在后面的代码中访问扩展控件的属性 [英] Accessing Extension Control's Property in Code Behind

问题描述

我已经在此处发布了扩展的TextBox控件. http://code.msdn.microsoft.com/Extended-Text-Box-b8c7b911

针对Dave的问题 来自这篇文章 关于控制文本框行为的bool属性，我向 控制.为了访问控件(不仅是文本框)，我还修改了代码以返回控件(此)，而不是 this.TextBox .  这是代码的样子

 

 object    IContentVisual  .Control
        {
          < span style ="color:blue">得到  {  此; }
       }
 
      < span style ="color:blue"> void    IContentVisual .展示()
        {
       } 

 

这是LSML部分.

      <   ControlProperty 
               "color:red">名称  = "  IsApply 
                 "color:red"> PropertyType   = " :Boolean 
                 "color:red">类别名称  = " 外观
                 "color:red"> EditorVisibility   = "  PropertySheet "       <   ControlProperty.Attributes  > 
       <   DisplayName     值  = " 可以自动加载吗?"  /> 
        <  说明 span>    值  = " 可以自动加载吗?"  /> 
     </  ControlProperty.Attributes  > 
 
      <   ControlProperty.DefaultValueSource  > 
       <   ScreenExpressionTree  > 
         <   ConstantExpression      ResultType   = < :布尔值"     Value   = "  True " /> 
       </  ScreenExpressionTree  > 
       </  ControlProperty.DefaultValueSource  > 
     </  ControlProperty     </  Control.Properties  跨线程访问"；错误.  然后，我将代码移到了主调度程序中，但是现在我收到了" UnauthorizedAccess Exception ".
  
这里有什么问题?
 
-Bala 
解决方案
 
 
  txtBox.IsApply =！ txtBox.IsApply  
您在哪里使用此代码?如果尝试从LightSwitch应用程序用户代码中使用它，则问题在于您无法从屏幕的调度程序访问或更改对象(这是导致跨线程访问异常的原因).你只能
 从主调度程序执行此操作(这是Silverlight的限制).
什么引发了UnauthorizedAccessException?在哪一行代码上?您能提供一个调用栈吗?您可以通过从工具"->选项"->调试"中关闭我的代码"，然后打破所有异常(至少打破UnauthorizedAccessException)来实现此目的.
 
 
 
I've posted a Extended TextBox control over here. http://code.msdn.microsoft.com/Extended-Text-Box-b8c7b911
In response to Dave's question
from this post regarding a bool property to control the textbox's behavior, I added a IsApply Property to the
 control.  In order to access the control (not just the TextBox), I also modified the code to return the Control (this) instead of
this.TextBox.  This is what the code looks like
 
        object IContentVisual.Control
        {
            get { return this; }
        }
 
        void IContentVisual.Show()
        {
        }
 
This is the LSML part.
      <ControlProperty
                Name="IsApply"
                PropertyType=":Boolean"
                CategoryName="Appearance"
                EditorVisibility="PropertySheet">
        <ControlProperty.Attributes>
          <DisplayName Value="Can Load Automatically?" />
          <Description Value="Can Load Automatically?" />
        </ControlProperty.Attributes>
 
        <ControlProperty.DefaultValueSource>
          <ScreenExpressionTree>
            <ConstantExpression ResultType=":Boolean" Value="True"/>
          </ScreenExpressionTree>
        </ControlProperty.DefaultValueSource>
      </ControlProperty>
    </Control.Properties>

 
Everything works perfect on the Design Time/Runtime designers. But when I tried to access the property from Code-Behind, something like...
txtBox.IsApply = !txtBox.IsApply
I receiving "Cross Thread Access" error.  Then I moved the code inside the Main Dispatcher, but now I'm getting a "UnauthorizedAccess Exception". 
 
Whats the issue here?
-Bala
解决方案
txtBox.IsApply = !txtBox.IsApply
Where are you using this code? If you are trying to use it from LightSwitch application user code, the problem is that you cannot access or mutate objects from the screen's dispatcher (this is what causes the cross thread access exception). You must only
 do it from the main dispatcher (this is a restriction by Silverlight).
What is throwing the UnauthorizedAccessException and on what line of code? Could you provide a callstack. You can get this by turning off Just My Code from Tools->Options->Debug and then breaking on all exceptions (at least break on the UnauthorizedAccessException).


                        
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