Screen Capture API を使用すると、ウェブ プラットフォームでタブ、ウィンドウ、画面を共有できます。getDisplayMedia()
メソッドを使用すると、ユーザーはメディア ストリームとしてキャプチャする画面を選択できます。このストリームは、MediaRecorder API を使用して録画したり、ネットワークを介して他のユーザーと共有したりできます。録画は、showOpenFilePicker()
メソッドを使用してローカル ファイルに保存できます。
以下の例は、ユーザーの画面を WebM 形式で録画し、同じページでローカル プレビューを行い、録画をユーザーのファイル システムに保存する方法を示しています。
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();
});
ブラウザ サポート
MediaDevices.getDisplayMedia()
MediaRecorder API
File System Access API の showSaveFilePicker()
関連情報
- W3C スクリーン キャプチャ仕様
- W3C MediaStream Recording Specification(W3C MediaStream 録画仕様)
- WICG ファイル システム アクセス仕様
デモ
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.");
});