.metadata.json

{
  "origin": "dartlab.org",
  "url": "http://dartlab.org/#:gistId",
  "history": [
    "bf1af9b3c187997b573c"
  ]
}

body.html

<h1>Clock</h1>

<p>An html5 clock using absolutely positioned elements.</p>

<div id="canvas-content"></div>

<footer>
  <p id="summary"> </p>
  <p id="notes"> </p>
</footer>

main.dart

// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

library clock;

import 'dart:async';
import 'dart:html';
import 'dart:math';

void main() {
  new CountDownClock();
}

num _fpsAverage;

/**
 * Display the animation's FPS in a div.
 */
void showFps(num fps) {
  if (_fpsAverage == null) {
    _fpsAverage = fps;
  } else {
    _fpsAverage = fps * 0.05 + _fpsAverage * 0.95;
    querySelector("#notes").text = "${_fpsAverage.round().toInt()} fps";
  }
}

class CountDownClock {
  static const double NUMBER_SPACING = 19.0;
  static const double BALL_WIDTH = 19.0;
  static const double BALL_HEIGHT = 19.0;

  List<ClockNumber> hours = new List<ClockNumber>(2);
  List<ClockNumber> minutes = new List<ClockNumber>(2);
  List<ClockNumber> seconds = new List<ClockNumber>(2);
  int displayedHour = -1;
  int displayedMinute = -1;
  int displayedSecond = -1;
  Balls balls = new Balls();

  CountDownClock() {
    var parent = querySelector("#canvas-content");

    createNumbers(parent, parent.client.width, parent.client.height);

    updateTime(new DateTime.now());

    window.requestAnimationFrame(tick);
  }

  void tick(num time) {
    updateTime(new DateTime.now());
    balls.tick(time);
    window.requestAnimationFrame(tick);
  }

  void updateTime(DateTime now) {
    if (now.hour != displayedHour) {
      setDigits(pad2(now.hour), hours);
      displayedHour = now.hour;
    }

    if (now.minute != displayedMinute) {
      setDigits(pad2(now.minute), minutes);
      displayedMinute = now.minute;
    }

    if (now.second != displayedSecond) {
      setDigits(pad2(now.second), seconds);
      displayedSecond = now.second;
    }
  }

  void setDigits(String digits, List<ClockNumber> numbers) {
    for (int i = 0; i < numbers.length; ++i) {
      int digit = digits.codeUnitAt(i) - '0'.codeUnitAt(0);
      numbers[i].setPixels(ClockNumbers.PIXELS[digit]);
    }
  }

  String pad3(int number) {
    if (number < 10) {
      return "00${number}";
    }
    if (number < 100) {
      return "0${number}";
    }
    return "${number}";
  }

  String pad2(int number) => number < 10 ? "0${number}" : "${number}";

  void createNumbers(Element parent, num width, num height) {
    DivElement root = new DivElement();
    makeRelative(root);
    root.style.textAlign = 'center';
    querySelector("#canvas-content").nodes.add(root);

    double hSize = (BALL_WIDTH * ClockNumber.WIDTH + NUMBER_SPACING) * 6
        + (BALL_WIDTH + NUMBER_SPACING) * 2;
    hSize -= NUMBER_SPACING;

    double vSize = BALL_HEIGHT * ClockNumber.HEIGHT;

    double x = (width - hSize) / 2;
    double y = (height - vSize) / 3;

    for (int i = 0; i < hours.length; ++i) {
      hours[i] = new ClockNumber(this, x, Balls.BLUE_BALL_INDEX);
      root.nodes.add(hours[i].root);
      setElementPosition(hours[i].root, x, y);
      x += BALL_WIDTH * ClockNumber.WIDTH + NUMBER_SPACING;
    }

    root.nodes.add(new Colon(x, y).root);
    x += BALL_WIDTH + NUMBER_SPACING;

    for (int i = 0; i < minutes.length; ++i) {
      minutes[i] = new ClockNumber(this, x, Balls.RED_BALL_INDEX);
      root.nodes.add(minutes[i].root);
      setElementPosition(minutes[i].root, x, y);
      x += BALL_WIDTH * ClockNumber.WIDTH + NUMBER_SPACING;
    }

    root.nodes.add(new Colon(x, y).root);
    x += BALL_WIDTH + NUMBER_SPACING;

    for (int i = 0; i < seconds.length; ++i) {
      seconds[i] = new ClockNumber(this, x, Balls.GREEN_BALL_INDEX);
      root.nodes.add(seconds[i].root);
      setElementPosition(seconds[i].root, x, y);
      x += BALL_WIDTH * ClockNumber.WIDTH + NUMBER_SPACING;
    }
  }
}

void makeAbsolute(Element elem) {
  elem.style.left = '0px';
  elem.style.top = '0px';
  elem.style.position = 'absolute';
}

void makeRelative(Element elem) {
  elem.style.position = 'relative';
}

void setElementPosition(Element elem, double x, double y) {
  elem.style.transform = 'translate(${x}px, ${y}px)';
}

void setElementSize(Element elem, double l, double t, double r, double b) {
  setElementPosition(elem, l, t);
  elem.style.right = "${r}px";
  elem.style.bottom = "${b}px";
}

int get clientWidth => window.innerWidth;

int get clientHeight => window.innerHeight;

class Balls {
  static const double RADIUS2 = Ball.RADIUS * Ball.RADIUS;

  static const int LT_GRAY_BALL_INDEX = 0;
  static const int GREEN_BALL_INDEX = 1;
  static const int BLUE_BALL_INDEX = 2;

  static const int DK_GRAY_BALL_INDEX = 4;
  static const int RED_BALL_INDEX = 5;
  static const int MD_GRAY_BALL_INDEX = 6;

  static const List<String> PNGS = const [
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-d9d9d9.png", 
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-009a49.png",
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-13acfa.png", 
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-265897.png",
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-b6b4b5.png", 
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-c0000b.png",
      "https://cdn.rawgit.com/dart-lang/sample-clock/master/web/images/ball-c9c9c9.png"
  ];

  DivElement root;
  num lastTime;
  List<Ball> balls;

  Balls() :
      lastTime = new DateTime.now().millisecondsSinceEpoch,
      balls = new List<Ball>() {
    root = new DivElement();
    document.body.nodes.add(root);
    makeAbsolute(root);
    setElementSize(root, 0.0, 0.0, 0.0, 0.0);
  }

  void tick(num now) {
    showFps(1000.0 / (now - lastTime + 0.01));

    double delta = min((now - lastTime) / 1000.0, 0.1);
    lastTime = now;

    // incrementally move each ball, removing balls that are offscreen
    balls = balls.where((ball) => ball.tick(delta)).toList();
    collideBalls(delta);
  }

  void collideBalls(double delta) {
    balls.forEach((b0) {
      balls.forEach((b1) {
        // See if the two balls are intersecting.
        double dx = (b0.x - b1.x).abs();
        double dy = (b0.y - b1.y).abs();
        double d2 = dx * dx + dy * dy;

        if (d2 < RADIUS2) {
          // Make sure they're actually on a collision path
          // (not intersecting while moving apart).
          // This keeps balls that end up intersecting from getting stuck
          // without all the complexity of keeping them strictly separated.
          if (newDistanceSquared(delta, b0, b1) > d2) {
            return;
          }

          // They've collided. Normalize the collision vector.
          double d = sqrt(d2);

          if (d == 0) {
            return;
          }

          dx /= d;
          dy /= d;

          // Calculate the impact velocity and speed along the collision vector.
          double impactx = b0.vx - b1.vx;
          double impacty = b0.vy - b1.vy;
          double impactSpeed = impactx * dx + impacty * dy;

          // Bump.
          b0.vx -= dx * impactSpeed;
          b0.vy -= dy * impactSpeed;
          b1.vx += dx * impactSpeed;
          b1.vy += dy * impactSpeed;
        }
      });
    });
  }

  double newDistanceSquared(double delta, Ball b0, Ball b1) {
    double nb0x = b0.x + b0.vx * delta;
    double nb0y = b0.y + b0.vy * delta;
    double nb1x = b1.x + b1.vx * delta;
    double nb1y = b1.y + b1.vy * delta;
    double ndx = (nb0x - nb1x).abs();
    double ndy = (nb0y - nb1y).abs();
    double nd2 = ndx * ndx + ndy * ndy;
    return nd2;
  }

  void add(double x, double y, int color) {
    balls.add(new Ball(root, x, y, color));
  }
}

class Ball {
  static const double GRAVITY = 400.0;
  static const double RESTITUTION = 0.8;
  static const double MIN_VELOCITY = 100.0;
  static const double INIT_VELOCITY = 800.0;
  static const double RADIUS = 14.0;

  static Random random;

  static double randomVelocity() {
    if (random == null) {
      random = new Random();
    }

    return (random.nextDouble() - 0.5) * INIT_VELOCITY;
  }

  Element root;
  ImageElement elem;
  double x, y;
  double vx, vy;
  double ax, ay;
  double age;

  Ball(this.root, this.x, this.y, int color) {
    elem = new ImageElement(src: Balls.PNGS[color]);
    makeAbsolute(elem);
    setElementPosition(elem, x, y);
    root.nodes.add(elem);

    ax = 0.0;
    ay = GRAVITY;

    vx = randomVelocity();
    vy = randomVelocity();
  }

  // return false => remove me
  bool tick(double delta) {
    // Update velocity and position.
    vx += ax * delta;
    vy += ay * delta;

    x += vx * delta;
    y += vy * delta;

    // Handle falling off the edge.
    if ((x < RADIUS) || (x > clientWidth)) {
      elem.remove();
      return false;
    }

    // Handle ground collisions.
    if (y > clientHeight) {
      y = clientHeight.toDouble();
      vy *= -RESTITUTION;
    }

    // Position the element.
    setElementPosition(elem, x - RADIUS, y - RADIUS);

    return true;
  }
}

class ClockNumber {
  static const int WIDTH = 4;
  static const int HEIGHT = 7;

  CountDownClock app;
  Element root;
  List<List<ImageElement>> imgs;
  List<List<int>> pixels;
  int ballColor;

  ClockNumber(this.app, double pos, this.ballColor) {
    imgs = new List<List<ImageElement>>(HEIGHT);

    root = new DivElement();
    makeAbsolute(root);
    setElementPosition(root, pos, 0.0);

    for (int y = 0; y < HEIGHT; ++y) {
      imgs[y] = new List<ImageElement>(WIDTH);
    }

    for (int y = 0; y < HEIGHT; ++y) {
      for (int x = 0; x < WIDTH; ++x) {
        imgs[y][x] = new ImageElement();
        root.nodes.add(imgs[y][x]);
        makeAbsolute(imgs[y][x]);
        setElementPosition(imgs[y][x],
            x * CountDownClock.BALL_WIDTH, y * CountDownClock.BALL_HEIGHT);
      }
    }
  }

  void setPixels(List<List<int>> px) {
    for (int y = 0; y < HEIGHT; ++y) {
      for (int x = 0; x < WIDTH; ++x) {
        ImageElement img = imgs[y][x];

        if (pixels != null) {
          if ((pixels[y][x] != 0) && (px[y][x] == 0)) {
            scheduleMicrotask(() {
              var r = img.getBoundingClientRect();
              double absx = r.left;
              double absy = r.top;

              app.balls.add(absx, absy, ballColor);
            });
          }
        }

        img.src = px[y][x] != 0 ? Balls.PNGS[ballColor] : Balls.PNGS[6];
      }
    }

    pixels = px;
  }
}

class Colon {
  Element root;

  Colon(double xpos, double ypos) {
    root = new DivElement();
    makeAbsolute(root);
    setElementPosition(root, xpos, ypos);

    ImageElement dot = new ImageElement(src: Balls.PNGS[Balls.DK_GRAY_BALL_INDEX]);
    root.nodes.add(dot);
    makeAbsolute(dot);
    setElementPosition(dot, 0.0, 2.0 * CountDownClock.BALL_HEIGHT);

    dot = new ImageElement(src: Balls.PNGS[Balls.DK_GRAY_BALL_INDEX]);
    root.nodes.add(dot);
    makeAbsolute(dot);
    setElementPosition(dot, 0.0, 4.0 * CountDownClock.BALL_HEIGHT);
  }
}

class ClockNumbers {
  static const PIXELS = const [
     const [
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ]
    ], const [
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 0 ],
       const[ 1, 0, 0, 0 ],
       const[ 1, 1, 1, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ]
    ], const [
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 0 ],
       const[ 1, 0, 0, 0 ],
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 0 ],
       const[ 1, 0, 0, 0 ],
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ]
    ], const [
       const[ 1, 1, 1, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 0, 0, 0, 1 ],
       const[ 1, 1, 1, 1 ]
    ]
  ];
}

style.css

/* Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file */
/* for details. All rights reserved. Use of this source code is governed by a */
/* BSD-style license that can be found in the LICENSE file. */

body {
  background-color: #F8F8F8;
  font-family: 'Open Sans', sans-serif;
  font-size: 14px;
  font-weight: normal;
  line-height: 1.2em;
  margin: 15px;
}

p {
  color: #333;
}

#canvas-content {
  width: 100%;
  height: 400px;
  position: relative;
  border: 1px solid #ccc;
  background-color: #fff;
}

#summary {
  float: left;
}

#notes {
  float: right;
  width: 120px;
  text-align: right;
}

.error {
  font-style: italic;
  color: red;
}

#container2 {
  width: 100px;
  height: 100px;
  position: relative;
  margin: auto;
}

#target {
  width: 100%;
  height: 100%;
  position: absolute;
}

#target figure {
  display: block;
  position: absolute;
  width: 150px;
  height: 80px;
  border: 1px solid #333;
  font-size: 36px;
  color: #222;
  background: #3291d8;
  text-align: center;
  line-height: 2em;
}