                ctx.lineTo(bx + rr, by + boxH);
                ctx.quadraticCurveTo(bx, by + boxH, bx, by + boxH - rr);
                ctx.lineTo(bx, by + rr);
                ctx.quadraticCurveTo(bx, by, bx + rr, by);
                ctx.closePath();
                ctx.fill();

                // 黑字
                ctx.fillStyle = '#000';
                for (let i = 0; i < lines.length; i++) {
                    ctx.fillText(lines[i], bx + pad, by + pad + i * lh);
                }

              