This example demonstrates using the zoom event to constrain the zoom behavior’s translation. This implementation is a bit heavy-handed, as the translate constraint is zoom-dependent.
Constrained Zoom
<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<style> | |
.overlay { | |
fill: none; | |
pointer-events: all; | |
} | |
.land { | |
fill: #000; | |
} | |
.boundary { | |
fill: none; | |
stroke: #fff; | |
stroke-linejoin: round; | |
stroke-linecap: round; | |
} | |
</style> | |
<script src="//d3js.org/d3.v3.min.js"></script> | |
<script src="//d3js.org/topojson.v1.min.js"></script> | |
<body> | |
<script> | |
var width = 960, | |
height = 500; | |
var projection = d3.geo.mercator() | |
.translate([0, 0]) | |
.scale(width / 2 / Math.PI); | |
var zoom = d3.behavior.zoom() | |
.scaleExtent([1, 8]) | |
.on("zoom", move); | |
var path = d3.geo.path() | |
.projection(projection); | |
var svg = d3.select("body").append("svg") | |
.attr("width", width) | |
.attr("height", height) | |
.append("g") | |
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")") | |
.call(zoom); | |
var g = svg.append("g"); | |
svg.append("rect") | |
.attr("class", "overlay") | |
.attr("x", -width / 2) | |
.attr("y", -height / 2) | |
.attr("width", width) | |
.attr("height", height); | |
d3.json("/mbostock/raw/4090846/world-50m.json", function(error, world) { | |
if (error) throw error; | |
g.append("path") | |
.datum(topojson.feature(world, world.objects.countries)) | |
.attr("class", "land") | |
.attr("d", path); | |
g.append("path") | |
.datum(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; })) | |
.attr("class", "boundary") | |
.attr("d", path); | |
}); | |
function move() { | |
var t = d3.event.translate, | |
s = d3.event.scale; | |
t[0] = Math.min(width / 2 * (s - 1), Math.max(width / 2 * (1 - s), t[0])); | |
t[1] = Math.min(height / 2 * (s - 1) + 230 * s, Math.max(height / 2 * (1 - s) - 230 * s, t[1])); | |
zoom.translate(t); | |
g.style("stroke-width", 1 / s).attr("transform", "translate(" + t + ")scale(" + s + ")"); | |
} | |
</script> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment