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Map scale adjusts and displays user-friendly units.

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Bryan Housel
2014-06-20 17:54:42 -04:00
parent 114cb33e05
commit d342e01326
1 changed files with 53 additions and 7 deletions
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60
js/id/ui/scale.js
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@@ -1,5 +1,7 @@
iD.ui.Scale = function(context) {
var projection = context.projection,
imperial = (iD.detect().locale === 'en-us'),
maxLength = 180,
tickHeight = 8;
// http://stackoverflow.com/a/27943/7620
@@ -15,22 +17,66 @@ iD.ui.Scale = function(context) {
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
var d = R * c; // Distance in m
return d;
}
function scaleDefs(loc1, loc2) {
var lat = (loc2[1] + loc1[1]) / 2,
conversion = (imperial ? 3.28084 : 1),
dist = distance(loc1, loc2) * conversion,
scale = { dist: 0, px: 0, text: '' },
buckets, i, val, dLon;
if (imperial) {
buckets = [5280000, 528000, 52800, 5280, 500, 50, 5, 1];
} else {
buckets = [5000000, 500000, 50000, 5000, 500, 50, 5, 1];
}
// determine a user-friendly endpoint for the scale
for (i = 0; i < buckets.length; i++) {
val = buckets[i];
if (dist >= val) {
scale.dist = Math.floor(dist / val) * val;
break;
}
}
dLon = scale.dist / (111132.954 * conversion) / Math.abs(Math.cos( lat * (Math.PI / 180)));
scale.px = Math.round(projection([loc1[0] + dLon, loc1[1]])[0]);
if (imperial) {
if (scale.dist >= 5280) {
scale.dist /= 5280;
scale.text = String(scale.dist) + ' mi';
} else {
scale.text = String(scale.dist) + ' ft';
}
} else {
if (scale.dist >= 1000) {
scale.dist /= 1000;
scale.text = String(scale.dist) + ' km';
} else {
scale.text = String(scale.dist) + ' m';
}
}
return scale;
};
function update(selection) {
var x = 180,
dims = context.map().dimensions(),
// choose loc1, loc2 along bottom of viewport (near where the scale will be drawn)
var dims = context.map().dimensions(),
loc1 = projection.invert([0, dims[1]]),
loc2 = projection.invert([x, dims[1]]),
dist = distance(loc1, loc2);
loc2 = projection.invert([maxLength, dims[1]]),
scale = scaleDefs(loc1, loc2);
selection.select('#scalepath')
.attr('d', 'M0.5,0.5v'+ tickHeight +'h' + x + 'v-' + tickHeight);
.attr('d', 'M0.5,0.5v' + tickHeight + 'h' + scale.px + 'v-' + tickHeight);
selection.select('#scaletext')
.attr('x', x + 5)
.attr('x', scale.px + 8)
.attr('y', tickHeight)
.text(String(Math.floor(dist)) + ' m');
.text(scale.text);
};
return function(selection) {