Roland Weigelt

After my blog post in June, here is another tale from a C# developer getting his feet wet with TypeScript.

TypeScript’s type checking makes my life so much easier, but it does not catch everything. Recently I forgot an important part of a for-loop. Here is a stripped-down example:

var items=["item0", "item1", "item2"];
for (var n=0;items.length;n++)
{
    // ...
}

The code compiles, but runs into an endless loop – the “n<” is missing in the condition.

If I write similar code in C#…

var items=new[] {"item0", "item1", "item2"};
for (var n=0;items.Length;n++)
{
    // ...
}

… the compiler tells me what I did wrong:

Cannot implicitly convert type 'int' to 'bool'

Ok, another (TypeScript) lesson learned.

I use Microsoft’s WebView2 control for a digital signage desktop application running in fullscreen mode (“kiosk client”). All visible content is HTML coming from a server (on a private network), so the kiosk client itself has to be updated very rarely.

Right now, I am exploring how to display the output of another computer that is (physically) standing nearby, but on a different network, using a video capture device. Showing the video stream in HTML is pretty straightforward using navigator.mediaDevices.getUserMedia(). I will not go into detail on this, as a web search for “webcam video getUserMedia” gives you helpful information on how to get things up and running very quickly.

Instead, the focus of this article is on two problems that I ran into:

How to avoid the request for permission to use the camera

When browsing the web with a normal browser, nobody wants a web page to be able to simply switch on a webcam or a microphone without the user’s consent. That is why it is a good thing that getUserMedia() opens a prompt asking the use for permission.

For an unattended kiosk display, though, such a prompt is a no-go. The request for permission must be handled programmatically. Fortunately, the WebView2 control offers a way to do this.

Let’s say you followed the first steps of the “Get started with WebView2 in WPF” tutorial in the Microsoft documentation, so you have WebView2 control called “webView” in your application window. Now, instead of setting the Source property in XAML, you add an event handler for the Loaded event. After calling EnsureCoreWebView2Async() you can add an event handler for the PermissionRequested event, where things work pretty much as expected: If the requested permission is for the camera, your code allows it.

public partial class MainWindow : Window
{
	public MainWindow()
	{
		InitializeComponent();
		Loaded += HandleLoaded;
	}
	
	private async void HandleLoaded(object sender, RoutedEventArgs e)
	{
		await webView.EnsureCoreWebView2Async(); // important
		webView.CoreWebView2.PermissionRequested += HandlePermissionRequested;
		webView.Source = new Uri("...URI of your page...");
	}
	
	private void HandlePermissionRequested(object? sender, CoreWebView2PermissionRequestedEventArgs e)
	{
		if (e.PermissionKind == CoreWebView2PermissionKind.Camera)
		{
			e.State = CoreWebView2PermissionState.Allow;
		}
	}
}

If you want, you can check the Uri property of the CoreWebView2PermissionRequestedEventArgs to lock down the automatic permission to specific URIs.

How to circumvent the requirement for HTTPS for getUserMedia() - for the purposes of this scenario

My digital signage solution is currently using HTTP. A web page loaded into Edge/WebView2 this way cannot use navigator.mediaDevices.getUserMedia(). What does work is using a file URI, both for a local file or a file a remote file share.

A local file deployed with the setup for the kiosk application could require more frequent update installations, though. And a file share for this sole purpose is not exactly an elegant solution.

So what I did was to use WebClient.DownloadFile to download the HTML file on startup via HTTP from the server to a local file in a temporary folder. Then I could navigate to that file using a file URI.

At some point in the future, I will move my application to HTTPS. But until then, this solution is good enough.

CamProps is a free utility for quickly adjusting and managing the properties of webcams and other video capture devices. I wrote it when I struggled with my Logitech C920 that required some manual tweaking to achieve a good picture quality. CamProps enables you to store and quickly recall settings which comes in handy if you have different lighting situations in your room – or when the webcam once again simply “forgets” its settings.

Recently José M. Alarcón contacted me to tell me he had written a Spanish article about CamProps. I seized the opportunity and asked him whether he could translate the UI texts. Thanks to José, version 1.1.0 of CamProps now supports Spanish in addition to English and German. When you first start CamProps, it selects the UI language according to your Windows settings. You can override this in the “•••” menu in the upper right corner of the window:

Where can I get it?

You can download CamProps at https://www.roland-weigelt.de/camprops/

Which devices can I use?

CamProps works with all webcams and video capture devices that support opening the webcam driver property dialog (either the default provided by Windows or a specific dialog by the manufacturer's driver).

For instance, when you press the “” button for a Logitech C920 without the Logitech software installed, this will open the following dialog:

(This dialog may look different for other devices)

For context: I am a C# developer who uses TypeScript just every now and then. Recently I added a few string constants to an existing TypeScript class. The program compiled just fine, but when I ran the program, the result was different from what I expected.

For a repro scenario, copy the following script code into the Windows clipboard:

class MyStrings {
    public static LoremIpsumDolorSitAmet = "Lorem ipsum dolor sit amet";
    public static ConsecteturAdipiscingElit = "consectetur adipiscing elit";
    public static VestibulumFeugiatLigulaEuOdioPosuereVelTristiqueDiamIaculis = "Vestibulum feugiat ligula eu odio posuere, vel tristique diam iaculis";
    public static FusceUrnaLiberoEfficiturNecTortorSed = "Fusce urna libero, efficitur nec tortor sed";
    public static UllamcorperFaucibusAugueProinUtPurusMetus = "ullamcorper faucibus augue. Proin ut purus metus";
    public static CurabiturAPosuereDiamSedElementumSedNislVitaeMaximus = "Curabitur a posuere diam. Sed elementum sed nisl vitae maximus";
    public static PraesentVitaeEnimVestibulumUltriciesNuncInGravidaSapien = "Praesent vitae enim vestibulum, ultricies nunc in, gravida sapien";
    public static ProinIaculisMiOrciUtRhoncusDuiVenenatisId : "Proin iaculis mi orci, ut rhoncus dui venenatis id";
    public static MorbiSedCongueLigulaSedFinibusNeque : "Morbi sed congue ligula, sed finibus neque";
    public static PellentesqueEuMolestieExIdFermentumEllus : "Pellentesque eu molestie ex, id fermentum tellus";
}

console.log(MyStrings.LoremIpsumDolorSitAmet);
console.log(MyStrings.ConsecteturAdipiscingElit);
console.log(MyStrings.VestibulumFeugiatLigulaEuOdioPosuereVelTristiqueDiamIaculis);
console.log(MyStrings.FusceUrnaLiberoEfficiturNecTortorSed);
console.log(MyStrings.UllamcorperFaucibusAugueProinUtPurusMetus);
console.log(MyStrings.CurabiturAPosuereDiamSedElementumSedNislVitaeMaximus);
console.log(MyStrings.PraesentVitaeEnimVestibulumUltriciesNuncInGravidaSapien);
console.log(MyStrings.ProinIaculisMiOrciUtRhoncusDuiVenenatisId);
console.log(MyStrings.MorbiSedCongueLigulaSedFinibusNeque);
console.log(MyStrings.PellentesqueEuMolestieExIdFermentumEllus);

Now head to the TypeScript Playground at https://www.typescriptlang.org/play, replace the text on the left side with the content of the clipboard and run the script.

This will give you the following output:

It took me a bit until it dawned on me why the last three strings are undefined – can you immediately figure out what the problem is?

A hint: Just before I edited the class, I worked on a couple of JSON files.

Am 4. Juni 2021 bin ich ab 20:30 wieder auf dem Twitch-Kanal von Gregor Biswanger zu Gast. Um mehr Zeit für Fragen und Antworten zu haben, hatten Gregor und ich den Workshop am 7. Mai spontan aufgeteilt.

Für diejenigen, die den ersten Teil verpasst haben:

• Gregor hat eine Aufnahme des Streams auf YouTube hochgeladen und mit detaillierten Kapitelmarken versehen.
• Ich werde mit einem groben Schnelldurchlauf starten.

Inhalt

Thema des zweiten Teils sind User Interface Patterns und andere Kochrezepte, die das Design von Bedienoberflächen vereinfachen. Die konkreten UI-Technologien spielen dabei keine Rolle, dementsprechend sind für den Workshop keine technischen Vorkenntnisse notwendig.

Darüber hinaus stelle ich vor, mit welchen Tools und Methoden ich in meinem Alltag Ideen skizziere, GUIs entwerfe und die Abläufe ausprobiere.

Wie beim ersten Mal wird die Interaktion mit Euch eine große Rolle spielen. Habt Ihr Fragen zum Was, Wann und Wie von UI/UX-Design im Umfeld der (agilen) Software-Entwicklung? Habt Ihr Screenshots von GUIs, die Ihr verbessern möchtet? Oder gibt es Designs, die Euch gefallen und die man gemeinsam auf wiederverwendbare Gestaltungsmittel und User Interface Patterns untersuchen könnte? Immer her damit, lasst uns darüber sprechen!

Wie nehme ich teil?

Wenn Ihr nur mal vorbeischauen möchtet, dann ruft am 7. Mai um 20:30 in Eurem Browser einfach https://www.twitch.tv/GregorBiswanger auf.

Um auch am Chat teilnehmen zu können, benötigt Ihr einen (kostenlosen) Twitch Account.

Am 7. Mai 2021 bin ich ab 20:30 auf dem Twitch-Kanal von Gregor Biswanger mit einem Workshop zu UI/UX-Grundlagen zu Gast.

Zielgruppe sind Entwickler und andere Interessierte, die entweder

• in einem Team ohne ein Budget für externe UI-Designer arbeiten, oder
• mit einem besseren Verständnis in die Zusammenarbeit mit Externen gehen möchten.

Inhalt

Nach Grundlagen des Visual Designs stelle ich wichtige UI/UX-Fachbegriffe und -Konzepte in Theorie und Praxis vor, z.B. User Interface Patterns, Empathie, mentale Modelle oder Szenarien. In Live-Demos zeige ich Möglichkeiten zum Skizzieren von User Interfaces.

Der Kanal von Gregor hat eine aktive Chat-Community, dementsprechend interaktiv werde ich den Workshop gestalten. Stellt Eure Fragen im Chat. Vielleicht habt Ihr eine UI, die Ihr gerne verbessern möchtet? Schickt Screenshots und wir wenden das Gelernte direkt live an.

An einem Freitagabend darf natürlich der Spaß nicht fehlen: Problemlösungen à la Indiana Jones, Datenbanken für außerirdische Lebensformen oder Gedanken zum Einfluss von Rallye-Streifen auf die Geschwindigkeit von Sportwagen. Alles frei nach dem Motto “Wenn das Beispiel merkwürdig genug ist, dann ist die Idee dahinter merk-würdig”. Last-but-not-least: Kein UI-Vortrag ohne Beispiele für epische UI-Fails!

Wie nehme ich teil?

Wenn Ihr nur mal vorbeischauen möchtet, dann ruft am 7. Mai um 20:30 in Eurem Browser einfach https://www.twitch.tv/GregorBiswanger auf. Um am Chat teilnehmen zu können, benötigt Ihr einen (kostenlosen) Twitch Account.

Emaroo is a free utility for browsing most recently used (MRU) file lists of programs like Visual Studio, VS Code, Word, Excel, PowerPoint, Photoshop, Illustrator and more. Quickly open files, jump to their folder in Windows Explorer, copy them (and their path) to the clipboard - or run your own tools on files and folders with custom actions!

• Download Emaroo on www.roland-weigelt.de/emaroo

About this Release

• Updated: Support for Visual Studio Code 1.55 (changes regarding list of most recently used folders/workspaces). Previous versions of Visual Studio Code are still supported.

In recent months, I wrote a few articles that hinted that I was developing a webcam-related utility (here, here, here and here). About two weeks ago, I released it to my colleagues who liked it and found it useful. Now, after some improvements, I am ready for a release to a larger audience.

What is it?

CamProps is a free utility for quickly adjusting and managing the properties of webcams and other video capture devices.

Where can I get it?

You can download CamProps at https://www.roland-weigelt.de/camprops/

Why should I use it?

The picture quality of many webcams can be improved by manually tweaking properties like focus, exposure or gain. When doing so, you may run into a few issues, though:

• If you are in a room with changing lighting conditions, you have to adjust the settings each time you want to use the camera.
• Some third-party software may decide to reset the camera back to default.
• And some devices simply forget all settings after a reboot.

CamProps lets you

• quickly adjust camera properties,
• manage different sets of configurations, and
• restore the settings with a single click.

Which devices can I use?

CamProps works with all webcams and video capture devices that support opening the webcam driver property dialog (either the default provided by Windows or a specific dialog by the manufacturer's driver).

For instance, when you press the “” button for a Logitech C920 without the Logitech software installed, this will open the following dialog:

(This dialog may look different for other devices)

How do I start?

• Head to https://www.roland-weigelt.de/camprops/
• Download and install the program.
• Read the “How to…” section on setting up your first configuration, activating a configuration and backing up the automatically stored settings.