如何在Android中以编程方式打开前闪光灯? [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闪光灯(不使用相机预览).我用Google搜索了它，但是找到的帮助却把我引到了此页面

有人有任何链接或示例代码吗?

解决方案

对于此问题，您应该:

1. 检查手电筒是否 有空吗?

2. 如果是，则关闭/打开

3. 如果没有，那么您可以根据自己的应用执行任何操作 需求.

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);

如果有闪存可用，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Google上搜索了有关android.permission.FLASHLIGHT的信息. Android清单的许可看起来很有希望:

 <!-- 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" />

然后使用相机并设置 FLASH_MODE_TORCH .

例如

代码段可打开相机手电筒.

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

代码段可关闭相机LED灯.

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

我刚找到一个使用此权限的项目.检查快速设置的src代码.此处 http://code.google.com/p/quick-settings/(注意:此链接现在已断开)

对于Flashlight，直接看 Galaxy Nexus上的LED手电可由什么API控制? 这似乎是可以在许多手机上使用的解决方案.

更新5 主要更新

我找到了一个替代链接(针对上面的断开链接): http://code.google.com/p/torch/source/browse/

更新2

显示如何在Motorola 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/关闭相机指示灯的小部件)

如果您要开发一个打开/关闭相机LED的小部件，则必须参考我的回答我可以更改Android设备的LED强度吗?全文.请注意，只有植根的HTC设备才支持此功能.

**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或什至没有FLASH_MODE_TORCH的设备，则手电筒无法打开等.

三星通常会产生很多问题.

您可以在下面的列表中参考问题:

在Android中使用相机手电

this page

Does anyone have any links or sample code?

解决方案

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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