實現Android照相機的拍照功能(Camera.takePicture)

前文描述了"Android的照相機預覽功能(Camera Preview)", 本文進一步新增照相機的拍照功能.



修改AndroidManifest.xml
- 授予使用照相機權限, "android.permission.CAMERA"
- 並設定屏幕在一定的方向, android:screenOrientation="portrait"

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.AndroidTakePicture"
     android:versionCode="1"
     android:versionName="1.0">
   <application android:icon="@drawable/icon" android:label="@string/app_name">
       <activity android:name=".AndroidTakePicture"
                 android:label="@string/app_name"
                 android:screenOrientation="portrait"
                 >
           <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>
       </activity>

   </application>
   <uses-sdk android:minSdkVersion="7" />
<uses-permission android:name="android.permission.CAMERA"></uses-permission>
</manifest>

修改佈局(main.xml), 再多添加一個Button.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   >
<TextView 
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/hello"
   />
<Button
   android:id="@+id/takebutton"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="- Take Picture -"
   />
<SurfaceView
android:id="@+id/previewsurface"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

主要代碼, AndroidTakePicture.java
主要是實踐ShutterCallback, 和PictureCallback, 調用takePicture()方法.
本應用程序運行的結果是一個圖片的Bitmap位圖, bitmapPicture.

package com.AndroidTakePicture;

import java.io.IOException;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

public class AndroidTakePicture extends Activity implements SurfaceHolder.Callback{

Camera myCamera;
SurfaceView previewSurfaceView;
SurfaceHolder previewSurfaceHolder;
boolean previewing = false;

   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
      
       getWindow().setFormat(PixelFormat.UNKNOWN);     
       previewSurfaceView = (SurfaceView)findViewById(R.id.previewsurface);
       previewSurfaceHolder = previewSurfaceView.getHolder();
       previewSurfaceHolder.addCallback(this);
       previewSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
      
       Button buttonTakePicture = (Button)findViewById(R.id.takebutton);
       buttonTakePicture.setOnClickListener(new Button.OnClickListener(){

  @Override
  public void onClick(View arg0) {
   // TODO Auto-generated method stub
   myCamera.takePicture(shutterCallback, rawPictureCallback, jpegPictureCallback);
  }});
   }
  
   ShutterCallback shutterCallback = new ShutterCallback(){

 @Override
 public void onShutter() {
  // TODO Auto-generated method stub
 
 }};

PictureCallback rawPictureCallback = new PictureCallback(){

 @Override
 public void onPictureTaken(byte[] arg0, Camera arg1) {
  // TODO Auto-generated method stub
 
 }};

PictureCallback jpegPictureCallback = new PictureCallback(){

  @Override
  public void onPictureTaken(byte[] arg0, Camera arg1) {
   // TODO Auto-generated method stub
   Bitmap bitmapPicture = BitmapFactory.decodeByteArray(arg0, 0, arg0.length);    

  }};

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
 // TODO Auto-generated method stub

 if(previewing){
  myCamera.stopPreview();
  previewing = false;
 }


 try {
  myCamera.setPreviewDisplay(arg0);
  myCamera.startPreview();
  previewing = true;
 } catch (IOException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }


}

@Override
public void surfaceCreated(SurfaceHolder arg0) {
 // TODO Auto-generated method stub
 myCamera = Camera.open();
}

@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
 // TODO Auto-generated method stub
 myCamera.stopPreview();
 myCamera.release();
 myCamera = null;
 previewing = false;
}
}

拍照後, 預覽顯示便會停止. 如果要不斷預覽的話, 需重新調用startPreview()方法.


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