This example demonstrates how to constrain d3-zoom such that a rectangular area of interest is not allowed to go outside the viewport.
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Constrained Zoom
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license: gpl-3.0 |
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<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<svg width="960" height="500"> | |
<g> | |
<image xlink:href="circle-limit-iv.jpg" x="455" y="225" width="50" height="50"></image> | |
</g> | |
</svg> | |
<script src="https://d3js.org/d3.v4.min.js"></script> | |
<script> | |
var zoom = d3.zoom().on("zoom", zoomed), | |
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; | |
// Don’t allow the zoomed area to be bigger than the viewport. | |
zoom.scaleExtent([1, Math.min(width / (x1 - x0), height / (y1 - y0))]); | |
function zoomed() { | |
var t = d3.event.transform; | |
if (t.invertX(0) > x0) t.x = -x0 * t.k; | |
else if (t.invertX(width) < x1) t.x = width - x1 * t.k; | |
if (t.invertY(0) > y0) t.y = -y0 * t.k; | |
else if (t.invertY(height) < y1) t.y = height - y1 * t.k; | |
g.attr("transform", t); | |
} | |
</script> |
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