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 any
                me.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;
        }
    });

最后效果图如下：

 

源代码：sample.1.5.rar

直接运行查看

（本文为原创，在引用代码和文字时请注明出处）