UX Markup Reference

UX Markup is an XML based language for expressing user interfaces, layout, effects and motion. UX Markup is an essential part of Fuse.

This chapter covers the meaning of the built-in syntaxes and attributes of the UX Markup language.

Use the menu to the left to navigate the different topics in this chapter.


Creating Objects

The basic function of a UX Markup element is to create (instantiate) an object of a certain class. For example, the following snippet creates instances of the App and Rectangle classes, and makes the Rectangle a child of the App.

    <Rectangle Color="Blue" />

The name of the element tag must be the name of an Uno class accessible in the project. In the above example, App and Rectangle are pre-defined classes within the Fuse libraries.

To make the Fuse libraries accessible in your project, make sure you add "Fuse" to the Packages section of your .unoproj

Creating Heirarchies

When one element (child) is placed inside another element (parent) in UX Markup, the outer element is called the parent, while the inner element is called the child.

<Grid Rows="1*,1*">
    <Rectangle Color="Blue" Margin="10" />
    <Rectangle Color="Blue" Margin="10" />

By default, UX Markup will find a suitable property on the parent element to which it can bind the child element.

To disable this behavior for a given child element, we can specify ux:AutoBind="false". This will create a loose object within your app that can be attached to your app later by logic.

To bind to a specific property of the parent, we can specify ux:Binding="TheProperty". This will disable auto-binding for the element, and instead bind to TheProperty.

Creating reusable classes (ux:Class)

Any UX element tree can be converted to a reusable class (component) by giving it the ux:Class attribute.

<Panel ux:Class="MyNamespace.MyComponent" Color="Yellow" >
        <Scale Factor="2" Duration="0.3" Easing="BackOut" />

This creates a new subclass of Panel called MyComponent in the MyNamespace namespace. Namespaces are optional, but recommended when creating components for reuse in other projects, to avoid name collisions.

Once a class is created, it can be instantiated just like any of the built-in classes:

<MyNamespace.MyComponent />

Each ux:Class creates a new root scope, which means that nodes inside the class have no access to names (ux:Name) outside of the class. This means dependencies must be injected explicitly.

The App tag

The App tag is the ultimate root of your app project.

    <!-- your app goes here -->

Any App tag is implicitly a ux:Class with the same name as the containing file excluding file extension. We can also give your app class a different name by specifying ux:Class manually:

<App ux:Class="MyNamespace.MyApp" />

Projects that don't contain an App tag does not produce an actual app, but a packages of components that can be referenced by other projects.


UX Markup supports XML namespaces (xmlns), but to keep code verbosity down, sensible defaults have been set. This is why you rarely see it used in UX markup files.

The default XML namespace (xmlns) points by default to all the standard Fuse namespaces, so classes from there (e.g. App and Rectangle) can be used without full namespace qualifier.

For other classes we can use the full qualified name of a class directly on a tag:

    <MyNamespace.MyClass />

Or, we can specify a custom xmlns declaration for a scope:

<App xmlns:m="MyNamespace">
    <m:MyClass />

Including UX files (ux:Include)

We can include the content of one UX file in another using ux:Include as follows:

<ux:Include File="Resources.ux" />

ux:Include is useful for declaring static resources such as Fonts, Images, colors, etc. in a separate file.

It is however not recommended practice for splitting parts of your view into files. See the Creating Components article for a better approach.