将默认的xml名称空间（xmlns）更改为自定义名称空间

Question

In a XAML file we usually use the default setting xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

How can I define a custom xmlns instead of the default one. Such as xmlns="http://www.mypage.com"

I don't mean add to a new xmlns, but replace the default one.

Answer 1

It's not really clear what your problem is... if you want to use the default namespace somehow different than suggested, just prefix the (normally) default namespace with a name:

<def:Window x:Class="WpfTests_2.MainWindow"
        xmlns:def="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns="clr-namespace:WpfTests_2"
        Title="MainWindow">
    <def:Window.Resources>
        <CustomBox x:Key="myLocalCustomBox"/>
    </def:Window.Resources>

    <def:Grid x:Name="grid1">
    </def:Grid>
</def:Window>

In this example, I make the project local namespace WpfTests_2 the default and name the (normal) default namespace as def .

For a typical WPF application, this is a bad idea because you will use many controls and you need to prefix your namespace name every time . But it is certainly possible.

If you don't use anything from the http://schemas.microsoft.com/winfx/2006/xaml/presentation namespace (no Window , no UserControl , no [whatever control]), you can remove/replace it without redefining it with a prefix.

Answer 2

I think it is possible, by second part doc below:

For almost all of the examples given in the WPF sections of the SDK, the default XAML namespace is mapped to the WPF namespace http://schemas.microsoft.com/winfx/2006/xaml/presentation.

Since almost all , That is there exists few example are not using this url, so it's possible.

Docs Of Microsoft

The WPF and XAML Namespace Declarations

Within the namespace declarations in the root tag of many XAML files, you will see that there are typically two XML namespace declarations. The first declaration maps the overall WPF client / framework XAML namespace as the default:

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

The second declaration maps a separate XAML namespace, mapping it (typically) to the x: prefix.

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Mapping to Custom Classes and Assemblies
...

Another Doc :

The root element also contains the attributes xmlns and xmlns:x . These attributes indicate to a XAML processor which XAML namespaces contain the type definitions for backing types that the markup will reference as elements.

The xmlns attribute specifically indicates the default XAML namespace. Within the default XAML namespace, object elements in the markup can be specified without a prefix. For most WPF application scenarios, and for almost all of the examples given in the WPF sections of the SDK, the default XAML namespace is mapped to the WPF namespace http://schemas.microsoft.com/winfx/2006/xaml/presentation .

The xmlns:x attribute indicates an additional XAML namespace, which maps the XAML language namespace http://schemas.microsoft.com/winfx/2006/xaml .

This usage of xmlns to define a scope for usage and mapping of a namescope is consistent with the XML 1.0 specification. XAML namescopes are different from XML namescopes only in that a XAML namescope also implies something about how the namescope's elements are backed by types when it comes to type resolution and parsing the XAML.

Note that the xmlns attributes are only strictly necessary on the root element of each XAML file. xmlns definitions will apply to all descendant elements of the root element (this behavior is again consistent with the XML 1.0 specification for xmlns .) xmlns attributes are also permitted on other elements underneath the root, and would apply to any descendant elements of the defining element. However, frequent definition or redefinition of XAML namespaces can result in a XAML markup style that is difficult to read.

The WPF implementation of its XAML processor includes an infrastructure that has awareness of the WPF core assemblies. The WPF core assemblies are known to contain the types that support the WPF mappings to the default XAML namespace. This is enabled through configuration that is part of your project build file and the WPF build and project systems. Therefore, declaring the default XAML namespace as the default xmlns is all that is necessary in order to reference XAML elements that come from WPF assemblies.