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Center mass of SVG path elements
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| import 'dart:convert'; | |
| import 'dart:html'; | |
| import 'dart:math'; | |
| import 'dart:svg' as svg; | |
| main() { | |
| HttpRequest.getString('svg-datas.json').then(JSON.decode).then(calculateGravity); | |
| } | |
| calculateGravity(Map<String, Map> paths) { | |
| paths.forEach((country, data) { | |
| var path = data['path']; | |
| var el = new svg.PathElement()..setAttribute('d', path); | |
| List<Point> points = el.pathSegList | |
| .where((ps) => !(ps is svg.PathSegClosePath)) | |
| .map((p) => new Point(p.x, p.y)).toList(); | |
| var g = gravity(points); | |
| print(""" "$country": { | |
| "path": "$path", | |
| "center": { | |
| "x": ${g.x}, | |
| "y": ${g.y} | |
| } | |
| },"""); | |
| }); | |
| } | |
| Point gravity(List<Point> points) { | |
| num sumArea = 0, sumX = 0, sumY = 0; | |
| for (int i = 0; i < points.length; i++) { | |
| var i_p = (i + 1) % points.length; | |
| var g = points[i].x * points[i_p].y - points[i_p].x * points[i].y; | |
| sumArea += g; | |
| sumX += (points[i].x + points[i_p].x) * g; | |
| sumY += (points[i].y + points[i_p].y) * g; | |
| } | |
| sumArea = 3 * sumArea; | |
| return new Point((sumX / sumArea).round(), (sumY / sumArea).round()); | |
| } |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
| <title>center</title> | |
| </head> | |
| <body> | |
| <p id="text"></p> | |
| <script type="application/dart" src="center.dart"></script> | |
| <!-- for this next line to work, your pubspec.yaml file must have a dependency on 'browser' --> | |
| <script src="packages/browser/dart.js"></script> | |
| </body> | |
| </html> |
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