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IToolboxUser Interface

Defines an interface for setting the currently selected toolbox item and indicating whether a designer supports a particular toolbox item.

Namespace:  System.Drawing.Design
Assembly:  System.Drawing (in System.Drawing.dll)

public interface IToolboxUser

The IToolboxUser type exposes the following members.

  NameDescription
Public methodGetToolSupportedGets a value indicating whether the specified tool is supported by the current designer.
Public methodToolPickedSelects the specified tool.
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This interface provides toolbox support functions to designers. The GetToolSupported method indicates whether the specified ToolboxItem can be used when the current designer is active. The ToolPicked method selects the specified ToolboxItem.

The following code example demonstrates an implementation of the IToolboxUser interface that can restrict support for specific types of ToolboxItem objects.

using System;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Design;
using System.Windows.Forms;
using System.Windows.Forms.Design;

// This example contains an IRootDesigner that implements the IToolboxUser interface. 
// This example demonstrates how to enable the GetToolSupported method of an IToolboxUser 
// designer in order to disable specific toolbox items, and how to respond to the  
// invocation of a ToolboxItem in the ToolPicked method of an IToolboxUser implementation. 
namespace IToolboxUserExample
{
    // This example component class demonstrates the associated IRootDesigner which  
    // implements the IToolboxUser interface. When designer view is invoked, Visual  
    // Studio .NET attempts to display a design mode view for the class at the top  
    // of a code file. This can sometimes fail when the class is one of multiple types  
    // in a code file, and has a DesignerAttribute associating it with an IRootDesigner.  
    // Placing a derived class at the top of the code file solves this problem. A  
    // derived class is not typically needed for this reason, except that placing the  
    // RootDesignedComponent class in another file is not a simple solution for a code  
    // example that is packaged in one segment of code. 
    public class RootViewSampleComponent : RootDesignedComponent
	{
	}

	// The following attribute associates the SampleRootDesigner with this example component.
	[DesignerAttribute(typeof(SampleRootDesigner), typeof(IRootDesigner))]
	public class RootDesignedComponent : System.Windows.Forms.Control
	{
	}

    // This example IRootDesigner implements the IToolboxUser interface and provides a  
    // Windows Forms view technology view for its associated component using an internal  
    // Control type.      
    // The following ToolboxItemFilterAttribute enables the GetToolSupported method of this 
    // IToolboxUser designer to be queried to check for whether to enable or disable all  
    // ToolboxItems which create any components whose type name begins with "System.Windows.Forms".
    [ToolboxItemFilterAttribute("System.Windows.Forms", ToolboxItemFilterType.Custom)]
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] 
    public class SampleRootDesigner : ParentControlDesigner, IRootDesigner, IToolboxUser
    {
        // This field is a custom Control type named RootDesignerView. This field references 
        // a control that is shown in the design mode document window. 
        private RootDesignerView view;

        // This string array contains type names of components that should not be added to  
        // the component managed by this designer from the Toolbox.  Any ToolboxItems whose  
        // type name matches a type name in this array will be marked disabled according to   
        // the signal returned by the IToolboxUser.GetToolSupported method of this designer. 
        private string[] blockedTypeNames =
        {
            "System.Windows.Forms.ListBox",
            "System.Windows.Forms.GroupBox"
        };

        // IRootDesigner.SupportedTechnologies is a required override for an IRootDesigner. 
        // This designer provides a display using the Windows Forms view technology.
        ViewTechnology[] IRootDesigner.SupportedTechnologies 
        {
            get { return new ViewTechnology[] {ViewTechnology.Default}; }
        }

        // This method returns an object that provides the view for this root designer.  
        object IRootDesigner.GetView(ViewTechnology technology) 
        {
            // If the design environment requests a view technology other than Windows  
            // Forms, this method throws an Argument Exception. 
            if (technology != ViewTechnology.Default)            
                throw new ArgumentException("An unsupported view technology was requested", 
                "Unsupported view technology.");            

            // Creates the view object if it has not yet been initialized. 
            if (view == null)                            
                view = new RootDesignerView(this);          

            return view;
        }

        // This method can signal whether to enable or disable the specified 
        // ToolboxItem when the component associated with this designer is selected. 
        bool IToolboxUser.GetToolSupported(ToolboxItem tool)
        {       
            // Search the blocked type names array for the type name of the tool 
            // for which support for is being tested. Return false to indicate the 
            // tool should be disabled when the associated component is selected. 
            for( int i=0; i<blockedTypeNames.Length; i++ )
                if( tool.TypeName == blockedTypeNames[i] )
                    return false;

            // Return true to indicate support for the tool, if the type name of the 
            // tool is not located in the blockedTypeNames string array. 
            return true;
        }

        // This method can perform behavior when the specified tool has been invoked. 
        // Invocation of a ToolboxItem typically creates a component or components,  
        // and adds any created components to the associated component. 
        void IToolboxUser.ToolPicked(ToolboxItem tool)
        {
        }

        // This control provides a Windows Forms view technology view object that  
        // provides a display for the SampleRootDesigner.
        [DesignerAttribute(typeof(ParentControlDesigner), typeof(IDesigner))]
        internal class RootDesignerView : Control
        {
            // This field stores a reference to a designer. 
            private IDesigner m_designer;

            public RootDesignerView(IDesigner designer)
            {
                // Perform basic control initialization.
                m_designer = designer;
                BackColor = Color.Blue;
                Font = new Font(Font.FontFamily.Name, 24.0f);                
            }

            // This method is called to draw the view for the SampleRootDesigner. 
            protected override void OnPaint(PaintEventArgs pe)
            {
                base.OnPaint(pe);
                // Draw the name of the component in large letters.
                pe.Graphics.DrawString(m_designer.Component.Site.Name, Font, Brushes.Yellow, ClientRectangle);
            }
        }
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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