The d3.zoomTransform() Function in D3.js is used to get the current transform for the specified node.
Syntax:
d3.zoomTransform(node)
Parameters: This function accepts a single parameter as mentioned above and described below
- node: This parameter is the element that received the input event.
Return Value: This function returns the transformed zoom behaviour.
Below programs illustrate the d3.zoomTransform() function in D3.js.
Example 1:
<!DOCTYPE html> < html >
< head >
< meta charset = "utf-8" >
</ 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 >
|
Output:
Example 2:
<!DOCTYPE html> < html >
< head >
< meta charset = "utf-8" >
</ 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 >
|
Output: