Camera Focus Issue

[moflaherty]

Hi! We updated to 2.1.13 in our Xamarin Forms/PCL project and now the camera does not auto focus. Sometimes exiting the scan form and going back in causes it to focus properly. We did not experience this issue with 2.0.4.46. We have tested this on a few devices--mine is a Moto X Gen 2. Any idea what is going on? I can go back to the older version, but that also fixes other issues that caused us grief. Thanks!

[edynamic90]

Hello, I'm not developper of this great project but I've a little bit information

With the last version 2.1.44, no focus, the preview is blurry

After flash activated and wait 3-5 seconds, focus is triggered and the preview is OK

But it's only after flashlight using, it's a bug

Best regards

[Redth]

The auto focus code was changed in this release. I suspect some devices don't do a good job of implementing proper auto focus. You can of course manually invoke AutoFocus ()...

I will test on more of my devices and see if I can find one that has these issues....

[moflaherty]

Redth, I did make a call to auto focus but that did not seem to help. However, I may not be using the method properly. We have two scenarios in our Xamarin Forms/PCL app: (1) we are using continuous scanning with an overlay, and (2) we acquire a single scan and immediately return. In either scenario, when should the auto focus call be made? I have noticed that when the camera is within range of a valid barcode, it will focus enough to capture the barcode. If the barcode is not in range, it is hit or miss if the camera focuses (sometimes it works.) However, if I hit the back button and then go back in, it seems to focus every time. Not sure if that helps.

[edynamic90]

Thanks for the answer

I just add this code before start scan to resolve this issue
//--- BEFORE ---
new Task(async () =>
{
await Task.Delay(3000);
oScanner.AutoFocus();
}).Start();
var oResult = await oScanner.Scan (oOptions);
ReadScanResult (oResult);

[Redth]

So, previous to 2.1.44 auto focus was done by calling .AutoFocus() on a timer (every few seconds). You could achieve the same pretty easily, but that's obviously not a great solution.

I'm going to to dig into the code a bit more and see if i can detect when a camera doesn't support autofocus and revert back to the 'old' way of calling AutoFocus on a timer. First I need to go through my devices and see if I can find one that doesn't support autofocusing properly...

[bmacadam]

I'm experiencing exactly what moflaherty and edynamic90 have already described. I'm testing with a Samsung Galaxy S3 (SGH i747) running 4.4 and a HTC One running 5.0.2. I have a client with a Nexus 5x running 6.0.2 who reported the same issue. All of these devices support autofocus.

I improved the situation by modifying the call to AutoFocus within the SetupCamera method in ZXingSurfaceView. I wrapped in a timer with a delay of 800 ms.

[rocuh]

Moto G2 and G3 also don't auto focus

[liveoset]

LG G4 the same problem

[dmrowca]

        ZXing.Net.Mobile.Forms.Android.Platform.Init();
        SetContentView(Resource.Layout.BarcodeFragment);

        scanFragment = new ZXingScannerFragment();


        SupportFragmentManager.BeginTransaction()
            .Replace(Resource.Id.fragment_container, scanFragment)
            .Commit();

    }

    protected override void OnResume()
    {
        base.OnResume();
        scan(); 

    }

    protected override void OnPause()
    {
        scanFragment.StopScanning();
        base.OnPause();
    }

    void scan()
    {
        var opts = new MobileBarcodeScanningOptions
        {
            AutoRotate = false,
            UseFrontCameraIfAvailable = true,
            TryHarder = true
        };


        scanFragment.StartScanning(result =>
        {
            if (result != null)
            {
                Intent myIntent = new Intent(this, typeof(MainActivity));
                myIntent.PutExtra("code", result.Text);
                SetResult(Result.Ok, myIntent);
                Finish();
            }
        }, opts);
    }

    public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
    {
        global::ZXing.Net.Mobile.Forms.Android.PermissionsHandler.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    }
}

After update to last stable version (2.1.47) auto-focus on continous scanning not working. Using .AutoFocus() method is not good idea. Tested on Samsung SM-A510F (Android API 23). Previous versions (before 2.1) was working very well

[kyluke]

J1 Mini is also facing the same problem.

[Mika571]

For anyone using Xamarin Forms the following works really well
ZXingScannerView zxing;
...
TimeSpan ts = new TimeSpan(0, 0, 0, 3, 0);
Device.StartTimer(ts, () => {
if (zxing.IsScanning)
zxing.AutoFocus();
return true;
});