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Step 6: programmatic zoom (bonus)
license: mit
<!DOCTYPE html>
<html lang="en">
<head>
<title>Planets</title>
<meta charset="utf-8">
<script src="//d3js.org/d3.v4.js"></script>
<style type="text/css">
/* HTML elements */
/* ============= */
/* Base elements */
body {
font-family: Avenir, sans-serif;
font-size: 0.75rem;
margin: 0;
}
#headline {
position: absolute;
top: 0;
left: 0;
width: 100%;
text-align: center;
color: #555;
}
#pink {
border-bottom: 2px solid deeppink;
padding-bottom: 0.25rem;
}
/* Links */
a {
color: #555;
transition: color 200ms;
}
a:link {
text-decoration: none;
}
a:visited {
color: #555;
}
a:hover {
color: deeppink;
}
a:active {
color: #555;
}
/* SVG elements */
/* ============ */
svg {
border: 1px solid #ccc;
}
/* Axes */
.tick text {
font-family: Avenir, sans-serif;
fill: #555;
font-size: 0.75rem;
}
.tick line, .lines {
stroke: #555;
stroke-width: 0.5;
shape-rendering: crispEdges;
}
path.domain {
display: none;
}
/* Chart */
circle {
fill: white;
stroke: deeppink;
stroke-width: 4px;
}
.label {
fill: #777;
}
</style>
</head>
<body>
<h1 id="headline">Measuring our planets'
<span id="pink">
<a href="https://en.wikipedia.org/wiki/Solar_System#Distances_and_scales" target="_blank">distances</a>
</span>
</h1>
<div id="vis"></div>
<script type="text/javascript">
function make(data) {
/* Set up */
/* ====== */
/* Dimensions and base */
/* ------------------- */
var margin = {
top: window.innerHeight * 0.3,
left: 50,
bottom: window.innerHeight * 0.4,
right: 50
};
// The chart *and* screen height.
var height = window.innerHeight - margin.top - margin.bottom;
// Calculate width
var mapScale = 1/10e4;
var maxDist = d3.max(data, function(d) { return d.distance; });
// The full width of all planets
var chartWidth = maxDist * mapScale;
// SVG width will only be as large as screen
var screenWidth = window.innerWidth - margin.left - margin.right;
/* SVG */
var svg = d3.select('#vis')
.append('svg')
.attr('width', screenWidth + margin.left + margin.right)
.attr('height', height + margin.top + margin.bottom)
.append('g')
.attr('class', 'chart')
.attr('transform', 'translate(' + margin.left + ', ' + margin.top + ')');
var listenerRect = svg
.append('rect')
.attr('class', 'listener-rect')
.attr('x', 0)
.attr('y', -margin.top)
.attr('width', screenWidth)
.attr('height', height + margin.top + margin.bottom)
.style('opacity', 0);
/* Scales */
/* ====== */
var rExtent = d3.extent(data, function(d) { return d.radius; });
var rScale = d3.scaleLinear()
.domain([0, rExtent[1]])
.range([3, height/2 * 0.9]);
var xScale = d3.scaleLinear()
.domain([0, maxDist])
.range([0, chartWidth]);
/* Axes components */
/* --------------- */
var xAxis = d3.axisBottom(xScale)
.tickSizeOuter(0)
.tickPadding(10)
.tickValues(data.map(function(el) { return el.distance; }))
.tickFormat(function(d, i) {
return data[i].planet + ' ' + d3.format(',')(d) + ' km';
});
/* Axes draw */
/* --------- */
// Drawing the axis
var xAxisDraw = svg.insert('g', ':first-child')
.attr('class', 'x axis')
.call(xAxis);
// Move the axis-labels and -lines down
var labelHeight = xAxisDraw.select('text').node().getBBox().height;
xAxisDraw.attr('transform', 'translate(0, ' + (height + labelHeight * data.length) + ')');
// Position the axis text
xAxisDraw.selectAll('text')
.attr('y', function(d, i) { return -(i * labelHeight + labelHeight); })
.attr('dx', '-0.15em')
.attr('dy', '1.15em')
.style('text-anchor', 'start');
// Draw the axis lines
xAxisDraw.selectAll('line')
.attr('y1', function(d, i) { return -(i * labelHeight + labelHeight); })
.attr('y2', function(d, i) {
return -(i * labelHeight + labelHeight + // the start position from axis-y 0
(data.length-1-i) * labelHeight + // label start to the chart bottom
height); // the height
});
/* Build vis */
/* ========= */
/* Sun and planets */
/* --------------- */
var gPlanets = svg.insert('g', '.listener-rect').attr('class', 'planet-group');
var planets = gPlanets.selectAll('.planet')
.data(data).enter()
.append('circle')
.attr('class', 'planet')
.attr('id', function(d) { return d.planet; })
.attr('cx', function(d) { return xScale(d.distance); })
.attr('cy', 0)
.attr('r', function(d) {
d.scaledRadius = rScale(d.radius);
return d.scaledRadius;
});
/* Zoom */
/* ==== */
// Cross-multiplication to get the minimum zoom so that the furthest away planet
// (Pluto) just fits on the screen. 0.75 gives some leeway for the label.
var minZoom = 1 / (chartWidth / window.innerWidth) * 0.75;
// Define the zoom behaviour
var zoom = d3.zoom()
.scaleExtent([minZoom, 20])
.on('zoom', zoomed);
// Listen for zoom events
listenerRect.call(zoom);
// Zoom function
function zoomed() {
// Get the transform
var transform = d3.event.transform;
// Lock at the Sun
transform.x = Math.min(0, transform.x);
// Re-scale the x scale
var xScaleNew = transform.rescaleX(xScale);
// Move the planets (semantic)
planets
.attr('cx', function(d) { return xScaleNew(d.distance); })
.attr('r', function(d) { return d.scaledRadius * transform.k; });
// Semantically zoom and pan the axis
xAxis.scale(xScaleNew);
xAxisDraw.call(xAxis);
// Stagger the axis-labels
xAxisDraw.selectAll('text')
.attr('y', function(d, i) { return -(i * labelHeight + labelHeight); })
// Stagger the axis-lines
xAxisDraw.selectAll('line')
.attr('y1', function(d, i) { return -(i * labelHeight + labelHeight); })
.attr('y2', function(d, i) {
return -(i * labelHeight + labelHeight + (data.length-1-i) * labelHeight + height);
});
} // zoomed()
/* Initial programmatic zoom */
/* ------------------------- */
// set an initial transform object on the zoom element
var initialTransform = d3.zoomIdentity.scale(20);
listenerRect.call(zoom.transform, initialTransform);
// Trigger programmatic zoom
progZoom()
// Programmatic zoom function
function progZoom() {
var zoomOutTransform = d3.zoomIdentity.translate(0, 0).scale(minZoom);
listenerRect
.transition()
.duration(5000)
.call(zoom.transform, zoomOutTransform)
.on('end', zoomToNormal)
function zoomToNormal() {
listenerRect
.transition()
.duration(3000)
.ease(d3.easeQuadInOut)
.call(zoom.transform, d3.zoomIdentity)
}
}
} // make()
/* Data load and visual */
/* ==================== */
function row(d) {
return {
planet: d.planet,
distance: +d.distance,
radius: +d.radius,
text: d.text
};
}
d3.csv('planets.csv', row, function(error, data) {
if (error) throw error;
console.log(data);
make(data);
});
</script>
</body>
</html>
planet distance radius
Sun 0 695000
Mercury 58000000 2440
Venus 108000000 6052
Earth 150000000 6378
Mars 228000000 3397
Jupiter 778000000 71492
Saturn 1429000000 60268
Uranus 2871000000 25559
Neptune 4504000000 24766
Pluto 5913000000 1150
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