/** 开关灯 */
 private void operateLight() {
   if (!mIsLightOpen) {
     cameraManager.openLight();
     mIsLightOpen = true;
     mLightBtn.setImageResource(R.drawable.light_pressed);
   } else {
     cameraManager.offLight();
     mIsLightOpen = false;
     mLightBtn.setImageResource(R.drawable.light_normal);
   }
 }