2015.7.2更新
由於很多人要代碼，我把代碼下載鏈接放在這里了。不過還是要說一下，surfaceTexture和OpenGL ES結合才能發揮出它最大的效果，我這種寫法只是我自己的想法，還有很多種解決方法，如果大家學習一下OpenGL ES，會發現更多有意思的東西。
SurfaceTexture是從Android3.0（API 11）加入的一個新類。這個類跟SurfaceView很像，可以從camera preview或者video decode里面獲取圖像流（image stream）。但是，和SurfaceView不同的是，SurfaceTexture在接收圖像流之后，不需要顯示出來。有做過Android camera開發的人都知道，比較頭疼的一個問題就是，從camera讀取到的預覽（preview）圖像流一定要輸出到一個可見的（Visible）SurfaceView上，然后通過Camera.PreviewCallback的public void onPreviewFrame(byte[] data, Camera camera)函數來獲得圖像幀數據的拷貝。這就存在一個問題，比如我希望隱藏攝像頭的預覽圖像或者對每一幀進行一些處理再顯示到手機顯示屏上，那么在Android3.0之前是沒有辦法做到的，或者說你需要用一些小技巧，比如用其他控件把SurfaceView給擋住，注意這個顯示原始camera圖像流的SurfaceView其實是依然存在的，也就是說被擋住的SurfaceView依然在接收從camera傳過來的圖像，而且一直按照一定幀率去刷新，這是消耗cpu的，而且如果一些參數設置的不恰當，后面隱藏的SurfaceView有可能會露出來，因此這些小技巧並不是好辦法。但是，有了SurfaceTexture之后，就好辦多了，因為SurfaceTexture不需要顯示到屏幕上，因此我們可以用SurfaceTexture接收來自camera的圖像流，然后從SurfaceTexture中取得圖像幀的拷貝進行處理，處理完畢后再送給另一個SurfaceView用於顯示即可。
在我的應用場景中，我需要從camera讀取圖像流，然后對其處理，最后將處理結果顯示到手機屏幕上。因此我寫了一個GameDisplay類用於處理以上所有事務，而在MainActivity中，只需要創建一個GameDisplay類的實例並且初始化即可。
1 package com.song.camgame; 2 3 import java.io.IOException; 4 import java.util.List; 5 import java.util.Timer; 6 import java.util.TimerTask; 7 8 import android.app.Activity; 9 import android.content.Context; 10 import android.graphics.Bitmap; 11 import android.graphics.Canvas; 12 import android.graphics.ImageFormat; 13 import android.graphics.Rect; 14 import android.graphics.SurfaceTexture; 15 import android.hardware.Camera; 16 import android.hardware.Camera.Size; 17 import android.util.Log; 18 import android.view.SurfaceHolder; 19 import android.view.SurfaceView; 20 21 public class GameDisplay extends SurfaceView implements SurfaceHolder.Callback, 22 Camera.PreviewCallback{ 23 public final static String TAG="GameDisplay"; 24 25 private static final int MAGIC_TEXTURE_ID = 10; 26 public static final int DEFAULT_WIDTH=800; 27 public static final int DEFAULT_HEIGHT=480; 28 public static final int BLUR = 0; 29 public static final int CLEAR = BLUR + 1; 30 //public static final int PAUSE = PLAY + 1; 31 //public static final int EXIT = PAUSE + 1; 32 public SurfaceHolder gHolder; 33 public SurfaceTexture gSurfaceTexture; 34 public Camera gCamera; 35 public byte gBuffer[]; 36 public int textureBuffer[]; 37 public ProcessThread gProcessThread; 38 private int bufferSize; 39 private Camera.Parameters parameters; 40 public int previewWidth, previewHeight; 41 public int screenWidth, screenHeight; 42 public Bitmap gBitmap; 43 private Rect gRect; 44 // timer 45 private Timer sampleTimer; 46 private TimerTask sampleTask; 47 48 public GameDisplay(Context context,int screenWidth,int screenHeight) { 49 super(context); 50 gHolder=this.getHolder(); 51 gHolder.addCallback(this); 52 gHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 53 gSurfaceTexture=new SurfaceTexture(MAGIC_TEXTURE_ID); 54 this.screenWidth=screenWidth; 55 this.screenHeight=screenHeight; 56 gRect=new Rect(0,0,screenWidth,screenHeight); 57 Log.v(TAG, "GameDisplay initialization completed"); 58 } 59 60 @Override 61 public void surfaceChanged(SurfaceHolder holder, int format, int width, 62 int height) { 63 Log.v(TAG, "GameDisplay surfaceChanged"); 64 parameters = gCamera.getParameters(); 65 List<Size> preSize = parameters.getSupportedPreviewSizes(); 66 previewWidth = preSize.get(0).width; 67 previewHeight = preSize.get(0).height; 68 for (int i = 1; i < preSize.size(); i++) { 69 double similarity = Math 70 .abs(((double) preSize.get(i).height / screenHeight) 71 - ((double) preSize.get(i).width / screenWidth)); 72 if (similarity < Math.abs(((double) previewHeight / screenHeight) 73 - ((double) previewWidth / screenWidth))) { 74 previewWidth = preSize.get(i).width; 75 previewHeight = preSize.get(i).height; 76 } 77 } 78 gBitmap= Bitmap.createBitmap(previewWidth, previewHeight, Bitmap.Config.ARGB_8888); 79 parameters.setPreviewSize(previewWidth, previewHeight); 80 gCamera.setParameters(parameters); 81 bufferSize = previewWidth * previewHeight; 82 textureBuffer=new int[bufferSize]; 83 bufferSize = bufferSize * ImageFormat.getBitsPerPixel(parameters.getPreviewFormat()) / 8; 84 gBuffer = new byte[bufferSize]; 85 gCamera.addCallbackBuffer(gBuffer); 86 gCamera.setPreviewCallbackWithBuffer(this); 87 gCamera.startPreview(); 88 //gProcessThread = new ProcessThread(surfaceView,handler,null,previewWidth,previewHeight); 89 //processThread.start(); 90 } 91 92 @Override 93 public void surfaceCreated(SurfaceHolder holder) { 94 Log.v(TAG, "GameDisplay surfaceCreated"); 95 if (gCamera == null) { 96 gCamera = Camera.open(); 97 } 98 gCamera.setPreviewTexture(gSurfaceTexture); 99 //sampleStart(); 100 } 101 102 @Override 103 public void surfaceDestroyed(SurfaceHolder holder) { 104 Log.v(TAG, "GameDisplay surfaceDestroyed"); 105 //gProcessThread.isRunning=false; 106 //sampleTimer.cancel(); 107 //sampleTimer = null; 108 //sampleTask.cancel(); 109 //sampleTask = null; 110 gCamera.stopPreview(); 111 gCamera.release(); 112 } 113 114 @Override 115 public void onPreviewFrame(byte[] data, Camera camera) { 116 Log.v(TAG, "GameDisplay onPreviewFrame"); 117 //gProcessThread.raw_data=data; 118 camera.addCallbackBuffer(gBuffer); 119 for(int i=0;i<textureBuffer.length;i++) 120 textureBuffer[i]=0xff000000|data[i]; 121 gBitmap.setPixels(textureBuffer, 0, previewWidth, 0, 0, previewWidth, previewHeight); 122 synchronized (gHolder) 123 { 124 Canvas canvas = this.getHolder().lockCanvas(); 125 canvas.drawBitmap(gBitmap, null,gRect, null); 126 //canvas.drawBitmap(textureBuffer, 0, screenWidth, 0, 0, screenWidth, screenHeight, false, null); 127 this.getHolder().unlockCanvasAndPost(canvas); 128 } 129 130 } 131 132 public void sampleStart() { 133 Log.v(TAG, "GameDisplay sampleStart"); 134 sampleTimer = new Timer(false); 135 sampleTask = new TimerTask() { 136 @Override 137 public void run() { 138 gProcessThread.timer=true; 139 } 140 }; 141 sampleTimer.schedule(sampleTask,0, 80); 142 } 143 }
以上程序中115-130行是最重要的部分，data是從SurfaceTexture獲得的camera圖像幀的拷貝，119-121行對其進行了簡單的處理，122-128行將處理過的圖像數據傳遞給負責顯示的SurfaceView並顯示出來。
MainActivity對GameDisplay的調用如下：
1 //聲明 2 private GameDisplay gameDisplay; 3 //初始化 4 gameDisplay.setVisibility(SurfaceView.VISIBLE); 5 DisplayMetrics dm = getResources().getDisplayMetrics(); 6 screenWidth = dm.widthPixels; 7 screenHeight = dm.heightPixels; 8 gameDisplay= new GameDisplay(this,dm.widthPixels,dm.heightPixels); 9 //加入到當前activity的layout中 10 FrameLayout root = (FrameLayout) findViewById(R.id.root); 11 root.addView(gameDisplay,0);