Use observer mode to switch user controls in Silverlight

For a tip, see

Http://tech.sina.com.cn/s/2008-07-03/1528718607.shtml

Or

Http://kb.cnblogs.com/page/42897? Page = 1

We will discuss how to use initparams inSilverlight 2 ApplicationProgramSwitch User ControlThis is a stupid but intuitive solution.

But what if the value is transmitted in the control? The above method will be useless!

Today, I saw a clever method on a foreigner's blog, and I am afraid to enjoy it exclusively. I will share it with you:

First, write an interface:

Namespace pageswitchsimple
{
Public interface iswitchable
{
Void utilizestate (Object State );
}
}

Then write a switch class:

Using system. Windows. controls;

Namespace pageswitchsimple
{
Public static class switcher
{
Public static pageswitcher;

Public static void switch (usercontrol Newpage)
{
Pageswitcher. navigate (Newpage );
}

Public static void switch (usercontrol Newpage, object state)
{
Pageswitcher. navigate (Newpage, State );
}
}
}

Pageswitcher member class:

Front-endCode:

<Usercontrol X: class = "pageswitchsimple. pageswitcher"
Xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
Xmlns: x = "http://schemas.microsoft.com/winfx/2006/xaml"
Width = "800" Height = "600">

</Usercontrol>

Background code:

Using system;
Using system. Windows. controls;

Namespace pageswitchsimple
{
Public partial class pageswitcher: usercontrol
{
Public pageswitcher ()
{
Initializecomponent ();
}

Public void navigate (usercontrol nextpage)
{
This. content = nextpage;
}

Public void navigate (usercontrol nextpage, object state)
{
This. content = nextpage;
Iswitchable S = nextpage as iswitchable;

// This is really clever. It is used to pass object parameters!
If (s! = NULL)
{
S. utilizestate (State );
}
Else
{
Throw new argumentexception ("nextpage is not iswitchable! "
+ Nextpage. Name. tostring ());
}
}
}
}

Then write two user controls that implement the iswitchable interface:

Control 1:

<Usercontrol X: class = "pageswitchsimple. Page"
Xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
Xmlns: x = "http://schemas.microsoft.com/winfx/2006/xaml"
Width = "400" Height = "300">
<Grid X: Name = "layoutroot" background = "white">
<Textblock text = "Your name:" fontsize = "18"/>
<Textbox X: Name = "name" fontsize = "18" width = "150" Height = "35" verticalignment = "TOP" margin = "5"/>
<Button X: Name = "changepage" content = "change" fontsize = "18" width = "100" Height = "50"/>
</GRID>
</Usercontrol>

Background code:

Using system. windows;
Using system. Windows. controls;

Namespace pageswitchsimple
{
Public partial class page: usercontrol, iswitchable
{
Public page ()
{
Initializecomponent ();
Changepage. Click + = new routedeventhandler (changepage_click );
}

Void changepage_click (Object sender, routedeventargs E)
{
Switcher. Switch (New page2 (), name. Text );
}
}
}

Control 2:

<Usercontrol X: class = "pageswitchsimple. page2"
Xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
Xmlns: x = "http://schemas.microsoft.com/winfx/2006/xaml"
Width = "400" Height = "300">
<Grid X: Name = "layoutroot" background = "bisque">
<Textblock X: Name = "message" text = "page2" fontsize = "18"/>
<Button X: Name = "changepage" content = "change" fontsize = "18" width = "100" Height = "50"/>
</GRID>
</Usercontrol>

Background code:

Using system. windows;
Using system. Windows. controls;

Namespace pageswitchsimple
{
Public partial class page2: usercontrol, iswitchable
{
Public page2 ()
{
Initializecomponent ();
Changepage. Click + = new routedeventhandler (changepage_click );
}

Public void utilizestate (object state)
{
Message. Text = state. tostring ();
}

Void changepage_click (Object sender, routedeventargs E)
{
Switcher. Switch (New Page ());
}
}
}

Last modified app. CS

Private void application_startup (Object sender, startupeventargs E)
{
Pageswitcher = new pageswitcher ();
This. rootvisual = pageswitcher;
Switcher. pageswitcher = pageswitcher;
Switcher. Switch (New Page ());
}

Cleverly uses the Observer Model to admire the author's ideas.