摘要：的插件系統做的相當完善可惜文檔沒有具體說到這里整理一下的插件插件大致分為四種類型行為可以理解為事件處理的插件就是和的樣式同樣是插件插件的布局之類這部分涉及的算法比較多插件就是自定義工具函數將其內置中這四種插件都有各自的寫法以及但是文檔中沒有

G6的插件系統做的相當完善, 可惜文檔沒有具體說到. 這里整理一下g6的插件.

插件大致分為四種類型:

behaviour 行為, 可以理解為事件處理

node, edge的插件, 就是node和edge的樣式, 同樣是插件

layout插件, node的布局之類, 這部分涉及的算法比較多

Util插件, 就是自定義工具函數, 將其內置G6.Util中

這四種插件都有各自的寫法以及api, 但是文檔中沒有提到, 這里簡單介紹一下. 一下都以官方插件為例.

寫完發現其實官方有這部分的文檔: https://www.yuque.com/antv/g6/custom-interaction

請看下面代碼, 這部分是注冊一個右鍵拖動的行為:

// g6/plugins/behaviour.analysis/index.js
function panCanvas(graph, button = "left", panBlank = false) {
  let lastPoint;
  if (button === "right") {
    graph.behaviourOn("contextmenu", ev => {
      ev.domEvent.preventDefault();
    });
  }
  graph.behaviourOn("mousedown", ev => {
    if (button === "left" && ev.domEvent.button === 0 ||
    button === "right" && ev.domEvent.button === 2) {
      if (panBlank) {
        if (!ev.shape) {
          lastPoint = {
            x: ev.domX,
            y: ev.domY
          };
        }
      } else {
        lastPoint = {
          x: ev.domX,
          y: ev.domY
        };
      }
    }
  });


// 鼠標右鍵拖拽畫布空白處平移畫布交互
G6.registerBehaviour("rightPanBlank", graph => {
  panCanvas(graph, "right", true);
})

然后在實例化graph的時候在modes中引入:

new Graph({
  modes: {
    default: ["panCanvas"]
  }
})

其實到這里我們已經知道了, 只要是在一些內置事件中注冊一下自定義事件再引入我們就可以稱之為一個行為插件. 但是我們還需要再深入一點, 看到底是不是這樣的.

// g6/src/mixin/mode.js
behaviourOn(type, fn) {
    const eventCache = this._eventCache;
    if (!eventCache[type]) {
      eventCache[type] = [];
    }
    eventCache[type].push(fn);
    this.on(type, fn);
},

照老虎畫貓我們最終可以實現一個自己的行為插件:

// 未經過驗證
function test(graph) {
 graph.behaviourOn("mousedown" () => alert(1) ) 
}


// 鼠標右鍵拖拽畫布空白處平移畫布交互
G6.registerBehaviour("test", graph => {
  test(graph);
})

new Graph({
  modes: {
    default: ["test"]
  }
})

關于node, edge的插件的插件其實官方文檔上面的自定義形狀和自定義邊.

// g6/plugins/edge.polyline/index.js
G6.registerEdge("polyline", {
  offset: 10,
  getPath(item) {
    const points = item.getPoints();
    const source = item.getSource();
    const target = item.getTarget();
    return this.getPathByPoints(points, source, target);
  },
  getPathByPoints(points, source, target) {
    const polylinePoints = getPolylinePoints(points[0], points[points.length - 1], source, target, this.offset);
    // FIXME default
    return Util.pointsToPolygon(polylinePoints);
  }
});

G6.registerEdge("polyline-round", {
  borderRadius: 9,
  getPathByPoints(points, source, target) {
    const polylinePoints = simplifyPolyline(
      getPolylinePoints(points[0], points[points.length - 1], source, target, this.offset)
    );
    // FIXME default
    return getPathWithBorderRadiusByPolyline(polylinePoints, this.borderRadius);
  }
}, "polyline");

這部分那么多代碼其實最重要的還是上面的部分, 注冊一個自定義邊, 直接引入就可以在shape中使用了, 具體就不展開了.
自定義邊
自定義節點

layout在初始化的時候即可以在 layout 字段中初始化也可以在plugins中.

const graph = new G6.Graph({
  container: "mountNode",
  layout: dagre
})

/* ---- */

const graph = new G6.Graph({
  container: "mountNode",
  plugins: [ dagre ]
})

原因在于寫插件的時候同時也把布局注冊為一個插件了:

// g6/plugins/layout.dagre/index.js
class Plugin {
  constructor(options) {
    this.options = options;
  }
  init() {
    const graph = this.graph;
    graph.on("beforeinit", () => {
      const layout = new Layout(this.options);
      graph.set("layout", layout);
    });
  }
}

G6.Plugins["layout.dagre"] = Plugin;

通過查看源碼我們可以知道自定義布局的核心方法就是execute, 再具體一點就是我們需要在每個布局插件中都有execute方法:

// g6/plugins/layout.dagre/layout.js
// 執行布局
  execute() {
    const nodes = this.nodes;
    const edges = this.edges;
    const nodeMap = {};
    const g = new dagre.graphlib.Graph();
    const useEdgeControlPoint = this.useEdgeControlPoint;
    g.setGraph({
      rankdir: this.getValue("rankdir"),
      align: this.getValue("align"),
      nodesep: this.getValue("nodesep"),
      edgesep: this.getValue("edgesep"),
      ranksep: this.getValue("ranksep"),
      marginx: this.getValue("marginx"),
      marginy: this.getValue("marginy"),
      acyclicer: this.getValue("acyclicer"),
      ranker: this.getValue("ranker")
    });
    g.setDefaultEdgeLabel(function() { return {}; });
    nodes.forEach(node => {
      g.setNode(node.id, { width: node.width, height: node.height });
      nodeMap[node.id] = node;
    });
    edges.forEach(edge => {
      g.setEdge(edge.source, edge.target);
    });
    dagre.layout(g);
    g.nodes().forEach(v => {
      const node = g.node(v);
      nodeMap[v].x = node.x;
      nodeMap[v].y = node.y;
    });
    g.edges().forEach((e, i) => {
      const edge = g.edge(e);
      if (useEdgeControlPoint) {
        edges[i].controlPoints = edge.points.slice(1, edge.points.length - 1);
      }
    });
  }

上面是官方插件有向圖的核心代碼, 用到了dagre算法, 再簡化一點其實可以理解為就是利用某種算法確定節點和邊的位置.

最終執行布局的地方:

// g6/src/controller/layout.js
graph._executeLayout(processor, nodes, edges, groups)

這類插件相對簡單許多, 就是將函數內置到Util中. 最后直接在G6.Util中使用即可

比如一個生成模擬數據的:

// g6/plugins/util.randomData/index.js
const G6 = require("@antv/g6");
const Util = G6.Util;
const randomData = {
  // generate chain graph data
  createChainData(num) {
    const nodes = [];
    const edges = [];
    for (let index = 0; index < num; index++) {
      nodes.push({
        id: index
      });
    }
    nodes.forEach((node, index) => {
      const next = nodes[index + 1];
      if (next) {
        edges.push({
          source: node.id,
          target: next.id
        });
      }
    });
    return {
      nodes,
      edges
    };
  },
  // generate cyclic graph data
  createCyclicData(num) {
    const data = randomData.createChainData(num);
    const { nodes, edges } = data;
    const l = nodes.length;
    edges.push({
      source: data.nodes[l - 1].id,
      target: nodes[0].id
    });
    return data;
  },
  // generate num * num nodes without edges
  createNodesData(num) {
    const nodes = [];
    for (let index = 0; index < num * num; index++) {
      nodes.push({
        id: index
      });
    }
    return {
      nodes
    };
  }
};
Util.mix(Util, randomData);