D3.js zoom.extent() Function

Last Updated : 09 Sep, 2020

The zoom.extent() Function in D3.js is used to set the viewport extent to the specified array of points [top-left corner, bottom-right corner].

Syntax:

zoom.extent([extent])

Parameters: This function accepts a single parameter as mentioned above and described below

extent: This parameter can be defined as specified as a function which returns such an array.

Return Value: This function returns the zoom behaviour.

Below programs illustrate the zoom.extent() function in D3.js

Example 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 | zoom.extent() Function</h3> 
          
        <div id="GFG"></div> 
          
        <script> 
            var svg = d3.select("#GFG") 
              .append("svg") 
                .attr("width", 300) 
                .attr("height", 200) 
                .call(d3.zoom() 
                .extent([[0, 0], [200, 200]]) 
                .on("zoom", function () { 
                   svg.attr( 
             "transform", d3.event.transform) 
                })) 
              .append("g") 
              
            svg 
              .append("circle") 
                .attr("cx", 150) 
                .attr("cy", 100) 
                .attr("r", 40) 
                .style("fill", "green") 
              
        </script>  
    </center> 
</body>  
  
</html>  

Output:

Example 2:

<!DOCTYPE html>  
<html>  
<head>  
    <meta charset="utf-8"> 
       
    <script src="https://d3js.org/d3.v4.min.js">  
    </script> 
       
    <style> 
        svg text {   
            fill: green;   
            font: 20px sans-serif;   
            text-anchor: center;   
        }   
           
        rect { 
          pointer-events: all; 
        } 
    </style> 
      
</head>  
     
<body>  
    <center> 
        <h1 style="color: green;">  
            Geeksforgeeks  
        </h1>  
       
        <h3>D3.js | zoom.extent() Function</h3> 
           
        <svg></svg> 
           
        <script> 
            var width = 400; 
            var height = 200; 
               
            var svg = d3.select("svg") 
              .attr("width", width) 
              .attr("height", height); 
                 
            // The scale used to display the axis. 
            var scale = d3.scaleLinear() 
              .range([10, width-20]) 
              .domain([0, 100]); 
                
            var shadowScale = scale.copy(); 
               
            var axis = d3.axisBottom() 
              .scale(scale); 
                 
            var g = svg.append("g") 
              .attr("transform", "translate(0, 50)") 
              .call(axis); 
                 
            // Standard zoom behavior: 
            var zoom = d3.zoom() 
              .extent([[0, 0], [width, height]]) 
              .on("zoom", zoomed); 
                
            // Call the Zoom. 
            var rect = svg.append("rect") 
              .attr("width", width) 
              .attr("height", height) 
              .attr("fill", "none") 
              .call(zoom); 
                
            function zoomed() { 
              var t = d3.event.transform; 
              scale.domain(t.rescaleX(shadowScale).domain()); 
              g.call(axis); 
            } 
        </script>  
    </center> 
</body>  
   
</html> 