John Messerly
9774313c4d
some hacks for our lack of corelib, but otherwise it works now. R=vsm@google.com Review URL: https://chromereviews.googleplex.com/133857013
56 lines
1.5 KiB
Dart
56 lines
1.5 KiB
Dart
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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library sunflower;
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import 'dart:math';
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import 'dom.dart';
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const String ORANGE = "orange";
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const int SEED_RADIUS = 2;
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const int SCALE_FACTOR = 4;
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const num TAU = PI * 2;
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const int MAX_D = 300;
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const num centerX = MAX_D / 2;
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const num centerY = centerX;
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Element querySelector(String selector) => document.querySelector(selector);
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final InputElement slider = querySelector("#slider");
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final Element notes = querySelector("#notes");
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final num PHI = (sqrt(5) + 1) / 2;
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int seeds = 0;
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final CanvasRenderingContext2D context =
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(querySelector("#canvas") as CanvasElement).getContext('2d');
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void main() {
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slider.addEventListener('change', (e) => draw());
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draw();
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}
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/// Draw the complete figure for the current number of seeds.
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void draw() {
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seeds = int.parse(slider.value);
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context.clearRect(0, 0, MAX_D, MAX_D);
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for (var i = 0; i < seeds; i++) {
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final num theta = i * TAU / PHI;
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final num r = sqrt(i) * SCALE_FACTOR;
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drawSeed(centerX + r * cos(theta), centerY - r * sin(theta));
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}
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notes.textContent = "${seeds} seeds";
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}
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/// Draw a small circle representing a seed centered at (x,y).
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void drawSeed(num x, num y) {
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context
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..beginPath()
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..lineWidth = 2
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..fillStyle = ORANGE
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..strokeStyle = ORANGE
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..arc(x, y, SEED_RADIUS, 0, TAU, false)
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..fill()
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..closePath()
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..stroke();
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}
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