Come registrare lo schermo dell'utente

François Beaufort
François Beaufort
GitHub

La condivisione di schede, finestre e schermate è possibile sulla piattaforma web con l'API Screen Capture. Il metodo getDisplayMedia() consente all'utente di selezionare una schermata da acquisire come stream multimediale. Questo stream può essere registrato con l'API MediaRecorder o condiviso con altri sulla rete. La registrazione può essere salvata su un file locale tramite il metodo showOpenFilePicker().

L'esempio seguente mostra come registrare lo schermo dell'utente in formato WebM, visualizzare l'anteprima localmente sulla stessa pagina e salvare la registrazione nel file system dell'utente.

let stream;
let recorder;

shareScreenButton.addEventListener("click", async () => {
  // Prompt the user to share their screen.
  stream = await navigator.mediaDevices.getDisplayMedia();
  recorder = new MediaRecorder(stream);
  // Preview the screen locally.
  video.srcObject = stream;
});

stopShareScreenButton.addEventListener("click", () => {
  // Stop the stream.
  stream.getTracks().forEach(track => track.stop());
  video.srcObject = null;
});

startRecordButton.addEventListener("click", async () => {
  // For the sake of more legible code, this sample only uses the
  // `showSaveFilePicker()` method. In production, you need to
  // cater for browsers that don't support this method, as
  // outlined in https://web.dev/patterns/files/save-a-file/.

  // Prompt the user to choose where to save the recording file.
  const suggestedName = "screen-recording.webm";
  const handle = await window.showSaveFilePicker({ suggestedName });
  const writable = await handle.createWritable();

  // Start recording.
  recorder.start();
  recorder.addEventListener("dataavailable", async (event) => {
    // Write chunks to the file.
    await writable.write(event.data);
    if (recorder.state === "inactive") {
      // Close the file when the recording stops.
      await writable.close();
    }
  });
});

stopRecordButton.addEventListener("click", () => {
  // Stop the recording.
  recorder.stop();
});

Supporto del browser

MediaDevices.getDisplayMedia()

Supporto dei browser

  • 72
  • 79
  • 66
  • 13

Fonte

API MediaRecorder

Supporto dei browser

  • 47
  • 79
  • 25
  • 14.1

Fonte

showSaveFileChooseer() dell'API File System Access

Supporto dei browser

  • 86
  • 86
  • x
  • x

Fonte

Per approfondire

Demo

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link
      rel="icon"
      href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🖥️</text></svg>"
    />
    <title>How to record the user's screen</title>
  </head>
  <body>
    <h1>How to record the user's screen</h1>
    <button id="startShareScreenButton">Start sharing screen</button>
    <button id="stopShareScreenButton" disabled>Stop sharing screen</button>
    <button id="startRecordButton" disabled>Start recording</button>
    <button id="stopRecordButton" disabled>Stop recording</button>
    <video autoplay muted playsinline></video>
    <pre id="logs"></pre>
  </body>
</html>

CSS


        :root {
  color-scheme: dark light;
}
html {
  box-sizing: border-box;
}
*,
*:before,
*:after {
  box-sizing: inherit;
}
body {
  margin: 1rem;
  font-family: system-ui, sans-serif;
}
button {
  display: block;
  margin-bottom: 4px;
}
video {
  display: block;
  margin-top: 10px;
  max-width: 100%;
  background: black;
  max-height: 480px;
}
pre {
  color: red;
  white-space: pre-line;
}

JS


        const video = document.querySelector('video');
const startShareScreenButton = document.querySelector('#startShareScreenButton');
const stopShareScreenButton = document.querySelector('#stopShareScreenButton');
const startRecordButton = document.querySelector('#startRecordButton');
const stopRecordButton = document.querySelector('#stopRecordButton');

let stream;
let recorder;

startShareScreenButton.addEventListener("click", async () => {
  // Prompt the user to share their screen.
  stream = await navigator.mediaDevices.getDisplayMedia();
  recorder = new MediaRecorder(stream);
  // Preview the screen locally.
  video.srcObject = stream;

  startRecordButton.disabled = false;
  stopShareScreenButton.disabled = false;
  log("Your screen is being shared.");
});

stopShareScreenButton.addEventListener("click", () => {
  // Stop the stream.
  stream.getTracks().forEach(track => track.stop());
  video.srcObject = null;

  stopShareScreenButton.disabled = true;
  startRecordButton.disabled = true;
  stopRecordButton.disabled = true;
  log("Your screen is not shared anymore.");
});

startRecordButton.addEventListener("click", async () => {
  // For the sake of more legible code, this sample only uses the
  // `showSaveFilePicker()` method. In production, you need to
  // cater for browsers that don't support this method, as
  // outlined in https://web.dev/patterns/files/save-a-file/.

  // Prompt the user to choose where to save the recording file.
  const suggestedName = "screen-recording.webm";
  const handle = await window.showSaveFilePicker({ suggestedName });
  const writable = await handle.createWritable();

  // Start recording.
  recorder.start();
  recorder.addEventListener("dataavailable", async (event) => {
    // Write chunks to the file.
    await writable.write(event.data);
    if (recorder.state === "inactive") {
      // Close the file when the recording stops.
      await writable.close();
    }
  });

  stopRecordButton.disabled = false;
  log("Your screen is being recorded locally.");
});

stopRecordButton.addEventListener("click", () => {
  // Stop the recording.
  recorder.stop();

  stopRecordButton.disabled = true;
  log("Your screen has been successfully recorded locally.");
});