计算连接线路径

动画.gif

• 定义

利用SVG <path>属性，绘制链接线路经
<path> 标签用来定义路径。
下面的命令可用于路径数据：
M = moveto
L = lineto
H = horizontal lineto
V = vertical lineto
C = curveto
S = smooth curveto
Q = quadratic Belzier curve
T = smooth quadratic Belzier curveto
A = elliptical Arc
Z = closepath

• 弧线绘制方式

export const computeLinePath = (start, end, lineOffsetY = 0) => {
    // 弧线绘制方式
    const x = Math.abs(start.x - end.x)
    const y = Math.abs(start.y - end.y)
    if (x === 0 || y === 0) {
        return `
            M ${start.x} ${start.y}
            L ${end.x} ${end.y}
        `
    }
    let dir
    let p1
    let p2

    if (end.y < start.y) {
        const offsetY = 100
        const offsetX = 150
        dir = end.x - start.x > 0 ? 1 : -1
        p1 = `${start.x + dir * offsetX}, ${start.y + offsetY}`
        p2 = `${end.x - dir * offsetX}, ${end.y - offsetY}`
        return `
            M ${start.x} ${start.y - lineOffsetY}
            C ${p1} ${p2} ${end.x} ${end.y}
        `
    }
    const OffsetXP1 = +(1 / 12 * x).toFixed(0)
    const OffsetXP2 = +(11 / 12 * x).toFixed(0)
    const offsetYP1 = +(1 / 3 * y).toFixed(0)
    const offsetYP2 = +(2 / 3 * y).toFixed(0)
    dir = start.x - end.x > 0 ? -1 : 1
    p1 = `${start.x + dir * OffsetXP1}, ${start.y + offsetYP1}`
    p2 = `${start.x + dir * OffsetXP2}, ${start.y + offsetYP2}`
    return `
        M ${start.x} ${start.y - lineOffsetY}
        C ${p1} ${p2} ${end.x} ${end.y}
    `
}

• 绘制箭头

export const computeTrianglePath = (start, width) => {
            return `
                    M ${start.x} ${start.y}
                    l ${width / 2} 0
                    l ${-width / 2} ${width}
                    l ${-width / 2} ${-width}
                    Z
                `
        }

• 获取绘制箭头起始位置

export const getTriangleStart = (end)  => {
            return ({ ...end, y: end.y - 10 })
}

• 监听鼠标点击目标事件，获取起始位置

        start = { x: 0, y: 0 }
        window.addEventListener('mousedown', (event) => {
            ...
             start = {
                        x: event.x,
                        y: event.y
            }
        })

• 监听鼠标移动事件

        window.addEventListener('mousemove', (event) => {
                      ...
                     let end = {
                            x: event.x,
                            y: event.y 
                        } 
                        this.linePath = computeLinePath(start, end, 0)
                        this.trianglePath = computeTrianglePath(getTriangleStart(end), 10)
        })

• 页面展示

    <svg class="processSvg-area">
      <path :d="linePath"  strokeWidth="1" fill="none"  stroke='#7083ff'/>
      <path :d='trianglePath' fill='#7083ff' stroke="none" /> 
    </svg>