Design-time rendering of User Control

Discussion in 'ASP .Net Building Controls' started by PV, Oct 29, 2003.

  1. PV

    PV Guest

    Like many others, I would like to replace the default "grey button" display
    of my user control with something that more closely (better yet exactly)
    resembles the runtime display of the control.

    In an attempt to do just this, I created my own designer class for my
    "Header" user control. For now, the designer just returns "<h1>Page
    Header</h1" from the GetDesignTimeHtml() method. Then I added the Designer
    attribute to the class definition for my Header user control's code-behind.
    There is no effect in the designer.

    I did a google search on this group, and have found suggestions, but not a
    confirmation that it is not possible to specify a designer for a user
    control. Can anybody confirm this for me? I don't see why it shouldn't
    work. Other than a "code in-front" page, what is the difference between a
    user control and a server control? They are just classes! Is it just
    laziness on the part of Microsoft? Or is there a real issue here?

    I would just avoid the situation and create a server control instead,
    however the very nature of my Header is such that I would like graphic
    designers to be able to modify it any time they want. Obviously a user
    control is what I need.

    I considered just wrapping my user control with a server control, but ...
    yeach. I don't want to go there.

    Suggestions?
     
    PV, Oct 29, 2003
    #1
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  2. PV

    PV Guest

    Further to this discussion, I discovered a class:
    System.Web.UI.Design.UserControlDesigner

    To test that it is being used by my user control, I removed my custom
    "Designer" attribute, and added the following code to the Page_Load method:

    System.ComponentModel.AttributeCollection attributes =
    TypeDescriptor.GetAttributes(this);

    DesignerAttribute myAttribute =

    (DesignerAttribute)attributes[typeof(DesignerAttribute)];

    this.Label1.Text = myAttribute.DesignerTypeName;

    Label1 did verify (at run time) that the UserControlDesigner is attached. I
    then added back in my custom designer attribute. Label1 verified that my
    new attribute was applied. However, there is no effect on the design-time
    environment. I even put code into the constructor of my designer to throw
    an exception. Still no effect in the design-time environment. It seems my
    custom designer isn't even being constructed!
     
    PV, Oct 29, 2003
    #2
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  3. You are correct. You can't do what you want.
     
    John Saunders, Oct 29, 2003
    #3
  4. PV

    JL Guest

    Ok but why? I'm curious..
     
    JL, Oct 30, 2003
    #4
  5. Because Microsoft said so. You'll have to ask them. They'll probably say
    something like "this is a limitation of user controls, which are meant to be
    convenient but not very feature-rich. These limitations can be overcome by
    writing a Web Custom Control".

    It would be nice if one or two of these feature limitations were removed in
    version 2.
     
    John Saunders, Oct 30, 2003
    #5
  6. Are User Control instanciated at design time ? It not it would explain the
    limited desing time support....

    Patrice

    --
     
    Patrice Scribe, Nov 3, 2003
    #6
  7. I assume that they are - Controls are instantiated and User Controls are
    Controls.

    --
    John


     
    John Saunders, Nov 4, 2003
    #7
  8. PV

    Teemu Keiski Guest

    Limited design-time support is just a design decision MS made with v.1. In
    becoming releases one can expect to see good design-time support for user
    controls as well (as is already with current version of Web Matrix).

    --
    Teemu Keiski
    MCP, Microsoft MVP (ASP.NET), AspInsiders member
    ASP.NET Forum Moderator, AspAlliance Columnist

     
    Teemu Keiski, Nov 6, 2003
    #8
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