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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

MediaTrackSettings dictionary's facingMode 特性为 DOMString indicating the direction in which the camera producing the video track represented by the MediaStreamTrack is currently facing. This lets you determine what value was selected to comply with your specified constraints for this property's value as described in the MediaTrackConstraints.facingMode property you provided when calling either getUserMedia() or MediaStreamTrack.applyConstraints() .

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.facingMode as returned by a call to MediaDevices.getSupportedConstraints() . However, typically this is unnecessary since browsers will simply ignore any constraints they're unfamiliar with.

因为 RTP doesn't include this information, tracks associated with a WebRTC RTCPeerConnection will never include this property.

句法

var facingMode = MediaTrackSettings.facingMode;
					

值

A DOMString whose value is one of the strings in VideoFacingModeEnum .

VideoFacingModeEnum

The following strings are permitted values for the facing mode. These may represent separate cameras, or they may represent directions in which an adjustable camera can be pointed.

"user"

The video source is facing toward the user; this includes, for example, the front-facing camera on a smartphone.

"environment"

The video source is facing away from the user, thereby viewing their environment. This is the back camera on a smartphone.

"left"

The video source is facing toward the user but to their left, such as a camera aimed toward the user but over their left shoulder.

"right"

The video source is facing toward the user but to their right, such as a camera aimed toward the user but over their right shoulder.

范例

见 Example: Constraint exerciser in Capabilities, constraints, and settings 范例。

规范

规范	状态	注释
媒体捕获和流 The definition of 'facingMode' in that specification.	候选推荐	最初的规范。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
facingMode	Chrome Yes	Edge ≤79	Firefox 69	IE ?	Opera Yes	Safari ?	WebView Android Yes	Chrome Android Yes	Firefox Android No	Opera Android Yes	Safari iOS ?	Samsung Internet Android Yes

图例

完整支持

完整支持

不支持

不支持

兼容性未知 ?

兼容性未知

另请参阅

• Media Capture and Streams API
• Capabilities, constraints, and settings
• MediaTrackConstraints.facingMode
• MediaTrackSettings

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. Media Streams API
2. MediaTrackSettings
3. 特性

   1. aspectRatio
   2. autoGainControl
   3. channelCount
   4. cursor
   5. deviceId
   6. displaySurface
   7. echoCancellation
   8. facingMode
   9. frameRate
   10. groupId
   11. height
   12. latency
   13. noiseSuppression
   14. sampleRate
   15. sampleSize
   16. volume
   17. width
4. Related pages for Media Capture and Streams

   1. AudioStreamTrack
   2. BlobEvent
   3. CanvasCaptureMediaStream
   4. ConstrainBoolean
   5. ConstrainDOMString
   6. ConstrainDouble
   7. ConstrainLong
   8. DoubleRange
   9. HTMLCanvasElement.captureStream()
   10. LongRange
   11. MediaDevices
   12. MediaStream
   13. MediaStreamTrack
   14. MediaStreamTrackEvent
   15. MediaTrackCapabilities
   16. MediaTrackConstraints
   17. MediaTrackSupportedConstraints
   18. Navigator.mediaDevices
   19. NavigatorUserMedia
   20. NavigatorUserMediaError
   21. VideoStreamTrack
   22. navigator.mediaDevices.getUserMedia()