javascript - 如何在javascript中的d3.js中获取拖动事件？

Question

以下是使用 d3.js 在 javascript 中绘制力有向图的代码

const graph = {
  nodes: [{
      name: 'john',
      age: 35
    },
    {
      name: 'simon',
      age: 37
    },
    {
      name: 'manjoor',
      age: 35
    },
    {
      name: 'lorg',
      age: 34
    },
    {
      name: 'kilvin',
      age: 32
    },
  ],
  links: [{
      source: 'john',
      target: 'simon'
    },
    {
      source: 'john',
      target: 'manjoor'
    },
    {
      source: 'simon',
      target: 'lorg'
    },
    {
      source: 'simon',
      target: 'kilvin'
    },
    {
      source: 'manjoor',
      target: 'kilvin'
    },
    {
      source: 'lorg',
      target: 'john'
    },
    {
      source: 'lorg',
      target: 'manjoor'
    },
    {
      source: 'kilvin',
      target: 'manjoor'
    },
  ]
}


const canvas = d3.select('#network')

const width = canvas.attr('width')
const height = canvas.attr('height')
const r = 30
const ctx = canvas.node().getContext('2d')

const color = d3.scaleOrdinal(d3.schemeAccent);

const simulation = d3.forceSimulation()
  .force('x', d3.forceX(width / 2))
  .force('y', d3.forceY(height / 2))
  .force('collide', d3.forceCollide(r + 20))
  .force('charge', d3.forceManyBody().strength(-100))
  .force('link', d3.forceLink().id(node => node.name))
  .on('tick', update)


simulation.nodes(graph.nodes)
simulation.force('link').links(graph.links)

canvas.call(d3.drag()
  .container(canvas.node())
  .subject(dragsubject).on('start', dragstarted)
  .on('drag', dragged).on('end', dragended)
)



function update() {
  ctx.clearRect(0, 0, width, height)

  ctx.beginPath()
  ctx.globalAlpha = 0.5
  ctx.strokeStyle = 'blue'
  graph.links.forEach(drawLink)
  ctx.stroke()


  ctx.beginPath()
  ctx.globalAlpha = 1
  graph.nodes.forEach(drawNode)
  ctx.fill()
}



function dragsubject(event) {
  return simulation.find(d3.event.x, d3.event.y)
}

function drawNode(d) {

  ctx.fillStyle = color(d.party)
  ctx.moveTo(d.x, d.y)
  ctx.arc(d.x, d.y, r, 0, Math.PI * 2)
}

function drawLink(l) {
  ctx.moveTo(l.source.x, l.source.y)
  ctx.lineTo(l.target.x, l.target.y)
}

function dragstarted(event) {
  if (!event.active) simulation.alphaTarget(0.3).restart();
  event.subject.fx = event.subject.x;
  event.subject.fy = event.subject.y;
}

function dragged(event) {
  event.subject.fx = event.x;
  event.subject.fy = event.y;
}

function dragended(event) {
  if (!event.active) simulation.alphaTarget(0);
  event.subject.fx = null;
  event.subject.fy = null;
}

update()

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/6.2.0/d3.js"></script>
<canvas id="network" width="600" height="300"></canvas>

我正在画布上获取图表。

但是我收到以下错误：

＆当我调试时，我可以看到这是发生错误的地方 return simulation.find(d3.event.x, d3.event.y)......似乎缺少事件......有没有办法解决这个问题。这发生在拖动...＆所以拖动每个节点都不起作用。

或者有人可以建议一种拖动节点的方法......

标签： javascriptd3.js

Answer 1

您使用的是 d3 版本 6。d3.event已被删除。请仔细阅读更改日志，降级您的 d3 版本，或查找更多最新示例。

const graph = {
  nodes: [{
      name: 'john',
      age: 35
    },
    {
      name: 'simon',
      age: 37
    },
    {
      name: 'manjoor',
      age: 35
    },
    {
      name: 'lorg',
      age: 34
    },
    {
      name: 'kilvin',
      age: 32
    },
  ],
  links: [{
      source: 'john',
      target: 'simon'
    },
    {
      source: 'john',
      target: 'manjoor'
    },
    {
      source: 'simon',
      target: 'lorg'
    },
    {
      source: 'simon',
      target: 'kilvin'
    },
    {
      source: 'manjoor',
      target: 'kilvin'
    },
    {
      source: 'lorg',
      target: 'john'
    },
    {
      source: 'lorg',
      target: 'manjoor'
    },
    {
      source: 'kilvin',
      target: 'manjoor'
    },
  ]
}


const canvas = d3.select('#network')

const width = canvas.attr('width')
const height = canvas.attr('height')
const r = 30
const ctx = canvas.node().getContext('2d')

const color = d3.scaleOrdinal(d3.schemeAccent);

const simulation = d3.forceSimulation()
  .force('x', d3.forceX(width / 2))
  .force('y', d3.forceY(height / 2))
  .force('collide', d3.forceCollide(r + 20))
  .force('charge', d3.forceManyBody().strength(-100))
  .force('link', d3.forceLink().id(node => node.name))
  .on('tick', update)


simulation.nodes(graph.nodes)
simulation.force('link').links(graph.links)

canvas.call(d3.drag()
  .container(canvas.node())
  .subject(dragsubject).on('start', dragstarted)
  .on('drag', dragged).on('end', dragended)
)



function update() {
  ctx.clearRect(0, 0, width, height)

  ctx.beginPath()
  ctx.globalAlpha = 0.5
  ctx.strokeStyle = 'blue'
  graph.links.forEach(drawLink)
  ctx.stroke()


  ctx.beginPath()
  ctx.globalAlpha = 1
  graph.nodes.forEach(drawNode)
  ctx.fill()
}



function dragsubject(event) {
  return simulation.find(event.x, event.y);
}

function drawNode(d) {

  ctx.fillStyle = color(d.party)
  ctx.moveTo(d.x, d.y)
  ctx.arc(d.x, d.y, r, 0, Math.PI * 2)
}

function drawLink(l) {
  ctx.moveTo(l.source.x, l.source.y)
  ctx.lineTo(l.target.x, l.target.y)
}

function dragstarted(event) {
  if (!event.active) simulation.alphaTarget(0.3).restart();
  event.subject.fx = event.subject.x;
  event.subject.fy = event.subject.y;
}

function dragged(event) {
  event.subject.fx = event.x;
  event.subject.fy = event.y;
}

function dragended(event) {
  if (!event.active) simulation.alphaTarget(0);
  event.subject.fx = null;
  event.subject.fy = null;
}

update()

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/6.2.0/d3.js"></script>
<canvas id="network" width="600" height="300"></canvas>