d3.js transform.invertY()用法及代码示例

D3.js库中的transform.invertY()函数用于获取指定y坐标的逆变换(y-t_y)/k。

用法:

transform.invertY( y )

参数：该函数接受上述和以下描述的以下参数

y:此参数为y坐标。

返回值：此函数返回转换后的缩放行为。

以下示例程序旨在说明D3.js库中的transform.invertY()函数。

范例1：

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <meta charset="utf-8"> 
  
    <script src="https://d3js.org/d3.v4.min.js"> 
    </script> 
  
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"> 
    </script> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green;"> 
            Geeksforgeeks 
        </h1> 
  
        <h3>D3.js | transform.invertY() Function</h3> 
  
        <svg width="300" height="300"> 
            <g> 
                <image xlink:href= 
"https://media.geeksforgeeks.org/wp-content/cdn-uploads/20190710102234/download3.png"
                x="150" y="150" width="50" height="50"> 
                </image> 
            </g> 
        </svg> 
  
        <script> 
            var zoom = d3.zoom() 
                .on("zoom", zoomed) 
                .constrain(constr); 
  
            var svg = d3.select("svg").call(zoom), 
                g = svg.select("g"), 
                image = g.select("image"), 
                width = +svg.attr("width"), 
                height = +svg.attr("height"), 
                x0 = +image.attr("x"), 
                y0 = +image.attr("y"), 
                x1 = +image.attr("width") + x0, 
                y1 = +image.attr("height") + y0; 
  
            zoom.scaleExtent([1, Math.min(width / 
                (x1 - x0), height / (y1 - y0))]); 
  
            function zoomed() { 
                var trans = d3.event.transform; 
                if (trans.invertX(0) > x0) 
                    trans.x = -x0 * trans.k; 
                else if (trans.invertX(width) < x1) 
                    trans.x = width - x1 * trans.k; 
                if (trans.invertY(0) > y0) 
                    trans.y = -y0 * trans.k; 
                else if (trans.invertY(height) < y1) 
                    trans.y = height - y1 * trans.k; 
                g.attr("transform", trans); 
            } 
  
            function constr(transform, extent,  
                            translateExtent) { 
                var dx0 = transform.invertX( 
                        extent[0][0]) - translateExtent[0][0], 
  
                    dx1 = transform.invertX( 
                        extent[1][0]) - translateExtent[1][0], 
  
                    dy0 = transform.invertY( 
                        extent[0][1]) - translateExtent[0][1], 
  
                    dy1 = transform.invertY( 
                        extent[1][1]) - translateExtent[1][1]; 
  
                return transform.translate( 
                    dx1 > dx0 ? (dx0 + dx1) / 2:  
                        Math.min(0, dx0) || Math.max(0, dx1), 
  
                    dy1 > dy0 ? (dy0 + dy1) / 2:  
                        Math.min(0, dy0) || Math.max(0, dy1) 
                ); 
            } 
        </script> 
    </center> 
</body> 
  
</html>

输出：

范例2：

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <meta charset="utf-8"> 
  
    <script src= 
        "https://d3js.org/d3.v4.min.js"> 
    </script> 
  
    <style> 
        circle { 
            opacity:0.7; 
        } 
    </style> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green;"> 
            Geeksforgeeks 
        </h1> 
  
        <h3>D3.js | zoom.invertY() Function</h3> 
  
        <svg></svg> 
  
        <script> 
            var radius = 15; 
            var svg = d3.select('svg'); 
            var dimension = document.body 
                .getBoundingClientRect(); 
  
            var data = d3.range(0, 50).map(function () { 
                return { 
                    x:getRandom(radius, 400 - radius), 
                    y:getRandom(radius, 200 - radius) 
                } 
            }); 
  
            var zoom = d3.zoom() 
                .constrain(mydata) 
                .on('zoom', function () { 
                    canvas.attr('transform',  
                            d3.event.transform); 
                }) 
  
            var canvas = svg.attr('width', 400) 
                .attr('height', 200) 
                .call(zoom) 
                .insert('g', ':first-child'); 
  
            canvas.selectAll('circle') 
                .data(data) 
                .enter() 
                .append('circle') 
                .attr('r', radius) 
                .attr('cx', function (d) { 
                    return d.x; 
                }) 
                .attr('cy', function (d) { 
                    return d.y; 
                }) 
                .style('fill', function () { 
                    return d3.schemeCategory10 
                            [getRandom(0, 9)] 
                }); 
  
            function getRandom(min, max) { 
                min = Math.ceil(min); 
                max = Math.floor(max); 
                return Math.floor(Math.random()  
                        * (max - min + 1)) + min; 
            } 
  
            function mydata(transform, extent,  
                            translateExtent) { 
                var dx0 = transform.invertX( 
                        extent[0][0]) - translateExtent[0][0], 
  
                    dx1 = transform.invertX( 
                        extent[1][0]) - translateExtent[1][0], 
  
                    dy0 = transform.invertY( 
                        extent[0][1]) - translateExtent[0][1], 
  
                    dy1 = transform.invertY( 
                        extent[1][1]) - translateExtent[1][1]; 
  
                return transform.translate( 
                    dx1 > dx0 ? (dx0 + dx1) / 2:  
                        Math.min(0, dx0) || Math.max(0, dx1), 
                          
                    dy1 > dy0 ? (dy0 + dy1) / 2:  
                        Math.min(0, dy0) || Math.max(0, dy1) 
                ); 
            } 
        </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 transform.invertY() 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。