zoukankan      html  css  js  c++  java
  • XAML控件不可访问,它具有一定的保护级别

    其它namespace的代码访问控件时会出现这个问题

    需要把控件状态由protected改为public

    <TextBlock x:FieldModifier="public" x:Name="AccessibleTextBlock" />

    The x:Name attribute in XAML creates named fields that you can use to access the controls from the code-behind. However, as opposed to WPF, in UWP these fields are private which means you can access them from the code-behind only, not from other classes. While noting it is a good idea from architectural standpoint, is it possible to change this behavior?

    Normal behavior

    Let’s define a simple TextBlock control in XAML.

    Now, what happens if we create a new class that takes the page as parameter of one of the methods and tries to access the TextBlock?

    The app will not compile, because the field is inaccessible due to its protection level.

    To see what actually happens behind the scenes, let’s open the auto-generated MainPage.g.i.cs file which can be found in the obj folder. We can find the following field there:

    Clearly, the field is defined as private.

    x:FieldModifier directive

    To change the code generation behavior, you can use the x:FieldModifier directive. This allows you to specify excatly which access modifier should be field have.

    Now, accessing the field from the outside works as a charm:

    Note that you are not limited to public and private only, and you can also set the field to be internalor protected.

    We can confirm the change of visiblity was reflected in the generated source code:

    WPF

    If you wonder, what is the default behavior in WPF, wonder no more!

    WPF’s convention is to set all named fields as internal by default:

    You can use the x:FieldModifier directive to modify the visibility the same way as in UWP.

  • 相关阅读:
    MVC把表格导出到Excel
    MVC借助Masonry实现图文瀑布流
    MVC Ajax Helper或jQuery异步方式加载部分视图
    MVC使用Entity Framework Code First,用漂亮表格显示1对多关系
    MVC使用jQuery从视图向控制器传递Model的2种方法
    MVC使用AdditionalMetadata为Model属性添加额外信息
    MVC日期格式化的2种方式
    MVC使用百度开源文本编辑器UEditor实现图文并茂,字数限制,上传图片或涂鸦
    MVC使用StructureMap实现依赖注入Dependency Injection
    通过扩展jQuery UI Widget Factory实现手动调整Accordion高度
  • 原文地址:https://www.cnblogs.com/xpvincent/p/10348605.html
Copyright © 2011-2022 走看看