Juergen

A camera for taking series of photos very fast

Running the project

To run the project use either npm or yarn to install the packages; however do not use npm start or yarn start as after installing a package this messes up the node_modules folder. So use this instead:

    npm i
    expo start

Timing

The timing issue seems to be relevant only for a presumably cluttered (android) phone; on another device this works flawlessly. The timing of setInterval does not seem to be very good. On my phone this.shoot is async and takes less than 2ms to fire. Then setInterval is invoked, but the first invokation of this.shoot happens after ~1.5s + interval; each subsequent shot is taken accurately. The timing of setTimeout seems to be even worse, as for each invokation ~1.5s are added. Some info can be found here - https://stackoverflow.com/questions/42100658/accuracy-of-settimeout-in-react-native

Flash

Camera.Constants.FlashMode.on & Camera.Constants.FlashMode.auto are not able to keep up when rapidly taking shots. This makes the photos blurry or very differently lit or both. In order to be consistent Camera.Constants.FlashMode.torch is used instead (only when actually taking shots) - the resulting photos are uniformly lit and do not have inferior quality.

Performance

If the camera cannot keep up takePictureAsync is invoked (???), but the promise is neither resolved nor rejected. Note that an attempt is still made - the flash might be turned on a few more times. takePictureAsync won't be resolved/rejected if the Camera is unmounted. takePictureAsync won't be resolved/rejected if the Camera is not visible. The code tries to ensure that the Camera is visible long enough so that all takePictureAsync invocations are resolved. The Camera is delibarately not unmounted to ensure that takePictureAsync is resolved/rejected. It seems that takePictureAsync can be unresolved for a variety of reasons:

• react-native-camera/react-native-camera#1311
• react-native-camera/react-native-camera#1373

Reloading the app

Note that hot reloading does not work particularly well with the camera - the app does not get reloaded; use live reload instead. This is one of the cases which the React Native docs mention - https://facebook.github.io/react-native/docs/debugging#automatic-reloading.

Networking

You need to make sure that your phone and dev machine are on the same wifi network.

Additionally you should use interface metric instead of automatic for your internet connection. To do so: Control Panel -> Network and Internet -> Network and Sharing Center -> {select primary connection}, then Properties -> select TCP/IPv4 -> Properties -> Advanced -> uncheck 'Automatic metric' -> set 10 for 'Interface metric'. Do the same thing for your secondary connection, but with a higher value (say 20);