[D3] 13. Cleaner D3 code with selection.call()

selection.call() method in D3 can aid in code organization and flexibility by eliminating the need to use chained method calls for every operation.

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <script src="../bower_components/underscore/underscore-min.js"></script>
    <script src="../ventor/d3.min.js"></script>
    <style type="text/css">

        body {
            padding-top: 50px;
            padding-left: 100px;

        }

        #chartArea {
            width: 400px;
            height: 300px;
            background-color: #CCC;
        }

        .bar {
            display: inline-block;
            width: 20px;
            height: 75px; /* Gets overriden by D3-assigned height below */
            margin-right: 2px;
            /* fill: teal; *//* SVG doesn't have background prop, use fill instead*/
            z-index: 99;
        }

        .bubble, .center {
            display: inline-block;
            fill: purple;
            fill-opacity: 0.5;
            stroke: black;
            stroke-weight: 1px;;
            z-index: 15;
        }

        .center {
            z-index: 10;
        }

        .active {
            fill: magenta;
            fill-opacity: 0.5;
            stroke-width: 3px;
        }

        .axis path, .axis line {
            fill: none;
            stroke: #000;
            stroke-width: 1px;
            shape-rendering: crispEdges;
        }

    </style>
</head>
<body>
<button onclick="update()">Update</button>
<section id="chartArea"></section>
<script>

    function planTrasition(selection, duration, color){

        selection
                .transition()
                .duration(duration)
                .style('fill', color)
                .attr('cx', function(each_data, index) {
                    return xScale(each_data.x);
                })
                .attr('cy', function(each_data) {
                    return yScale(each_data.y);
                })
                .attr('r', function(each_data, i) {
                    return each_data.r;
                });
    }

    function stepTransition(selection) {

        selection.transition()
                .duration(600)
                .style('fill', "lightblue")
                .attr('cx', function(each_data, index) {
                    return xScale(each_data.x);
                })
                .transition()
                .duration(600)
                .attr('cy', function(each_data) {
                    return yScale(each_data.y);
                })
                .transition()
                .duration(600)
                .attr('r', function(each_data, i) {
                    return each_data.r;
                });
    }

    function newData(d){
        d.x = Math.round(Math.random() * 100);
        d.y = Math.round(Math.random() * 100);
        d.r = Math.round(5 + Math.random() * 10);
    }

    function update(){

        //Only the data which x < 50 will get update
        svg.selectAll('circle')
                .filter(function(d) {
                    return d.x < 50;
                })
                .each( newData)
                .call(stepTransition);

        svg.selectAll('circle')
                .filter(function(d) {
                    return d.x >= 50;
                })
                .each( newData)
                .call(planTrasition, 2000, "red");
    }

    var dataset = _.map(_.range(30), function(num) {
                return {
                    x: Math.round(Math.random() * 100),
                    y: Math.round(Math.random() * 100),
                    r: Math.round(5 + Math.random() * 10)
                };
            }), //reandom generate 15 data from 1 to 50
            margin = {top: 20, right: 20, bottom: 40, left: 40},
            w = 400 - margin.left - margin.right,
            h = 300 - margin.top - margin.bottom;

    var svg = d3.select('#chartArea').append('svg')
            .attr('width', w + margin.left + margin.right)
            .attr('height', h + margin.top + margin.bottom)
            .append('g') //The last step is to add a G element which is a graphics container in SBG.
            .attr('transform', 'translate(' + margin.left + ', ' + margin.top + ')'); //Then offset that graphic element by our left and top margins.


    var yScale = d3.scale.linear()
            .domain([0, d3.max(dataset, function(d) {
                return d.y; //tell the max function just need to care about y prop
            })])
            .range([h, 0]);

    var yAxis = d3.svg.axis()
            .scale(yScale)
            .orient('left')
            .ticks(10)
            .innerTickSize(10)
            .outerTickSize(10)
            .tickPadding(10);
    svg.append('g')
            .attr('class', 'y axis')
            .attr('transform', 'translate(0,0)')
            .call(yAxis);

    var xScale = d3.scale.linear()
            .domain([0, 100])
            .range([0, w]);

    var xAxis = d3.svg.axis()
            .scale(xScale)
            .orient('bottom')
            .ticks(10)
            .innerTickSize(6)
            .outerTickSize(12)
            .tickPadding(12);

    svg.append('g')
            .attr('class', 'x axis')
            .attr('transform', 'translate(0, ' + h + ')')
            .call(xAxis);

    svg.selectAll('circle')
            .data(dataset)
            .enter()
            .append('circle')// svg doesn't have div, use rect instead
            .attr('class', "bubble")
            .attr('cx', function(each_data, index) {
                return xScale(each_data.x);
            })
            .attr('cy', function(each_data) {
                return yScale(each_data.y);
            })
            .attr('r', function(each_data, i) {
                return each_data.r;
            })
            .on('mouseover', function() {
                d3.select(this).classed('active', true)
            })
            .on('mouseleave', function() {
                d3.select(this).classed('active', false)
            })
            .on('mousedown', function(d) {
                var p_cx = d.x, p_cy = d.y, p_r = d.r;
                d3.select(this).transition().duration(500).attr('r', d.r * 1.5);
                svg.append('circle')
                        .attr('class', "center")
                        .attr('cx', function() {
                            return xScale(p_cx);
                        })
                        .attr('cy', function() {
                            return yScale(p_cy);
                        })
                        .attr('r', function() {
                            return p_r / 4;
                        })
                        .style('fill', 'red');
            })
            .on('mouseup', function(d) {

                d3.select(this).transition().duration(250).delay(100).attr('r', d.r)
            });
</script>
</body>
</html>

原文地址:https://www.cnblogs.com/Answer1215/p/4555701.html