MailFileEditor Class
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MailFileEditor Class


Provides a user interface for selecting and editing a mail file name for a property at design time.

Namespace:   System.Web.UI.Design
Assembly:  System.Design (in System.Design.dll)


[SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)]
public class MailFileEditor : UrlEditor


Initializes a new instance of the MailFileEditor class.


Gets the caption for the editor dialog.(Overrides UrlEditor.Caption.)


Gets the file filter string for the dialog (such as "*.txt").(Overrides UrlEditor.Filter.)


Gets a value indicating whether drop-down editors should be resizable by the user.(Inherited from UITypeEditor.)


Gets the options for the URL builder to use.(Inherited from UrlEditor.)

System_CAPS_pubmethodEditValue(IServiceProvider, Object)

Edits the value of the specified object using the editor style indicated by the GetEditStyle method.(Inherited from UITypeEditor.)

System_CAPS_pubmethodEditValue(ITypeDescriptorContext, IServiceProvider, Object)

Edits the value of the specified object using the editor style provided by the GetEditStyle method.(Inherited from UrlEditor.)


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Gets the editor style used by the EditValue method.(Inherited from UITypeEditor.)


Gets the editing style of the EditValue method.(Inherited from UrlEditor.)


Serves as the default hash function. (Inherited from Object.)


Indicates whether this editor supports painting a representation of an object's value.(Inherited from UITypeEditor.)


Indicates whether the specified context supports painting a representation of an object's value within the specified context.(Inherited from UITypeEditor.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodPaintValue(Object, Graphics, Rectangle)

Paints a representation of the value of the specified object to the specified canvas.(Inherited from UITypeEditor.)


Paints a representation of the value of an object using the specified PaintValueEventArgs.(Inherited from UITypeEditor.)


Returns a string that represents the current object.(Inherited from Object.)

The MailFileEditor class is an UITypeEditor object that can be used at design time to select and edit a mail file name as a string, and assign the string to a control property. For example, the EmbeddedMailObject control uses the MailFileEditor class at design time to set the value of the Path property.

Use the EditorAttribute attribute to associate the MailFileEditor with a property. When the associated property is edited in the design surface, the designer host calls the EditValue method. The EditValue method displays a dialog box for selecting a mail file name from a filtered list of files, and returns the file name that is selected by the user. The GetEditStyle method indicates the display style of the user interface.

Derive a class from the MailFileEditor to define a custom editor for a mail file name property. For example, a derived class can override the EditValue method, and display an OpenFileDialog instance with a custom mail file filter or title.

The following code example demonstrates how to associate an instance of the MailFileEditor class with a property that is contained within a custom control. When the control property is edited in the design surface, the MailFileEditor class provides the user interface to select and edit a mail file name for the property value.

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Web.UI;
using System.Web.UI.Design;
using System.Web.UI.Design.WebControls;
using System.Web.UI.WebControls;

namespace ControlDesignerSamples.CS
    // Define a simple text control, derived from the 
    // System.Web.UI.WebControls.Label class.
    public class SimpleTextControl : Label
        // Define a private member to store the file name value in the control.
        private string _filename = "";
        private string _internalText = "";

        // Define the public file name property.  Indicate that the
        // property can be edited at design-time with the MailFileEditor class.
        public string MailFileName
                return _filename;
                _filename = value;

        // Define a property that returns the timestamp
        // for the selected file.
        public string LastChanged
                if ((_filename != null) && (_filename.Length > 0))
                    if (System.IO.File.Exists(_filename))
                        DateTime lastChangedStamp = System.IO.File.GetLastWriteTime(_filename);
                        return lastChangedStamp.ToLongDateString();
                return "";


        // Override the control Text property, setting the default
        // text to the LastChanged string value for the selected
        // file name.  If the file name has not been set in the
        // design view, then default to an empty string.
        public override string Text
                if ((_internalText == "") && (LastChanged.Length > 0))
                    // If the internally stored value hasn't been set,
                    // and the file name property has been set,
                    // return the last changed timestamp for the file.
                    _internalText = LastChanged;
                return _internalText;

                if ((value != null) && (value.Length > 0))
                    _internalText = value;
                else {
                    _internalText = "";


.NET Framework
Available since 2.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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