zoukankan      html  css  js  c++  java
  • ******Can anyone explain me what do you mean by CreateControl

    from:
    http://social.msdn.microsoft.com/Forums/en/winforms/thread/eebdfa0d-696e-43c4-bcfc-7aabe027a44f

        Hi..i would like to know what is CreateControl() method.I have gone through msdn but i dint get any clear idea about its functioning.I would be glad if someone can explain it in simple words with an example.Thanks & Regards Nazima Mahmood
            ReplyReply
            QuoteQuote

    Answers

        Wednesday, November 16, 2011 10:26 AM
        Avatar of Bob Wu-MT
        Bob Wu-MT
        Chinasoft
        (MSFT CSG)
        2,010
         Answer
        Sign In to Vote
        0
        Sign In to Vote

        Hi Nazima,

        CreateControl() method is used to force a handle to be created for the control and its child controls, which means it create a windows handle.

        So, what is windows handle?

        Wiki give a great Explanation about handle. Widows handle is similar, it is  a handle which hides a real memory address from the API user, but allowing the system to reorganize physical memory transparently to the program(From: http://stackoverflow.com/questions/902967/what-is-a-windows-handle ).

        In my opinion, windows handle is an identifier of a control. MSDN also mentioned: simply calling a control's constructor does not create the Handle.

        To prove this, please try the code below:

        TabControl control = new TabControl();

        TabPage page = new TabPage();

        page.Name = "Some Name";

        page.Text = "Some Text";

        page.Tag = new UserControl();

        //control.CreateControl();          

        control.TabPages.Insert(0, page);

         

        If we try to get the value of control.TabPages.Count and control.TabCount, both of them are zero.

        If we call control.CreateControl(); method in the code, both of them are one.

        The reason is that the new usercontol call the constructor,which will not create the handle, and the windows can’t find it without a handle in first situation. If we call the CreateControl() method, a handle is created and we get the right result.

        Best Regards,

          
        Bob Wu [MSFT]
        MSDN Community Support | Feedback to us
            Marked As Answer byNazimaMonday, November 21, 2011 8:01 AM
             
            ReplyReply
            QuoteQuote

    All Replies

        Wednesday, November 16, 2011 10:26 AM
        Avatar of Bob Wu-MT
        Bob Wu-MT
        Chinasoft
        (MSFT CSG)
        2,010
         Answer
        Sign In to Vote
        0
        Sign In to Vote

        Hi Nazima,

        CreateControl() method is used to force a handle to be created for the control and its child controls, which means it create a windows handle.

        So, what is windows handle?

        Wiki give a great Explanation about handle. Widows handle is similar, it is  a handle which hides a real memory address from the API user, but allowing the system to reorganize physical memory transparently to the program(From: http://stackoverflow.com/questions/902967/what-is-a-windows-handle ).

        In my opinion, windows handle is an identifier of a control. MSDN also mentioned: simply calling a control's constructor does not create the Handle.

        To prove this, please try the code below:

        TabControl control = new TabControl();

        TabPage page = new TabPage();

        page.Name = "Some Name";

        page.Text = "Some Text";

        page.Tag = new UserControl();

        //control.CreateControl();          

        control.TabPages.Insert(0, page);

         

        If we try to get the value of control.TabPages.Count and control.TabCount, both of them are zero.

        If we call control.CreateControl(); method in the code, both of them are one.

        The reason is that the new usercontol call the constructor,which will not create the handle, and the windows can’t find it without a handle in first situation. If we call the CreateControl() method, a handle is created and we get the right result.

        Best Regards,

          
        Bob Wu [MSFT]
        MSDN Community Support | Feedback to us
            Marked As Answer byNazimaMonday, November 21, 2011 8:01 AM
             
            ReplyReply
            QuoteQuote
        Monday, November 21, 2011 8:02 AM
        Avatar of Nazima
        Nazima
        30
         
        Sign In to Vote
        0
        Sign In to Vote
        Thank You..Thanks & Regards Nazima Mahmood

  • 相关阅读:
    cogs 775. 山海经
    [HZOI 2016][Tyvj 1729]文艺平衡树 这道题我真是哭了,调了一下午,一晚上
    几种平衡树
    bzoj1124 [POI2008]枪战Maf
    [Usaco2007 Open]Fliptile 翻格子游戏
    团队冲刺08
    团队冲刺07
    团队冲刺06
    团队冲刺05
    团队冲刺04
  • 原文地址:https://www.cnblogs.com/luoyaoquan/p/2293590.html
Copyright © 2011-2022 走看看