d3.js geoWagner7()用法及代码示例

D3.js是一个JavaScript库，用于在Web浏览器中生成动态的交互式数据可视化。它利用可伸缩矢量图形，HTML5和级联样式表标准。

d3.js中的geoWagner7()函数用于绘制Wagner VII投影。

用法：

d3.geoWagner7()

参数：此方法不接受任何参数。

返回值：此方法根据给定的JSON数据创建Wagner7投影。

范例1：下面的示例对中心为(0,0)且旋转为0的世界进行Wagner7投影。

HTML

<!DOCTYPE html>  
<html lang="en">  
  
<head>  
    <meta charset="UTF-8" />  
    <meta name="viewport"
        content="width=device-width,  
                initial-scale=1.0"/>  
  
    <script src="https://d3js.org/d3.v4.js"></script> 
  
    <script src= 
        "https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script>   
</head>  
  
<body>  
    <div style="width:700px; height:500px;">  
        <svg width="600" height="450">  
        </svg>  
    </div>  
      
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Wagner7 projection 
        // Center(0,0) with 0 rotation 
        var gfg = d3.geoWagner7() 
            .scale(width / 1.5 / Math.PI) 
            .rotate([0,0]) 
            .center([0,0]) 
            .translate([width / 2, height / 2]) 
  
        // Loading the json data 
        d3.json( 
            "https://raw.githubusercontent.com/" 
            +"janasayantan/datageojson/master/world.json",  
            function(data){ 
                // Draw the map 
                svg.append("g") 
                    .selectAll("path") 
                    .data(data.features) 
                    .enter().append("path") 
                    .attr("fill", "BLACK") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
        }) 
    </script> 
</body>  
  
</html>

输出：

Wagner7世界的投影，无旋转且以(0,0)为中心

范例2：以下示例在自定义中心和旋转之后制作了Wagner7的世界投影。

HTML

<!DOCTYPE html>  
<html lang="en">  
  
<head>  
    <meta charset="UTF-8" />  
    <meta name="viewport"
        content="width=device-width,  
                initial-scale=1.0"/>  
  
    <script src="https://d3js.org/d3.v4.js"></script> 
  
    <script src= 
"https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
</head>  
  
<body>  
    <div style="width:500px; height:600px;">  
        <svg width="500" height="450">  
        </svg>  
    </div>  
      
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Wagner7  projection 
        // Center(50,50) and 40 degree 
        // rotation w.r.t Y axis 
        var gfg = d3.geoWagner7() 
            .scale(width / 1.3 / Math.PI) 
            .rotate([40,0]) 
            .center([50,50]) 
            .translate([width / 2, height / 2]) 
  
        // Loading the json data 
        d3.json( 
            "https://raw.githubusercontent.com/" 
            +"janasayantan/datageojson/master/world.json",  
            function(data){ 
                // Draw the map 
                svg.append("g") 
                    .selectAll("path") 
                    .data(data.features) 
                    .enter().append("path") 
                    .attr("fill", "Grey") 
                    .attr("d", d3.geoPath() 
                    .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
        }) 
    </script> 
</body>  
  
</html>

输出：

Wagner7投影，Y轴旋转40度，并以(50,50)为中心

相关用法

注：本文由纯净天空筛选整理自jana_sayantan大神的英文原创作品 D3.js geoWagner7() Function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。