Javascript GIF.js Project to Record Screen and Download it as GIF Animation File in Browser Using HTML5

Welcome folks today in this blog post we will be talking about how to record screen using gif.js library and download it as gif animation file in browser using html5. All the full source code of the application is shown below.

Get Started

In order to get started you need to make an index.html file and copy paste the following code

index.html

<!DOCTYPE html>
<html>

<head>
  <title>gifcap</title>
  <link href='https://fonts.googleapis.com/css?family=Baloo+2:700' rel='stylesheet' type='text/css'>
  <link href='https://fonts.googleapis.com/css?family=Roboto' rel='stylesheet' type='text/css'>
  <link rel='stylesheet' type='text/css' media='screen' href='main.css'>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/mithril/2.0.4/mithril.min.js"
    integrity="sha256-8cl9GQUonfQFzoyXWdf5ZsGnUJ/FC8PE6E7E9U6JE30=" crossorigin="anonymous"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gif.js/0.2.0/gif.js"
    integrity="sha256-qLERBxuzsSPDAuYYLAHWs1UPk6S2JzmLB8RoddhAkLs=" crossorigin="anonymous"></script>
</head>

<body>
  <header id="app-header">
    <h1><span class="gif">gif</span><span class="cap">cap</span></h1>
  </header>
  <section id="app-container"></section>
  <script src='main.js'></script>
</body>
</html>

<!DOCTYPE html>

<html>

<head>

<title>gifcap</title>

integrity="sha256-8cl9GQUonfQFzoyXWdf5ZsGnUJ/FC8PE6E7E9U6JE30=" crossorigin="anonymous"></script>

integrity="sha256-qLERBxuzsSPDAuYYLAHWs1UPk6S2JzmLB8RoddhAkLs=" crossorigin="anonymous"></script>

</head>

<body>

</header>

</body>

</html>

As you can see we are copy paste the above html code. Also here as you can see we are including the gif.js cdn which is the gif animation encoder. And also we are including the mithrill cdn also

Adding the CSS Stylesheet

Now we need to copy paste the css code to style the app as well. So this is the css code you need to copy paste below

style.css

@import url('https://unpkg.com/chota@0.7.1');

:root {
  --color-primary: #AD2C2C;
  --color-lightGrey: #d2d6dd;
  --color-grey: #5e5e5e;
  --color-darkGrey: #3f4144;
  --color-error: #d43939;
  --color-success: #28bd14;
  --grid-maxWidth: 120rem;
  --grid-gutter: 2rem;
  --font-size: 1.6rem;
  --font-family: 'Roboto', sans-serif;
}

html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
}

body {
  display: flex;
  flex-direction: column;
  color: #333;
}

img {
  max-width: initial !important;
}

.hidden {
  display: none;
}

#app-header {
  display: flex;
  justify-content: center;
  flex-direction: column;
  align-items: center;
}

#app-footer {
  display: flex;
  justify-content: space-between;
  padding: 1em;
  background: #333333;
  color: #c5c5c5;
  border-top: 1px solid #9e9e9e;
  font-size: 0.8em;
}

#app-footer a {
  color: #ce6464;
}

#app-footer img {
  vertical-align: middle;
}

h1 {
  font-family: 'Baloo 2', cursive;
  font-size: 5em;
}

.gif {
  color: #AD2C2C;
}

.cap {
  color: #2E2E2E;
}

.button {
  display: flex;
  box-shadow: 0px 0px 5px 0px #00000054;
}

.button:active {
  box-shadow: 0px 0px 3px 0px #00000054;
}

button:not(.icon-only) > img {
  margin-right: 0.3em;
}

.actions {
  padding: 2em;
  display: flex;
  border-top: 1px solid #9e9e9e;
}

.actions:empty {
  display: none;
}

.status {
  display: flex;
  justify-content: center;
}

#app-container {
  flex: 1;
}

.view {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
}

.content {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  box-shadow: inset 0 0 4px #a5a5a5;
  border-top: 1px solid #9e9e9e;
  font-size: 20px;
  text-align: center;
  background: #fafafa;
  position: relative;
  overflow: hidden;
}

.recording, .preview {
  box-shadow: 0px 0px 5px 1px #00000054;
}

.recording {
  max-width: 90vw;
  max-height: 90vh;
  display: block;
}

.preview {
  position: absolute;
}

.preview > canvas,
.preview > .crop-box {
  position: absolute;
  top: 0;
  left: 0;
}

.preview > canvas {
  width: 100%;
  height: 100%;
}

.recording-card > footer {
  border-top: 1px solid #9e9e9e;
  margin-top: 18px;
  padding-top: 10px;
  display: flex;
  justify-content: space-between;
}

.tag, .tag > a {
  display: flex;
  align-items: center;
}

.tag img {
  margin-right: 0.3em;
}

.crop {
  cursor: crosshair;
}

.crop-box {
  position: absolute;
  background: rgba(193, 193, 193, 0.69);
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.playbar {
  flex: 1;
  margin: 0 10px;
  position: relative;
}

.playbar > input {
  height: 50%;
  margin: 0;
}

.playbar > input:disabled {
  opacity: 1;
}

.playbar > .trim-bar {
  border-top: 2px solid #AD2C2C;
  position: absolute;
  top: calc(50% + 4px);
}

.playbar > .trim-bar > .trim-start, 
.playbar > .trim-bar > .trim-end {
  position: absolute;
  border: 6px solid #AD2C2C;
  border-bottom-color: transparent;
  cursor: pointer;
}

.playbar > .trim-bar > .trim-start {
  top: 0;
  left: 0;
  border-right-color: transparent;
}

.playbar > .trim-bar > .trim-end {
  top: 0;
  right: 0;
  border-left-color: transparent;
}

input[type="range"] {
  padding-left: 0 !important;
  padding-right: 0 !important;
}

.button.outline {
  border: none;
}

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@import url('https://unpkg.com/chota@0.7.1');

:root {

--color-primary: #AD2C2C;

--color-lightGrey: #d2d6dd;

--color-grey: #5e5e5e;

--color-darkGrey: #3f4144;

--color-error: #d43939;

--color-success: #28bd14;

--grid-maxWidth: 120rem;

--grid-gutter: 2rem;

--font-size: 1.6rem;

--font-family: 'Roboto', sans-serif;

}

html, body {

margin: 0;

padding: 0;

width: 100%;

height: 100%;

}

body {

display: flex;

flex-direction: column;

color: #333;

}

img {

max-width: initial !important;

}

.hidden {

display: none;

}

#app-header {

display: flex;

justify-content: center;

flex-direction: column;

align-items: center;

}

#app-footer {

display: flex;

justify-content: space-between;

padding: 1em;

background: #333333;

color: #c5c5c5;

border-top: 1px solid #9e9e9e;

font-size: 0.8em;

}

#app-footer a {

color: #ce6464;

}

#app-footer img {

vertical-align: middle;

}

h1 {

font-family: 'Baloo 2', cursive;

font-size: 5em;

}

.gif {

color: #AD2C2C;

}

.cap {

color: #2E2E2E;

}

.button {

display: flex;

box-shadow: 0px 0px 5px 0px #00000054;

}

.button:active {

box-shadow: 0px 0px 3px 0px #00000054;

}

button:not(.icon-only) > img {

margin-right: 0.3em;

}

.actions {

padding: 2em;

display: flex;

border-top: 1px solid #9e9e9e;

}

.actions:empty {

display: none;

}

.status {

display: flex;

justify-content: center;

}

#app-container {

flex: 1;

}

.view {

width: 100%;

height: 100%;

display: flex;

flex-direction: column;

}

.content {

flex: 1;

display: flex;

justify-content: center;

align-items: center;

flex-direction: column;

box-shadow: inset 0 0 4px #a5a5a5;

border-top: 1px solid #9e9e9e;

font-size: 20px;

text-align: center;

background: #fafafa;

position: relative;

overflow: hidden;

}

.recording, .preview {

box-shadow: 0px 0px 5px 1px #00000054;

}

.recording {

max-width: 90vw;

max-height: 90vh;

display: block;

}

.preview {

position: absolute;

}

.preview > canvas,

.preview > .crop-box {

position: absolute;

top: 0;

left: 0;

}

.preview > canvas {

width: 100%;

height: 100%;

}

.recording-card > footer {

border-top: 1px solid #9e9e9e;

margin-top: 18px;

padding-top: 10px;

display: flex;

justify-content: space-between;

}

.tag, .tag > a {

display: flex;

align-items: center;

}

.tag img {

margin-right: 0.3em;

}

.crop {

cursor: crosshair;

}

.crop-box {

position: absolute;

background: rgba(193, 193, 193, 0.69);

top: 0;

left: 0;

width: 100%;

height: 100%;

}

.playbar {

flex: 1;

margin: 0 10px;

position: relative;

}

.playbar > input {

height: 50%;

margin: 0;

}

.playbar > input:disabled {

opacity: 1;

}

.playbar > .trim-bar {

border-top: 2px solid #AD2C2C;

position: absolute;

top: calc(50% + 4px);

}

.playbar > .trim-bar > .trim-start,

.playbar > .trim-bar > .trim-end {

position: absolute;

border: 6px solid #AD2C2C;

border-bottom-color: transparent;

cursor: pointer;

}

.playbar > .trim-bar > .trim-start {

top: 0;

left: 0;

border-right-color: transparent;

}

.playbar > .trim-bar > .trim-end {

top: 0;

right: 0;

border-left-color: transparent;

}

input[type="range"] {

padding-left: 0 !important;

padding-right: 0 !important;

}

.button.outline {

border: none;

}

As you can see we have the start recording button where the user can record the screen and convert it as gif animation and share it on social media websites. Here the data is not uploaded to the server. Only recording is done at the client side.

Now we need to make the main.js file and copy paste the following code. This will be the javascript code which is required for this application

main.js

const FPS = 10;
const FRAME_DELAY = Math.floor(1000 / FPS);

function timediff(millis) {
  const abs = Math.floor(millis / 1000);
  const mins = Math.floor(abs / 60);
  const secs = abs % 60;
  const s = `${secs < 10 ? '0' : ''}${secs}`;
  const m = mins > 0 ? `${mins < 10 ? '0' : ''}${mins}` : '00';
  return `${m}:${s}`;
}

function humanSize(size) {
  if (size < 1024) {
    return '1 KB';
  }

  size = Math.round(size / 1024);
  return size < 1024 ? `${size} KB` : `${Math.floor(size / 1024 * 100) / 100} MB`;
}

const Button = {
  view(vnode) {
    return m('button', {
      class: `button ${vnode.attrs.primary ? 'primary' : 'secondary'} ${vnode.attrs.label ? '' : 'icon-only'} ${vnode.attrs.outline ? 'outline' : ''}`,
      onclick: vnode.attrs.onclick,
      title: vnode.attrs.title || vnode.attrs.label,
      disabled: vnode.attrs.disabled
    }, [
      m('img', { src: `https://icongr.am/${vnode.attrs.iconset || 'octicons'}/${vnode.attrs.icon}.svg?size=16&color=${vnode.attrs.outline ? '333333' : 'ffffff'}` }),
      vnode.attrs.label
    ]);
  }
};

const Timer = {
  view(vnode) {
    return m('span.tag.is-small', [
      m('img', { src: 'https://icongr.am/octicons/clock.svg?size=16&color=333333' }),
      timediff(vnode.attrs.duration)
    ]);
  }
};

const View = {
  view(vnode) {
    return m('section', { class: 'view' }, [
      m('section', { class: `content ${vnode.attrs.contentClass || ''}`, ...(vnode.attrs.contentProps || {}) }, vnode.children),
      m('section', { class: 'actions' }, vnode.attrs.actions)
    ]);
  }
};


const isMobile = /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);

class IdleView {

  constructor(vnode) {
    this.app = vnode.attrs.app;
  }

  view() {
    let content, actions;

    if (this.app.recording) {
      content = m('.recording-card', [
        m('a', { href: this.app.recording.url, target: '_blank' }, [
          m('img.recording', { src: this.app.recording.url })
        ]),
        m('footer', [
          m(Timer, { duration: this.app.recording.duration }),
          m('span.tag.is-small', [
            m('a.recording-detail', { href: this.app.recording.url, target: '_blank' }, [
              m('img', { src: 'https://icongr.am/octicons/cloud-download.svg?size=16&color=333333' }),
              humanSize(this.app.recording.size)
            ])
          ]),
        ]),
      ]);

      actions = [
        m(Button, { label: 'Start Recording', icon: 'play', onclick: () => this.app.startRecording(), primary: true }),
        m(Button, { label: 'Discard', icon: 'trashcan', onclick: () => this.app.cancel() })
      ];
    } else {
      content = [
        m('p', 'Create animated GIFs from a screen recording.'),
        m('p', 'Client-side only, no data is uploaded. Modern browser required.'),
        isMobile ? m('p', 'Sorry, mobile does not support screen recording.') : undefined,
        isMobile ? undefined : m(Button, { label: 'Start Recording', icon: 'play', onclick: () => this.app.startRecording(), primary: true }),
      ];
    }

    return [m(View, { actions }, content)];
  }
}

class RecordView {

  constructor(vnode) {
    this.app = vnode.attrs.app;
    this.recording = this.app.recording;
    this.startTime = undefined;
  }

  async oncreate(vnode) {
    const video = vnode.dom.getElementsByTagName('video')[0];
    const canvas = vnode.dom.getElementsByTagName('canvas')[0];

    let captureStream;

    try {
      captureStream = await navigator.mediaDevices.getDisplayMedia({ video: true });
    } catch (err) {
      console.error(err);
      this.app.cancel();
      m.redraw();
      return;
    }

    video.srcObject = captureStream;

    const ctx = canvas.getContext('2d');

    const frameInterval = setInterval(() => {
      if (video.videoWidth === 0) {
        return;
      }

      const first = typeof this.startTime === 'undefined';

      if (first) {
        const width = video.videoWidth;
        const height = video.videoHeight;

        this.startTime = new Date().getTime();
        this.recording.width = width;
        this.recording.height = height;
        canvas.width = `${width}`;
        canvas.height = `${height}`;
      }

      ctx.drawImage(video, 0, 0);

      this.recording.frames.push(ctx.getImageData(0, 0, this.recording.width, this.recording.height));
    }, FRAME_DELAY);

    const redrawInterval = setInterval(() => m.redraw(), 1000);

    const track = captureStream.getVideoTracks()[0];
    const endedListener = () => {
      this.app.stopRecording();
      m.redraw();
    };
    track.addEventListener('ended', endedListener);

    this.onbeforeremove = () => {
      clearInterval(frameInterval);
      clearInterval(redrawInterval);
      track.removeEventListener('ended', endedListener);
      track.stop();
    };

    m.redraw();
  }

  view() {
    const actions = [
      m(Button, { label: 'Stop', icon: 'primitive-square', onclick: () => this.app.stopRecording() })
    ];

    return [
      m(View, { actions }, [
        m(Timer, { duration: typeof this.startTime === 'number' ? new Date().getTime() - this.startTime : 0 }),
        m('canvas.hidden', { width: 640, height: 480 }),
        m('video.hidden', { autoplay: true, playsinline: true }),
      ]),
    ];
  }
}

class PreviewView {

  constructor(vnode) {
    this.app = vnode.attrs.app;
    this.recording = this.app.recording;
    this.canvas = undefined;
    this.playbar = undefined;
    this.content = undefined;

    this.viewportDisposable = undefined;
    this.viewport = {
      width: undefined,
      height: undefined,
      top: 0,
      left: 0,
      zoom: 1
    };

    this.playback = {
      index: undefined,
      disposable: undefined,
      reset: false
    };

    this.trim = {
      start: 0,
      end: this.recording.frames.length - 1
    };

    this.crop = {
      top: 0,
      left: 0,
      width: this.recording.width,
      height: this.recording.height
    };
  }

  get isPlaying() { return !!this.playback.disposable; }

  oncreate(vnode) {
    this.canvas = vnode.dom.getElementsByTagName('canvas')[0];
    this.playbar = vnode.dom.querySelector('.playbar');
    this.content = vnode.dom.querySelector('.content');

    const viewportListener = () => this.updateViewport();
    window.addEventListener('resize', viewportListener);
    this.viewportDisposable = () => window.removeEventListener('resize', viewportListener);
    this.updateViewport();
    this.zoomToFit();

    m.redraw(); // prevent flickering
    setTimeout(() => this.play());
  }

  zoomToFit() {
    this.viewport.zoom = Math.max(0.1, Math.min(1, this.viewport.width * .95 / this.recording.width, this.viewport.height * .95 / this.recording.height));
  }

  updateViewport() {
    this.viewport.width = Math.floor(this.content.clientWidth);
    this.viewport.height = Math.floor(this.content.clientHeight);
  }

  onbeforeremove() {
    this.pause();
    this.viewportDisposable();
  }

  view() {
    const isCropped = this.crop.top !== 0 || this.crop.left !== 0 || this.crop.width !== this.recording.width || this.crop.height !== this.recording.height;
    const actions = [
      m(Button, { title: this.isPlaying ? 'Pause' : 'Play', iconset: 'material', icon: this.isPlaying ? 'pause' : 'play', primary: true, onclick: () => this.togglePlayPause() }),
      m('.playbar', [
        m('input', { type: 'range', min: 0, max: `${this.recording.frames.length - 1}`, value: `${this.playback.index}`, disabled: this.isPlaying, oninput: e => this.onPlaybarInput(e) }),
        m('.trim-bar', { style: { left: `${this.trim.start * 100 / (this.recording.frames.length - 1)}%`, width: `${(this.trim.end - this.trim.start) * 100 / (this.recording.frames.length - 1)}%` } }, [
          m('.trim-start', { onmousedown: e => this.onTrimMouseDown('start', e) }),
          m('.trim-end', { onmousedown: e => this.onTrimMouseDown('end', e) }),
        ])
      ]),
      m(Button, { title: 'Discard', icon: 'trashcan', onclick: () => this.app.cancel() }),
      m(Button, { label: 'Render', icon: 'gear', onclick: () => this.app.startRendering({ trim: this.trim, crop: this.crop }), primary: true }),
    ];

    const scale = value => value * this.viewport.zoom;
    const width = scale(this.recording.width);
    const height = scale(this.recording.height);
    const top = Math.floor(scale(this.viewport.top) + (this.viewport.height / 2) - (height / 2));
    const left = Math.floor(scale(this.viewport.left) + (this.viewport.width / 2) - (width / 2));

    return [
      m(View, {
        actions,
        contentClass: 'crop',
        contentProps: {
          onwheel: e => this.onContentWheel(e),
          onmousedown: e => this.onContentMouseDown(e),
          oncontextmenu: e => e.preventDefault()
        }
      }, [
        m('.preview', { style: { top: `${top}px`, left: `${left}px`, width: `${width}px`, height: `${height}px` } }, [
          m('canvas', { width: this.recording.width, height: this.recording.height }),
          isCropped && m('.crop-box', {
            style: {
              // here be dragons!
              clipPath: `polygon(evenodd, 0 0, 0 ${scale(this.recording.height)}px, ${scale(this.recording.width)}% ${scale(this.recording.height)}px, ${scale(this.recording.width)}% 0, 0 0, ${scale(this.crop.left)}px ${scale(this.crop.top)}px, ${scale(this.crop.left)}px ${scale(this.crop.top + this.crop.height)}px, ${scale(this.crop.left + this.crop.width)}px ${scale(this.crop.top + this.crop.height)}px, ${scale(this.crop.left + this.crop.width)}px ${scale(this.crop.top)}px, ${scale(this.crop.left)}px ${scale(this.crop.top)}px)`
            }
          })
        ]),
      ])
    ];
  }

  onTrimMouseDown(handle, event) {
    event.preventDefault();

    const ctx = this.canvas.getContext('2d');
    const start = {
      width: this.playbar.clientWidth,
      screenX: event.screenX,
      index: handle === 'start' ? this.trim.start : this.trim.end,
      min: handle === 'start' ? 0 : this.trim.start + 1,
      max: handle === 'start' ? this.trim.end - 1 : this.recording.frames.length - 1
    };

    const onMouseMove = e => {
      const diff = e.screenX - start.screenX;
      const index = start.index + Math.round(diff * (this.recording.frames.length - 1) / start.width);
      const previous = this.trim[handle];
      this.trim[handle] = Math.max(start.min, Math.min(start.max, index));

      if (!this.isPlaying && previous !== this.trim[handle]) {
        ctx.putImageData(this.recording.frames[this.trim[handle]], 0, 0);
      }

      m.redraw();
    };

    const onMouseUp = () => {
      document.body.removeEventListener('mousemove', onMouseMove);
      document.body.removeEventListener('mouseup', onMouseUp);

      this.playback.reset = true;

      if (this.isPlaying) {
        this.play();
      } else {
        ctx.putImageData(this.recording.frames[this.playback.index], 0, 0);
      }

      m.redraw();
    };

    if (!this.isPlaying) {
      ctx.putImageData(this.recording.frames[this.trim[handle]], 0, 0);
    }

    document.body.addEventListener('mousemove', onMouseMove);
    document.body.addEventListener('mouseup', onMouseUp);
  }

  onContentWheel(event) {
    event.preventDefault();
    const zoom = this.viewport.zoom - event.deltaY / 180 * 0.1;
    this.viewport.zoom = Math.max(0.1, Math.min(2, zoom));
  }

  onContentMouseDown(event) {
    if (event.button === 0 && !event.ctrlKey && !event.metaKey && !event.shiftKey) {
      this.onCrop(event);
    } else {
      this.onViewportMove(event);
    }
  }

  onCrop(event) {
    const width = this.recording.width * this.viewport.zoom;
    const height = this.recording.height * this.viewport.zoom;
    const top = Math.floor(this.viewport.top * this.viewport.zoom + (this.viewport.height / 2) - (height / 2));
    const left = Math.floor(this.viewport.left * this.viewport.zoom + (this.viewport.width / 2) - (width / 2));
    const offsetTop = event.currentTarget.offsetTop;
    const offsetLeft = event.currentTarget.offsetLeft;
    const mouseTop = event => Math.max(0, Math.min(this.recording.height, (event.clientY - offsetTop - top) / this.viewport.zoom));
    const mouseLeft = event => Math.max(0, Math.min(this.recording.width, (event.clientX - offsetLeft - left) / this.viewport.zoom));
    const point = event => ({ top: mouseTop(event), left: mouseLeft(event) });
    const from = point(event);

    let didMove = false;
    const onMouseMove = event => {
      const to = point(event);
      const top = Math.max(0, Math.min(from.top, to.top));
      const left = Math.max(0, Math.min(from.left, to.left));
      const width = Math.min(this.recording.width - left, Math.abs(from.left - to.left));
      const height = Math.min(this.recording.height - top, Math.abs(from.top - to.top));

      this.crop = { top, left, width, height };
      didMove = true;
      m.redraw();
    };

    const onMouseUp = event => {
      event.preventDefault();
      document.body.removeEventListener('mousemove', onMouseMove);
      document.body.removeEventListener('mouseup', onMouseUp);

      if (!didMove || this.crop.width < 10 || this.crop.height < 10) {
        this.crop = {
          top: 0,
          left: 0,
          width: this.recording.width,
          height: this.recording.height
        };
      }

      m.redraw();
    };

    event.preventDefault();
    document.body.addEventListener('mousemove', onMouseMove);
    document.body.addEventListener('mouseup', onMouseUp);
  }

  onViewportMove(event) {
    const start = {
      top: this.viewport.top,
      left: this.viewport.left,
      screenX: event.screenX,
      screenY: event.screenY
    };

    const onMouseMove = e => {
      this.viewport.top = start.top + (e.screenY - start.screenY) / this.viewport.zoom;
      this.viewport.left = start.left + (e.screenX - start.screenX) / this.viewport.zoom;
      m.redraw();
    };

    const onMouseUp = event => {
      event.preventDefault();
      document.body.removeEventListener('mousemove', onMouseMove);
      document.body.removeEventListener('mouseup', onMouseUp);
      m.redraw();
    };

    event.preventDefault();
    document.body.addEventListener('mousemove', onMouseMove);
    document.body.addEventListener('mouseup', onMouseUp);
  }

  onPlaybarInput(e) {
    this.playback.index = Number(e.target.value);

    const ctx = this.canvas.getContext('2d');
    ctx.putImageData(this.recording.frames[this.playback.index], 0, 0);
  }

  play() {
    if (this.playback.disposable) {
      this.playback.disposable();
    }

    if (this.playback.reset) {
      this.playback.index = undefined;
      this.playback.reset = false;
    }

    const range = {
      start: this.trim.start,
      end: this.trim.end
    };

    const ctx = this.canvas.getContext('2d');
    const duration = (range.end - range.start + 1) * FRAME_DELAY;
    const start = range.start * FRAME_DELAY + new Date().getTime() - ((this.playback.index || range.start) * FRAME_DELAY);
    let animationFrame = undefined;

    const draw = () => {
      const index = range.start + Math.floor(((new Date().getTime() - start) % duration) / FRAME_DELAY);

      if (this.playback.index !== index) {
        ctx.putImageData(this.recording.frames[index], 0, 0);
        m.redraw();
      }

      this.playback.index = index;
      animationFrame = requestAnimationFrame(draw);
    };

    animationFrame = requestAnimationFrame(draw);

    this.playback.disposable = () => {
      cancelAnimationFrame(animationFrame);
    };
  }

  pause() {
    if (this.playback.disposable) {
      this.playback.disposable();
      this.playback.disposable = undefined;
    }
  }

  togglePlayPause() {
    if (this.isPlaying) {
      this.pause();
    } else {
      this.play();
    }
  }
}

class RenderView {

  constructor(vnode) {
    this.app = vnode.attrs.app;
    this.recording = this.app.recording;
    this.trim = this.app.renderOptions.trim;
    this.crop = this.app.renderOptions.crop;
    this.progress = 0;
  }

  async oncreate(vnode) {
    const isCropped = this.crop.top !== 0 || this.crop.left !== 0 || this.crop.width !== this.recording.width || this.crop.height !== this.recording.height;
    const gif = new GIF({
      workers: navigator.hardwareConcurrency,
      quality: 10,
      width: this.crop.width,
      height: this.crop.height,
      workerScript: 'gif.worker.js',
    });

    gif.on('progress', progress => {
      this.progress = progress;
      m.redraw();
    });

    gif.once('finished', blob => {
      this.app.setRenderedRecording({
        duration: (this.trim.end - this.trim.start + 1) * FRAME_DELAY,
        size: blob.size,
        url: URL.createObjectURL(blob),
      });
      m.redraw();
    });

    const ctx = isCropped && vnode.dom.getElementsByTagName('canvas')[0].getContext('2d');
    let first = true;

    for (let i = this.trim.start; i <= this.trim.end; i++) {
      let frame = this.recording.frames[i];

      if (isCropped) {
        ctx.putImageData(frame, 0, 0);
        frame = ctx.getImageData(this.crop.left, this.crop.top, this.crop.width, this.crop.height);
      }

      gif.addFrame(frame, { delay: first ? 0 : FRAME_DELAY });
      first = false;
    }

    this.onbeforeremove = () => {
      gif.abort();
    };

    gif.render();
  }

  view() {
    const isCropped = this.crop.top !== 0 || this.crop.left !== 0 || this.crop.width !== this.recording.width || this.crop.height !== this.recording.height;
    const actions = [
      m(Button, { label: 'Cancel', icon: 'primitive-square', onclick: () => this.app.cancel() })
    ];

    return [
      m(View, { actions }, [
        m('progress', { max: '1', value: this.progress, title: 'Rendering...' }, `Rendering: ${Math.floor(this.progress * 100)}%`),
        isCropped && m('canvas.hidden', { width: this.recording.width, height: this.recording.height }),
      ])
    ];
  }
}

class App {

  constructor() {
    this.state = 'idle';
    this.recording = undefined;
    window.onbeforeunload = () => this.recording ? '' : null;
  }

  view() {
    switch (this.state) {
      case 'idle': return m(IdleView, { app: this });
      case 'recording': return m(RecordView, { app: this });
      case 'preview': return m(PreviewView, { app: this });
      case 'rendering': return m(RenderView, { app: this });
    }
  }

  startRecording() {
    if (this.recording && !window.confirm('This will discard the current recording, are you sure you want to continue?')) {
      return;
    }

    this.state = 'recording';
    this.recording = {
      width: undefined,
      height: undefined,
      frames: []
    };
  }

  stopRecording() {
    this.state = 'preview';
  }

  startRendering(renderOptions) {
    this.state = 'rendering';
    this.renderOptions = renderOptions;
  }

  setRenderedRecording(recording) {
    this.state = 'idle';
    this.recording = recording;
    this.renderOptions = undefined;
  }

  cancel() {
    this.state = 'idle';
    this.recording = undefined;
    this.renderOptions = undefined;
  }
}

function main() {
  m.mount(document.getElementById('app-container'), App);
}

main();

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const FPS = 10;

const FRAME_DELAY = Math.floor(1000 / FPS);

function timediff(millis) {

const abs = Math.floor(millis / 1000);

const mins = Math.floor(abs / 60);

const secs = abs % 60;

const s = `${secs < 10 ? '0' : ''}${secs}`;

const m = mins > 0 ? `${mins < 10 ? '0' : ''}${mins}` : '00';

return `${m}:${s}`;

}

function humanSize(size) {

if (size < 1024) {

return '1 KB';

}

size = Math.round(size / 1024);

return size < 1024 ? `${size} KB` : `${Math.floor(size / 1024 * 100) / 100} MB`;

}

const Button = {

view(vnode) {

return m('button', {

class: `button ${vnode.attrs.primary ? 'primary' : 'secondary'} ${vnode.attrs.label ? '' : 'icon-only'} ${vnode.attrs.outline ? 'outline' : ''}`,

onclick: vnode.attrs.onclick,

title: vnode.attrs.title || vnode.attrs.label,

disabled: vnode.attrs.disabled

}, [

m('img', { src: `https://icongr.am/${vnode.attrs.iconset || 'octicons'}/${vnode.attrs.icon}.svg?size=16&color=${vnode.attrs.outline ? '333333' : 'ffffff'}` }),

vnode.attrs.label

]);

}

};

const Timer = {

view(vnode) {

return m('span.tag.is-small', [

m('img', { src: 'https://icongr.am/octicons/clock.svg?size=16&color=333333' }),

timediff(vnode.attrs.duration)

]);

}

};

const View = {

view(vnode) {

return m('section', { class: 'view' }, [

m('section', { class: `content ${vnode.attrs.contentClass || ''}`, ...(vnode.attrs.contentProps || {}) }, vnode.children),

m('section', { class: 'actions' }, vnode.attrs.actions)

]);

}

};

class IdleView {

constructor(vnode) {

this.app = vnode.attrs.app;

}

view() {

let content, actions;

if (this.app.recording) {

content = m('.recording-card', [

m('a', { href: this.app.recording.url, target: '_blank' }, [

m('img.recording', { src: this.app.recording.url })

]),

m('footer', [

m(Timer, { duration: this.app.recording.duration }),

m('span.tag.is-small', [

m('a.recording-detail', { href: this.app.recording.url, target: '_blank' }, [

m('img', { src: 'https://icongr.am/octicons/cloud-download.svg?size=16&color=333333' }),

humanSize(this.app.recording.size)

])

]),

]);

actions = [

m(Button, { label: 'Start Recording', icon: 'play', onclick: () => this.app.startRecording(), primary: true }),

m(Button, { label: 'Discard', icon: 'trashcan', onclick: () => this.app.cancel() })

];

} else {

content = [

m('p', 'Create animated GIFs from a screen recording.'),

m('p', 'Client-side only, no data is uploaded. Modern browser required.'),

isMobile ? m('p', 'Sorry, mobile does not support screen recording.') : undefined,

isMobile ? undefined : m(Button, { label: 'Start Recording', icon: 'play', onclick: () => this.app.startRecording(), primary: true }),

];

}

return [m(View, { actions }, content)];

}

class RecordView {

constructor(vnode) {

this.app = vnode.attrs.app;

this.recording = this.app.recording;

this.startTime = undefined;

}

async oncreate(vnode) {

const video = vnode.dom.getElementsByTagName('video')[0];

const canvas = vnode.dom.getElementsByTagName('canvas')[0];

let captureStream;

try {

captureStream = await navigator.mediaDevices.getDisplayMedia({ video: true });

} catch (err) {

console.error(err);

this.app.cancel();

m.redraw();

return;

}

video.srcObject = captureStream;

const ctx = canvas.getContext('2d');

const frameInterval = setInterval(() => {

if (video.videoWidth === 0) {

return;

}

const first = typeof this.startTime === 'undefined';

if (first) {

const width = video.videoWidth;

const height = video.videoHeight;

this.startTime = new Date().getTime();

this.recording.width = width;

this.recording.height = height;

canvas.width = `${width}`;

canvas.height = `${height}`;

}

ctx.drawImage(video, 0, 0);

this.recording.frames.push(ctx.getImageData(0, 0, this.recording.width, this.recording.height));

}, FRAME_DELAY);

const redrawInterval = setInterval(() => m.redraw(), 1000);

const track = captureStream.getVideoTracks()[0];

const endedListener = () => {

this.app.stopRecording();

m.redraw();

};

track.addEventListener('ended', endedListener);

this.onbeforeremove = () => {

clearInterval(frameInterval);

clearInterval(redrawInterval);

track.removeEventListener('ended', endedListener);

track.stop();

};

m.redraw();

}

view() {

const actions = [

m(Button, { label: 'Stop', icon: 'primitive-square', onclick: () => this.app.stopRecording() })

];

return [

m(View, { actions }, [

m(Timer, { duration: typeof this.startTime === 'number' ? new Date().getTime() - this.startTime : 0 }),

m('canvas.hidden', { width: 640, height: 480 }),

m('video.hidden', { autoplay: true, playsinline: true }),

]),

];

}

class PreviewView {

constructor(vnode) {

this.app = vnode.attrs.app;

this.recording = this.app.recording;

this.canvas = undefined;

this.playbar = undefined;

this.content = undefined;

this.viewportDisposable = undefined;

this.viewport = {

width: undefined,

height: undefined,

top: 0,

left: 0,

zoom: 1

};

this.playback = {

index: undefined,

disposable: undefined,

reset: false

};

this.trim = {

start: 0,

end: this.recording.frames.length - 1

};

this.crop = {

top: 0,

left: 0,

width: this.recording.width,

height: this.recording.height

};

}

get isPlaying() { return !!this.playback.disposable; }

oncreate(vnode) {

this.canvas = vnode.dom.getElementsByTagName('canvas')[0];

this.playbar = vnode.dom.querySelector('.playbar');

this.content = vnode.dom.querySelector('.content');

const viewportListener = () => this.updateViewport();

window.addEventListener('resize', viewportListener);

this.viewportDisposable = () => window.removeEventListener('resize', viewportListener);

this.updateViewport();

this.zoomToFit();

m.redraw(); // prevent flickering

setTimeout(() => this.play());

}

zoomToFit() {

this.viewport.zoom = Math.max(0.1, Math.min(1, this.viewport.width * .95 / this.recording.width, this.viewport.height * .95 / this.recording.height));

}

updateViewport() {

this.viewport.width = Math.floor(this.content.clientWidth);

this.viewport.height = Math.floor(this.content.clientHeight);

}

onbeforeremove() {

this.pause();

this.viewportDisposable();

}

view() {

const isCropped = this.crop.top !== 0 || this.crop.left !== 0 || this.crop.width !== this.recording.width || this.crop.height !== this.recording.height;

const actions = [

m(Button, { title: this.isPlaying ? 'Pause' : 'Play', iconset: 'material', icon: this.isPlaying ? 'pause' : 'play', primary: true, onclick: () => this.togglePlayPause() }),

m('.playbar', [

m('input', { type: 'range', min: 0, max: `${this.recording.frames.length - 1}`, value: `${this.playback.index}`, disabled: this.isPlaying, oninput: e => this.onPlaybarInput(e) }),

m('.trim-bar', { style: { left: `${this.trim.start * 100 / (this.recording.frames.length - 1)}%`, width: `${(this.trim.end - this.trim.start) * 100 / (this.recording.frames.length - 1)}%` } }, [

m('.trim-start', { onmousedown: e => this.onTrimMouseDown('start', e) }),

m('.trim-end', { onmousedown: e => this.onTrimMouseDown('end', e) }),

])

]),

m(Button, { title: 'Discard', icon: 'trashcan', onclick: () => this.app.cancel() }),

m(Button, { label: 'Render', icon: 'gear', onclick: () => this.app.startRendering({ trim: this.trim, crop: this.crop }), primary: true }),

];

const scale = value => value * this.viewport.zoom;

const width = scale(this.recording.width);

const height = scale(this.recording.height);

const top = Math.floor(scale(this.viewport.top) + (this.viewport.height / 2) - (height / 2));

const left = Math.floor(scale(this.viewport.left) + (this.viewport.width / 2) - (width / 2));

return [

m(View, {

actions,

contentClass: 'crop',

contentProps: {

onwheel: e => this.onContentWheel(e),

onmousedown: e => this.onContentMouseDown(e),

oncontextmenu: e => e.preventDefault()

}

}, [

m('.preview', { style: { top: `${top}px`, left: `${left}px`, width: `${width}px`, height: `${height}px` } }, [

m('canvas', { width: this.recording.width, height: this.recording.height }),

isCropped && m('.crop-box', {

style: {

// here be dragons!

clipPath: `polygon(evenodd, 0 0, 0 ${scale(this.recording.height)}px, ${scale(this.recording.width)}% ${scale(this.recording.height)}px, ${scale(this.recording.width)}% 0, 0 0, ${scale(this.crop.left)}px ${scale(this.crop.top)}px, ${scale(this.crop.left)}px ${scale(this.crop.top + this.crop.height)}px, ${scale(this.crop.left + this.crop.width)}px ${scale(this.crop.top + this.crop.height)}px, ${scale(this.crop.left + this.crop.width)}px ${scale(this.crop.top)}px, ${scale(this.crop.left)}px ${scale(this.crop.top)}px)`

}

})

]),

])

];

}

onTrimMouseDown(handle, event) {

event.preventDefault();

const ctx = this.canvas.getContext('2d');

const start = {

width: this.playbar.clientWidth,

screenX: event.screenX,

index: handle === 'start' ? this.trim.start : this.trim.end,

min: handle === 'start' ? 0 : this.trim.start + 1,

max: handle === 'start' ? this.trim.end - 1 : this.recording.frames.length - 1

};

const onMouseMove = e => {

const diff = e.screenX - start.screenX;

const index = start.index + Math.round(diff * (this.recording.frames.length - 1) / start.width);

const previous = this.trim[handle];

this.trim[handle] = Math.max(start.min, Math.min(start.max, index));

if (!this.isPlaying && previous !== this.trim[handle]) {

ctx.putImageData(this.recording.frames[this.trim[handle]], 0, 0);

}

m.redraw();

};

const onMouseUp = () => {

document.body.removeEventListener('mousemove', onMouseMove);

document.body.removeEventListener('mouseup', onMouseUp);

this.playback.reset = true;

if (this.isPlaying) {

this.play();

} else {

ctx.putImageData(this.recording.frames[this.playback.index], 0, 0);

}

m.redraw();

};

if (!this.isPlaying) {

ctx.putImageData(this.recording.frames[this.trim[handle]], 0, 0);

}

document.body.addEventListener('mousemove', onMouseMove);

document.body.addEventListener('mouseup', onMouseUp);

}

onContentWheel(event) {

event.preventDefault();

const zoom = this.viewport.zoom - event.deltaY / 180 * 0.1;

this.viewport.zoom = Math.max(0.1, Math.min(2, zoom));

}

onContentMouseDown(event) {

if (event.button === 0 && !event.ctrlKey && !event.metaKey && !event.shiftKey) {

this.onCrop(event);

} else {

this.onViewportMove(event);

}

onCrop(event) {

const width = this.recording.width * this.viewport.zoom;

const height = this.recording.height * this.viewport.zoom;

const top = Math.floor(this.viewport.top * this.viewport.zoom + (this.viewport.height / 2) - (height / 2));

const left = Math.floor(this.viewport.left * this.viewport.zoom + (this.viewport.width / 2) - (width / 2));

const offsetTop = event.currentTarget.offsetTop;

const offsetLeft = event.currentTarget.offsetLeft;

const mouseTop = event => Math.max(0, Math.min(this.recording.height, (event.clientY - offsetTop - top) / this.viewport.zoom));

const mouseLeft = event => Math.max(0, Math.min(this.recording.width, (event.clientX - offsetLeft - left) / this.viewport.zoom));

const point = event => ({ top: mouseTop(event), left: mouseLeft(event) });

const from = point(event);

let didMove = false;

const onMouseMove = event => {

const to = point(event);

const top = Math.max(0, Math.min(from.top, to.top));

const left = Math.max(0, Math.min(from.left, to.left));

const width = Math.min(this.recording.width - left, Math.abs(from.left - to.left));

const height = Math.min(this.recording.height - top, Math.abs(from.top - to.top));

this.crop = { top, left, width, height };

didMove = true;

m.redraw();

};

const onMouseUp = event => {

event.preventDefault();

document.body.removeEventListener('mousemove', onMouseMove);

document.body.removeEventListener('mouseup', onMouseUp);

if (!didMove || this.crop.width < 10 || this.crop.height < 10) {

this.crop = {

top: 0,

left: 0,

width: this.recording.width,

height: this.recording.height

};

}

m.redraw();

};

event.preventDefault();

document.body.addEventListener('mousemove', onMouseMove);

document.body.addEventListener('mouseup', onMouseUp);

}

onViewportMove(event) {

const start = {

top: this.viewport.top,

left: this.viewport.left,

screenX: event.screenX,

screenY: event.screenY

};

const onMouseMove = e => {

this.viewport.top = start.top + (e.screenY - start.screenY) / this.viewport.zoom;

this.viewport.left = start.left + (e.screenX - start.screenX) / this.viewport.zoom;

m.redraw();

};

const onMouseUp = event => {

event.preventDefault();

document.body.removeEventListener('mousemove', onMouseMove);

document.body.removeEventListener('mouseup', onMouseUp);

m.redraw();

};

event.preventDefault();

document.body.addEventListener('mousemove', onMouseMove);

document.body.addEventListener('mouseup', onMouseUp);

}

onPlaybarInput(e) {

this.playback.index = Number(e.target.value);

const ctx = this.canvas.getContext('2d');

ctx.putImageData(this.recording.frames[this.playback.index], 0, 0);

}

play() {

if (this.playback.disposable) {

this.playback.disposable();

}

if (this.playback.reset) {

this.playback.index = undefined;

this.playback.reset = false;

}

const range = {

start: this.trim.start,

end: this.trim.end

};

const ctx = this.canvas.getContext('2d');

const duration = (range.end - range.start + 1) * FRAME_DELAY;

const start = range.start * FRAME_DELAY + new Date().getTime() - ((this.playback.index || range.start) * FRAME_DELAY);

let animationFrame = undefined;

const draw = () => {

const index = range.start + Math.floor(((new Date().getTime() - start) % duration) / FRAME_DELAY);

if (this.playback.index !== index) {

ctx.putImageData(this.recording.frames[index], 0, 0);

m.redraw();

}

this.playback.index = index;

animationFrame = requestAnimationFrame(draw);

};

animationFrame = requestAnimationFrame(draw);

this.playback.disposable = () => {

cancelAnimationFrame(animationFrame);

};

}

pause() {

if (this.playback.disposable) {

this.playback.disposable();

this.playback.disposable = undefined;

}

togglePlayPause() {

if (this.isPlaying) {

this.pause();

} else {

this.play();

}

class RenderView {

constructor(vnode) {

this.app = vnode.attrs.app;

this.recording = this.app.recording;

this.trim = this.app.renderOptions.trim;

this.crop = this.app.renderOptions.crop;

this.progress = 0;

}

async oncreate(vnode) {

const isCropped = this.crop.top !== 0 || this.crop.left !== 0 || this.crop.width !== this.recording.width || this.crop.height !== this.recording.height;

const gif = new GIF({

workers: navigator.hardwareConcurrency,

quality: 10,

width: this.crop.width,

height: this.crop.height,

workerScript: 'gif.worker.js',

});

gif.on('progress', progress => {

this.progress = progress;

m.redraw();

});

gif.once('finished', blob => {

this.app.setRenderedRecording({

duration: (this.trim.end - this.trim.start + 1) * FRAME_DELAY,

size: blob.size,

url: URL.createObjectURL(blob),

});

m.redraw();

});

const ctx = isCropped && vnode.dom.getElementsByTagName('canvas')[0].getContext('2d');

let first = true;

for (let i = this.trim.start; i <= this.trim.end; i++) {

let frame = this.recording.frames[i];

if (isCropped) {

ctx.putImageData(frame, 0, 0);

frame = ctx.getImageData(this.crop.left, this.crop.top, this.crop.width, this.crop.height);

}

gif.addFrame(frame, { delay: first ? 0 : FRAME_DELAY });

first = false;

}

this.onbeforeremove = () => {

gif.abort();

};

gif.render();

}

view() {

const isCropped = this.crop.top !== 0 || this.crop.left !== 0 || this.crop.width !== this.recording.width || this.crop.height !== this.recording.height;

const actions = [

m(Button, { label: 'Cancel', icon: 'primitive-square', onclick: () => this.app.cancel() })

];

return [

m(View, { actions }, [

m('progress', { max: '1', value: this.progress, title: 'Rendering...' }, `Rendering: ${Math.floor(this.progress * 100)}%`),

isCropped && m('canvas.hidden', { width: this.recording.width, height: this.recording.height }),

])

];

}

class App {

constructor() {

this.state = 'idle';

this.recording = undefined;

window.onbeforeunload = () => this.recording ? '' : null;

}

view() {

switch (this.state) {

case 'idle': return m(IdleView, { app: this });

case 'recording': return m(RecordView, { app: this });

case 'preview': return m(PreviewView, { app: this });

case 'rendering': return m(RenderView, { app: this });

}

startRecording() {

if (this.recording && !window.confirm('This will discard the current recording, are you sure you want to continue?')) {

return;

}

this.state = 'recording';

this.recording = {

width: undefined,

height: undefined,

frames: []

};

}

stopRecording() {

this.state = 'preview';

}

startRendering(renderOptions) {

this.state = 'rendering';

this.renderOptions = renderOptions;

}

setRenderedRecording(recording) {

this.state = 'idle';

this.recording = recording;

this.renderOptions = undefined;

}

cancel() {

this.state = 'idle';

this.recording = undefined;

this.renderOptions = undefined;

}

function main() {

m.mount(document.getElementById('app-container'), App);

}

main();

Now we need to write the gif.worker.js file and copy paste the following code

gif.worker.js

// gif.worker.js 0.2.0 - https://github.com/jnordberg/gif.js
(function e(t, n, r) { function s(o, u) { if (!n[o]) { if (!t[o]) { var a = typeof require == "function" && require; if (!u && a) return a(o, !0); if (i) return i(o, !0); var f = new Error("Cannot find module '" + o + "'"); throw f.code = "MODULE_NOT_FOUND", f } var l = n[o] = { exports: {} }; t[o][0].call(l.exports, function (e) { var n = t[o][1][e]; return s(n ? n : e) }, l, l.exports, e, t, n, r) } return n[o].exports } var i = typeof require == "function" && require; for (var o = 0; o < r.length; o++)s(r[o]); return s })({ 1: [function (require, module, exports) { var NeuQuant = require("./TypedNeuQuant.js"); var LZWEncoder = require("./LZWEncoder.js"); function ByteArray() { this.page = -1; this.pages = []; this.newPage() } ByteArray.pageSize = 4096; ByteArray.charMap = {}; for (var i = 0; i < 256; i++)ByteArray.charMap[i] = String.fromCharCode(i); ByteArray.prototype.newPage = function () { this.pages[++this.page] = new Uint8Array(ByteArray.pageSize); this.cursor = 0 }; ByteArray.prototype.getData = function () { var rv = ""; for (var p = 0; p < this.pages.length; p++) { for (var i = 0; i < ByteArray.pageSize; i++) { rv += ByteArray.charMap[this.pages[p][i]] } } return rv }; ByteArray.prototype.writeByte = function (val) { if (this.cursor >= ByteArray.pageSize) this.newPage(); this.pages[this.page][this.cursor++] = val }; ByteArray.prototype.writeUTFBytes = function (string) { for (var l = string.length, i = 0; i < l; i++)this.writeByte(string.charCodeAt(i)) }; ByteArray.prototype.writeBytes = function (array, offset, length) { for (var l = length || array.length, i = offset || 0; i < l; i++)this.writeByte(array[i]) }; function GIFEncoder(width, height) { this.width = ~~width; this.height = ~~height; this.transparent = null; this.transIndex = 0; this.repeat = -1; this.delay = 0; this.image = null; this.pixels = null; this.indexedPixels = null; this.colorDepth = null; this.colorTab = null; this.neuQuant = null; this.usedEntry = new Array; this.palSize = 7; this.dispose = -1; this.firstFrame = true; this.sample = 10; this.dither = false; this.globalPalette = false; this.out = new ByteArray } GIFEncoder.prototype.setDelay = function (milliseconds) { this.delay = Math.round(milliseconds / 10) }; GIFEncoder.prototype.setFrameRate = function (fps) { this.delay = Math.round(100 / fps) }; GIFEncoder.prototype.setDispose = function (disposalCode) { if (disposalCode >= 0) this.dispose = disposalCode }; GIFEncoder.prototype.setRepeat = function (repeat) { this.repeat = repeat }; GIFEncoder.prototype.setTransparent = function (color) { this.transparent = color }; GIFEncoder.prototype.addFrame = function (imageData) { this.image = imageData; this.colorTab = this.globalPalette && this.globalPalette.slice ? this.globalPalette : null; this.getImagePixels(); this.analyzePixels(); if (this.globalPalette === true) this.globalPalette = this.colorTab; if (this.firstFrame) { this.writeLSD(); this.writePalette(); if (this.repeat >= 0) { this.writeNetscapeExt() } } this.writeGraphicCtrlExt(); this.writeImageDesc(); if (!this.firstFrame && !this.globalPalette) this.writePalette(); this.writePixels(); this.firstFrame = false }; GIFEncoder.prototype.finish = function () { this.out.writeByte(59) }; GIFEncoder.prototype.setQuality = function (quality) { if (quality < 1) quality = 1; this.sample = quality }; GIFEncoder.prototype.setDither = function (dither) { if (dither === true) dither = "FloydSteinberg"; this.dither = dither }; GIFEncoder.prototype.setGlobalPalette = function (palette) { this.globalPalette = palette }; GIFEncoder.prototype.getGlobalPalette = function () { return this.globalPalette && this.globalPalette.slice && this.globalPalette.slice(0) || this.globalPalette }; GIFEncoder.prototype.writeHeader = function () { this.out.writeUTFBytes("GIF89a") }; GIFEncoder.prototype.analyzePixels = function () { if (!this.colorTab) { this.neuQuant = new NeuQuant(this.pixels, this.sample); this.neuQuant.buildColormap(); this.colorTab = this.neuQuant.getColormap() } if (this.dither) { this.ditherPixels(this.dither.replace("-serpentine", ""), this.dither.match(/-serpentine/) !== null) } else { this.indexPixels() } this.pixels = null; this.colorDepth = 8; this.palSize = 7; if (this.transparent !== null) { this.transIndex = this.findClosest(this.transparent, true) } }; GIFEncoder.prototype.indexPixels = function (imgq) { var nPix = this.pixels.length / 3; this.indexedPixels = new Uint8Array(nPix); var k = 0; for (var j = 0; j < nPix; j++) { var index = this.findClosestRGB(this.pixels[k++] & 255, this.pixels[k++] & 255, this.pixels[k++] & 255); this.usedEntry[index] = true; this.indexedPixels[j] = index } }; GIFEncoder.prototype.ditherPixels = function (kernel, serpentine) { var kernels = { FalseFloydSteinberg: [[3 / 8, 1, 0], [3 / 8, 0, 1], [2 / 8, 1, 1]], FloydSteinberg: [[7 / 16, 1, 0], [3 / 16, -1, 1], [5 / 16, 0, 1], [1 / 16, 1, 1]], Stucki: [[8 / 42, 1, 0], [4 / 42, 2, 0], [2 / 42, -2, 1], [4 / 42, -1, 1], [8 / 42, 0, 1], [4 / 42, 1, 1], [2 / 42, 2, 1], [1 / 42, -2, 2], [2 / 42, -1, 2], [4 / 42, 0, 2], [2 / 42, 1, 2], [1 / 42, 2, 2]], Atkinson: [[1 / 8, 1, 0], [1 / 8, 2, 0], [1 / 8, -1, 1], [1 / 8, 0, 1], [1 / 8, 1, 1], [1 / 8, 0, 2]] }; if (!kernel || !kernels[kernel]) { throw "Unknown dithering kernel: " + kernel } var ds = kernels[kernel]; var index = 0, height = this.height, width = this.width, data = this.pixels; var direction = serpentine ? -1 : 1; this.indexedPixels = new Uint8Array(this.pixels.length / 3); for (var y = 0; y < height; y++) { if (serpentine) direction = direction * -1; for (var x = direction == 1 ? 0 : width - 1, xend = direction == 1 ? width : 0; x !== xend; x += direction) { index = y * width + x; var idx = index * 3; var r1 = data[idx]; var g1 = data[idx + 1]; var b1 = data[idx + 2]; idx = this.findClosestRGB(r1, g1, b1); this.usedEntry[idx] = true; this.indexedPixels[index] = idx; idx *= 3; var r2 = this.colorTab[idx]; var g2 = this.colorTab[idx + 1]; var b2 = this.colorTab[idx + 2]; var er = r1 - r2; var eg = g1 - g2; var eb = b1 - b2; for (var i = direction == 1 ? 0 : ds.length - 1, end = direction == 1 ? ds.length : 0; i !== end; i += direction) { var x1 = ds[i][1]; var y1 = ds[i][2]; if (x1 + x >= 0 && x1 + x < width && y1 + y >= 0 && y1 + y < height) { var d = ds[i][0]; idx = index + x1 + y1 * width; idx *= 3; data[idx] = Math.max(0, Math.min(255, data[idx] + er * d)); data[idx + 1] = Math.max(0, Math.min(255, data[idx + 1] + eg * d)); data[idx + 2] = Math.max(0, Math.min(255, data[idx + 2] + eb * d)) } } } } }; GIFEncoder.prototype.findClosest = function (c, used) { return this.findClosestRGB((c & 16711680) >> 16, (c & 65280) >> 8, c & 255, used) }; GIFEncoder.prototype.findClosestRGB = function (r, g, b, used) { if (this.colorTab === null) return -1; if (this.neuQuant && !used) { return this.neuQuant.lookupRGB(r, g, b) } var c = b | g << 8 | r << 16; var minpos = 0; var dmin = 256 * 256 * 256; var len = this.colorTab.length; for (var i = 0, index = 0; i < len; index++) { var dr = r - (this.colorTab[i++] & 255); var dg = g - (this.colorTab[i++] & 255); var db = b - (this.colorTab[i++] & 255); var d = dr * dr + dg * dg + db * db; if ((!used || this.usedEntry[index]) && d < dmin) { dmin = d; minpos = index } } return minpos }; GIFEncoder.prototype.getImagePixels = function () { var w = this.width; var h = this.height; this.pixels = new Uint8Array(w * h * 3); var data = this.image; var srcPos = 0; var count = 0; for (var i = 0; i < h; i++) { for (var j = 0; j < w; j++) { this.pixels[count++] = data[srcPos++]; this.pixels[count++] = data[srcPos++]; this.pixels[count++] = data[srcPos++]; srcPos++ } } }; GIFEncoder.prototype.writeGraphicCtrlExt = function () { this.out.writeByte(33); this.out.writeByte(249); this.out.writeByte(4); var transp, disp; if (this.transparent === null) { transp = 0; disp = 0 } else { transp = 1; disp = 2 } if (this.dispose >= 0) { disp = dispose & 7 } disp <<= 2; this.out.writeByte(0 | disp | 0 | transp); this.writeShort(this.delay); this.out.writeByte(this.transIndex); this.out.writeByte(0) }; GIFEncoder.prototype.writeImageDesc = function () { this.out.writeByte(44); this.writeShort(0); this.writeShort(0); this.writeShort(this.width); this.writeShort(this.height); if (this.firstFrame || this.globalPalette) { this.out.writeByte(0) } else { this.out.writeByte(128 | 0 | 0 | 0 | this.palSize) } }; GIFEncoder.prototype.writeLSD = function () { this.writeShort(this.width); this.writeShort(this.height); this.out.writeByte(128 | 112 | 0 | this.palSize); this.out.writeByte(0); this.out.writeByte(0) }; GIFEncoder.prototype.writeNetscapeExt = function () { this.out.writeByte(33); this.out.writeByte(255); this.out.writeByte(11); this.out.writeUTFBytes("NETSCAPE2.0"); this.out.writeByte(3); this.out.writeByte(1); this.writeShort(this.repeat); this.out.writeByte(0) }; GIFEncoder.prototype.writePalette = function () { this.out.writeBytes(this.colorTab); var n = 3 * 256 - this.colorTab.length; for (var i = 0; i < n; i++)this.out.writeByte(0) }; GIFEncoder.prototype.writeShort = function (pValue) { this.out.writeByte(pValue & 255); this.out.writeByte(pValue >> 8 & 255) }; GIFEncoder.prototype.writePixels = function () { var enc = new LZWEncoder(this.width, this.height, this.indexedPixels, this.colorDepth); enc.encode(this.out) }; GIFEncoder.prototype.stream = function () { return this.out }; module.exports = GIFEncoder }, { "./LZWEncoder.js": 2, "./TypedNeuQuant.js": 3 }], 2: [function (require, module, exports) { var EOF = -1; var BITS = 12; var HSIZE = 5003; var masks = [0, 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535]; function LZWEncoder(width, height, pixels, colorDepth) { var initCodeSize = Math.max(2, colorDepth); var accum = new Uint8Array(256); var htab = new Int32Array(HSIZE); var codetab = new Int32Array(HSIZE); var cur_accum, cur_bits = 0; var a_count; var free_ent = 0; var maxcode; var clear_flg = false; var g_init_bits, ClearCode, EOFCode; function char_out(c, outs) { accum[a_count++] = c; if (a_count >= 254) flush_char(outs) } function cl_block(outs) { cl_hash(HSIZE); free_ent = ClearCode + 2; clear_flg = true; output(ClearCode, outs) } function cl_hash(hsize) { for (var i = 0; i < hsize; ++i)htab[i] = -1 } function compress(init_bits, outs) { var fcode, c, i, ent, disp, hsize_reg, hshift; g_init_bits = init_bits; clear_flg = false; n_bits = g_init_bits; maxcode = MAXCODE(n_bits); ClearCode = 1 << init_bits - 1; EOFCode = ClearCode + 1; free_ent = ClearCode + 2; a_count = 0; ent = nextPixel(); hshift = 0; for (fcode = HSIZE; fcode < 65536; fcode *= 2)++hshift; hshift = 8 - hshift; hsize_reg = HSIZE; cl_hash(hsize_reg); output(ClearCode, outs); outer_loop: while ((c = nextPixel()) != EOF) { fcode = (c << BITS) + ent; i = c << hshift ^ ent; if (htab[i] === fcode) { ent = codetab[i]; continue } else if (htab[i] >= 0) { disp = hsize_reg - i; if (i === 0) disp = 1; do { if ((i -= disp) < 0) i += hsize_reg; if (htab[i] === fcode) { ent = codetab[i]; continue outer_loop } } while (htab[i] >= 0) } output(ent, outs); ent = c; if (free_ent < 1 << BITS) { codetab[i] = free_ent++; htab[i] = fcode } else { cl_block(outs) } } output(ent, outs); output(EOFCode, outs) } function encode(outs) { outs.writeByte(initCodeSize); remaining = width * height; curPixel = 0; compress(initCodeSize + 1, outs); outs.writeByte(0) } function flush_char(outs) { if (a_count > 0) { outs.writeByte(a_count); outs.writeBytes(accum, 0, a_count); a_count = 0 } } function MAXCODE(n_bits) { return (1 << n_bits) - 1 } function nextPixel() { if (remaining === 0) return EOF; --remaining; var pix = pixels[curPixel++]; return pix & 255 } function output(code, outs) { cur_accum &= masks[cur_bits]; if (cur_bits > 0) cur_accum |= code << cur_bits; else cur_accum = code; cur_bits += n_bits; while (cur_bits >= 8) { char_out(cur_accum & 255, outs); cur_accum >>= 8; cur_bits -= 8 } if (free_ent > maxcode || clear_flg) { if (clear_flg) { maxcode = MAXCODE(n_bits = g_init_bits); clear_flg = false } else { ++n_bits; if (n_bits == BITS) maxcode = 1 << BITS; else maxcode = MAXCODE(n_bits) } } if (code == EOFCode) { while (cur_bits > 0) { char_out(cur_accum & 255, outs); cur_accum >>= 8; cur_bits -= 8 } flush_char(outs) } } this.encode = encode } module.exports = LZWEncoder }, {}], 3: [function (require, module, exports) { var ncycles = 100; var netsize = 256; var maxnetpos = netsize - 1; var netbiasshift = 4; var intbiasshift = 16; var intbias = 1 << intbiasshift; var gammashift = 10; var gamma = 1 << gammashift; var betashift = 10; var beta = intbias >> betashift; var betagamma = intbias << gammashift - betashift; var initrad = netsize >> 3; var radiusbiasshift = 6; var radiusbias = 1 << radiusbiasshift; var initradius = initrad * radiusbias; var radiusdec = 30; var alphabiasshift = 10; var initalpha = 1 << alphabiasshift; var alphadec; var radbiasshift = 8; var radbias = 1 << radbiasshift; var alpharadbshift = alphabiasshift + radbiasshift; var alpharadbias = 1 << alpharadbshift; var prime1 = 499; var prime2 = 491; var prime3 = 487; var prime4 = 503; var minpicturebytes = 3 * prime4; function NeuQuant(pixels, samplefac) { var network; var netindex; var bias; var freq; var radpower; function init() { network = []; netindex = new Int32Array(256); bias = new Int32Array(netsize); freq = new Int32Array(netsize); radpower = new Int32Array(netsize >> 3); var i, v; for (i = 0; i < netsize; i++) { v = (i << netbiasshift + 8) / netsize; network[i] = new Float64Array([v, v, v, 0]); freq[i] = intbias / netsize; bias[i] = 0 } } function unbiasnet() { for (var i = 0; i < netsize; i++) { network[i][0] >>= netbiasshift; network[i][1] >>= netbiasshift; network[i][2] >>= netbiasshift; network[i][3] = i } } function altersingle(alpha, i, b, g, r) { network[i][0] -= alpha * (network[i][0] - b) / initalpha; network[i][1] -= alpha * (network[i][1] - g) / initalpha; network[i][2] -= alpha * (network[i][2] - r) / initalpha } function alterneigh(radius, i, b, g, r) { var lo = Math.abs(i - radius); var hi = Math.min(i + radius, netsize); var j = i + 1; var k = i - 1; var m = 1; var p, a; while (j < hi || k > lo) { a = radpower[m++]; if (j < hi) { p = network[j++]; p[0] -= a * (p[0] - b) / alpharadbias; p[1] -= a * (p[1] - g) / alpharadbias; p[2] -= a * (p[2] - r) / alpharadbias } if (k > lo) { p = network[k--]; p[0] -= a * (p[0] - b) / alpharadbias; p[1] -= a * (p[1] - g) / alpharadbias; p[2] -= a * (p[2] - r) / alpharadbias } } } function contest(b, g, r) { var bestd = ~(1 << 31); var bestbiasd = bestd; var bestpos = -1; var bestbiaspos = bestpos; var i, n, dist, biasdist, betafreq; for (i = 0; i < netsize; i++) { n = network[i]; dist = Math.abs(n[0] - b) + Math.abs(n[1] - g) + Math.abs(n[2] - r); if (dist < bestd) { bestd = dist; bestpos = i } biasdist = dist - (bias[i] >> intbiasshift - netbiasshift); if (biasdist < bestbiasd) { bestbiasd = biasdist; bestbiaspos = i } betafreq = freq[i] >> betashift; freq[i] -= betafreq; bias[i] += betafreq << gammashift } freq[bestpos] += beta; bias[bestpos] -= betagamma; return bestbiaspos } function inxbuild() { var i, j, p, q, smallpos, smallval, previouscol = 0, startpos = 0; for (i = 0; i < netsize; i++) { p = network[i]; smallpos = i; smallval = p[1]; for (j = i + 1; j < netsize; j++) { q = network[j]; if (q[1] < smallval) { smallpos = j; smallval = q[1] } } q = network[smallpos]; if (i != smallpos) { j = q[0]; q[0] = p[0]; p[0] = j; j = q[1]; q[1] = p[1]; p[1] = j; j = q[2]; q[2] = p[2]; p[2] = j; j = q[3]; q[3] = p[3]; p[3] = j } if (smallval != previouscol) { netindex[previouscol] = startpos + i >> 1; for (j = previouscol + 1; j < smallval; j++)netindex[j] = i; previouscol = smallval; startpos = i } } netindex[previouscol] = startpos + maxnetpos >> 1; for (j = previouscol + 1; j < 256; j++)netindex[j] = maxnetpos } function inxsearch(b, g, r) { var a, p, dist; var bestd = 1e3; var best = -1; var i = netindex[g]; var j = i - 1; while (i < netsize || j >= 0) { if (i < netsize) { p = network[i]; dist = p[1] - g; if (dist >= bestd) i = netsize; else { i++; if (dist < 0) dist = -dist; a = p[0] - b; if (a < 0) a = -a; dist += a; if (dist < bestd) { a = p[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; best = p[3] } } } } if (j >= 0) { p = network[j]; dist = g - p[1]; if (dist >= bestd) j = -1; else { j--; if (dist < 0) dist = -dist; a = p[0] - b; if (a < 0) a = -a; dist += a; if (dist < bestd) { a = p[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; best = p[3] } } } } } return best } function learn() { var i; var lengthcount = pixels.length; var alphadec = 30 + (samplefac - 1) / 3; var samplepixels = lengthcount / (3 * samplefac); var delta = ~~(samplepixels / ncycles); var alpha = initalpha; var radius = initradius; var rad = radius >> radiusbiasshift; if (rad <= 1) rad = 0; for (i = 0; i < rad; i++)radpower[i] = alpha * ((rad * rad - i * i) * radbias / (rad * rad)); var step; if (lengthcount < minpicturebytes) { samplefac = 1; step = 3 } else if (lengthcount % prime1 !== 0) { step = 3 * prime1 } else if (lengthcount % prime2 !== 0) { step = 3 * prime2 } else if (lengthcount % prime3 !== 0) { step = 3 * prime3 } else { step = 3 * prime4 } var b, g, r, j; var pix = 0; i = 0; while (i < samplepixels) { b = (pixels[pix] & 255) << netbiasshift; g = (pixels[pix + 1] & 255) << netbiasshift; r = (pixels[pix + 2] & 255) << netbiasshift; j = contest(b, g, r); altersingle(alpha, j, b, g, r); if (rad !== 0) alterneigh(rad, j, b, g, r); pix += step; if (pix >= lengthcount) pix -= lengthcount; i++; if (delta === 0) delta = 1; if (i % delta === 0) { alpha -= alpha / alphadec; radius -= radius / radiusdec; rad = radius >> radiusbiasshift; if (rad <= 1) rad = 0; for (j = 0; j < rad; j++)radpower[j] = alpha * ((rad * rad - j * j) * radbias / (rad * rad)) } } } function buildColormap() { init(); learn(); unbiasnet(); inxbuild() } this.buildColormap = buildColormap; function getColormap() { var map = []; var index = []; for (var i = 0; i < netsize; i++)index[network[i][3]] = i; var k = 0; for (var l = 0; l < netsize; l++) { var j = index[l]; map[k++] = network[j][0]; map[k++] = network[j][1]; map[k++] = network[j][2] } return map } this.getColormap = getColormap; this.lookupRGB = inxsearch } module.exports = NeuQuant }, {}], 4: [function (require, module, exports) { var GIFEncoder, renderFrame; GIFEncoder = require("./GIFEncoder.js"); renderFrame = function (frame) { var encoder, page, stream, transfer; encoder = new GIFEncoder(frame.width, frame.height); if (frame.index === 0) { encoder.writeHeader() } else { encoder.firstFrame = false } encoder.setTransparent(frame.transparent); encoder.setRepeat(frame.repeat); encoder.setDelay(frame.delay); encoder.setQuality(frame.quality); encoder.setDither(frame.dither); encoder.setGlobalPalette(frame.globalPalette); encoder.addFrame(frame.data); if (frame.last) { encoder.finish() } if (frame.globalPalette === true) { frame.globalPalette = encoder.getGlobalPalette() } stream = encoder.stream(); frame.data = stream.pages; frame.cursor = stream.cursor; frame.pageSize = stream.constructor.pageSize; if (frame.canTransfer) { transfer = function () { var i, len, ref, results; ref = frame.data; results = []; for (i = 0, len = ref.length; i < len; i++) { page = ref[i]; results.push(page.buffer) } return results }(); return self.postMessage(frame, transfer) } else { return self.postMessage(frame) } }; self.onmessage = function (event) { return renderFrame(event.data) } }, { "./GIFEncoder.js": 1 }] }, {}, [4]);
//# sourceMappingURL=https://cdnjs.cloudflare.com/ajax/libs/gif.js/0.2.0/gif.worker.js.map

// gif.worker.js 0.2.0 - https://github.com/jnordberg/gif.js

(function e(t, n, r) { function s(o, u) { if (!n[o]) { if (!t[o]) { var a = typeof require == "function" && require; if (!u && a) return a(o, !0); if (i) return i(o, !0); var f = new Error("Cannot find module '" + o + "'"); throw f.code = "MODULE_NOT_FOUND", f } var l = n[o] = { exports: {} }; t[o][0].call(l.exports, function (e) { var n = t[o][1][e]; return s(n ? n : e) }, l, l.exports, e, t, n, r) } return n[o].exports } var i = typeof require == "function" && require; for (var o = 0; o < r.length; o++)s(r[o]); return s })({ 1: [function (require, module, exports) { var NeuQuant = require("./TypedNeuQuant.js"); var LZWEncoder = require("./LZWEncoder.js"); function ByteArray() { this.page = -1; this.pages = []; this.newPage() } ByteArray.pageSize = 4096; ByteArray.charMap = {}; for (var i = 0; i < 256; i++)ByteArray.charMap[i] = String.fromCharCode(i); ByteArray.prototype.newPage = function () { this.pages[++this.page] = new Uint8Array(ByteArray.pageSize); this.cursor = 0 }; ByteArray.prototype.getData = function () { var rv = ""; for (var p = 0; p < this.pages.length; p++) { for (var i = 0; i < ByteArray.pageSize; i++) { rv += ByteArray.charMap[this.pages[p][i]] } } return rv }; ByteArray.prototype.writeByte = function (val) { if (this.cursor >= ByteArray.pageSize) this.newPage(); this.pages[this.page][this.cursor++] = val }; ByteArray.prototype.writeUTFBytes = function (string) { for (var l = string.length, i = 0; i < l; i++)this.writeByte(string.charCodeAt(i)) }; ByteArray.prototype.writeBytes = function (array, offset, length) { for (var l = length || array.length, i = offset || 0; i < l; i++)this.writeByte(array[i]) }; function GIFEncoder(width, height) { this.width = ~~width; this.height = ~~height; this.transparent = null; this.transIndex = 0; this.repeat = -1; this.delay = 0; this.image = null; this.pixels = null; this.indexedPixels = null; this.colorDepth = null; this.colorTab = null; this.neuQuant = null; this.usedEntry = new Array; this.palSize = 7; this.dispose = -1; this.firstFrame = true; this.sample = 10; this.dither = false; this.globalPalette = false; this.out = new ByteArray } GIFEncoder.prototype.setDelay = function (milliseconds) { this.delay = Math.round(milliseconds / 10) }; GIFEncoder.prototype.setFrameRate = function (fps) { this.delay = Math.round(100 / fps) }; GIFEncoder.prototype.setDispose = function (disposalCode) { if (disposalCode >= 0) this.dispose = disposalCode }; GIFEncoder.prototype.setRepeat = function (repeat) { this.repeat = repeat }; GIFEncoder.prototype.setTransparent = function (color) { this.transparent = color }; GIFEncoder.prototype.addFrame = function (imageData) { this.image = imageData; this.colorTab = this.globalPalette && this.globalPalette.slice ? this.globalPalette : null; this.getImagePixels(); this.analyzePixels(); if (this.globalPalette === true) this.globalPalette = this.colorTab; if (this.firstFrame) { this.writeLSD(); this.writePalette(); if (this.repeat >= 0) { this.writeNetscapeExt() } } this.writeGraphicCtrlExt(); this.writeImageDesc(); if (!this.firstFrame && !this.globalPalette) this.writePalette(); this.writePixels(); this.firstFrame = false }; GIFEncoder.prototype.finish = function () { this.out.writeByte(59) }; GIFEncoder.prototype.setQuality = function (quality) { if (quality < 1) quality = 1; this.sample = quality }; GIFEncoder.prototype.setDither = function (dither) { if (dither === true) dither = "FloydSteinberg"; this.dither = dither }; GIFEncoder.prototype.setGlobalPalette = function (palette) { this.globalPalette = palette }; GIFEncoder.prototype.getGlobalPalette = function () { return this.globalPalette && this.globalPalette.slice && this.globalPalette.slice(0) || this.globalPalette }; GIFEncoder.prototype.writeHeader = function () { this.out.writeUTFBytes("GIF89a") }; GIFEncoder.prototype.analyzePixels = function () { if (!this.colorTab) { this.neuQuant = new NeuQuant(this.pixels, this.sample); this.neuQuant.buildColormap(); this.colorTab = this.neuQuant.getColormap() } if (this.dither) { this.ditherPixels(this.dither.replace("-serpentine", ""), this.dither.match(/-serpentine/) !== null) } else { this.indexPixels() } this.pixels = null; this.colorDepth = 8; this.palSize = 7; if (this.transparent !== null) { this.transIndex = this.findClosest(this.transparent, true) } }; GIFEncoder.prototype.indexPixels = function (imgq) { var nPix = this.pixels.length / 3; this.indexedPixels = new Uint8Array(nPix); var k = 0; for (var j = 0; j < nPix; j++) { var index = this.findClosestRGB(this.pixels[k++] & 255, this.pixels[k++] & 255, this.pixels[k++] & 255); this.usedEntry[index] = true; this.indexedPixels[j] = index } }; GIFEncoder.prototype.ditherPixels = function (kernel, serpentine) { var kernels = { FalseFloydSteinberg: [[3 / 8, 1, 0], [3 / 8, 0, 1], [2 / 8, 1, 1]], FloydSteinberg: [[7 / 16, 1, 0], [3 / 16, -1, 1], [5 / 16, 0, 1], [1 / 16, 1, 1]], Stucki: [[8 / 42, 1, 0], [4 / 42, 2, 0], [2 / 42, -2, 1], [4 / 42, -1, 1], [8 / 42, 0, 1], [4 / 42, 1, 1], [2 / 42, 2, 1], [1 / 42, -2, 2], [2 / 42, -1, 2], [4 / 42, 0, 2], [2 / 42, 1, 2], [1 / 42, 2, 2]], Atkinson: [[1 / 8, 1, 0], [1 / 8, 2, 0], [1 / 8, -1, 1], [1 / 8, 0, 1], [1 / 8, 1, 1], [1 / 8, 0, 2]] }; if (!kernel || !kernels[kernel]) { throw "Unknown dithering kernel: " + kernel } var ds = kernels[kernel]; var index = 0, height = this.height, width = this.width, data = this.pixels; var direction = serpentine ? -1 : 1; this.indexedPixels = new Uint8Array(this.pixels.length / 3); for (var y = 0; y < height; y++) { if (serpentine) direction = direction * -1; for (var x = direction == 1 ? 0 : width - 1, xend = direction == 1 ? width : 0; x !== xend; x += direction) { index = y * width + x; var idx = index * 3; var r1 = data[idx]; var g1 = data[idx + 1]; var b1 = data[idx + 2]; idx = this.findClosestRGB(r1, g1, b1); this.usedEntry[idx] = true; this.indexedPixels[index] = idx; idx *= 3; var r2 = this.colorTab[idx]; var g2 = this.colorTab[idx + 1]; var b2 = this.colorTab[idx + 2]; var er = r1 - r2; var eg = g1 - g2; var eb = b1 - b2; for (var i = direction == 1 ? 0 : ds.length - 1, end = direction == 1 ? ds.length : 0; i !== end; i += direction) { var x1 = ds[i][1]; var y1 = ds[i][2]; if (x1 + x >= 0 && x1 + x < width && y1 + y >= 0 && y1 + y < height) { var d = ds[i][0]; idx = index + x1 + y1 * width; idx *= 3; data[idx] = Math.max(0, Math.min(255, data[idx] + er * d)); data[idx + 1] = Math.max(0, Math.min(255, data[idx + 1] + eg * d)); data[idx + 2] = Math.max(0, Math.min(255, data[idx + 2] + eb * d)) } } } } }; GIFEncoder.prototype.findClosest = function (c, used) { return this.findClosestRGB((c & 16711680) >> 16, (c & 65280) >> 8, c & 255, used) }; GIFEncoder.prototype.findClosestRGB = function (r, g, b, used) { if (this.colorTab === null) return -1; if (this.neuQuant && !used) { return this.neuQuant.lookupRGB(r, g, b) } var c = b | g << 8 | r << 16; var minpos = 0; var dmin = 256 * 256 * 256; var len = this.colorTab.length; for (var i = 0, index = 0; i < len; index++) { var dr = r - (this.colorTab[i++] & 255); var dg = g - (this.colorTab[i++] & 255); var db = b - (this.colorTab[i++] & 255); var d = dr * dr + dg * dg + db * db; if ((!used || this.usedEntry[index]) && d < dmin) { dmin = d; minpos = index } } return minpos }; GIFEncoder.prototype.getImagePixels = function () { var w = this.width; var h = this.height; this.pixels = new Uint8Array(w * h * 3); var data = this.image; var srcPos = 0; var count = 0; for (var i = 0; i < h; i++) { for (var j = 0; j < w; j++) { this.pixels[count++] = data[srcPos++]; this.pixels[count++] = data[srcPos++]; this.pixels[count++] = data[srcPos++]; srcPos++ } } }; GIFEncoder.prototype.writeGraphicCtrlExt = function () { this.out.writeByte(33); this.out.writeByte(249); this.out.writeByte(4); var transp, disp; if (this.transparent === null) { transp = 0; disp = 0 } else { transp = 1; disp = 2 } if (this.dispose >= 0) { disp = dispose & 7 } disp <<= 2; this.out.writeByte(0 | disp | 0 | transp); this.writeShort(this.delay); this.out.writeByte(this.transIndex); this.out.writeByte(0) }; GIFEncoder.prototype.writeImageDesc = function () { this.out.writeByte(44); this.writeShort(0); this.writeShort(0); this.writeShort(this.width); this.writeShort(this.height); if (this.firstFrame || this.globalPalette) { this.out.writeByte(0) } else { this.out.writeByte(128 | 0 | 0 | 0 | this.palSize) } }; GIFEncoder.prototype.writeLSD = function () { this.writeShort(this.width); this.writeShort(this.height); this.out.writeByte(128 | 112 | 0 | this.palSize); this.out.writeByte(0); this.out.writeByte(0) }; GIFEncoder.prototype.writeNetscapeExt = function () { this.out.writeByte(33); this.out.writeByte(255); this.out.writeByte(11); this.out.writeUTFBytes("NETSCAPE2.0"); this.out.writeByte(3); this.out.writeByte(1); this.writeShort(this.repeat); this.out.writeByte(0) }; GIFEncoder.prototype.writePalette = function () { this.out.writeBytes(this.colorTab); var n = 3 * 256 - this.colorTab.length; for (var i = 0; i < n; i++)this.out.writeByte(0) }; GIFEncoder.prototype.writeShort = function (pValue) { this.out.writeByte(pValue & 255); this.out.writeByte(pValue >> 8 & 255) }; GIFEncoder.prototype.writePixels = function () { var enc = new LZWEncoder(this.width, this.height, this.indexedPixels, this.colorDepth); enc.encode(this.out) }; GIFEncoder.prototype.stream = function () { return this.out }; module.exports = GIFEncoder }, { "./LZWEncoder.js": 2, "./TypedNeuQuant.js": 3 }], 2: [function (require, module, exports) { var EOF = -1; var BITS = 12; var HSIZE = 5003; var masks = [0, 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535]; function LZWEncoder(width, height, pixels, colorDepth) { var initCodeSize = Math.max(2, colorDepth); var accum = new Uint8Array(256); var htab = new Int32Array(HSIZE); var codetab = new Int32Array(HSIZE); var cur_accum, cur_bits = 0; var a_count; var free_ent = 0; var maxcode; var clear_flg = false; var g_init_bits, ClearCode, EOFCode; function char_out(c, outs) { accum[a_count++] = c; if (a_count >= 254) flush_char(outs) } function cl_block(outs) { cl_hash(HSIZE); free_ent = ClearCode + 2; clear_flg = true; output(ClearCode, outs) } function cl_hash(hsize) { for (var i = 0; i < hsize; ++i)htab[i] = -1 } function compress(init_bits, outs) { var fcode, c, i, ent, disp, hsize_reg, hshift; g_init_bits = init_bits; clear_flg = false; n_bits = g_init_bits; maxcode = MAXCODE(n_bits); ClearCode = 1 << init_bits - 1; EOFCode = ClearCode + 1; free_ent = ClearCode + 2; a_count = 0; ent = nextPixel(); hshift = 0; for (fcode = HSIZE; fcode < 65536; fcode *= 2)++hshift; hshift = 8 - hshift; hsize_reg = HSIZE; cl_hash(hsize_reg); output(ClearCode, outs); outer_loop: while ((c = nextPixel()) != EOF) { fcode = (c << BITS) + ent; i = c << hshift ^ ent; if (htab[i] === fcode) { ent = codetab[i]; continue } else if (htab[i] >= 0) { disp = hsize_reg - i; if (i === 0) disp = 1; do { if ((i -= disp) < 0) i += hsize_reg; if (htab[i] === fcode) { ent = codetab[i]; continue outer_loop } } while (htab[i] >= 0) } output(ent, outs); ent = c; if (free_ent < 1 << BITS) { codetab[i] = free_ent++; htab[i] = fcode } else { cl_block(outs) } } output(ent, outs); output(EOFCode, outs) } function encode(outs) { outs.writeByte(initCodeSize); remaining = width * height; curPixel = 0; compress(initCodeSize + 1, outs); outs.writeByte(0) } function flush_char(outs) { if (a_count > 0) { outs.writeByte(a_count); outs.writeBytes(accum, 0, a_count); a_count = 0 } } function MAXCODE(n_bits) { return (1 << n_bits) - 1 } function nextPixel() { if (remaining === 0) return EOF; --remaining; var pix = pixels[curPixel++]; return pix & 255 } function output(code, outs) { cur_accum &= masks[cur_bits]; if (cur_bits > 0) cur_accum |= code << cur_bits; else cur_accum = code; cur_bits += n_bits; while (cur_bits >= 8) { char_out(cur_accum & 255, outs); cur_accum >>= 8; cur_bits -= 8 } if (free_ent > maxcode || clear_flg) { if (clear_flg) { maxcode = MAXCODE(n_bits = g_init_bits); clear_flg = false } else { ++n_bits; if (n_bits == BITS) maxcode = 1 << BITS; else maxcode = MAXCODE(n_bits) } } if (code == EOFCode) { while (cur_bits > 0) { char_out(cur_accum & 255, outs); cur_accum >>= 8; cur_bits -= 8 } flush_char(outs) } } this.encode = encode } module.exports = LZWEncoder }, {}], 3: [function (require, module, exports) { var ncycles = 100; var netsize = 256; var maxnetpos = netsize - 1; var netbiasshift = 4; var intbiasshift = 16; var intbias = 1 << intbiasshift; var gammashift = 10; var gamma = 1 << gammashift; var betashift = 10; var beta = intbias >> betashift; var betagamma = intbias << gammashift - betashift; var initrad = netsize >> 3; var radiusbiasshift = 6; var radiusbias = 1 << radiusbiasshift; var initradius = initrad * radiusbias; var radiusdec = 30; var alphabiasshift = 10; var initalpha = 1 << alphabiasshift; var alphadec; var radbiasshift = 8; var radbias = 1 << radbiasshift; var alpharadbshift = alphabiasshift + radbiasshift; var alpharadbias = 1 << alpharadbshift; var prime1 = 499; var prime2 = 491; var prime3 = 487; var prime4 = 503; var minpicturebytes = 3 * prime4; function NeuQuant(pixels, samplefac) { var network; var netindex; var bias; var freq; var radpower; function init() { network = []; netindex = new Int32Array(256); bias = new Int32Array(netsize); freq = new Int32Array(netsize); radpower = new Int32Array(netsize >> 3); var i, v; for (i = 0; i < netsize; i++) { v = (i << netbiasshift + 8) / netsize; network[i] = new Float64Array([v, v, v, 0]); freq[i] = intbias / netsize; bias[i] = 0 } } function unbiasnet() { for (var i = 0; i < netsize; i++) { network[i][0] >>= netbiasshift; network[i][1] >>= netbiasshift; network[i][2] >>= netbiasshift; network[i][3] = i } } function altersingle(alpha, i, b, g, r) { network[i][0] -= alpha * (network[i][0] - b) / initalpha; network[i][1] -= alpha * (network[i][1] - g) / initalpha; network[i][2] -= alpha * (network[i][2] - r) / initalpha } function alterneigh(radius, i, b, g, r) { var lo = Math.abs(i - radius); var hi = Math.min(i + radius, netsize); var j = i + 1; var k = i - 1; var m = 1; var p, a; while (j < hi || k > lo) { a = radpower[m++]; if (j < hi) { p = network[j++]; p[0] -= a * (p[0] - b) / alpharadbias; p[1] -= a * (p[1] - g) / alpharadbias; p[2] -= a * (p[2] - r) / alpharadbias } if (k > lo) { p = network[k--]; p[0] -= a * (p[0] - b) / alpharadbias; p[1] -= a * (p[1] - g) / alpharadbias; p[2] -= a * (p[2] - r) / alpharadbias } } } function contest(b, g, r) { var bestd = ~(1 << 31); var bestbiasd = bestd; var bestpos = -1; var bestbiaspos = bestpos; var i, n, dist, biasdist, betafreq; for (i = 0; i < netsize; i++) { n = network[i]; dist = Math.abs(n[0] - b) + Math.abs(n[1] - g) + Math.abs(n[2] - r); if (dist < bestd) { bestd = dist; bestpos = i } biasdist = dist - (bias[i] >> intbiasshift - netbiasshift); if (biasdist < bestbiasd) { bestbiasd = biasdist; bestbiaspos = i } betafreq = freq[i] >> betashift; freq[i] -= betafreq; bias[i] += betafreq << gammashift } freq[bestpos] += beta; bias[bestpos] -= betagamma; return bestbiaspos } function inxbuild() { var i, j, p, q, smallpos, smallval, previouscol = 0, startpos = 0; for (i = 0; i < netsize; i++) { p = network[i]; smallpos = i; smallval = p[1]; for (j = i + 1; j < netsize; j++) { q = network[j]; if (q[1] < smallval) { smallpos = j; smallval = q[1] } } q = network[smallpos]; if (i != smallpos) { j = q[0]; q[0] = p[0]; p[0] = j; j = q[1]; q[1] = p[1]; p[1] = j; j = q[2]; q[2] = p[2]; p[2] = j; j = q[3]; q[3] = p[3]; p[3] = j } if (smallval != previouscol) { netindex[previouscol] = startpos + i >> 1; for (j = previouscol + 1; j < smallval; j++)netindex[j] = i; previouscol = smallval; startpos = i } } netindex[previouscol] = startpos + maxnetpos >> 1; for (j = previouscol + 1; j < 256; j++)netindex[j] = maxnetpos } function inxsearch(b, g, r) { var a, p, dist; var bestd = 1e3; var best = -1; var i = netindex[g]; var j = i - 1; while (i < netsize || j >= 0) { if (i < netsize) { p = network[i]; dist = p[1] - g; if (dist >= bestd) i = netsize; else { i++; if (dist < 0) dist = -dist; a = p[0] - b; if (a < 0) a = -a; dist += a; if (dist < bestd) { a = p[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; best = p[3] } } } } if (j >= 0) { p = network[j]; dist = g - p[1]; if (dist >= bestd) j = -1; else { j--; if (dist < 0) dist = -dist; a = p[0] - b; if (a < 0) a = -a; dist += a; if (dist < bestd) { a = p[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; best = p[3] } } } } } return best } function learn() { var i; var lengthcount = pixels.length; var alphadec = 30 + (samplefac - 1) / 3; var samplepixels = lengthcount / (3 * samplefac); var delta = ~~(samplepixels / ncycles); var alpha = initalpha; var radius = initradius; var rad = radius >> radiusbiasshift; if (rad <= 1) rad = 0; for (i = 0; i < rad; i++)radpower[i] = alpha * ((rad * rad - i * i) * radbias / (rad * rad)); var step; if (lengthcount < minpicturebytes) { samplefac = 1; step = 3 } else if (lengthcount % prime1 !== 0) { step = 3 * prime1 } else if (lengthcount % prime2 !== 0) { step = 3 * prime2 } else if (lengthcount % prime3 !== 0) { step = 3 * prime3 } else { step = 3 * prime4 } var b, g, r, j; var pix = 0; i = 0; while (i < samplepixels) { b = (pixels[pix] & 255) << netbiasshift; g = (pixels[pix + 1] & 255) << netbiasshift; r = (pixels[pix + 2] & 255) << netbiasshift; j = contest(b, g, r); altersingle(alpha, j, b, g, r); if (rad !== 0) alterneigh(rad, j, b, g, r); pix += step; if (pix >= lengthcount) pix -= lengthcount; i++; if (delta === 0) delta = 1; if (i % delta === 0) { alpha -= alpha / alphadec; radius -= radius / radiusdec; rad = radius >> radiusbiasshift; if (rad <= 1) rad = 0; for (j = 0; j < rad; j++)radpower[j] = alpha * ((rad * rad - j * j) * radbias / (rad * rad)) } } } function buildColormap() { init(); learn(); unbiasnet(); inxbuild() } this.buildColormap = buildColormap; function getColormap() { var map = []; var index = []; for (var i = 0; i < netsize; i++)index[network[i][3]] = i; var k = 0; for (var l = 0; l < netsize; l++) { var j = index[l]; map[k++] = network[j][0]; map[k++] = network[j][1]; map[k++] = network[j][2] } return map } this.getColormap = getColormap; this.lookupRGB = inxsearch } module.exports = NeuQuant }, {}], 4: [function (require, module, exports) { var GIFEncoder, renderFrame; GIFEncoder = require("./GIFEncoder.js"); renderFrame = function (frame) { var encoder, page, stream, transfer; encoder = new GIFEncoder(frame.width, frame.height); if (frame.index === 0) { encoder.writeHeader() } else { encoder.firstFrame = false } encoder.setTransparent(frame.transparent); encoder.setRepeat(frame.repeat); encoder.setDelay(frame.delay); encoder.setQuality(frame.quality); encoder.setDither(frame.dither); encoder.setGlobalPalette(frame.globalPalette); encoder.addFrame(frame.data); if (frame.last) { encoder.finish() } if (frame.globalPalette === true) { frame.globalPalette = encoder.getGlobalPalette() } stream = encoder.stream(); frame.data = stream.pages; frame.cursor = stream.cursor; frame.pageSize = stream.constructor.pageSize; if (frame.canTransfer) { transfer = function () { var i, len, ref, results; ref = frame.data; results = []; for (i = 0, len = ref.length; i < len; i++) { page = ref[i]; results.push(page.buffer) } return results }(); return self.postMessage(frame, transfer) } else { return self.postMessage(frame) } }; self.onmessage = function (event) { return renderFrame(event.data) } }, { "./GIFEncoder.js": 1 }] }, {}, [4]);

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