如何在 Android 中以编程方式打开前置闪光灯? [英] How to turn on front flash light programmatically in Android?

问题描述

我想在 Android 中以编程方式打开前置闪光灯(不带相机预览).我用谷歌搜索了它，但我发现的帮助让我参考了this页面

有人有任何链接或示例代码吗?

解决方案

对于 2021 年，有了 CameraX，现在变得非常简单:https://stackoverflow.com/a/66585201/294884

---

对于这个问题，你应该:

1. 检查手电筒是否可用与否?

2. 如果是，则关闭/打开

3. 如果没有，那么你可以根据你的应用做任何事情需要.

对于检查设备中闪存的可用性:

您可以使用以下内容:

 context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);

如果 flash 可用则返回 true，否则返回 false.

请参阅:
http://developer.android.com/reference/android/content/pm/PackageManager.html 了解更多信息.

用于打开/关闭手电筒:

我在谷歌上搜索了关于 android.permission.FLASHLIGHT 的信息.Android manifests 的许可看起来很有希望:

 <permission android:name="android.permission.FLASHLIGHT";android:permissionGroup="android.permission-group.HARDWARE_CONTROLS";android:protectionLevel=正常"android:label="@string/permlab_flashlight";android:description="@string/permdesc_flashlight";/>

然后使用 Camera 并设置 Camera.Parameters.这里使用的主要参数是FLASH_MODE_TORCH.>

例如

用于打开相机手电筒的代码片段.

Camera cam = Camera.open();参数 p = cam.getParameters();p.setFlashMode(Parameters.FLASH_MODE_TORCH);cam.setParameters(p);cam.startPreview();

关闭摄像头 LED 灯的代码片段.

 cam.stopPreview();cam.release();

我刚刚发现了一个使用此权限的项目.检查快速设置的 src 代码.这里 http://code.google.com/p/quick-settings/(注意:此链接现已失效)

对于手电筒直接查看http://code.google.com/p/quick-settings/source/browse/trunk/quick-settings/#quick-settings/src/com/bwx/bquick/flashlight(注意:此链接现已失效)

更新 6您也可以尝试添加一个 SurfaceView，如本答案 可以通过什么 API 控制 Galaxy Nexus 上的 LED 手电筒?这似乎是适用于许多手机的解决方案.

更新 5 重大更新

我找到了一个替代链接(对于上面断开的链接):http://www.java2s.com/Open-Source/Android/Tools/quick-settings/com.bwx.bequick.flashlight.htm 您现在可以使用这个链接.[更新:14/9/2012 此链接现已失效]

更新 1

另一个开源代码:http://code.google.com/p/torch/source/browse/

更新 2

显示如何在摩托罗拉 Droid 上启用 LED 的示例:http://code.google.com/p/droidled/

另一个开源代码:

http://code.google.com/p/covedesigndev/
http://code.google.com/p/search-light/

更新 3(用于打开/关闭摄像头 LED 的小工具)

如果您想开发一个可以打开/关闭摄像头 LED 的小部件，那么您必须参考我的回答 用于在 android 中打开/关闭相机手电筒的小部件.

更新 4

如果您想设置从摄像头 LED 发出的光强度，您可以参考 我可以更改 Android 设备的 LED 强度吗? 完整帖子.请注意，只有 HTC 设备支持此功能.

** 问题:**

打开/关闭手电筒时也有一些问题.例如.对于没有 FLASH_MODE_TORCH 的设备，或者即使有，手电筒也不会打开等.

通常三星会产生很多问题.

您可以参考以下列表中的问题:

在 Android 中使用相机手电筒

在三星 Galaxy Ace 2.2.1 & 中打开/关闭相机 LED/闪光灯Galaxy Tab

I want to turn on front flash light (not with camera preview) programmatically in Android. I googled for it but the help i found referred me to this page

Does anyone have any links or sample code?

解决方案

For 2021, with CameraX, it is now dead easy: https://stackoverflow.com/a/66585201/294884

---

For this problem you should:

1. Check whether the flashlight is available or not?

2. If so then Turn Off/On

3. If not then you can do whatever, according to your app needs.

For Checking availability of flash in the device:

You can use the following:

 context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);

which will return true if a flash is available, false if not.

See:
http://developer.android.com/reference/android/content/pm/PackageManager.html for more information.

For turning on/off flashlight:

I googled out and got this about android.permission.FLASHLIGHT. Android manifests' permission looks promising:

 <!-- Allows access to the flashlight -->
 <permission android:name="android.permission.FLASHLIGHT"
             android:permissionGroup="android.permission-group.HARDWARE_CONTROLS"
             android:protectionLevel="normal"
             android:label="@string/permlab_flashlight"
             android:description="@string/permdesc_flashlight" />

Then make use of Camera and set Camera.Parameters. The main parameter used here is FLASH_MODE_TORCH.

eg.

Code Snippet to turn on camera flashlight.

Camera cam = Camera.open();     
Parameters p = cam.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
cam.setParameters(p);
cam.startPreview();

Code snippet to turn off camera led light.

  cam.stopPreview();
  cam.release();

I just found a project that uses this permission. Check quick-settings' src code. here http://code.google.com/p/quick-settings/ (Note: This link is now broken)

For Flashlight directly look http://code.google.com/p/quick-settings/source/browse/trunk/quick-settings/#quick-settings/src/com/bwx/bequick/flashlight (Note: This link is now broken)

Update6 You could also try to add a SurfaceView as described in this answer LED flashlight on Galaxy Nexus controllable by what API? This seems to be a solution that works on many phones.

Update 5 Major Update

I have found an alternative Link (for the broken links above): http://www.java2s.com/Open-Source/Android/Tools/quick-settings/com.bwx.bequick.flashlight.htm You can now use this link. [Update: 14/9/2012 This link is now broken]

Update 1

Another OpenSource Code : http://code.google.com/p/torch/source/browse/

Update 2

Example showing how to enable the LED on a Motorola Droid: http://code.google.com/p/droidled/

Another Open Source Code :

http://code.google.com/p/covedesigndev/
http://code.google.com/p/search-light/

Update 3 (Widget for turning on/off camera led)

If you want to develop a widget that turns on/off your camera led, then you must refer my answer Widget for turning on/off camera flashlight in android.

Update 4

If you want to set the intensity of light emerging from camera LED you can refer Can I change the LED intensity of an Android device? full post. Note that only rooted HTC devices support this feature.

** Issues:**

There are also some problems while turning On/Off flashlight. eg. for the devices not having FLASH_MODE_TORCH or even if it has, then flashlight does not turn ON etc.

Typically Samsung creates a lot of problems.

You can refer to problems in the given below list:

Use camera flashlight in Android

Turn ON/OFF Camera LED/flash light in Samsung Galaxy Ace 2.2.1 & Galaxy Tab

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