从页面调用用户控件中的函数 [英] Calling function in usercontrol from page

问题描述

大家好，

我有一个小问题...
场景:

1.我在Silverlight(SL)中有一个导航应用程序
2.我在主页上有一个名为MainMenu的菜单控件(只是简单的按钮).
3.单击按钮(在菜单中)登录"时，SL应用程序将通过导航面板导航到该页面.
4.登录时，菜单必须更改(例如，登录按钮应变为注销).

在这一点上，我不知道如何让用户控件MainMenu知道需要更改按钮.

我试图看一下，但我不知道在哪里看以及用什么关键字.

非常基本:如何从页面的主页上的用户控件中调用函数?

有人可以帮忙吗?

谢谢！

Hi all,

I have a small problem...
Scenario:

1. I have a navigation application in Silverlight (SL)
2. I have a usercontrol with the menu (just simple buttons) called MainMenu on the mainpage.
3. When I click on the button (in the menu) "Login", the SL app navigates to that page by a navigationpanel.
4. When I login the menu has to change (button Login should become Logout for example).

At this point I have no clue how I can let the usercontrol MainMenu know the button needs to change.

I tried to look, but I have no idea where to look and on what keywords.

So very basic: How can I call a function in a usercontrol on the mainpage from a page?

Can anybody help?

Thanks!

推荐答案

我不会尝试查找或跟踪控件(在将来的代码版本中可能会更改)并在运行时使用代码对其进行修改，使用以数据为中心的方法-为此而制作了WPF/Silverlight.

从Visual Studio项目模板生成业务应用程序示例...检出LoginStatus.xaml/LoginStatus.xaml.cs文件，以查看通过绑定和可视状态执行此操作的另一种方法.
基本上，有一个单例/静态对象代表登录/注销状态.此类具有用于登录和注销的事件.您需要知道状态何时更改的任何元素(如用户控件)都可以订阅这些事件，并在事件处理程序中适当地设置其状态(例如将登录"按钮更改为注销").这样可以将代码放在usercontrol的类中，而不必从其他页面/控件中跟踪或查找usercontrol.

例如，如果您将身份验证代码包装在像这样的单例类中，

Instead of trying to find or keep track of controls (which may change in future versions of your code) and modifying them with code at runtime, I would go with a more data-centric method - WPF/Silverlight are made for this.

Generate a business application sample from the visual studio project templates...check out the LoginStatus.xaml/LoginStatus.xaml.cs files to see another way of doing this with bindings and visual states.
Basically, there''s a singleton/static object that represents the logged-in/logged-out state. This class has events for loggedin and loggedout. Any element (like a usercontrol) you have that needs to know when the state changes can subscribe to these events and in the event handlers set its state appropriately (like changing a "log in" button to "log out"). This puts the code right in the usercontrol''s class instead of having to track or find usercontrols from other pages/controls.

For example, if you wrapped your authentication code in a singleton class like this

public class AuthenticationService : INotifyPropertyChanged
{
    #region INotifyPropertyChanged Implementation

    public event PropertyChangedEventHandler PropertyChanged;
    void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
    }

    #endregion

    private static volatile AuthenticationService instance;
    private static object syncRoot = new Object();

    private AuthenticationService()
    {
    }

    public static AuthenticationService Current
    {
        get
        {
            if (instance == null)
            {
                lock (syncRoot)
                {
                    if (instance == null)
                        instance = new AuthenticationService();
                }
            }

            return instance;
        }
    }

    public event EventHandler<EventArgs> LoggedIn;
    public event EventHandler<EventArgs> LoggedOut;

    public void LogIn()
    {
        //if and when loginsuccessful
        //{

        IsLoggedIn = true;

        EventHandler<EventArgs> evnt = LoggedIn;
            if (evnt != null)
            {
                evnt(this, new EventArgs());
            }
        //}
    }

    public void LogOut()
    {
        //if and when logoutsuccessful
        //{

        IsLoggedIn = false;

        EventHandler<EventArgs> evnt = LoggedOut;
        if (evnt != null)
        {
            evnt(this, new EventArgs());
        }
        //}
    }

    bool _isLoggedIn = false;
    public bool IsLoggedIn
    {
        get { return _isLoggedIn; }
        set
        {
            if (_isLoggedIn != value)
            {
                _isLoggedIn = value;
                OnPropertyChanged("IsLoggedIn");
            }
        }
    }
}

...然后需要根据登录/注销状态进行更新的用户控件可以简单地执行以下操作

...then a usercontrol that needs to update itself based on the loggedin/loggedout status can simply do something like this

public MyUserControl()
{
    InitializeComponent();

    // Subscribe to loggedin/loggedout events so we can update our UI
    AuthenticationService authentication = AuthenticationService.Current;
    authentication.LoggedIn += new EventHandler<EventArgs>(authentication_LoggedIn);
    authentication.LoggedOut += new EventHandler<EventArgs>(authentication_LoggedOut);
}

void authentication_LoggedIn(object sender, EventArgs e)
{
    // Change button text to "Log Out"
}

void authentication_LoggedOut(object sender, EventArgs e)
{
    // Change button text to "Log In"
}

不需要其他页面来了解MyUserControl:)

No need for another page to know about MyUserControl :)

Humm，很多代码...在应用程序中找不到我需要的答案的方式... A请给我一点提示吗?也许我需要一些代码?请知道，我不需要此功能仅用于登录/注销.该应用程序的其他部分具有相似的功能/需求.

谢谢

Humm, alot of code... Can''t really find my way in the application to the answer I need... A little hint please? Perhaps some code I need? Please know I don''t need this functionality for login/-out only. In other parts of the app are similar functions/needs.

Thanks

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