Camera

DIPS.Mobile.UI provides ways for you to use the camera of the phone with different APIs. The APIs require a CameraPreview which visually changes when using it with the different APIs.

Camera prerequisites

iOS

Add NSCameraUsageDescription to your Info.plist.

<key>NSCameraUsageDescription</key>
<string>This app uses the camera take pictures and scan barcodes, which is used for ..... </string>

Make sure your description is clear and obvious as to what you are using it for. We've experienced that Apple denies uploading to App Store if this is not.

Android

Add android.permission.CAMERA permission to your android manifest.

<uses-permission android:name="android.permission.CAMERA" />

Preview the camera

To start off, add a CameraPreview to your page and give it a x:Name. This lets us refer it in the code behind.

<dui:ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
                 xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                 ...>
    <dui:CameraPreview x:Name="CameraPreview"/>
</dui:ContentPage>

Scan barcodes

DIPS.Mobile.UI provides a camera API for people to scan barcodes. The implementations are optimised and is inspired by ML Kit Barcode scanning for Android and AVCamBarcode from Apple for iOS.

Start scanning

To get started, create an BarcodeScanner object in your code behind, and Start() it when it makes sense for people.

public MyPage()
{
    InitializeComponent();
    m_scanner = new BarcodeScanner();
}

In many cases, starting it when page appear makes sense:

protected override void OnAppearing()
{
    try
    {
        await m_scanner.Start(CameraPreview, result =>
        {
            var theBarCode = result.Barcode.RawValue;
        });
    }
    catch (Exception e)
    {
        //Todo: catch exception
    }
    base.OnAppearing();
}

Notice that CameraPreview is the code behind reference from the preview guide.

Stop scanning

Remember to release resources to make sure your page does not leak memory.

In most cases it makes sense to do this when the page disappear. Other cases can be when people got the result.

protected override void OnDisappearing()
{
    base.OnDisappearing();
    m_scanner.Stop();
}

Debuggable result

DIPS.Mobile.UI provides a tailored view that you can use where it makes sense. This is helpful when you need to debug the values of the barcode live in the app when an error occurs.

<dui:BarcodeScanResultView BarcodeScanResult="{Binding BarcodeScanResult}" />

This gives you an overview of the current barcode along with all the barcodes that was detected during scanning.The barcode you get is the "most detected" barcode.