchEventStrelka(MotionEvent event) {

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:

                isDrawing = true;
                mStartX = mx;
                mStartY = my;

                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                isDrawing = false;
                mCanvas.drawLine(mStartX, mStartY, mx, my, mPaintFinal) ;
				fillArrow(mPaintFinal,mCanvas,mStartX,mStartY,mx,my);
				fillArrow(mPaintFinal,mCanvas,mx,my,mStartX,mStartY);

				mCenter= mx/2+mStartX/2 ;
				mCenter2=my/2+ mStartY/2;
				String txt = "0000" ;
				mCanvas.drawText (txt, mCenter,mCenter2,mPaintText);
                invalidate();
			
                break;
        }
    }