25:["$","title",null,{"children":"Programmatic Zoom | Christopher Pietsch | Observable"}] 49:T6b9,chart = { const zoom = d3.zoom() .scaleExtent([1, 40]) .on("zoom", zoomed); const svg = d3.create("svg") .attr("viewBox", [0, 0, width, height]) .on("click", reset); const g = svg.append("g"); g.selectAll("circle") .data(data) .join("circle") .attr("cx", ([x]) => x) .attr("cy", ([, y]) => y) .attr("r", radius) .attr("fill", (d, i) => d3.interpolateRainbow(i / 360)) .on("click", clicked) svg.call(zoom) .on("mousemove", mousemove); function random() { const [x, y] = data[Math.floor(Math.random() * data.length)]; svg.transition().duration(2500).call( zoom.transform, d3.zoomIdentity.translate(width / 2, height / 2).scale(40).translate(-x, -y) ); } function reset() { svg.transition().duration(750).call( zoom.transform, d3.zoomIdentity, d3.zoomTransform(svg.node()).invert([width / 2, height / 2]) ); } function mousemove() { const p = d3.zoomTransform(this).invert(d3.mouse(this)) const q = quadtree.find(p[0], p[1]) // used to be zoom.center(q) g.selectAll("circle").attr("r", p => p == q ? radius + 3 : radius) } function clicked([x, y]) { d3.event.stopPropagation(); svg.transition().duration(750).call( zoom.transform, d3.zoomIdentity.translate(width / 2, height / 2).scale(40).translate(-x, -y), d3.mouse(svg.node()) ); } function zoomed() { g.attr("transform", d3.event.transform); } return Object.assign(svg.node(), { zoomIn: () => svg.transition().call(zoom.scaleBy, 2), zoomOut: () => svg.transition().call(zoom.scaleBy, 0.5), zoomRandom: random, zoomReset: reset }); }4a:[] 29:{"id":"3ac31317d41c1765","slug":null,"title":"Programmatic 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[*zoom*.scaleBy](https://github.com/d3/d3-zoom/blob/master/README.md#zoom_scaleBy).`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":38,"value":"{\n const form = html``;\n form.in.onclick = () => chart.zoomIn();\n form.out.onclick = () => chart.zoomOut();\n form.random.onclick = () => chart.zoomRandom();\n form.reset.onclick = () => chart.zoomReset();\n return 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5","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":203,"value":"quadtree = d3.quadtree()\n .addAll(data)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":6,"value":"data = Array.from({length: 1000}, (_, i) => {\n const radius = step * Math.sqrt(i += 0.5), a = theta * i;\n return [\n width / 2 + radius * Math.cos(a),\n height / 2 + radius * Math.sin(a)\n ];\n})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":58,"value":"theta = Math.PI * (3 - 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