Last week there was a discussion on X (former Twitter) about the usage of the NumberBox in WinUI apps. Should it accept letter inputs or not. The 'conlusion' was that it should because you can enter formulas. But there are also a few developers which don't like this. So I took up the challenge to find a solution for this problem. My first guess was that I should create an AttachedProperty or Behavior for this. I was wrong. AttachedProperties can't be used for this. You can't use them for handing events on controls. Behaviors can but they require you to add an extra NuGet package to the project. Something you might not want. So I decided to use compiled binding (x:Bind) to events, also known as Event Binding.
You can customize the appearance of your apps in many ways by using the XAML framework like WPF, UWP, WinUI and MAUI. Styles let you set control properties and reuse those settings for a consistent appearance across multiple controls. Styling is to XAML what CSS is to HTML. Using styles, you can group a set of properties and assign them to specific controls or all controls of a specific type, and just like in CSS, a style can inherit (BasedOn) from another style.
Starting with WinUI 2.6 there are new styles for most of the controls. It is encourage you to use the new styles, as they better match the design direction of Windows. You can read more about styling.
Accelerator keys (or keyboard accelerators) are keyboard shortcuts that improve the usability and accessibility of your Windows applications by providing an intuitive way for users to invoke common actions or commands without navigating the app UI. You can add them to a Button using the KeyboardAccelerators property. See the example below.
In the XAML of WinUI3 apps you can use the inline syntax for creating Rows and Columns inside a Grid. This is a feature which Avalonia had for a long time. It is more compact and works fine as long as you don't need a Max or Min Width/Height.
The following screenshot shows you a Grid with 2 Rows and Columns. Both in equal size. Using 4 Rectangle elements I created the Microsoft logo inside this Grid.
The following screenshot shows you the same Grid but now with inline RowDefinitions and ColumnDefinitions. It saves you a few lines of XAML.
You can customize the appearance of your apps in many ways by using the XAML framework. Styles let you set control properties and reuse those settings for a consistent appearance across multiple controls.
With Lightweight styling you override the system brushes, and the color override will affect all controls that reference that brush. Although this is called styling you are not defining a style. You just create a ResourceDictionary with a ThemeDictionary in which you override the system brushes.
If you write business apps, there are a lot of controls for data input: TextBox, CheckBox, ComboBox, DatePicker, ToggleSwitch, TimePicker, RadioButton, Slider, etc. I always wondered why there was no NumberBox. Numeric input is very common so it needs its own control for it. Luckily there is the Windows UI Library (WinUI), an open source project from Microsoft. I proposed the NumberBox last year and the team did a great job implementing it. It is released in version 2.3 and most of the issues are now solved. Time for a blog post showing of its features.
This animated GIF demonstrates a few of the features like AcceptsExpression, PlaceholderText, SpinButtons and NumberFormatter. I 'stole' it from this tweet.
The possibility to create your own Markup Extensions where added to UWP in the Windows Falls Creators Update SDK (16299, 1709). I only used it once. I created an OnDevice Markup Extensions which I added to the Windows Community Toolkit.
Last month Pedro Lamas wrote the blog post Making the case for XAML Markup Extensions. He demonstrates a FontIconExtension which he uses to shorten the XAML of an AppBarButton. I love his solution. His blog post inspired me to write some new Markup Extensions with the same goal, short XAML.
I'm in the process of learning the new Windows 10 SDK Preview Build 18323. It includes a new control named TwoPaneView. The TwoPaneView is a Panel control which contains two Panes. The Panes are shown next to each other if there is enough room, otherwise below each other. If that is not possible only one pane is shown. You can use it in situations in which you normally used a RelativePanel in combination with some ViewStates to reposition one panel beside or below another depending off the size (AdaptiveTriggers). This was always a lot of work which is now very easy with the new control.
I'm in the process of learning the new Windows SDK Preview. This SDK has made it possible to set the Kind property of a StandardUICommand. The StandardUICommand was added in the 1809 SDK (17763) but the StandardUICommandKind property was readonly which made it impossible to use from XAML. You could only set the Kind using a constructor parameter in code. Now you can define the StandardUICommand in XAML inside your AppBarButton, MenuFlyoutItem and MenuBarItem.
I'm in the process of learning the new Windows SDK Preview. Today's subject is the new IsEditable and Text properties of the ComboBox control.