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如何使用raphael.js绘制一个多边形，每个顶点都有控制点

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3

如何使用raphael.js绘制带有每个角落控制点的多边形形状。

控制点应该是可拖动的，当控制点移动时，相关的线条也应该移动。有什么想法吗？

你尝试过什么？哪些方法不起作用？你能做一个可拖动的点吗？你能在动态坐标之间画一条线吗？ - Joan Charmant
2个回答
8
这里有一种方法来完成这个操作。首先为每个控制点绘制一个圆圈，如下所示：
// Creates canvas
var paper = Raphael("canvas1", "100%", "100%");

// create small circle for each polygon point
var p1 = paper.circle(150, 50, 5).attr("fill", "blue");
var p2 = paper.circle(200, 100, 5).attr("fill", "blue");
var p3 = paper.circle(200, 200, 5).attr("fill", "blue");
var p4 = paper.circle(100, 200, 5).attr("fill", "blue");
var p5 = paper.circle(100, 100, 5).attr("fill", "blue");

接下来，我们需要以一种方式连接控制点，使得线条在更新后能够自动重绘。在这个问题中有一个方便的函数可以实现此功能，我稍作修改以适应我们的需求（它现在监听drag事件，将线条属性作为参数接受，并修复了我在原问题评论中指出的一个错误）：

// Modified from: https://dev59.com/nGLVa4cB1Zd3GeqPty2O
// Call paper.connect(obj1,obj2,attributes)
// That draws a line between the two objects and maintains the line when the objects are animated
Raphael.fn.connect = function(obj1, obj2, attribs) {
    // list of paths each object has
    if (!obj1.connections) obj1.connections = []
    if (!obj2.connections) obj2.connections = []
    // get the bounding box of each object
    var box1 = obj1.getBBox()
    var box2 = obj2.getBBox()
    // create a line/path from object 1 to object 2
    var p = this.path("M" + (box1.x + box1.width / 2) + ","
            + (box1.y + box1.height / 2) + "L" + (box2.x + box2.width / 2)
            + "," + (box2.y + box2.height / 2))
    // adjust attributes of the path
    p.attr(attribs)
    // set the start and end element for this path
    p.startElement = obj1;
    p.endElement = obj2;
    // add the path to each of the object
    obj1.connections.push(p)
    obj2.connections.push(p)
    // mark each object as being connected
    obj1.connected = true;
    obj2.connected = true;
    // listen for the Raphael frame event
    eve.on("raphael.drag.*", function(obj) {
        // if the object the frame event is fired on is connected
        if (this.connected) {
            // for each connection on this object
            for ( var c in this.connections) {
                var path = this.connections[c]; // temp path
                var b1 = path.startElement.getBBox(); // get the current
                                                        // location of start
                                                        // element
                var b2 = path.endElement.getBBox();// get the current location
                                                    // of end element
                // move the path to the new locations
                path.attr({
                    path : "M " + (b1.x + b1.width / 2) + " "
                            + (b1.y + b1.height / 2) + "L "
                            + (b2.x + b2.width / 2) + " "
                            + (b2.y + b2.height / 2),
                    opacity : Math.max(path.startElement.attr('opacity'),
                            path.endElement.attr('opacity'))
                });
            }
        }
    });
}

使用此功能，我们现在可以连接相邻的控制点。
// connect adjacent polygon points
paper.connect(p1,p2,{stroke:"red"});
paper.connect(p2,p3,{stroke:"red"});
paper.connect(p3,p4,{stroke:"red"});
paper.connect(p4,p5,{stroke:"red"});
paper.connect(p5,p1,{stroke:"red"});

下一步我们希望使控制点可拖动。我们可以按照以下步骤实现：
// make points draggable
var start = function () {
    this.ox = this.attr("cx");
    this.oy = this.attr("cy");
},
move = function (dx, dy) {
    this.attr({cx: this.ox + dx, cy: this.oy + dy});
},
up = function () {};
paper.set(p1,p2,p3,p4,p5).drag(move, start, up);

把所有这些东西结合起来，将会给你一个带有可拖动顶点和边缘的多边形，当顶点被拖动时，它们会更新。你可以在这里看到它的示例。
我知道这个已经过时了，但我正在进行实验，并发现使用矩形（而不是圆形）制作控制点不起作用？矩形无法拖动。 - Ecropolis
1
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