使用线/线连接两个元素mannualy

我可以给一些指针开始。

线描

在节点的选择，你可以画线和其他节点上掉落。继续捕获节点ID，如果列表中有1,2,6表示其正确或错误

function drawLine(x, y) { 
    ctx.beginPath(); 
    ctx.moveTo(startX, startY); 
    ctx.lineTo(x, y); 
    ctx.closePath(); 
    ctx.stroke(); 
    ctx.restore(); 
} 
canvas.onmousedown = function (e) { 
    ctx.save(); 
    e.preventDefault(); 
    e.stopPropagation(); 
    startX = parseInt(e.clientX - offsetX); 
    startY = parseInt(e.clientY - offsetY); 
    isDown = true; 
} 
canvas.onmousemove = function (e) { 
    if (!isDown) { 
     return; 
    } 
    e.preventDefault(); 
    e.stopPropagation(); 
    mouseX = parseInt(e.clientX - offsetX); 
    mouseY = parseInt(e.clientY - offsetY); 
    drawLine(mouseX, mouseY); 
} 
canvas.onmouseup = function (e) { 
    if (!isDown) { 
     return; 
    } 
    e.preventDefault(); 
    e.stopPropagation(); 
    isDown = false; 
}