引言：
在做用户的头像时，忽然想到前段时间（可能是很久以前了），支付宝传出偷偷拍摄用户的生活照，真实头像，被喷的很厉害。然而作为Android开发者的我第一反应竟然是握草，他是怎么实现的。在我印象中，iOS对权限的控制是很严格的，偷偷调起摄像头这种行为应该是很困难的。然而Android4.2之前可以说开发者几乎拥有了系统权限，能力之强简直可怕。而现在Android已经到了7.0，虽然大多说用户还是在4.4到6.0的。我想我也来做一个静默拍摄的app。
正文：
所谓静默拍摄就是在用户毫无感知的情况下拍摄。
一般的拍照都会有预览区域，拍照声。去掉这些东西才算是真正意义上的静默拍摄。
首先，做了一个非常正常的自拍软件，就一个按钮。拍完之后存到文件夹的一个位置。然后我试了一下，完全ok并没有什么难度。然后就是清空surfaceView了。我首先想到的就是setVisiblity为gone，然后就报错了。很尴尬。下一个方案就是用高度和宽度都是0的方法，然而并没有什么卵用，更加尴尬。
然后想想没有有什么好办法了那就把这个surfaceView盖住好了，非常完美，随便搞一搞就盖住了，然后照片照样拍。合理。
但是“咔嚓”一声的拍照声实在令人尴尬，然后我就想到了静音，在页面打开的时候就设置静音。看上去这是一个非常稳健的方法，然后就发生了更加尴尬的事情。设置静音的时候，手机振动了一下，震一下也就算了，关键是还没有把拍照的声音去除。然后我就去查了查了相机音量应该是哪个。之后悲催的事情就发生了：
Google的Android开发者为了Android用户的用户体验，也为了避免开发者开发出静默拍摄的app从而侵犯了隐私，他们就把快门声音的播放函数写在了拍照的方法里面，还是写在framework层的。瞬间我就很难过了。作为一个平凡的第三方开发者，我并没有那么多权限去改变framework层的方法。
然后智慧的我决定曲线救国。因为在预览的时候，并没有进行拍照，但实际上我们已经拿到了相机带来的图片流。这很关键。然后我就把这个图片流变成了bitmap，然后保存到了本地，接着就把相机关了。神不知鬼不觉地把自拍拿到了。当然其中有一点小问题，比如图片编码，图片旋转，本地存储，获取帧图像都是各种各样的问题。但这些都是可以解决的。思路依旧是我上面提到的思路，各种表现方式可以由大家自己搞。
public class MainActivity extends AppCompatActivity {
static final String TAG = "CAMERA ACTIVITY";
//Camera object
Camera mCamera;
//Preview surface
SurfaceView surfaceView;
//Preview surface handle for callback
SurfaceHolder surfaceHolder;
//Camera button
Button btnCapture;
//Note if preview windows is on.
boolean previewing;
int mCurrentCamIndex = 0;
private AudioManager manager;
private int volumn;
private boolean canTake=false;
private ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnCapture = (Button) findViewById(R.id.btn_capture);
imageView =(ImageView)findViewById(R.id.iv);
btnCapture.setOnClickListener(new Button.OnClickListener() {
public void onClick(View arg0) {
canTake=true;
}
});
surfaceView = (SurfaceView) findViewById(R.id.surfaceView1);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(new SurfaceViewCallback());
//surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void getSurfacePic(byte[] data, Camera camera,String name){
Camera.Size size = camera.getParameters().getPreviewSize();
YuvImage image = new YuvImage(data, ImageFormat.NV21, size.width, size.height, null);
if(image!=null){
ByteArrayOutputStream stream = new ByteArrayOutputStream();
image.compressToJpeg(new Rect(0, 0, size.width, size.height), 80, stream);
Bitmap bmp = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());
/
public void saveBitmap(Bitmap bm,String name) {
Log.e(TAG, "保存图片");
File f = new File("/sdcard/namecard/", name);
if (f.exists()) {
f.delete();
}
try {
FileOutputStream out = new FileOutputStream(f);
bm.compress(Bitmap.CompressFormat.PNG, 90, out);
out.flush();
out.close();
Log.e(TAG, "已经保存");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private boolean saveBitmapTofile(byte[] bmp) {
String fileName = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM)
.toString()
+ File.separator
+ "PicTest_" + System.currentTimeMillis() + ".jpg";
File file = new File(fileName);
if (!file.getParentFile().exists()) {
file.getParentFile().mkdir();
}
try {
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream(file));
bos.write(bmp);
bos.flush();
bos.close();
scanFileToPhotoAlbum(file.getAbsolutePath());
Toast.makeText(MainActivity.this, "[Test] Photo take and store in" + file.toString(),Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(MainActivity.this, "Picture Failed" + e.toString(),
Toast.LENGTH_LONG).show();
}
return true;
}
public void saveMyBitmap(Bitmap mBitmap,String bitName) {
String fileName = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM)
.toString()
+ File.separator
+ "PicTest_" + System.currentTimeMillis() + ".jpg";
File file = new File(fileName);
if (!file.getParentFile().exists()) {
file.getParentFile().mkdir();
}
FileOutputStream fOut = null;
try {
fOut = new FileOutputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
if (null != fOut) {
mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fOut);
fOut.flush();
fOut.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void rotateMyBitmap(Bitmap bmp,String name){
/
public static Bitmap compressImage(Bitmap image) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中
image.compress(Bitmap.CompressFormat.JPEG, 100, baos);
// 把压缩后的数据baos存放到ByteArrayInputStream中
ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());
// 把ByteArrayInputStream数据生成图片
Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);
return bitmap;
}
Camera.ShutterCallback shutterCallback = new Camera.ShutterCallback() {
@Override
public void onShutter() {
}
};
Camera.PictureCallback rawPictureCallback = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] arg0, Camera arg1) {
}
};
Camera.PictureCallback jpegPictureCallback = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] arg0, Camera arg1) {
String fileName = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM)
.toString()
+ File.separator
+ "PicTest_" + System.currentTimeMillis() + ".jpg";
File file = new File(fileName);
if (!file.getParentFile().exists()) {
file.getParentFile().mkdir();
}
try {
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream(file));
bos.write(arg0);
bos.flush();
bos.close();
scanFileToPhotoAlbum(file.getAbsolutePath());
Toast.makeText(MainActivity.this, "[Test] Photo take and store in" + file.toString(),Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(MainActivity.this, "Picture Failed" + e.toString(),
Toast.LENGTH_LONG).show();
}
};
};
public void setVolumnSilence(){
manager = (AudioManager) this
.getSystemService(Context.AUDIO_SERVICE);
manager.setStreamMute(AudioManager.STREAM_SYSTEM, false);
volumn = manager.getStreamVolume(AudioManager.STREAM_SYSTEM);
if (volumn != 0) {
// 如果需要静音并且当前未静音（muteMode的设置可以放在Preference中）
manager.setStreamVolume(AudioManager.STREAM_SYSTEM, 0,
AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE);
}
}
public void scanFileToPhotoAlbum(String path) {
MediaScannerConnection.scanFile(MainActivity.this,
new String[] { path }, null,
new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(String path, Uri uri) {
Log.i("TAG", "Finished scanning " + path);
}
});
}
public void cameraRefresh(String picPath) {
Toast.makeText(this,picPath,Toast.LENGTH_SHORT).show();
}
private final class SurfaceViewCallback implements android.view.SurfaceHolder.Callback {
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
{
if (previewing) {
mCamera.stopPreview();
previewing = false;
}
try {
mCamera.setPreviewDisplay(arg0);
mCamera.startPreview();
previewing = true;
setCameraDisplayOrientation(MainActivity.this, mCurrentCamIndex, mCamera);
} catch (Exception e) {}
}
public void surfaceCreated(SurfaceHolder holder) {
// mCamera = Camera.open();
//change to front camera
mCamera = openFrontFacingCameraGingerbread();
// get Camera parameters
Camera.Parameters params = mCamera.getParameters();
List<String> focusModes = params.getSupportedFocusModes();
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
// Autofocus mode is supported
}
mCamera.setPreviewCallback(new Camera.PreviewCallback() {
@Override
public void onPreviewFrame(byte[] bytes, Camera camera) {
Log.e("stuart","onPreviewFrame "+canTake);
if(canTake) {
getSurfacePic(bytes, camera, "hahahaah");
canTake=false;
}
}
});
}
public void surfaceDestroyed(SurfaceHolder holder) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
previewing = false;
}
}
private Camera openFrontFacingCameraGingerbread() {
int cameraCount = 0;
Camera cam = null;
Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
cameraCount = Camera.getNumberOfCameras();
for (int camIdx = 0; camIdx < cameraCount; camIdx++) {
Camera.getCameraInfo(camIdx, cameraInfo);
if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
try {
cam = Camera.open(camIdx);
mCurrentCamIndex = camIdx;
} catch (RuntimeException e) {
Log.e(TAG, "Camera failed to open: " + e.getLocalizedMessage());
}
}
}
return cam;
}
private static void setCameraDisplayOrientation(Activity activity, int cameraId, Camera camera)
{
Camera.CameraInfo info = new Camera.CameraInfo();
Camera.getCameraInfo(cameraId, info);
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
//degrees the angle that the picture will be rotated clockwise. Valid values are 0, 90, 180, and 270.
//The starting position is 0 (landscape).
int degrees = 0;
switch (rotation)
{
case Surface.ROTATION_0: degrees = 0; break;
case Surface.ROTATION_90: degrees = 90; break;
case Surface.ROTATION_180: degrees = 180; break;
case Surface.ROTATION_270: degrees = 270; break;
}
int result;
if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT)
{
result = (info.orientation + degrees) % 360;
result = (360 - result) % 360; // compensate the mirror
}
else
{
// back-facing
result = (info.orientation - degrees + 360) % 360;
}
camera.setDisplayOrientation(result);
}
}
基本上呢，这一个代码就能实现简单的静默拍照了。
依旧存在的问题：
图片质量实在有点低。
目前来看这也是没有办法的，因为我只能取到surfaceView的帧图像，而显示在preview中的帧图像质量又是非常感人的。所以不得不说这真是没什么办法。
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