是否可以通过网站控制手机上的摄像头灯？通过 Chrome 或 Firefox 说。我知道可以使用 Android 或 iOS 应用程序，那里有许多手电筒应用程序。而且我知道可以通过 getUserMedia 系列功能控制摄像机。如果没有，有谁知道什么时候可以使用？
【问题讨论】：
标签： javascript google-chrome mobile getusermedia
这是一个用于网站的小“火炬应用”：
编辑1：我还发了jsfiddle
//Test browser support
const SUPPORTS_MEDIA_DEVICES = 'mediaDevices' in navigator;
if (SUPPORTS_MEDIA_DEVICES) {
//Get the environment camera (usually the second one)
navigator.mediaDevices.enumerateDevices().then(devices => {
const cameras = devices.filter((device) => device.kind === 'videoinput');
if (cameras.length === 0) {
throw 'No camera found on this device.';
}
const camera = cameras[cameras.length - 1];
// Create stream and get video track
navigator.mediaDevices.getUserMedia({
video: {
deviceId: camera.deviceId,
facingMode: ['user', 'environment'],
height: {ideal: 1080},
width: {ideal: 1920}
}
}).then(stream => {
const track = stream.getVideoTracks()[0];
//Create image capture object and get camera capabilities
const imageCapture = new ImageCapture(track)
const photoCapabilities = imageCapture.getPhotoCapabilities().then(() => {
//todo: check if camera has a torch
//let there be light!
const btn = document.querySelector('.switch');
btn.addEventListener('click', function(){
track.applyConstraints({
advanced: [{torch: true}]
});
});
});
});
});
//The light will be on as long the track exists
}<button class="switch">On / Off</button>代码深受repository、webseries 和blog-post 的启发
编辑 2： 这仅适用于 Chrome（也许还有 Opera）。它不适用于 iOS 上的 Chrome，because Chrome cannot access the camera。 我现在无法在 android 上测试它。我创建了一个带有输出的新 jsfiddle。如果你有一部安卓手机，但它不适合你，它可能会告诉你原因： https://jsfiddle.net/jpa1vwed/
随意调试、评论和编辑。
【讨论】：
ImageCapture 目前只在 Chrome 和 Opera 中支持（我没有安装 Opera，所以我无法测试它）。它不再适用于 Iphone 上的 chrome，我目前正在研究它。
<input type="file" accept="image/*" capture="environment">“环境”用于背面，“用户”用于正面。
您可以通过从 VideoStreamTrack 创建 ImageCapture 并将选项 "fillLightMode" 设置为 " 来使用 MediaStream Image Capture API闪光” 或 “火炬”。示例：
<video autoplay="true"></video>
<img />
<button onclick="takePhoto()">Take Photo</button>
<script type="text/javascript">
var imageCapture = null;
var deviceConfig = {
video: {
width: 480,
height: 640,
facingMode: "environment", /* may not work, see https://bugs.chromium.org/p/chromium/issues/detail?id=290161 */
deviceId: null
}
};
var imageCaptureConfig = {
fillLightMode: "torch", /* or "flash" */
focusMode: "continuous"
};
// get the available video input devices and choose the one that represents the backside camera
navigator.mediaDevices.enumerateDevices()
/* replacement for not working "facingMode: 'environment'": use filter to get the backside camera with the flash light */
.then(mediaDeviceInfos => mediaDeviceInfos.filter(mediaDeviceInfo => ((mediaDeviceInfo.kind === 'videoinput')/* && mediaDeviceInfo.label.includes("back")*/)))
.then(mediaDeviceInfos => {
console.log("mediaDeviceInfos[0].label: " + mediaDeviceInfos[0].label);
// get the device ID of the backside camera and use it for media stream initialization
deviceConfig.video.deviceId = mediaDeviceInfos[0].deviceId;
navigator.mediaDevices.getUserMedia(deviceConfig)
.then(_gotMedia)
.catch(err => console.error('getUserMedia() failed: ', err));
});
function takePhoto () {
imageCapture.takePhoto()
.then(blob => {
console.log('Photo taken: ' + blob.type + ', ' + blob.size + 'B');
// get URL for blob data and use as source for the image element
const image = document.querySelector('img');
image.src = URL.createObjectURL(blob);
})
.catch(err => console.error('takePhoto() failed: ', err));
}
function _gotMedia (mediastream) {
// use the media stream as source for the video element
const video = document.querySelector('video');
video.srcObject = mediastream;
// create an ImageCapture from the first video track
const track = mediastream.getVideoTracks()[0];
imageCapture = new ImageCapture(track);
// set the image capture options (e.g. flash light, autofocus, ...)
imageCapture.setOptions(imageCaptureConfig)
.catch(err => console.error('setOptions(' + JSON.stringify(imageCaptureConfig) + ') failed: ', err));
}
</script>
注意：
另见：
【讨论】：
ImageCapture 支持比底层轨道更多的操作，例如在没有再次请求许可的情况下关闭和打开手电筒。也许根本不可能支持所有设备，所以他们不得不修剪它。
我修复了 Daniel 的答案，现在按钮可以在 Android 手机上正常工作。 IOS仍然不受支持。
https://jsfiddle.net/nzw5tv1q/
//have a console on mobile
const consoleOutput = document.getElementById("console");
const log = function (msg) {
consoleOutput.innerText = `${consoleOutput.innerText}\n${msg}`;
console.log(msg);
}
//Test browser support
const SUPPORTS_MEDIA_DEVICES = 'mediaDevices' in navigator;
if (SUPPORTS_MEDIA_DEVICES) {
//Get the environment camera (usually the second one)
navigator.mediaDevices.enumerateDevices().then(devices => {
const cameras = devices.filter((device) => device.kind === 'videoinput');
if (cameras.length === 0) {
log('No camera found on this device.');
}
// Create stream and get video track
navigator.mediaDevices.getUserMedia({
video: {
facingMode: 'environment',
}
}).then(stream => {
const track = stream.getVideoTracks()[0];
//Create image capture object and get camera capabilities
const imageCapture = new ImageCapture(track)
imageCapture.getPhotoCapabilities().then(capabilities => {
//let there be light!
const btn = document.querySelector('.switch');
const torchSupported = !!capabilities.torch || (
'fillLightMode' in capabilities &&
capabilities.fillLightMode.length != 0 &&
capabilities.fillLightMode != 'none'
);
if (torchSupported) {
let torch = false;
btn.addEventListener('click', function (e) {
try {
track.applyConstraints({
advanced: [{
torch: (torch = !torch)
}]
});
} catch (err) {
log(err);
}
});
} else {
log("No torch found");
}
}).catch(log);
}).catch(log);
}).catch(log);
//The light will be on as long the track exists
}<button class="switch">On / Off</button>
<h2>
Console output
</h2>
<div id="console">
</div>【讨论】：