protected void grow(int sx, int sy) {
		if (subPixelResolution() && xpf!=null) {
			growFloat(sx, sy);
			return;
		}
		int ox = ic.offScreenX(sx);
		int oy = ic.offScreenY(sy);
		if (ox<0) ox = 0;
		if (oy<0) oy = 0;
		if (ox>xMax) ox = xMax;
		if (oy>yMax) oy = yMax;
		if (ox!=xp[nPoints-1]+x || oy!=yp[nPoints-1]+y) {
			xp[nPoints] = ox-x;
			yp[nPoints] = oy-y;
			nPoints++;
			if (nPoints==xp.length)
				enlargeArrays();
			drawLine();
		}
	}