The transform.scale() function in D3.js library is used to get the transformation whose scale k₁ is equal to k₀k, where k₀ is the transform’s scale.
Syntax:
transform.scale(k)
Parameters: This function accepts a single parameter as mentioned above and described below.
- k: This parameter is the scale argument.
Return value: This function returns the transformed zoom behaviour.
Below programs illustrate the transform.scale() function in D3.js library.
Example 1:
HTML
<!DOCTYPE html> < html >
< head >
< meta charset = "utf-8" >
</ script >
</ head >
< body >
< center >
< h1 style = "color: green;" >
Geeksforgeeks
</ h1 >
< h3 >D3.js | transform.scale() Function</ h3 >
< script >
var svg = d3.select("body").append("svg")
.attr("width", 400)
.attr("height", 300);
var g1 = svg.append("g"), g2 = svg.append("g");
var zoom1 = d3.zoom().on("zoom", function () {
g1.attr("transform", d3.event.transform);
});
var zoom2 = d3.zoom().on("zoom", function () {
g2.attr("transform", d3.event.transform);
});
g1.call(zoom1.transform, d3.zoomIdentity
.translate(150, 100)
.scale(2));
g2.call(zoom2.transform, d3.zoomIdentity
.translate(150, 100)
.scale(2));
g1.append("rect")
.attr("x", 20)
.attr("y", 20)
.attr("width", 60)
.attr("height", 60);
g2.append("rect")
.attr("x", 25)
.attr("y", 25)
.attr("width", 50)
.attr("height", 50)
.attr("fill", "green");
d3.selectAll("rect").on("click", function () {
g1.transition()
.duration(3000)
.attr("transform", d3.zoomIdentity)
.on("end", function () {
d3.select(this).call(zoom1.transform,
d3.zoomIdentity);
})
g2.transition()
.duration(2000)
.call(zoom2.transform,
d3.zoomIdentity)
});
</ script >
</ center >
</ body >
</ html >
|
Output:
Example 2:
HTML
<!DOCTYPE html> < html >
< head >
< meta charset = "utf-8" >
</ script >
</ head >
< body >
< center >
< h1 style = "color: green;" >
Geeksforgeeks
</ h1 >
< h3 >D3.js | transform.scale() 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(300).map(phyllotaxis(10)),
point = points.pop();
var zoom = d3.zoom()
.on("zoom", zoomed);
canvas
.call(zoom.transform, transform)
.call(transition);
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);
drawPoints();
context.restore();
}
function drawPoints() {
context.beginPath();
points.forEach(drawPoint);
context.fillStyle = "#8d0396";
context.fill();
context.beginPath();
drawPoint(point);
context.fillStyle = "#00ab1c";
context.fill();
context.stroke();
}
function drawPoint(point) {
context.moveTo(point[0] + radius, point[1]);
context.arc(point[0], point[1],
radius, 0, 2 * Math.PI);
}
function transform() {
return d3.zoomIdentity
.translate(width / 2, height / 2)
.scale(8)
.translate(-point[0], -point[1]);
}
function transition(canvas) {
var n = points.length,
i = Math.random() * n | 0,
c = points[i]; // Pick a random point.
points[i] = points[n - 1];
points[n - 1] = point;
point = c;
canvas.transition()
.delay(500)
.duration(3000)
.call(zoom.transform, transform)
.on("end", function ()
{ canvas.call(transition); });
}
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: