d3.js zoomTransform()用法及代码示例

D3.js中的d3.zoomTransform()函数用于获取指定节点的当前转换。

用法:

d3.zoomTransform(node)

参数：该函数接受如上所述和以下描述的单个参数

node:此参数是接收输入事件的元素。

返回值：此函数返回转换后的缩放行为。

以下程序说明了D3.js中的d3.zoomTransform()函数。

范例1：

<!DOCTYPE html>  
<html>  
<head>  
    <meta charset="utf-8"> 
   
    <script src="https://d3js.org/d3.v4.min.js">  
   </script>  
      
</head>  
     
<body>  
    <center> 
        <h1 style="color:green;">  
            Geeksforgeeks  
        </h1>  
       
        <h3>D3.js | d3.zoomTransform() Function</h3> 
           
        <svg width="400" height="250"></svg> 
           
        <script> 
            var svg = d3.select("svg"), 
                width = +svg.attr("width"), 
                height = +svg.attr("height"); 
                  
            var radius = 30;     
            var circle1 = {x:100, y:height /2 } ;  
            var circle2 = {x:300, y:height /2 } ; 
              
            var circle1 = svg.append("circle") 
                .attr("cx", circle1.x) 
                .attr("cy", circle1.y) 
                .attr("r", radius) 
                .attr("fill", "red"); 
                  
            var circle2 = svg.append("circle") 
                .attr("cx", circle2.x) 
                .attr("cy", circle2.y) 
                .attr("r", radius) 
                .attr("fill", "green"); 
                  
            //define zoom behaviour  
            var zoom_handler = d3.zoom() 
                .on("zoom", zoom_actions); 
              
            zoom_handler(circle2); 
              
            function zoom_actions(){ 
             var transform = d3.zoomTransform(this); 
             /* same as  this.setAttribute( 
                "transform", "translate(" + 
                 transform.x + ", "  
                 + transform.y + ") scale( 
              " + transform.k + ")"); */ 
             this.setAttribute("transform", transform) 
            } 
  
        </script>  
    </center> 
</body>  
   
</html>

输出：

范例2：

<!DOCTYPE html>  
<html>  
<head>  
    <meta charset="utf-8"> 
    <script src="https://d3js.org/d3.v4.min.js">  
   </script>  
      
</head>  
     
<body>  
    <center> 
        <h1 style="color:green;">  
            Geeksforgeeks  
        </h1>  
       
        <h3>D3.js | d3.zoomTransform() Function</h3> 
           
        <canvas width="500" height="300"></canvas> 
           
        <script> 
           var canvas = d3.select("canvas"), 
                context = canvas.node().getContext("2d"), 
                width = canvas.property("width"), 
                height = canvas.property("height"), 
                radius = 2.5; 
              
            var points = d3.range(200).map(phyllotaxis(10)); 
              
            canvas.call(d3.zoom() 
                .scaleExtent([1 / 2, 4]) 
                .on("zoom", zoomed)); 
              
            drawPoints(); 
              
              
            var k = 1; 
              
            function zoomed() { 
              context.save(); 
              context.clearRect(0, 0, width, height); 
              context.translate(d3.event.transform.x, d3.event.transform.y); 
              context.scale(d3.event.transform.k, d3.event.transform.k); 
              k = d3.event.transform.k; 
              drawPoints(); 
              context.restore(); 
            } 
              
            function drawPoints() { 
              context.beginPath(); 
              points.forEach(drawPoint); 
              context.fill(); 
            } 
              
            function drawPoint(point) { 
              context.moveTo(point[0] + radius, point[1]); 
              context.arc(point[0], point[1], radius, 0, 2 * Math.PI); 
            } 
              
            function phyllotaxis(radius) { 
              var theta = Math.PI * (3 - Math.sqrt(5)); 
              return function(i) { 
                var r = radius * Math.sqrt(i), a = theta * i; 
                return [ 
                  width / 2 + r * Math.cos(a), 
                  height / 2 + r * Math.sin(a) 
                ]; 
              }; 
            } 
        </script>  
    </center> 
</body>  
   
</html>

输出：

相关用法

注：本文由纯净天空筛选整理自SHUBHAMSINGH10大神的英文原创作品 D3.js zoomTransform() 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。