照相機濾鏡使用，優化解碼和濾鏡致使的預覽卡屏現象

這幾天看到亞瑟boy的技術連載，也試着作了下帶濾鏡特效的照相機，效果也出來了，可是發現添加濾鏡特效後的預覽窗口卡屏現象很嚴重，因而本身索性 試着嘗試修改，在亞瑟和其餘網友的代碼中基本上都是對於照相機data視頻流先進行解碼，而後對解碼出的幀Bitmap進行濾鏡算法處理，這個是必走的流 程，而每一幀在處理解碼和濾鏡時都須要用掉大量時間，我測了下，解碼須要300毫秒左右，濾鏡處理須要600毫秒左右（冰凍濾鏡），如此一來，處理完這兩 個流程須要的時間要在900毫秒甚至更長，咱們知道若是看上去比較流暢的話咱們須要每秒更新三幀的圖片，而這麼處理只能更新一張，明顯的卡屏。

因而試着去縮小處理的Bitmap大小，在照相機預覽返回照片大小中設置：

Camera.Parameters parameters = camera.getParameters();
parameters.setPreviewSize(display.getWidth()/2, display.getHeight()/2);// 設置預覽照片的大小

原來默認是返回屏幕大小的預覽圖片，此時我改爲了屏幕大小一半的圖片，發現處理過程明顯加快了（固然也有稍微的卡屏），最後在預覽回調接口 PreviewCallBack中再將圖片放大到屏幕大小，有雨我預覽圖片返回時只是縮小了一半，此時放大回屏幕大小時仍然是很是清晰的，若是你想速度更 快的話能夠繼續縮小預覽圖片的返回大小。

代碼以下：

public class CameraActivity extends NoSearchActivity {
         private static final String TAG = "CameraActivity";
         private SurfaceView surfaceView;
         private Camera camera;
         private boolean preview;
         private ImageButton take_picture;
         private int width,height;
 
        @Override
         public void onCreate(Bundle savedInstanceState) {
                 super.onCreate(savedInstanceState);
                 Window window = getWindow();
                 requestWindowFeature(Window.FEATURE_NO_TITLE);// 沒有標題
                 window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                                 WindowManager.LayoutParams.FLAG_FULLSCREEN);// 設置全屏
                 window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);// 高亮
 
                setContentView(R.layout.camera_view);
 
                ButtonClickingListener buttonlistener = new ButtonClickingListener();
                 surfaceView = (SurfaceView) this.findViewById(R.id.camera_surface);
                 WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
                 Display display = wm.getDefaultDisplay();
                 width = display.getWidth();
                 height = display.getHeight();
 
                take_picture = (ImageButton) findViewById(R.id.take_picture);//拍照
                 take_picture.setOnClickListener(buttonlistener);
                 surfaceView.getHolder().setFixedSize(width, height); // 設置分辨率
                 /* 下面設置Surface不維護本身的緩衝區，而是等待屏幕的渲染引擎將內容推送到用戶面前 */
                 surfaceView.getHolder().addCallback(new SurfaceCallback());
         }
         //按鈕監聽
         private final class ButtonClickingListener implements View.OnClickListener {
                 @Override
                 public void onClick(View v) {
                         if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                                 Toast.makeText(CameraActivity.this, R.string.sdcarderror, 1).show();
                                 return;
                         }
                         try {
                                 switch (v.getId()) {
                                 case R.id.take_picture:
                                         camera.takePicture(null, null, new TakePictureCallback());
                                         break;
                                 }
                         } catch (Exception e) {
                                 Toast.makeText(CameraActivity.this, R.string.error, 1).show();
                                 Log.e(TAG, e.toString());
                         }
                 }
         }
         @Override
         protected void onDestroy() {
                 // TODO Auto-generated method stub
                 if(camera!=null){
                         camera.setPreviewCallback(null) ;
             camera.stopPreview();
             camera.release();
             camera = null;
                 }
                 super.onDestroy();
         }
         private final class SurfaceCallback implements SurfaceHolder.Callback {
 
                @Override
                 public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {}
                 @Override
                 public void surfaceCreated(SurfaceHolder holder) {
                         if(camera==null){
                                 camera = Camera.open();//打開相機
                         }else{
                                 Toast.makeText(CameraActivity.this, "相機正在使用中", 1).show();
                         }
                         WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
                         Display display = wm.getDefaultDisplay();
                         Camera.Parameters parameters = camera.getParameters();
                         parameters.setPreviewSize(display.getWidth()/2, display.getHeight()/2);// 設置預覽照片的大小
                         parameters.setPreviewFrameRate(3);// 每秒3幀
                         parameters.setPictureFormat(PixelFormat.JPEG);// 設置照片的輸出格式
                         parameters.set("jpeg-quality", 100);// 照片質量
                         parameters.setPictureSize(display.getWidth(), display.getHeight());// 設置照片的大小
                         
                        camera.setParameters(parameters);
                         camera.setPreviewCallback(new PreviewCallBack());// 經過SurfaceView顯示取景畫面
                         camera.startPreview();//開始預覽
                         preview = true;
                 }
 
                @Override
                 public void surfaceDestroyed(SurfaceHolder holder) {
                         if (camera != null) {
                                 if (preview)
                                         camera.stopPreview();
                                 camera.release();
                         }
                 } 
        }
 
        @Override
         public boolean onKeyDown(int keyCode, KeyEvent event) {
                 if (camera != null && event.getRepeatCount() == 0) {
                         switch (keyCode) {
                                 case KeyEvent.KEYCODE_MENU:
                                         camera.autoFocus(null);// 自動對焦
                                         break;
                                 case KeyEvent.KEYCODE_CAMERA:
                                 case KeyEvent.KEYCODE_DPAD_CENTER:
                                         camera.takePicture(null, null, new TakePictureCallback());
                                         break;
                                 case KeyEvent.KEYCODE_BACK:
                                         new AlertDialog.Builder(CameraActivity.this).setTitle("提示")
                                         .setMessage("肯定退出照相機?").setPositiveButton("肯定",
                                                         new DialogInterface.OnClickListener() {
                                                 public void onClick(DialogInterface dialog,int whichButton) {
                                                         Intent exit = new Intent(Intent.ACTION_MAIN);
                                                         exit.addCategory(Intent.CATEGORY_HOME);
                                                         exit.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                                         startActivity(exit);
                                                         System.exit(0);
                                                 }
                                         }).setNegativeButton("取消",new DialogInterface.OnClickListener() {
                                                 public void onClick(DialogInterface dialog,int whichButton) {
                                                         // 取消按鈕事件
                                                         dialog.cancel();
                                                 }
                                         }).show();
                                         break;
                         }
                 }
                 return super.onKeyDown(keyCode, event); // 不會回到 home 頁面
         }
         //預覽回調接口
         private final class PreviewCallBack implements Camera.PreviewCallback {
                 public void onPreviewFrame(byte[] data, Camera camera) {
                         if (data != null) {
                                 int imageWidth = camera.getParameters().getPreviewSize().width;
                                 int imageHeight = camera.getParameters().getPreviewSize().height;
                                 int RGBData[] = new int[imageWidth * imageHeight];
                                 decodeYUV420SP(RGBData, data, imageWidth, imageHeight); //解碼
                                 Bitmap bm = Bitmap.createBitmap(RGBData, imageWidth, imageHeight, Config.ARGB_8888);
 //                                bm = toGrayscale(bm);//實時濾鏡效果，如今是變成黑白效果
                                 bm = ice(bm);//冰凍效果
                                 Canvas canvas = surfaceView.getHolder().lockCanvas();
                     // 判斷非null，才能drawBitmap.
                     if (bm != null) {
                             bm = Bitmap.createScaledBitmap(bm, width, height,false);
                         canvas.drawBitmap(bm, 0, 0, null);
                     }
                     surfaceView.getHolder().unlockCanvasAndPost(canvas);
                         }
         }
         }

灰度效果（黑白照片）

public static Bitmap toGrayscale(Bitmap bmp) {
                 int height = bmp.getHeight();
                 int width = bmp.getWidth();
 
                Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
                 Canvas c = new Canvas(bmpGrayscale);
                 Paint paint = new Paint();
                 ColorMatrix cm = new ColorMatrix();
                 cm.setSaturation(0);
                 ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
                 paint.setColorFilter(f);
                 c.drawBitmap(bmp, 0, 0, paint);
                 return bmpGrayscale;
         }

冰凍特效

public static Bitmap ice(Bitmap bmp) {
                 int width = bmp.getWidth();
                 int height = bmp.getHeight();
                 Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
                 int dst[] = new int[width * height];
                 bmp.getPixels(dst, 0, width, 0, 0, width, height);
                 int R, G, B, pixel;
                 int pos, pixColor;
                 for (int y = 0; y < height; y++) {
                         for (int x = 0; x < width; x++) {
                                 pos = y * width + x;
                                 pixColor = dst[pos]; // 獲取圖片當前點的像素值
                                 R = Color.red(pixColor); // 獲取RGB三原色
                                 G = Color.green(pixColor);
                                 B = Color.blue(pixColor);
                                 pixel = R - G - B;
                                 pixel = pixel * 3 / 2;

                                 if (pixel < 0)
                                         pixel = -pixel;
                                 if (pixel > 255)
                                         pixel = 255;

                                 R = pixel; // 計算後重置R值，如下類同
                                 pixel = G - B - R;
                                 pixel = pixel * 3 / 2;

                                 if (pixel < 0)
                                         pixel = -pixel;
                                 if (pixel > 255)
                                         pixel = 255;

                                 G = pixel;
                                 pixel = B - R - G;
                                 pixel = pixel * 3 / 2;

                                 if (pixel < 0)
                                         pixel = -pixel;
                                 if (pixel > 255)
                                         pixel = 255;
                                 B = pixel;
                                 dst[pos] = Color.rgb(R, G, B); // 重置當前點的像素值
                                 } // x
                         } // y
                 bitmap.setPixels(dst, 0, width, 0, 0, width, height);
                 return bitmap;
         }

獲取照片回調

private final class TakePictureCallback implements PictureCallback {
                 @Override
                 public void onPictureTaken(byte[] data, Camera camera) {
                         try {
                                 Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0,data.length);
                                 bitmap = ice(bitmap);
                                 File file = new File(Environment.getExternalStorageDirectory(),System.currentTimeMillis() + ".jpg");//保存在SD卡根目錄下，以當前時間毫秒命名
                                 FileOutputStream outStream = new FileOutputStream(file);
                                 bitmap.compress(CompressFormat.JPEG, 100, outStream);
                                 outStream.close();
                                 camera.stopPreview();
                                 camera.startPreview();//從新開始照相預覽
                         } catch (Exception e) {
                                 Log.e(TAG, e.toString());
                         }
                 }
         }

 解碼

static public void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) {
                 final int frameSize = width * height;
                 for (int j = 0, yp = 0; j < height; j++) {
                         int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;
                         for (int i = 0; i < width; i++, yp++) {
                                 int y = (0xff & ((int) yuv420sp[yp])) - 16;
                                 if (y < 0)y = 0;
                                 if ((i & 1) == 0) {
                                         v = (0xff & yuv420sp[uvp++]) - 128;
                                         u = (0xff & yuv420sp[uvp++]) - 128;
                                 }

                                 int y1192 = 1192 * y;
                                 int r = (y1192 + 1634 * v);
                                 int g = (y1192 - 833 * v - 400 * u);
                                 int b = (y1192 + 2066 * u);
 
                                if (r < 0)r = 0;
                                 else if (r > 262143)r = 262143;
                                 if (g < 0)g = 0;
                                 else if (g > 262143)g = 262143;
                                 if (b < 0)b = 0;
                                 else if (b > 262143)
                                         b = 262143;
                                 rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
                         }
                 }
         }
 }

camera_view 代碼：

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:orientation="horizontal" android:layout_width="fill_parent"
         android:layout_height="fill_parent" android:background="#000000">
         <SurfaceView android:id="@+id/camera_surface"
                 android:layout_height="fill_parent"
                 android:layout_width="fill_parent"
                 android:layout_weight="2.0" />
         <LinearLayout android:orientation="vertical"
                 android:layout_width="50dip"
                 android:layout_height="fill_parent"
                 android:gravity="center_vertical">
                 <ImageButton android:layout_width="48dip"
                         android:layout_height="48dip"
                         android:src="@android:drawable/ic_menu_camera"
                         android:id="@+id/take_picture" />
                 <View android:layout_width="40dip"
                     android:layout_height="fill_parent"
                     android:layout_weight="2.0"/>
         </LinearLayout>
 </LinearLayout>