stroke和closePath

先stroke后closePath就不会有连接

cav_round1.beginPath();

            cav_round1.moveTo(0, -round1_R[0]);

            cav_round1.lineTo(0, -round1_R[1]);

            cav_round1.arc(0, 0, round1_R[1], -90*Math.PI/180, -30*Math.PI/180);

            cav_round1.stroke();

            cav_round1.closePath();