这几天看到亚瑟boy的技术连载，也试着做了下带滤镜特效的照相机，效果也出来了，但是发现添加滤镜特效后的预览窗口卡屏现象很严重，于是自己索性 试着尝试修改，在亚瑟和其他网友的代码中基本上都是对于照相机data视频流先进行解码，然后对解码出的帧Bitmap进行滤镜算法处理，这个是必走的流 程，而每一帧在处理解码和滤镜时都需要用掉大量时间，我测了下，解码需要300毫秒左右，滤镜处理需要600毫秒左右（冰冻滤镜），如此一来，处理完这两 个流程需要的时间要在900毫秒甚至更长，我们知道如果看上去比较流畅的话我们需要每秒更新三帧的图片，而这么处理只能更新一张，明显的卡屏。
于是试着去缩小处理的Bitmap大小，在照相机预览返回照片大小中设置：
Camera.Parameters parameters = camera.getParameters();
parameters.setPreviewSize(display.getWidth()/2, display.getHeight()/2);// 设置预览照片的大小
原来默认是返回屏幕大小的预览图片，此时我改成了屏幕大小一半的图片，发现处理过程明显加快了（当然也有稍微的卡屏），最后在预览回调接口 PreviewCallBack中再将图片放大到屏幕大小，有雨我预览图片返回时只是缩小了一半，此时放大回屏幕大小时仍然是非常清晰的，如果你想速度更 快的话可以继续缩小预览图片的返回大校
代码如下：
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);// 没有标题
window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);// 设置全屏
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); // 设置分辨率
/* 下面设置Surface不维护自己的缓冲区，而是等待屏幕的渲染引擎将内容推送到用户面前 */
surfaceView.getHolder().addCallback(new SurfaceCallback());
}
//按钮监听
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();//打开相机
}else{
Toast.makeText(CameraActivity.this, "相机正在使用中", 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);// 设置预览照片的大小
parameters.setPreviewFrameRate(3);// 每秒3帧
parameters.setPictureFormat(PixelFormat.JPEG);// 设置照片的输出格式
parameters.set("jpeg-quality", 100);// 照片质量
parameters.setPictureSize(display.getWidth(), display.getHeight());// 设置照片的大小
camera.setParameters(parameters);
camera.setPreviewCallback(new PreviewCallBack());// 通过SurfaceView显示取景画面
camera.startPreview();//开始预览
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);// 自动对焦
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("确定退出照相机?").setPositiveButton("确定",
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) {
// 取消按钮事件
dialog.cancel();
}
}).show();
break;
}
}
return super.onKeyDown(keyCode, event); // 不会回到 home 页面
}
//预览回调接口
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); //解码
Bitmap bm = Bitmap.createBitmap(RGBData, imageWidth, imageHeight, Config.ARGB_8888);
//bm = toGrayscale(bm);//实时滤镜效果，现在是变成黑白效果
bm = ice(bm);//冰冻效果
Canvas canvas = surfaceView.getHolder().lockCanvas();
// 判断非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;
}
冰冻特效
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]; // 获取图片当前点的像素值
R = Color.red(pixColor); // 获取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; // 计算后重置R值，以下类同
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); // 重置当前点的像素值
} // x
} // y
bitmap.setPixels(dst, 0, width, 0, 0, width, height);
return bitmap;
}
获取照片回调
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卡根目录下，以当前时间毫秒命名
FileOutputStream outStream = new FileOutputStream(file);
bitmap.compress(CompressFormat.JPEG, 100, outStream);
outStream.close();
camera.stopPreview();
camera.startPreview();//重新开始照相预览
} catch (Exception e) {
Log.e(TAG, e.toString());
}
}
}
解码
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 代码：
<?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>
