Created
March 14, 2014 23:12
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Fitting D3 map inside a viewport and constrain panning.
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <title>d3 geo map</title> | |
| <meta charset="utf-8"> | |
| <style> | |
| svg { | |
| border: 1px solid #ccc; | |
| } | |
| .overlay { | |
| fill: none; | |
| pointer-events: all; | |
| } | |
| .feature { | |
| fill: #aaa; | |
| stroke: #fff; | |
| stroke-linejoin: round; | |
| stroke-linecap: round; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| <script src="http://d3js.org/topojson.v1.min.js"></script> | |
| <script> | |
| var featureBounds, | |
| geoParent, | |
| geo, | |
| geoLayer = {}, | |
| slast, | |
| tlast; | |
| var width = 960, | |
| height = 350; | |
| var projection = d3.geo.albersUsa() | |
| .scale(1000) | |
| .translate([width / 2, height / 2]); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var zoom = d3.behavior.zoom() | |
| .translate([0, 0]) | |
| .scale(1) | |
| .center([width/2, height/2]) | |
| .scaleExtent([1, 8]) | |
| .on("zoom", zoomed); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| function getFeaturesBox() { | |
| return { | |
| x: featureBounds[0][0], | |
| y: featureBounds[0][1], | |
| width: featureBounds[1][0] - featureBounds[0][0], | |
| height: featureBounds[1][1] - featureBounds[0][1] | |
| }; | |
| } | |
| // fits the geometry layer inside the viewport | |
| function fitGeoInside() { | |
| var bbox = getFeaturesBox(), | |
| scale = 0.95 / Math.max(bbox.width / width, bbox.height / height), | |
| trans = [-(bbox.x + bbox.width / 2) * scale + width / 2, -(bbox.y + bbox.height / 2) * scale + height / 2]; | |
| geoLayer.scale = scale; | |
| geoLayer.translate = trans; | |
| geo.attr('transform', [ | |
| 'translate(' + geoLayer.translate + ')', | |
| 'scale(' + geoLayer.scale + ')' | |
| ].join(' ')); | |
| postTransformOperations(geoLayer.scale); | |
| } | |
| // transform geoParent | |
| function setGeoTransform(scale, trans) { | |
| zoom.scale(scale) | |
| .translate(trans); | |
| tlast = trans; | |
| slast = scale; | |
| geoParent.attr('transform', [ | |
| 'translate(' + trans + ')', | |
| 'scale(' + scale + ')' | |
| ].join(' ')); | |
| postTransformOperations(scale * geoLayer.scale); | |
| } | |
| // scale strokes for fussy browsers | |
| function postTransformOperations(scale) { | |
| geo.selectAll('path') | |
| .style('stroke-width', 1 / scale); | |
| } | |
| // limits panning | |
| // XXX: this could be better | |
| function limitBounds(scale, trans) { | |
| var bbox = getFeaturesBox(); | |
| var outer = width - width * scale; | |
| var geoWidth = bbox.width * geoLayer.scale * scale, | |
| geoLeft = -((width * scale) / 2 - ((geoWidth) / 2)), | |
| geoRight = outer - geoLeft; | |
| if (scale === slast) { | |
| //trans[0] = Math.min(0, Math.max(trans[0], width - width * scale)); | |
| trans[1] = Math.min(0, Math.max(trans[1], height - height * scale)); | |
| if(geoWidth > width) { | |
| if(trans[0] < tlast[0] ) { // panning left | |
| trans[0] = Math.max(trans[0], geoRight); | |
| } else if (trans[0] > tlast[0]) { // panning right | |
| trans[0] = Math.min(trans[0], geoLeft); | |
| } | |
| } else { | |
| if (trans[0] < geoLeft) { | |
| trans[0] = geoLeft; | |
| } else if (trans[0] > geoRight) { | |
| trans[0] = geoRight; | |
| } | |
| } | |
| } | |
| setGeoTransform(scale, trans); | |
| } | |
| // zoom behavior on 'zoom' handler | |
| function zoomed() { | |
| var e = d3.event, | |
| scale = (e && e.scale) ? e.scale : zoom.scale(), | |
| trans = (e && e.translate) ? e.translate : zoom.translate(); | |
| limitBounds(scale, trans); | |
| } | |
| // set the map's initial state | |
| // geoParent layer to scale 1 | |
| // geo layer is scaled to fit viewport | |
| function initialize() { | |
| tlast = null; | |
| slast = null; | |
| setGeoTransform(1, [0,0]); | |
| fitGeoInside(); | |
| } | |
| // load topojson & make map | |
| d3.json("us-states.json", function(error, topology) { | |
| if (error) return; | |
| var features = topojson.feature(topology, topology.objects['us-states']).features; | |
| var collection = { | |
| 'type': 'FeatureCollection', | |
| 'features' : features | |
| }; | |
| featureBounds = path.bounds(collection); | |
| geoParent = svg.append("g"); | |
| geoParent | |
| .append('rect') | |
| .attr('class', 'bg') | |
| .attr('pointer-events', 'none') | |
| .attr('fill', 'none') | |
| .attr('width', width) | |
| .attr('height', height); | |
| geo = geoParent.append("g"); | |
| geo.selectAll('.feature') | |
| .data(features) | |
| .enter() | |
| .append("path") | |
| .attr("class", "feature") | |
| .attr("d", path); | |
| svg.append("rect") | |
| .attr("class", "overlay") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .call(zoom); | |
| initialize(); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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