7.组件连线(贝塞尔曲线)--从零起步实现基于Html5的WEB设计器Jquery插件（含源码）...

上节讲到如何创建组件，清除设计器视图，以及设计视图的持久化和恢复，本节将重点讲如何实现组件间的连线，前面章节有提到为了方便从持久化文件中恢复，组件和连线是分别存放的：nodes和lines对象，两个组件实现连线主要也还是通过鼠标拖动事件实现，但前提是有一个连接点的概念，即我们要从组件上、下、左、右四个锚点中开始拖动，在拖动过程中绘制跟随线，拖到目标组件上时出现锚点，在锚点上释放鼠标，在两个锚点间绘制连线，并将连线加到lines数组中。

下图是要实现的锚点图样例：

锚点为红色边框，整个组件可以作为一个锚点，同时四个x也可作为特定方位的锚点，锚点出现时鼠标为十字形状，代表允许按下鼠标拖动连线了。大家注意，我在打开按钮的边上增加了一个checkbox连线，用来指示是在连线状态与否，取消这个勾选，是不会出现连线锚点的，选择、拖动组件只有在非连线状态下进行，两者互斥。

    function Connector(node) {this.node = node;this.group = null;}Connector.prototype = {destroy: function () {this.group.remove();},hiTest: function (event) {var bounds = this.node.getBound();if (event.point.x >= bounds.x - 5 && event.point.x <= bounds.x + 5 && event.point.y >= bounds.y + bounds.height / 2 - 5 && event.point.y <= bounds.y + bounds.height / 2 + 5){//在左连线指示器框中this.group.children[0].bounds.x = bounds.x - 5;this.group.children[0].bounds.y = bounds.y + bounds.height / 2 - 5;this.group.children[0].bounds.width = 10;this.group.children[0].bounds.height = 10;}else if (event.point.x >= bounds.x + bounds.width - 5 && event.point.x <= bounds.x + bounds.width  + 5 && event.point.y >= bounds.y + bounds.height / 2 - 5 && event.point.y <= bounds.y + bounds.height / 2 + 5) {//在右连线指示器框中this.group.children[0].bounds.x = bounds.x + bounds.width  - 5;this.group.children[0].bounds.y = bounds.y + bounds.height / 2 - 5;this.group.children[0].bounds.width = 10;this.group.children[0].bounds.height = 10;}else if (event.point.x >= bounds.x + bounds.width / 2 - 5 && event.point.x <= bounds.x + bounds.width / 2  + 5 && event.point.y >= bounds.y  - 5 && event.point.y <= bounds.y  + 5) {//在上连线指示器框中this.group.children[0].bounds.x = bounds.x + bounds.width / 2  - 5;this.group.children[0].bounds.y = bounds.y  - 5;this.group.children[0].bounds.width = 10;this.group.children[0].bounds.height = 10;}else if (event.point.x >= bounds.x + bounds.width / 2 - 5 && event.point.x <= bounds.x + bounds.width / 2  + 5 && event.point.y >= bounds.y + bounds.height - 5 && event.point.y <= bounds.y + bounds.height+ 5) {//在下连线指示器框中this.group.children[0].bounds.x = bounds.x + bounds.width / 2  - 5;this.group.children[0].bounds.y = bounds.y + bounds.height  - 5;this.group.children[0].bounds.width = 10;this.group.children[0].bounds.height = 10;}else{this.group.children[0].bounds.x = bounds.x this.group.children[0].bounds.y = bounds.y;this.group.children[0].bounds.width = bounds.width;this.group.children[0].bounds.height = bounds.height;}},render: function () {var me = this;var color = 'white';this.group = new paper.Group();var rect = new paper.Path.Rectangle({point: [this.node.getBound().x, this.node.getBound().y],size: [this.node.getBound().width, this.node.getBound().height],strokeColor: 'red',strokeWidth: 2})rect.onMouseDown = function (event) {debugger;};this.group.addChild(rect);var bounds = this.node.getBound();var topCross1 = new paper.Path.Line({ from: [bounds.x + bounds.width / 2 - 2.5, bounds.y - 2.5], to: [bounds.x + bounds.width / 2 + 2.5, bounds.y + 2.5], strokeColor: 'blue' });this.group.addChild(topCross1);var topCross2 = new paper.Path.Line({ from: [bounds.x + bounds.width / 2 - 2.5, bounds.y + 2.5],to: [bounds.x + bounds.width / 2 + 2.5, bounds.y - 2.5], strokeColor: 'blue' });this.group.addChild(topCross2);var rightCross1 = new paper.Path.Line({ from: [bounds.x + bounds.width - 2.5, bounds.y + bounds.height / 2 - 2.5], to: [bounds.x + bounds.width + 2.5, bounds.y + bounds.height / 2 + 2.5], strokeColor: 'blue' });this.group.addChild(rightCross1);var rightCross2 = new paper.Path.Line({ from: [bounds.x + bounds.width - 2.5, bounds.y + bounds.height / 2 + 2.5], to: [bounds.x + bounds.width + 2.5, bounds.y + bounds.height / 2 - 2.5], strokeColor: 'blue' });this.group.addChild(rightCross2);var leftCross1 = new paper.Path.Line({ from: [bounds.x - 2.5, bounds.y + bounds.height / 2 - 2.5], to: [bounds.x + 2.5, bounds.y + bounds.height / 2 + 2.5], strokeColor: 'blue' });this.group.addChild(leftCross1);var leftCross2 = new paper.Path.Line({ from: [bounds.x - 2.5, bounds.y + bounds.height / 2 + 2.5], to: [bounds.x + 2.5, bounds.y + bounds.height / 2 - 2.5], strokeColor: 'blue' });this.group.addChild(leftCross2);var bottomCross1 = new paper.Path.Line({ from: [bounds.x + bounds.width / 2 - 2.5, bounds.y + bounds.height - 2.5], to: [bounds.x + bounds.width / 2 + 2.5, bounds.y + bounds.height + 2.5], strokeColor: 'blue' });this.group.addChild(bottomCross1);var bottomCross2 = new paper.Path.Line({ from: [bounds.x + bounds.width / 2 - 2.5, bounds.y + bounds.height + 2.5], to: [bounds.x + bounds.width / 2 + 2.5, bounds.y + bounds.height  - 2.5], strokeColor: 'blue' });this.group.addChild(bottomCross2);this.group.bringToFront();var drag = false;return this;}};

上面代码hiTest方法用于测式当前鼠标位置是显示哪个锚点：整个组件/上/下/左/右，并移动对应的锚点红色矩形。render画了一个红色矩形和四个连接点x。

在VisualDesigner中增加lining属性指示是否画线状态，

在Component中增加activeConnector指示当前活动的连接器锚点

在Component.init方法中增加了鼠标进入，退出后的连接点创建和删除，如下代码片断：

    Component.prototype.init = function (options) {if (options == undefined)options = {};this.properties = $.extend(options, Component.DEFAULTS);this.group = new paper.Group();this.designer = undefined; //当前设计器，createElement时赋值var me = this;var drag = false;this.activateConnector = null; //活动的连线指示符this.group.onClick = function (event) {if (!me.designer.lining) //非画线状态才允许选中me.group.children[0].selected = !me.group.children[0].selected;}this.group.onMouseDown = function (event) {if (!me.designer.lining) //非画线状态才允许拖动drag = (event.event.button == 0);else {drawing = true;}}this.group.onMouseUp = function () {drag = false;document.body.style.cursor = 'default';}this.group.onMouseDrag = function (event) {if (drag && !me.designer.lining) //非画线状态才允许拖动
            {if (me.activateConnector) //在拖动元素时如果有连线指示器则清除。
                {me.activateConnector.destroy();me.activateConnector = null;}me.properties.x += event.delta.x;me.properties.y += event.delta.y;this.translate(event.delta.x, event.delta.y);document.body.style.cursor = 'move';}}this.group.onMouseEnter = function (event) {if (!me.activateConnector && me.designer.lining) //还没有创建连接指示框，且当前为连线状态
            {me.designer.selectAll(false);//取消选中所有元素，if anyme.activateConnector = new Connector(me).render();document.body.style.cursor = 'crosshair';}}this.group.onMouseLeave = function (event) {if (me.designer.lining && me.activateConnector) { //当前为连线状态，且移出了组件范围 ，擦除连线指示框
                me.activateConnector.destroy();me.activateConnector = null;console.log("delete in group")document.body.style.cursor = 'default';}}this.group.onMouseMove = function (event) {if (me.designer.lining && me.activateConnector) { //当前为连线状态，且在组件范围 ，检测四个边线连线指示框
                me.activateConnector.hiTest(event)}}return this;}

这里说一个小插曲，因为要在组件的代码里访问设计器的成员（如是否画线状态visualDesigner.lining），我在Component里增加了一个designer对象来保存当前设计器，并在代码中访问，可保存设计视图时出现JSON对象序例化时出现递归的异常，因为序列化nodes组件对象数组时，每一个组件里有VisualDesigner对象而VisualDesigner对象里又有nodes对象的数组，首先想到的是特定的属性不要序列化，查资料后发现JSON.stringify里有第二个参数，可以为可序列化属性名称的白名单数组，也可以为函数，此外因为属性名称并不完全确定，所以用函数：

    VisualDesigner.prototype.getContent = function () {debugger;return JSON.stringify({ "nodes": this.nodes, "lines": this.lines },function (k, v) {if (k == "designer") {return undefined;}return v;});}

依据面向对象的编程方法单一职责原则，增加了一个类（lineManager)，专门用来管理连线的过程管理，在连线时要保持住前一个结点，在拖动结束时画出线，代码如下：

    function LineManager(designer) {this.designer = designer;this.line = null;//当前跟随线this.start = null;//当前正在画线的起点元素this.startPos=null;var tool=new paper.Tool();//设计器元素之外的移动也要显示跟随线，var me=this;tool.onMouseMove=function(event){me.draging(event.point);}tool.onMouseUp=function(event){//设计器元素之外的释放不生成连线，清除已有开始结点等信息，if (me.line)me.line.remove();me.start=null;me.startPos=null;me.line=null;}}LineManager.prototype = {dragStart: function (co,pos) {this.start = co;var xy = co.node.getConnectorCenter(pos); //获取当前鼠标位置处连接点的中央坐标this.startPos=xy;this.line = new paper.Path.Line({from: [xy.x, xy.y],to: [xy.x, xy.y],strokeWidth: 2,strokeColor: 'red'});},draging: function (pos) {if (this.line !== null ) {var txy = this.calcLine(this.startPos.x, this.startPos.y, pos.x, pos.y);this.line.set({ pathData: 'M' + this.startPos.x + ',' + this.startPos.y + ' L' + txy.x + ',' + txy.y });}},dragEnd:function(co,pos){var xy = co.node.getConnectorCenter(pos); //获取当前鼠标位置处连接点的中央坐标if (this.line !== null  ) {if (this.start.node.properties.id!=co.node.properties.id){this.designer.createLine("曲线",{targetType:co.node.getConnectorDirection(this.startPos,pos),source:this.start.node.properties.id,target:co.node.properties.id,sxy:this.startPos,txy:xy});}this.line.remove();}this.start=null; //清除画线状态，等待重新画线this.startPos=null;},calcLine: function (x1, y1, x2, y2) {var vx = x2 - x1;var vy = y2 - y1;var d = Math.sqrt(vx * vx + vy * vy);vx /= d;vy /= d;d = Math.max(0, d - 5);return {'x': Math.round(x1 + vx * d),'y': Math.round(y1 + vy * d)}}}

同时增加了曲线的类（贝塞尔曲线），

function BezierLine() {}BezierLine.prototype = $.extend({}, Component.prototype);BezierLine.prototype = $.extend(BezierLine.prototype, {render: function (options) {this.properties.typeName = "曲线";this.properties.strokeWidth = 2;this.properties.strokeColor = 'red';this.properties=$.extend(this.properties,options)this.properties.x = Math.min(this.properties.sxy.x, this.properties.txy.x);this.properties.y = Math.min(this.properties.sxy.y, this.properties.txy.y);this.properties.width = Math.abs(this.properties.txy.x - this.properties.sxy.x);this.properties.height = Math.abs(this.properties.txy.y - this.properties.sxy.y);var wire = new paper.Path(this.calcPath(this.properties.targetType, this.properties.sxy.x, this.properties.sxy.y, this.properties.txy.x, this.properties.txy.y));wire.strokeWidth = this.properties.strokeWidth;wire.strokeColor=this.properties.strokeColor;wire.sendToBack();this.group=new paper.Group();this.group.addChild(wire);//this.group.translate(this.properties.x, this.properties.y);return this;},calcPath:function(type, x1, y1, x2, y2){var path= "";if(type =="left" || type == "right")path= 'M ' + x1 + ', ' + y1 + 'C ' +(x1 + (x2 - x1) / 2) + ', ' + y1 + ' ' +(x2 - (x2 - x1) / 2) + ', ' + y2 + ' ' +x2 + ', ' + y2;else if (type=="up" || type == "down")path='M' + x1 + ', ' + y1 + 'C ' +x1 + ', ' + (y1 + (y2 - y1) / 2) + ' ' +x2 + ', ' + (y2 - (y2 - y1) / 2) + ' ' +x2 + ', ' + y2;return path;}});