背景

需要实现一个工作流，支持拖拽节点生成工作流。

业务实现

支持页面布局缩放
支持节点
支持if else
支持多分支

技术点

网格背景
工作流缩放
工作流技术实现
节点拖拽

技术选型

vue
jsplumb
sortablejs(vue-draggable)

难点攻破

网格背景

主要是利用css的 linear-gradient 和 background-size 实现的。

<div class="flow-layout">
    <div class="flow-editor">
        <div class="canvas-container">
        </div>
    </div>
</div>

.flow-layout {
  display: flex;
  flex-direction: column;
}

.flow-editor {
  position: relative;
  display: flex;
  flex-direction: row;
  flex: 1;
  overflow: hidden;
}

.canvas-container {
  flex: 1;
  overflow: auto;
  z-index: 0;
}

.canvas-container:before {
  content: "";
  height: 10px;
  width: 100%;
  display: block;
  background-repeat-y: no-repeat;
  position: absolute;
  background-image: linear-gradient(90deg, #ccc 1px, transparent 0), linear-gradient(90deg, #ddd 1px, transparent 0);
  background-size: 75px 10px, 5px 5px;
}

.canvas-container:after {
  content: "";
  height: 100%;
  width: 10px;
  display: block;
  background-repeat-x: no-repeat;
  position: absolute;
  top: 0;
  background-image: linear-gradient(#ccc 1px, transparent 0), linear-gradient(#ddd 1px, transparent 0);
  background-size: 10px 75px, 5px 5px;
}

工作流缩放

主要结合 css的属性选择符 E[att="val"] ,通过修改zoom的值，来实现缩放功能。

<div class="flow-zoom" :data-zoom="canvasDataRoom + '%'">
    <div class="zoom-btn">
        <el-button size="mini" :class="{'el-button--primary':canvasRoomMinusEnable}" icon="el-icon-minus"
                   circle
                   @click="handleMinusCanvas"></el-button>
    </div>
    <div class="zoom-btn">
        <el-button size="mini" :class="{'el-button--primary':canvasRoomPlusEnable}" icon="el-icon-plus"
                   circle
                   @click="handlePlusCanvas"></el-button>
    </div>
</div>


<div class="canvas-container" :data-zoom="canvasDataRoom">
    <div class="campaignCanvas"></div>
</div>

.canvas-container[data-zoom="100"] {
  background-image: linear-gradient(#eee 1px, transparent 0), linear-gradient(90deg, #eee 1px, transparent 0), linear-gradient(#f5f5f5 1px, transparent 0), linear-gradient(90deg, #f5f5f5 1px, transparent 0);
  background-size: 75px 75px, 75px 75px, 15px 15px, 15px 15px;
}

.canvas-container[data-zoom="90"] {
  background-image: linear-gradient(#eee 1px, transparent 0), linear-gradient(90deg, #eee 1px, transparent 0), linear-gradient(#f5f5f5 1px, transparent 0), linear-gradient(90deg, #f5f5f5 1px, transparent 0);
  background-size: 70px 70px, 70px 70px, 14px 14px, 14px 14px;
}

.canvas-container[data-zoom="80"] {
  background-image: linear-gradient(#eee 1px, transparent 0), linear-gradient(90deg, #eee 1px, transparent 0), linear-gradient(#f5f5f5 1px, transparent 0), linear-gradient(90deg, #f5f5f5 1px, transparent 0);
  background-size: 60px 60px, 60px 60px, 12px 12px, 12px 12px;
}

.canvas-container[data-zoom="70"] {
  background-image: linear-gradient(#eee 1px, transparent 0), linear-gradient(90deg, #eee 1px, transparent 0), linear-gradient(#f5f5f5 1px, transparent 0), linear-gradient(90deg, #f5f5f5 1px, transparent 0);
  background-size: 55px 55px, 55px 55px, 11px 11px, 11px 11px;
}

.canvas-container[data-zoom="60"] {
  background-image: linear-gradient(#eee 1px, transparent 0), linear-gradient(90deg, #eee 1px, transparent 0), linear-gradient(#f5f5f5 1px, transparent 0), linear-gradient(90deg, #f5f5f5 1px, transparent 0);
  background-size: 45px 45px, 45px 45px, 9px 9px, 9px 9px;
}

.canvas-container[data-zoom="50"] {
  background-image: linear-gradient(#eee 1px, transparent 0), linear-gradient(90deg, #eee 1px, transparent 0), linear-gradient(#f5f5f5 1px, transparent 0), linear-gradient(90deg, #f5f5f5 1px, transparent 0);
  background-size: 40px 40px, 40px 40px, 8px 8px, 8px 8px;
}

工作流技术实现

主要是依赖 jsplumb 实现的。

主要利用 jsplumb 实现两个节点的连接。

让dom节点变成jsplumb 可拖拽节点

<div id="_uuid">
</div>

jsPlumb.draggable(_uuid, {});

两个节点的连接。

jsPlumb.connect({
    source: source,
    target: target,
    endpoint: 'Dot',
    // 连接线的样式
    connectorStyle: {strokeStyle: "#ccc", joinStyle: "round", outlineColor: "#ccc"}, // 链接 style
    // 连接线配置，起点可用
    connector: ["Flowchart", {
        stub: [10, 20],
        gap: 1,
        cornerRadius: 2,
        alwaysRespectStubs: true
    }], //  链接
    //
    endpointStyle: {fill: 'transparent', outlineStroke: 'transparent', outlineWidth: 2},
    // 线的样式
    paintStyle: {stroke: 'lightgray', strokeWidth: 2},
    // 锚点的位置
    anchor: ['BottomCenter', 'TopCenter'],
    // 遮罩层-设置箭头
    overlays: [
        ['PlainArrow', {width: 10, length: 10, location: 1}],
        ['Custom', {
            location: .5,
            id: 'nodeTempSmall',
            create: function () {
                let $el = that.$refs[target][0].$el;
                $el.dataset.target = target;
                $el.dataset.source = source;
                return $el;
            },
            visible: false
        }],
        ['Label', {location: 1, id: "flowItemDesc", cssClass: "node-item-label", visible: true}] //
    ]
});

删除一个节点

jsPlumb.removeAllEndpoints(uuid);

两个节点之间创建节点

 function createFlowConnectionLabel(sourceList, target) {

    if (!Array.isArray(sourceList)) {
        sourceList = [sourceList];
    }

    sourceList.forEach((source) => {
        //
        let lines = this.$options.jsPlumb.getConnections({
            source: source,
            target: target
        });
        //
        lines.forEach((line) => {
            line.getOverlay('nodeTempSmall').setVisible(true);
            line.bind('click', this.handleFlowLabelClick);
        });
    });
}

两个节点之间的文案创建

 function createFlowItemLabel(source, target, label) {
    this.$nextTick(() => {
        let lines = this.$options.jsPlumb.getConnections({
            source: source,
            target: target
        });
        if (lines.length > 0) {
            lines[0].getOverlay("flowItemDesc").setLabel(`<span class="node-item-title" title="${label}">${label}</span>`);
        }
    });
}

节点拖拽

主要是依赖 sortablejs 实现的

主要利用vue-draggable 封装好的组件，来实现拖拽。核心代码

拖拽的目的地区域。

<draggable class="flow-item node-temp node-temp-img"
           ref="tempNode"
           :id="flowItem.uuid"
           :group="{name:'sortable', pull:false, put: true }">
</draggable>

被拖拽的目标对象。

<draggable class="items-box"
           :key="index"
           :list="flowItem.children"
           :group="{name:'sortable', pull: 'clone', put: false }"
           v-bind="dragConfig"
           :move="handleFlowMoveItem"
           @start="handleFlowMoveStart"
           @end="handleFlowMoveEnd"
           :sort="false"
           :ref="flowItem.ref">
        <div class="node-temp-img"></div>
    </template>
</draggable>