android 手電筒的實現

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android手機用閃光燈做成手電筒的應用非常多，可是有的不能用。

後來發現是除了把 camera device的 flashmode設定成torch外還要開啟預覽：

以下是代碼：

MainActivity.java

package com.android.flashlight;import android.app.Activity;import android.os.Bundle;import android.view.MotionEvent;import android.widget.ImageView;public class MainActivity extends Activity{private FlashlightSurface mSurface;private ImageView mImageView;private boolean isFlashlightOn = false;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);Contants.LogI("MainActivity: onCreate()");mSurface = (FlashlightSurface) findViewById(R.id.surfaceview);mImageView = (ImageView) findViewById(R.id.image);}@Overridepublic boolean onTouchEvent(MotionEvent event) {if(MotionEvent.ACTION_UP == event.getAction()){Contants.LogI("MainActivity: onTouchEvent() : ACTION_UP");if(isFlashlightOn){mSurface.setFlashlightSwitch(false);isFlashlightOn = false;mImageView.setImageResource(R.drawable.flashlight_off);}else{mSurface.setFlashlightSwitch(true);isFlashlightOn = true;mImageView.setImageResource(R.drawable.flashlight_on);}}return super.onTouchEvent(event);}}

FlashlightSurface.java

package com.android.flashlight;import android.content.Context;import android.graphics.PixelFormat;import android.hardware.Camera;import android.util.AttributeSet;import android.view.SurfaceHolder;import android.view.SurfaceView;public class FlashlightSurface extends SurfaceView implements SurfaceHolder.Callback{private SurfaceHolder mHolder;private Camera mCameraDevices;private Camera.Parameters mParameters;public FlashlightSurface(Context context, AttributeSet attrs) {super(context, attrs);Contants.LogI("FlashlightSurface");mHolder = this.getHolder();mHolder.addCallback(this);mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {Contants.LogI("surfaceChanged");mParameters = mCameraDevices.getParameters();if(mParameters != null)mParameters.setPictureFormat(PixelFormat.JPEG);mParameters.setPreviewSize(320, 480);mParameters.setPictureSize(320, 480);mCameraDevices.setParameters(mParameters);mCameraDevices.startPreview();}@Overridepublic void surfaceCreated(SurfaceHolder holder) {Contants.LogI("surfaceCreated");try {mCameraDevices = Camera.open();mCameraDevices.setPreviewDisplay(mHolder);} catch (Exception e) {if(mCameraDevices != null)mCameraDevices.release();mCameraDevices = null;}}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {Contants.LogI("surfaceDestroyed");if(mCameraDevices == null) return;mCameraDevices.stopPreview();mCameraDevices.release();mCameraDevices = null;}/** * 設定手電筒的開關狀態 * @param on ： true則開啟，false則關閉 */public void setFlashlightSwitch(boolean on){if(mCameraDevices == null) return;if(mParameters == null){mParameters = mCameraDevices.getParameters();}if(on){mParameters.setFlashMode(Contants.FLASH_MODE_TORCH);}else{mParameters.setFlashMode(Contants.FLASH_MODE_OFF);}Contants.LogI("setFlashlightSwitch-----------------" + on);mCameraDevices.setParameters(mParameters);}}

布局檔案main.xml

<?xml version="1.0" encoding="utf-8"?>   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="fill_parent"      android:layout_height="fill_parent" >    <com.android.flashlight.FlashlightSurface        android:id="@+id/surfaceview"        android:layout_width="fill_parent"      android:layout_height="fill_parent"        ></com.android.flashlight.FlashlightSurface>    <ImageView         android:id="@+id/image"        android:layout_width="fill_parent"      android:layout_height="fill_parent"    android:src="@drawable/flashlight_off"    android:background="#FFFFFFFF"        />    </RelativeLayout>

顯然這裡開啟了一個預覽，可是被圖片蓋上了，看不見而已。不然閃光燈不亮。

這裡有個Demo：http://download.csdn.net/detail/liu_zhen_wei/4801779

包含widget表單小組件的使用方法和手電筒的功能實現，安裝後，加入表單小組件（手電筒）到案頭，然後點擊小組件後，開啟手電筒的介面

點擊介面，實現 開啟/關閉 手電筒。

android 手電筒的實現