dotnet windows forms designtime: I am writing a Windows Forms application using .NET 1.1, VS 2003 and C#.

There is a section of code in one of my form's constructors that needs to be
skipped over if the constructor is being called at design time.

Is there a way to conditionally execute this code only at runtime and not at
design time?

Thanks,
Dave
--
Dave Leach

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You can check form's Site.DesignMode property, which is set to true at
design time. The caveat there is that constructor is too early to
check for that as component is not yet sited at that point. You could
try overriding OnLoad() to see if that helps.
--
Sergey Mishkovskiy
http://www.usysware.com/dpack/ - DPack - free VS add-ons
http://www.usysware.com/blog/

Hi Dave,

Firstly, when we open a form in the designer, the code in the form's
constructor won't be called.

You have mentioned that you have a section of code in one of your form's
constructors that needs to be skipped over if the constructor is being
called at design time. It seems that the section of code must be in a base
form's constructor, and what you open in the form designer is an inherited
form.

It's no use to make use of the form's DesignMode property in the
constructor to determine whether it is at design time or run time, because
the Site property of the form has not been assigned when the form is being
constructed. The DesignMode property of the form always returns false when
we get its value in the constructor.

When the form's Load event handler is called, the form has already finished
the construction and the DesignMode property has a valid value. So the
solution is to move the section of code that you need to prevent from being
executed at design time to the form's Load event handler, and add a
condition of "! this.DesignMode" on the section of code.

Alternatively, you could implement the ISupportInitialize interface for the
base form and move the section of code to either of the ISupportInitialize
members -- BeginInit or EndInit method (of course, you still need to add "!
this.DesignMode" condition on the section of code).

When the base form implements the ISupportInitialize interface and we open
the inherited form in the designer, the code to call the
ISupportInitialize.BeginInit and ISupportInitilize.EndInit methods are
serialized in the InitializeComponent method of the inherited form. When
the ISupportInitialize.BeginInit or ISupportInitialize.EndInit method is
executed, the base form has already finished the construction, thus the
DesignMode property returns a valid value at this time.

Hope this helps.
If you have anything unclear, please feel free to let me know.


Sincerely,
Linda Liu
Microsoft Online Community Support

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Linda,

I have experimented with the ISupportInitialize interface, but without
success. I have copied some very simplified code below to demonstrate how I
have tried to use this interface. Note that I am applying the interface to a
derived control instead of the derived form as the original message stated.
This seemed like the more correct location for my application.

When I try to display the "DerivedForm" with the Forms Designer, the code
that causes the assert is still being reached, even though that code is
called from the EndInit() method and includes a test for DesignMode.

Please look at the code below and let me know if I am missing something.

Thanks,
Dave

===============Code Starts Here=================
public class MyPanelBase : System.Windows.Forms.UserControl,
ISupportInitialize
{
public MyPanelBase()
{
InitializeComponent();
}

protected virtual void FinishConstruction()
{
DoSomethingThatAssertsAtDesignTime();
}

// Virtual method overridden by derived class.
protected virtual void DoSomethingThatAssertsAtDesignTime()
{}

public void BeginInit()
{}

public void EndInit()
{
if ( !this.DesignMode )
{
DoSomethingThatAssertsAtDesignTime();
}
}
}

public class DerivedPanel : MyPanelBase
{
public DerivedPanel() : base()
{
InitializeComponent();
}

protected override void DoSomethingThatAssertsAtDesignTime()
{
DoSomethingAtRuntime(); // Causes VS2003 Assert at DesignTime.
}

private void InitializeComponent()
{
((System.ComponentModel.ISupportInitialize)(this)).BeginInit();
this.SuspendLayout();

// Controls go here...

((System.ComponentModel.ISupportInitialize)(this)).EndInit();
this.ResumeLayout(false);
}
}

public class DerivedForm : ChildFormBase
{
private DerivedPanel myDerivedPanel;

public DerivedForm() : base()
{
InitializeComponent();
}

private void InitializeComponent()
{
this.myDerivedPanel = new DerivedPanel();

((System.ComponentModel.ISupportInitialize)(this.myDerivedPanel)).BeginInit();
this.SuspendLayout();
//
// myDerivedPanel
//
this.myDerivedPanel.Location = new System.Drawing.Point(0, 50);
this.myDerivedPanel.Name = "myDerivedPanel";
this.myDerivedPanel.Size = new System.Drawing.Size(410, 140);
this.myDerivedPanel.TabIndex = 0;
//
// DerivedForm
//
this.AutoScaleBaseSize = new System.Drawing.Size(7, 17);
this.ClientSize = new System.Drawing.Size(432, 643);
this.Controls.Add(this.myDerivedPanel);
this.Icon =
((System.Drawing.Icon)(resources.GetObject("$this.Icon")));
this.Name = "DerivedForm";
this.Text = "My Form";

((System.ComponentModel.ISupportInitialize)(this.myDerivedPanel)).EndInit();
this.ResumeLayout(false);
}
}
===============Code Ends Here==================
--
Dave Leach
Agilent Technologies, Inc.


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