Camera/Image stream: show error message?

Developers
1

I’m extending the Blink app and got struggle with the image recovery.
The Blink server gives a http error if the camera (http post for creating new snapshot) is busy. In this case I want to abort the image refresh in the Homey app and show a red message “camera is busy”.

I followed the Homey API description and trow an error. But the camera view is still busy with the circeling refresh icon and no message is shown.

The code is:

        const _snapshotImage = new Homey.Image();
        _snapshotImage.setStream(async stream => {
            self.log('_registerSnapshotImage() -> setStream -> Capture_snap');
            self._getNewSnapshotUrl()
                .then( 
                     //...get the immage via URL
                    res.body.pipe(stream);
                })
                .catch((error) => {
                    self.log("_registerSnapshotImage Error calling _getNewSnapshotUrl: "+error);
                    throw new Error('Camera is busy');
                });
        _snapshotImage.register()
            .then(() => self.log('_registerSnapshotImage() -> registered'))
            .then(() => self.setCameraImage('snapshot', 'Snapshot', _snapshotImage))
            .catch(self.error);

I think it’s similar to the example below “Using a stream”:
https://apps-sdk-v2.developer.athom.com/tutorial-Images.html

Has anyone an example how to deal with errors on image refresh? Many thanks.
Ronny

2

Do you also use the rest of the code as shown in the example, specifically this:

_snapshotImage.register().catch(console.error);

If so, you’re just catching the error and showing it on console, but I don’t think it will be propagated back the the SDK.

You could also try and explicitly destroy the stream:

…
.catch(error => {
  self.log(…);
  const err = Error('Camera is busy');
  stream.destroy(err);
  throw err;
});
3

Hello Robert,

the _snapshotImage.register() is there. I edited the code above.

The stream.destroy results in an exception and the app is killed.
Instead, stream.close( ) is working. One step ahead :slight_smile:

The image refresh ist stopped, but it seems I can’t set an error text. Homey displays the default error caused by the empty stream.

Screenshot_20210709-133821_Homey
Screenshot_20210709-133821_Homey1080×2280 67.9 KB

It seems, Homey is checking the exception in another way I thought. After throwing the error, Homey tries to get the image again (but then there is stil the http error), and that’s causing a delay until the refresh got his timeout. So invalid_content_typüe is not nice, but working for the moment.

4

Have you tried removing the .catch() after the .register()?

5

Yes, for one try. But thats not the fault. The register( ) doesnt throw an exeption. Thanks for your help.

I have implemented a way to wait for a updated snapshot URL if the camera is too slow. So I hope this error will not occour in the normal usage.