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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

MediaTrackConstraints dictionary's aspectRatio 特性为 ConstrainDouble describing the requested or mandatory constraints placed upon the value of the aspectRatio constrainable property.

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

句法

var constraintsObject = { aspectRatio: constraint };
constraintsObject.aspectRatio = constraint;
					

值

A ConstrainDouble describing the acceptable or required value(s) for a video track's aspect ratio. The value is the width divided by the height and is rounded to ten decimal places. For example, the standard high-definition video aspect ratio of 16:9 can be computed as 1920/1080, or 1.7777777778.

If this value is a number, the user agent will attempt to obtain media whose aspect ratio is as close as possible to this number given the capabilities of the hardware and the other constraints specified. Otherwise, the value of this ConstrainDouble will guide the user agent in its efforts to provide an exact match to the required aspect ratio (if exact is specified or both min and max are provided and have the same value) or to a best-possible value.

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 'aspectRatio' 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
aspectRatio	Chrome 59	Edge ≤79	Firefox 不支持 No	IE 不支持 No	Opera Yes	Safari ?	WebView Android 59	Chrome Android 59	Firefox Android 29	Opera Android ?	Safari iOS ?	Samsung Internet Android 7.0

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
• MediaDevices.getSupportedConstraints()
• MediaTrackSupportedConstraints
• MediaStreamTrack

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. Media Streams API
2. MediaTrackConstraints
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. logicalSurface
   14. noiseSuppression
   15. sampleRate
   16. sampleSize
   17. volume
   18. 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. MediaTrackSettings
   17. MediaTrackSupportedConstraints
   18. Navigator.mediaDevices
   19. NavigatorUserMedia
   20. NavigatorUserMediaError
   21. VideoStreamTrack
   22. navigator.mediaDevices.getUserMedia()