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D3.js zoom.extent() Function

  • Last Updated : 09 Sep, 2020
Geek Week

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>

Output:

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