canvas绘制圆圈

作者: 许三多儿 | 来源:发表于2018-05-10 14:30 被阅读0次

canvas绘制圆圈
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//全局定义投影变量projection，把上海中心坐标定位于canvas中心点 
var projection = d3.geoMercator()
    .center([121.5, 31.1]) //最终要换成上海的中心坐标
    .scale(40000)
    .translate([canvasWidth / 2, canvasHeight / 2]) //渲染容器的中心点
d3.queue()

    .defer(d3.json, 'geo_shanghai_full.json')
    .defer(d3.csv, 'site.csv')
    .defer(d3.csv, 'spot.csv')
    .defer(d3.csv, 'shop.csv')
    .defer(d3.csv, 'schedulePenalty.csv')
    .await(function(error, shanghaiMapData, siteData, spotData, shopData, scheduleData) {
        console.log(shanghaiMapData);
        drawCanvasMap(shanghaiMapData, projection)
        drawGeoCirclesSytem('canvasOfCircles', siteData, spotData, shopData, projection)        
    })

function drawGeoCirclesSytem(canvasId, siteData, spotData, shopData, projection) {

    var canvas = document.getElementById(canvasId)
    var context = canvas.getContext('2d')
    context.globalCompositeOperation = 'lighter'

    canvas.width = window.innerWidth
    canvas.height = window.innerHeight

    var geoCirclesSytem = createGeoCirclesSytem(siteData, spotData, shopData, projection)

    geoCirclesSytem.forEach(d => {
        d.forEach(e => {
            e.draw(context)
        })
    })
//由于两个循环遍历，所以要用两个forEach
//forEach数组中每个元素都来一遍
//=>ES6匿名函数（箭头函数）
//等价于
//geoCirclesSytem.forEach(function(d) {
//d.forEach(function(e) {
//e.draw(context)
//})
//})
}

function createGeoCirclesSytem(siteData, spotData, shopData, projection) {
    var geoCircleSystem
    var sites = []
    var shops = []
    var spots = []

    var siteStyle = {
        r: 8,
        color: 'rgba(255, 14, 12, 0.7)'
}
        var shopStyle = {
            r: 4,
            color: 'rgba(255, 125, 22, 0.6)'
}
        var spotStyle = {
            r: 2,
            color: 'rgba(81, 233, 71, 0.5)'
    }

    sites = createCircleSystem(siteData, siteStyle)
    shops = createCircleSystem(shopData, shopStyle)
    spots = createCircleSystem(spotData, spotStyle)

    geoCircleSystem = [sites, shops, spots]

    return geoCircleSystem

    function createCircleSystem(geoData, style) {
        var circleHolder = []

        geoData.forEach(d => {
            var postionProjected = projection([+d.Lng, +d.Lat])
            var xPosition = postionProjected[0]
            var yPosition = postionProjected[1]
            var circle = new Circle(xPosition, yPosition, style)

            circleHolder.push(circle)
        })
        console.log(circleHolder);
        return circleHolder
    }
}

function Circle(x, y, style) {
    this.x = x || 0
    this.y = y || 0
    this.r = style.r || 5
    this.color = style.color || 'Orange'
    this.particleBackground = 'rgba(0, 0, 0, 0.1)'
    //“||”运算遇到true就返回。
    //例如：a || b ,如果 a 为false，直接返回b，而不管b为true或者false 。
    //如果 a 为true，直接返回a，而不会继续往下执行。
}

Circle.prototype.draw = function(context) { //prototype原型函数，增加属性，用来实现基于原型的继承与属性的共享。
    context.beginPath()

    var fillStyle = context.createRadialGradient(this.x, this.y, this.r * 0.001, this.x, this.y, this.r)
    fillStyle.addColorStop(0, this.color)
    fillStyle.addColorStop(1, this.particleBackground)
    //createRadialGradient放射状圆形渐变

    context.fillStyle = fillStyle
    context.beginPath()
    context.arc(this.x, this.y, this.r, 0, Math.PI * 2)
    context.fill()
}

全部代码如下

<html>
    <head>
        <meta charset=utf-8 />
        <title>drawcanvasmap</title>
        <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
        <script src='https://api.mapbox.com/mapbox.js/v3.1.1/mapbox.js'></script>
        <link href='https://api.mapbox.com/mapbox.js/v3.1.1/mapbox.css' rel='stylesheet' />
        <script src='https://api.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v1.0.0/leaflet.markercluster.js'></script>
        <link href='https://api.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v1.0.0/MarkerCluster.css' rel='stylesheet' />
        <link href='https://api.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v1.0.0/MarkerCluster.Default.css' rel='stylesheet' />

    </head>
    <style>
        body,
        html {
            /*margin: 0;
            padding: 0;*/
        }
        
        body {
            background-color: black;
        }
        
        #canvasOfCircles {
            position: absolute;
            left: 0;
            top: 0;
            z-index: 70;
        }
        
        #shanghaiMap {
            position: absolute;
            left: 0;
            top: 0;
        }
        
        #map {
            padding: 0;
            margin: 0;
            height: 100%;
            width: 100%;
            background-color: #0f0f0f;
            color: #ddd;
        }
    </style>

    <body>
        <!--<div id="map"></div>-->
        <canvas id="shanghaiMap"></canvas>
        <canvas id="canvasOfCircles"></canvas>
        
        <script src="d3.js"></script>
        <script src="http://d3js.org/d3.v4.0.0-alpha.44.min.js"></script>
        <script>

            document.body.onmousewheel = function(event) {
                event = event || window.event;
                console.dir(event);
                //zoomShanghaiMap()
            };
            var canvasWidth = window.innerWidth
            var canvasHeight = window.innerHeight

            var projection = d3.geoMercator()
                .center([121.5, 31.1]) //最终要换成上海的中心坐标
                .scale(40000)
                .translate([canvasWidth / 2, canvasHeight / 2]) //渲染容器的中心点

            var initialProjectionScale = 40000
            var globalProjection = d3.geoMercator()
                .center([121.5, 31.1]) //最终要换成上海的中心坐标
                .scale(initialProjectionScale)
                .translate([window.innerWidth / 2, window.innerHeight / 2]) //渲染容器的中心点

            d3.queue()

                .defer(d3.json, 'geo_shanghai_full.json')
                .defer(d3.csv, 'site.csv')
                .defer(d3.csv, 'spot.csv')
                .defer(d3.csv, 'shop.csv')
                .defer(d3.csv, 'schedulePenalty.csv')
                .await(function(error, shanghaiMapData, siteData, spotData, shopData, scheduleData) {
                    console.log(shanghaiMapData, siteData);
                    drawCanvasMap(shanghaiMapData, projection)
                    drawGeoCirclesSytem('canvasOfCircles', siteData, spotData, shopData, projection)
                })

            function drawCanvasMap(mapData, projection) {
                var canvas = document.getElementById('shanghaiMap')
                var context = canvas.getContext('2d')
                context.globalCompositeOperation = 'lighter'

                canvas.width = window.innerWidth
                canvas.height = window.innerHeight

                var path = d3.geoPath()
                    .projection(projection)
                    .context(context)

                // console.log(mapData.features)

                mapData.features.forEach(d => {
                    context.beginPath()
                    path(d)
                    context.strokeStyle = 'rgba(255, 255, 255, 0.2)'
                    context.lineWidth = 1
                    context.stroke()
                })

            }

            function drawGeoCirclesSytem(canvasId, siteData, spotData, shopData, projection) {

                var canvas = document.getElementById(canvasId)
                var context = canvas.getContext('2d')
                context.globalCompositeOperation = 'lighter'

                canvas.width = window.innerWidth
                canvas.height = window.innerHeight

                var geoCirclesSytem = createGeoCirclesSytem(siteData, spotData, shopData, projection)
                console.log(geoCirclesSytem);
                geoCirclesSytem.forEach(d => {
                    d.forEach(e => {
                        e.draw(context)
                    })
                })
                //由于两个循环遍历，所以要用两个forEach
                //forEach数组中每个元素都来一遍
                //=>箭头函数
                //              等价于
                //              geoCirclesSytem.forEach(function(d) {
                //                  d.forEach(function(e) {
                //                      e.draw(context)
                //                  })
                //              })

            }

            function createGeoCirclesSytem(siteData, spotData, shopData, projection) {
                var geoCircleSystem
                var sites = []
                var shops = []
                var spots = []

                var siteStyle = {
                    r: 8,
                    color: 'rgba(255, 14, 12, 0.7)'
                }
                var shopStyle = {
                    r: 4,
                    color: 'rgba(255, 125, 22, 0.6)'
                }
                var spotStyle = {
                    r: 2,
                    color: 'rgba(81, 233, 71, 0.5)'
                }

                sites = createCircleSystem(siteData, siteStyle)
                shops = createCircleSystem(shopData, shopStyle)
                spots = createCircleSystem(spotData, spotStyle)

                geoCircleSystem = [sites, shops, spots]

                return geoCircleSystem

                function createCircleSystem(geoData, style) {
                    var circleHolder = []

                    geoData.forEach(d => {
                        var postionProjected = projection([+d.Lng, +d.Lat])
                        var xPosition = postionProjected[0]
                        var yPosition = postionProjected[1]
                        var circle = new Circle(xPosition, yPosition, style)

                        circleHolder.push(circle)
                    })
                    console.log(circleHolder);
                    return circleHolder
                }
            }

            function Circle(x, y, style) {
                this.x = x || 0
                this.y = y || 0
                this.r = style.r || 5
                this.color = style.color || 'Orange'
                this.particleBackground = 'rgba(0, 0, 0, 0.1)'
                //“||”运算遇到true就返回。
                //例如：a || b ,如果 a 为false，直接返回b，而不管b为true或者false 。
                //如果 a 为true，直接返回a，而不会继续往下执行。
            }

            Circle.prototype.draw = function(context) { //prototype原型函数，增加属性，用来实现基于原型的继承与属性的共享。
                context.beginPath()

                var fillStyle = context.createRadialGradient(this.x, this.y, this.r * 0.001, this.x, this.y, this.r)
                fillStyle.addColorStop(0, this.color)
                fillStyle.addColorStop(1, this.particleBackground)
                //createRadialGradient放射状圆形渐变

                context.fillStyle = fillStyle
                context.beginPath()
                context.arc(this.x, this.y, this.r, 0, Math.PI * 2)
                context.fill()
            }
        </script>
    </body>

</html>

canvas绘制圆圈
全部代码如下
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