How to use Layui to develop an editable flowchart designer

How to use Layui to develop a flowchart designer that supports editability

Introduction:
With the rapid development of informatization, flowcharts are used in all walks of life The applications in are becoming more and more widespread. However, the selection of flowchart editors currently on the market is limited, and most require payment. This article will introduce how to use the Layui framework to develop an editable flowchart designer and provide specific code examples.

1. Introduction to Layui:
Layui is a simple and easy-to-use front-end framework that provides a wealth of components and interfaces to quickly build a Web interface. It is characterized by lightweight, modularity, responsiveness, etc., which is very suitable for quickly developing simple web applications.

2. Design ideas:

1. HTML structure design:
   We first need to design the HTML structure of the flow chart designer, including the toolbar on the left and the canvas on the right area. The toolbar is used to select different flowchart elements, and the canvas area is used to display and edit the flowchart.

The sample code is as follows:

<div class="toolbar">
  <button class="layui-btn layui-btn-primary" id="start">开始节点</button>
  <button class="layui-btn layui-btn-primary" id="process">流程节点</button>
  <button class="layui-btn layui-btn-primary" id="decision">决策节点</button>
</div>
<div id="canvas"></div>

2. Initialize the toolbar and canvas:
   Next, use Layui’s JavaScript modularization mechanism to initialize the toolbar and canvas. It should be noted that in order to realize the drag and drop and connection functions of the flow chart, we need to introduce the jsPlumb library.

The sample code is as follows:

layui.use(['jquery', 'layer'], function(){
  var $ = layui.jquery;
  var layer = layui.layer;

  // 初始化工具栏按钮
  $('#start').click(function(){
    // 创建开始节点元素并在画布中显示
    ...
  });

  $('#process').click(function(){
    // 创建流程节点元素并在画布中显示
    ...
  });

  $('#decision').click(function(){
    // 创建决策节点元素并在画布中显示
    ...
  });

  // 初始化画布
  var canvas = $('#canvas');
  jsPlumb.ready(function(){
    jsPlumb.setContainer(canvas);
    ...
  });
});

3. Realize the dragging and connecting of nodes:
   Through the interface provided by jsPlumb, we can realize the dragging and connecting functions of nodes . After the node is created, we can call the makeSource method to make it draggable and the makeTarget method to make it connectable.

The sample code is as follows:

// 创建开始节点元素
var start = $('<div class="node start">开始</div>');
canvas.append(start);

jsPlumb.makeSource(start, {
  filter: '.node',
  anchor: 'Continuous',
  connectorStyle: {
    strokeStyle: '#999',
    lineWidth: 2
  },
  connectionType: 'basic',
  extract:{
    "action":"the-action"
  },
  maxConnections: 1,
  onMaxConnections: function(info, e) {
    layer.msg("不能再添加连接了！", {time: 1000});
  }
}).initDraggable();

// 创建流程节点元素
var process = $('<div class="node process">流程节点</div>');
canvas.append(process);

jsPlumb.makeSource(process, {
  filter: '.node',
  anchor: 'Continuous',
  connectorStyle: {
    strokeStyle: '#999',
    lineWidth: 2
  },
  connectionType: 'basic',
  extract:{
    "action":"the-action"
  },
  maxConnections: -1,
  onMaxConnections: function(info, e) {
    layer.msg("不能再添加连接了！", {time: 1000});
  }
}).initDraggable();

// 创建决策节点元素
var decision = $('<div class="node decision">决策节点</div>')
canvas.append(decision);

jsPlumb.makeSource(decision, {
  filter: '.node',
  anchor: 'Continuous',
  connectorStyle: {
    strokeStyle: '#999',
    lineWidth: 2
  },
  connectionType: 'basic',
  extract:{
    "action":"the-action"
  },
  maxConnections: -1,
  onMaxConnections: function(info, e) {
    layer.msg("不能再添加连接了！", {time: 1000});
  }
}).initDraggable();

4. Implement the connection line between nodes:
   Using the connect method of the jsPlumb engine, we can achieve Connection lines between nodes. Right-click on the node, and a menu will pop up for the user to select the target node to connect to.

The sample code is as follows:

canvas.on('contextmenu', '.node', function(e){
  e.preventDefault();
  var node = $(this);
  var menu = $('<div class="menu"></div>');

  // 获取所有可连接的节点
  var targets = canvas.find('.node').not(node);

  // 创建菜单项
  targets.each(function(){
    var target = $(this);
    var item = $('<div class="menu-item"></div>').text(target.text());
    item.click(function(){
      // 添加连接线
      jsPlumb.connect({
        source: node,
        target: target,
        ... // 连接线的样式和属性设置
      });
      menu.remove();
    });
    menu.append(item);
  });

  // 显示菜单
  menu.css({ top: e.pageY, left: e.pageX });
  canvas.append(menu);
});

3. Summary:
This article introduces how to use Layui to develop a flowchart designer that supports editability. Through HTML and JavaScript code examples, we have implemented functions such as initialization of the toolbar, dragging and connecting nodes, and connecting lines between nodes. Readers can further improve and expand the flowchart designer according to their needs. I hope this article will be helpful to readers who use Layui for flowchart development.

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