##Usage
<com.objectlife.cameralibrary.camera.CameraPreview
android:id="@+id/camera_preview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
cameraPreview = (CameraPreview) findViewById(R.id.camera_preview);
camera = CameraManager.getCameraInstance(this);
cameraPreview.setCamera(camera);
@Override
protected void onResume() {
super.onResume();
CameraManager.startPreview();
}