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android Camera 如何判断当前使用的摄像头是前置还是后置

android Camera 如何判断当前使用的摄像头是前置还是后

标签:现在android 平台的智能手机一般都标配有两颗摄像头。在Camera 中都存在摄像头切换的功能。

并且有一些功能前后置摄像头上会有所不同。譬如人脸检测,人脸识别,自动对焦,闪光灯等功能,

如果前置摄像头的像素太低,不支持该功能的话,就需要在前置摄像头上关掉该feature.

那么是如何判断并切换前后置摄像头的呢?

我们先来看下CameraInfo 这个类,

1 /**

2 * Information about a camera

3 */

4 public static class CameraInfo {

5 /**

6 * The facing of the camera is opposite to that of the screen.

7 */

8 public static final int CAMERA_FACING_BACK =

0;

9

10 /**

11 * The facing of the camera is the same as that of the screen.

12 */

13 public static final int CAMERA_FACING_FRONT = 1;

14

15 /**

16 * The direction that the camera faces. It should be

17 * CAMERA_FACING_BACK or

CAMERA_FACING_FRONT.

18 */

19 public int facing;

20

21 /**

22 * <p>The orientation of the camera image. The value is the angle that the

23 * camera image needs to be rotated clockwise so it shows correctly on

24 * the display in its natural orientation. It should be

0, 90, 180, or 270.</p>

25 *

26 * <p>For example, suppose a device has a naturally tall screen. The

27 * back-facing camera sensor is mounted in landscape. You are looking at

28 * the screen. If the top side of the camera sensor is aligned with the

29 * right edge of the screen in natural orientation, the value should be

30 * 90. If the top side of a front-facing camera sensor is aligned with

31 * the right of the screen, the value should be 270.</p>

32 *

33 * @see #setDisplayOrientation(int)

34 * @see Parameters#setRotation(int)

35 * @see Parameters#setPreviewSize(int, int)

36 * @see Parameters#setPictureSize(int, int)

37 * @see Parameters#setJpegThumbnailSize(int, int)

38 */

39 public int orientation;

40 };

见名知义,它就是一个Camera 信息类。它是通过与屏幕的方向是否一致来定义前后置摄像头的。

与屏幕方向相反即为BACK_FACING_CAMERA

与屏幕方向一致即为FRONT_FACING_CAMERA

那么在代码中我们是如何获取当前使用的CamerInfo 呢

1 Camera.CameraInfo info = new Camera.CameraInfo();

2 Camera.getCameraInfo(cameraId, info);

当然,使用该代码的前提是要import

android.hardware.Camera.CameraInfo;

判断使用是前置还是后置摄像头,可以通过if (info.facing == CameraInfo.CAMERA_FACING_FRONT) 来判断。

当Camera 的实例已经创建了的情况下,则需要通过如下方式来判断。

1 CameraInfo info =

CameraHolder.instance().getCameraInfo()[mCameraId];

2 if (info.facing ==

CameraInfo.CAMERA_FACING_FRONT) {

3 //stopFaceDetection();

4 }

也可以通过if(mCameraId ==

CameraInfo.CAMERA_FACING_FRONT) 来判断。

其中mCameraId 是当前使用的CameraId, 一般前置为1,后置为0。android Camera 如何判断当前使用的摄像头是

前置还是后置标签:

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