javascript - 将拖动运动限制在圆形 SVG 边界内

Question

Here is a sample of the D3.js visualization我现在正在做的事情:

这里，灰色圆圈是SVG容器。我想将绿色气泡的阻力限制在灰色圆圈边界。

我找到了this example我在代码中使用了它，但出现了两个错误:

Uncaught TypeError: Cannot read property 'apply' of undefined // points to d3.v3.min.js:3
Uncaught TypeError: Cannot read property 'each' of undefined  // points to line X marked in the code below

看来我无法将 .call(drag) 与强制布局一起使用。

我该如何让它发挥作用？ jsFiddle

JS:

var data = {
    name: "layout",
    children: [
        {name: "AxisLayout", size: 6725},
        {name: "BundledEdgeRouter", size: 3727},
        {name: "CircleLayout", size: 9317},
        {name: "CirclePackingLayout", "size": 12003},
        {name: "DendrogramLayout", "size": 4853},
        {name: "ForceDirectedLayout", "size": 8411},
        {name: "IcicleTreeLayout", "size": 4864},
        {name: "IndentedTreeLayout", "size": 3174},
        {name: "Layout", "size": 7881},
        {name: "NodeLinkTreeLayout", "size": 12870},
        {name: "PieLayout", "size": 2728},
        {name: "RadialTreeLayout", "size": 12348},
        {name: "RandomLayout", "size": 870},
        {name: "StackedAreaLayout", "size": 9121},
        {name: "TreeMapLayout", "size": 9191}
    ]
};

var margin = {
    top: 0,
    right: 0,
    bottom: 0,
    left: 0
},
width = 400 - margin.left - margin.right,
    height = 400 - margin.top - margin.bottom;

var n = data.children.length,
    m = 1,
    padding = 6,
    radius = d3.scale.sqrt().range([0, 12]),
    color = d3.scale.category10().domain(d3.range(m)),
    x = d3.scale.ordinal().domain(d3.range(m)).rangePoints([0, width], 1);

var nodes = d3.range(n).map(function () {
    var i = Math.floor(Math.random() * m), //color
        v = (i + 1) / m * -Math.log(Math.random()); //value
    return {
        radius: radius(v),
        color: color(i),
        cx: x(i),
        cy: height / 2,
    };

});

nodes.forEach(function(item, index){
    item.radius = 20;
});

//console.dir(nodes);

var force = d3.layout.force()
    .nodes(nodes)
    .size([width, height])
    .gravity(0)
    .charge(0)
    .on("tick", tick)
    .start();

var svg = d3.select("#chart").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var circle = svg.selectAll("circle")
    .data(nodes)
    .enter().append("circle")
    .attr("r", function (d) {
    return d.radius;
    })
    .style("fill", function (d,i) {
        return "green";
    })
    .call(force.drag)
    .call(drag);

var drag = d3.behavior.drag()
    .origin(function(d) { return d; })
    .on("drag", dragmove);

function tick(e) {
    circle.each(gravity(.2 * e.alpha))    // line X
        .each(collide(.5))
        .attr("cx", function (d) {
        return d.x;
    })
        .attr("cy", function (d) {
        return d.y;
    });
}

// Move nodes toward cluster focus.
function gravity(alpha) {
    return function (d) {
        d.y += (d.cy - d.y) * alpha;
        d.x += (d.cx - d.x) * alpha;
    };
}

// Resolve collisions between nodes.
function collide(alpha) {
    var quadtree = d3.geom.quadtree(nodes);
    return function (d) {
        var r = d.radius + radius.domain()[1] + padding,
            nx1 = d.x - r,
            nx2 = d.x + r,
            ny1 = d.y - r,
            ny2 = d.y + r;
        quadtree.visit(function (quad, x1, y1, x2, y2) {
            if (quad.point && (quad.point !== d)) {
                var x = d.x - quad.point.x,
                    y = d.y - quad.point.y,
                    l = Math.sqrt(x * x + y * y),
                    r = d.radius + quad.point.radius + (d.color !== quad.point.color) * padding;
                if (l < r) {
                    l = (l - r) / l * alpha;
                    d.x -= x *= l;
                    d.y -= y *= l;
                    quad.point.x += x;
                    quad.point.y += y;
                }
            }
            return x1 > nx2 || x2 < nx1 || y1 > ny2 || y2 < ny1;
        });
    };
}

function dragmove(){
    console.log("dragging..");
}

Answer 1

好吧，经过评论中的长时间讨论，我想出了这个最终解决方案:

var pointerEl = document.getElementById("pointer");
var canvasEl = document.getElementById("canvas");
var canvas = {
    width: canvasEl.offsetWidth,
    height: canvasEl.offsetHeight,
    top: canvasEl.offsetTop,
    left: canvasEl.offsetLeft
};
canvas.center = [canvas.left + canvas.width / 2, canvas.top + canvas.height / 2];
canvas.radius = canvas.width / 2;


window.onmousemove = function(e) {
    var result = limit(e.x, e.y);
        pointer.style.left = result.x + "px";
        pointer.style.top = result.y + "px";
}

function limit(x, y) {
    var dist = distance([x, y], canvas.center);
    if (dist <= canvas.radius) {
        return {x: x, y: y};
    } 
    else {
        x = x - canvas.center[0];
        y = y - canvas.center[1];
        var radians = Math.atan2(y, x)
           return {
               x: Math.cos(radians) * canvas.radius + canvas.center[0],
               y: Math.sin(radians) * canvas.radius + canvas.center[1]
           }
        } 
    }

function distance(dot1, dot2) {
    var x1 = dot1[0],
        y1 = dot1[1],
        x2 = dot2[0],
        y2 = dot2[1];
    return Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
}

jsfiddle

该解决方案使用了其他 jsfiddle .