Class RadDropDownList

Represents a combo box control that displays a list of items from which the user can select. The RadDropDownList class is essentially a wrapper for the RadDropDownListElement component which implements the core UI and logic functionality. This control supports various selection modes, data binding, customization options, and can be integrated with other Telerik controls.

Inheritance
System.Object
RadControl
RadEditorControl
RadDropDownList
RadCheckedDropDownList
RadDomainUpDown
Inherited Members
Namespace: Telerik.WinControls.UI
Assembly: Telerik.WinControls.UI.dll

Syntax

[TelerikToolboxCategory("Data Controls")]
public class RadDropDownList : RadEditorControl, INotifyPropertyChanged, ISupportInitializeNotification, ISupportInitialize, IComponentTreeHandler, ILayoutHandler, IPCHost, IAnalyticsProvider, ISupportRootUIAutomation

Constructors

RadDropDownList()

Initializes a new instance of the RadDropDownList class. Sets default properties such as AutoSize to true, configures the control to be selectable, and establishes property bindings between the root element and dropdown list element.

Declaration
public RadDropDownList()

Fields

CreatingVisualListItemEventKey

Declaration
public static readonly object CreatingVisualListItemEventKey
Field Value
System.Object

KeyDownEventKey

Declaration
public static readonly object KeyDownEventKey
Field Value
System.Object

KeyPressEventKey

Declaration
public static readonly object KeyPressEventKey
Field Value
System.Object

KeyUpEventKey

Declaration
public static readonly object KeyUpEventKey
Field Value
System.Object

ListItemDataBindingEventKey

Declaration
public static readonly object ListItemDataBindingEventKey
Field Value
System.Object

ListItemDataBoundEventKey

Declaration
public static readonly object ListItemDataBoundEventKey
Field Value
System.Object

PopupClosedEventKey

Declaration
public static readonly object PopupClosedEventKey
Field Value
System.Object

PopupClosingEventKey

Declaration
public static readonly object PopupClosingEventKey
Field Value
System.Object

PopupOpenedEventKey

Declaration
public static readonly object PopupOpenedEventKey
Field Value
System.Object

PopupOpeningEventKey

Declaration
public static readonly object PopupOpeningEventKey
Field Value
System.Object

SelectedIndexChangedEventKey

Declaration
public static readonly object SelectedIndexChangedEventKey
Field Value
System.Object

SelectedIndexChangingEventKey

Declaration
public static readonly object SelectedIndexChangingEventKey
Field Value
System.Object

SelectedValueChangedEventKey

Declaration
public static readonly object SelectedValueChangedEventKey
Field Value
System.Object

SelectionRangeChangedKey

Declaration
public static readonly object SelectionRangeChangedKey
Field Value
System.Object

SortStyleChangedKey

Declaration
public static readonly object SortStyleChangedKey
Field Value
System.Object

VisualItemFormattingKey

Declaration
public static readonly object VisualItemFormattingKey
Field Value
System.Object

Properties

AllowShowFocusCues

Gets or sets a value indicating whether visual focus cues are displayed when the control has input focus. Focus cues are visual indicators (like a border or highlight) that show which control is currently active, improving accessibility and keyboard navigation feedback for users.

Declaration
public override bool AllowShowFocusCues { get; set; }
Property Value
System.Boolean

Overrides

AutoCompleteDataSource

Gets or sets the object that provides data items for the AutoComplete suggestion feature. When typing in the control with AutoComplete enabled, this data source is used to generate suggestions based on what the user is typing.

Declaration
public virtual object AutoCompleteDataSource { get; set; }
Property Value
System.Object

AutoCompleteDisplayMember

Gets or sets the property name used to display text for each item in the AutoComplete suggestion list. This property specifies which field from the AutoCompleteDataSource objects should be displayed in the suggestion list. Cannot be set to null - will be converted to an empty string.

Declaration
[RadDescription("DisplayMember", typeof(RadListElement))]
public virtual string AutoCompleteDisplayMember { get; set; }
Property Value
System.String

AutoCompleteMode

Gets or sets the mode for the automatic text completion feature used in the RadDropDownList. This property determines how autocomplete behavior works: None (disabled), Suggest (shows matching items), Append (automatically completes text in the editor), or SuggestAppend (combines both behaviors). This feature assists users in quickly finding and selecting items while typing.

Declaration
[RadDescription("AutoCompleteMode", typeof(RadDropDownListElement))]
public virtual AutoCompleteMode AutoCompleteMode { get; set; }
Property Value
System.Windows.Forms.AutoCompleteMode

AutoCompleteValueMember

Gets or sets the property name used to determine the value of items in the AutoComplete suggestion list. This property specifies which field from the AutoCompleteDataSource objects should be used as the underlying value when an AutoComplete suggestion is selected. Cannot be set to null - will be converted to an empty string.

Declaration
[RadDescription("ValueMember", typeof(RadListElement))]
public virtual string AutoCompleteValueMember { get; set; }
Property Value
System.String

AutoSize

Gets or sets a value indicating whether the RadDropDownList control automatically adjusts its size. When enabled, the control will resize itself to properly display its content and selected item, ensuring that text is not cut off and visual elements are properly aligned.

Declaration
public override bool AutoSize { get; set; }
Property Value
System.Boolean

Overrides

AutoSizeItems

Gets or sets a value that indicates whether items will be sized according to their content. When enabled, each item will automatically adjust its height based on its text, image, and other content. For fine-grained control, you can set the Height property of individual RadListDataItem objects in the Items collection to override the automatic sizing behavior for specific items.

Declaration
public virtual bool AutoSizeItems { get; set; }
Property Value
System.Boolean

CaseSensitive

Gets or sets a value indicating whether string comparisons are case-sensitive. When enabled, searching, filtering, and item selection operations will match the exact letter case, distinguishing between uppercase and lowercase letters. This affects text matching operations such as finding items during typing or when filtering the dropdown list.

Declaration
[RadDescription("CaseSensitive", typeof(RadDropDownListElement))]
public virtual bool CaseSensitive { get; set; }
Property Value
System.Boolean

CausesValidation

Gets or sets a value indicating whether the control causes validation to be performed on any controls that require validation when it receives focus. When set to true, this property ensures that validation rules are applied to other controls on the form before the focus moves to this control.

Declaration
public bool CausesValidation { get; set; }
Property Value
System.Boolean

true if the control causes validation to be performed on any controls requiring validation when it receives focus; otherwise, false. The default value is true.

DataMember

Gets or sets the name of the specific list or table within the data source that the RadDropDownList should display. This is particularly useful when the data source contains multiple tables or lists and you need to specify which one to use.

Declaration
public string DataMember { get; set; }
Property Value
System.String

DataSource

Gets or sets the data source for the RadDropDownList control. The data source can be any object that implements the IList or IListSource interface, such as a DataTable or an array of objects.

Declaration
[RadDefaultValue("DataSource", typeof(RadListElement))]
[RadDescription("DataSource", typeof(RadListElement))]
public object DataSource { get; set; }
Property Value
System.Object

DefaultItemsCountInDropDown

Gets or sets the default number of items displayed in the drop-down portion of the RadDropDownList before scrolling is required. This value is used to calculate the default dropdown height when no explicit height is specified.

Declaration
public virtual int DefaultItemsCountInDropDown { get; set; }
Property Value
System.Int32

DefaultSize

Gets the default size of the RadDropDownList control when it is first created. This defines the initial dimensions before any auto-sizing or manual resizing occurs.

Declaration
protected override Size DefaultSize { get; }
Property Value
System.Drawing.Size

A System.Drawing.Size object representing the default size of the control (125x20 pixels).

DescriptionTextMember

Gets or sets the property name used to extract descriptive text from data source items. When the control is bound to a data source, this property specifies which field provides additional descriptive text for each item. This text is accessible via the Value property of each RadListDataItem in the Items collection.

Declaration
public string DescriptionTextMember { get; set; }
Property Value
System.String

DisplayMember

Gets or sets the property name used to display text for each item in the dropdown list. When the control is bound to a data source, this property specifies which field from the data source objects should be displayed as text in the list items. Cannot be set to null - will be converted to an empty string.

Declaration
[RadDescription("DisplayMember", typeof(RadListElement))]
public string DisplayMember { get; set; }
Property Value
System.String

DropDownAnimationEasing

Gets or sets the easing type for the dropdown animation. The easing type controls the rate of change of the animation over time, creating effects like acceleration, deceleration, bouncing, etc. This property only has an effect when DropDownAnimationEnabled is true.

Declaration
public virtual RadEasingType DropDownAnimationEasing { get; set; }
Property Value
RadEasingType

DropDownAnimationEnabled

Gets or sets a value indicating whether the dropdown portion of the control will use animation effects when opening and closing. When enabled, the dropdown slides into view with a smooth transition effect rather than appearing instantly.

Declaration
public virtual bool DropDownAnimationEnabled { get; set; }
Property Value
System.Boolean

DropDownAnimationFrames

Gets or sets the number of frames that will be used when the dropdown is being animated. Higher frame counts result in smoother animations but may require more processing power. This property only has an effect when DropDownAnimationEnabled is true.

Declaration
public virtual int DropDownAnimationFrames { get; set; }
Property Value
System.Int32

DropDownHeight

Gets or sets the height in pixels of the drop-down portion of the RadDropDownList. This controls the vertical size of the popup that displays the list items when the dropdown is activated. If there are more items than can fit in the specified height, a scrollbar appears.

Declaration
[RadDescription("DropDownHeight", typeof(RadDropDownListElement))]
public virtual int DropDownHeight { get; set; }
Property Value
System.Int32

DropDownListElement

Gets the core RadDropDownListElement that implements the functionality of this control. This element manages the dropdown behavior, item display, and selection operations.

Declaration
public virtual RadDropDownListElement DropDownListElement { get; }
Property Value
RadDropDownListElement

DropDownMaxSize

Gets or sets the maximum size of the drop-down portion of the RadDropDownList. This defines the largest dimensions the dropdown can have, even when resizable or when containing many items. This helps ensure the dropdown remains manageable on screen.

Declaration
[RadDefaultValue("DropDownMaxSize", typeof(RadDropDownListElement))]
public virtual Size DropDownMaxSize { get; set; }
Property Value
System.Drawing.Size

DropDownMinSize

Gets or sets the minimum size of the drop-down portion of the RadDropDownList control. This defines the smallest dimensions the dropdown can have, regardless of content or the number of items. Setting a larger minimum size can improve usability by ensuring the dropdown is always large enough to be easily interacted with.

Declaration
public virtual Size DropDownMinSize { get; set; }
Property Value
System.Drawing.Size

DropDownSizingMode

Gets or sets a value from the SizingMode enumeration that determines how the drop-down popup can be resized by the user. Options include vertical resizing, horizontal resizing, resizing in both directions, or no resizing at all. When enabled, this allows users to dynamically adjust the size of the dropdown to see more items or view longer item content.

Declaration
public virtual SizingMode DropDownSizingMode { get; set; }
Property Value
SizingMode

DropDownStyle

Gets or sets a value specifying the style of the RadDropDownList. This determines how the control behaves: DropDown style allows direct text editing, while DropDownList style only permits selection from the dropdown list.

Declaration
[RadPropertyDefaultValue("DropDownStyle", typeof(RadDropDownListElement))]
public virtual RadDropDownStyle DropDownStyle { get; set; }
Property Value
RadDropDownStyle

EnableAlternatingItemColor

Gets or sets a value indicating whether alternating item color is enabled. When enabled, list items will be displayed with alternating background colors for better visual distinction between adjacent items in the dropdown list.

Declaration
public virtual bool EnableAlternatingItemColor { get; set; }
Property Value
System.Boolean

EnableKineticScrolling

Gets or sets a value indicating whether the kinetic scrolling function is enabled. When enabled, the dropdown list will support momentum-based scrolling, providing a more natural touch-friendly experience where scrolling continues briefly after the user releases their touch gesture, simulating physical inertia.

Declaration
public virtual bool EnableKineticScrolling { get; set; }
Property Value
System.Boolean

EnableMouseWheel

Gets or sets a value indicating whether mouse wheel scrolling is enabled. When enabled, users can navigate through the dropdown list items by rotating the mouse wheel, changing the selected item without having to click directly on items.

Declaration
public bool EnableMouseWheel { get; set; }
Property Value
System.Boolean

EnableUIAutomation

Gets or sets a value indicating whether UI Automation support is enabled for this control. When enabled, the control provides accessibility information to assistive technologies.

Declaration
public override bool EnableUIAutomation { get; set; }
Property Value
System.Boolean

Overrides
Implements

Filter

Gets or sets a predicate function that determines which RadListDataItem objects should be visible in the dropdown list. Items for which the predicate returns true will be displayed, while items for which it returns false will be hidden. This provides programmatic filtering capability.

Declaration
public Predicate<RadListDataItem> Filter { get; set; }
Property Value
System.Predicate<RadListDataItem>

FilterExpression

Gets or sets a string expression that determines which items will be visible in the dropdown list. The filter expression is a string-based alternative to the Filter predicate, allowing filtering to be specified declaratively in design-time properties or through data binding.

Declaration
public string FilterExpression { get; set; }
Property Value
System.String

FindStringComparer

Gets or sets an object that implements IFindStringComparer interface. This property provides custom string comparison functionality used by the FindString methods when searching for items in the drop-down list. It allows you to implement custom search logic such as case-insensitive or culture-specific comparisons.

Declaration
public IFindStringComparer FindStringComparer { get; set; }
Property Value
IFindStringComparer

FitItemsToSize

Gets or sets a value indicating whether items should be resized to fit the available width in the drop-down list. When enabled, items will automatically adjust their width to match the width of the dropdown area, preventing horizontal scrolling and ensuring all content fits within the visible area.

Declaration
public virtual bool FitItemsToSize { get; set; }
Property Value
System.Boolean

Font

Gets or sets the font used for text display in the control. This property affects the font of the root element. Setting this property to null resets the font to the default value defined in the currently applied theme. This provides consistent typography styling across themed controls.

Declaration
public override Font Font { get; set; }
Property Value
System.Drawing.Font

Overrides

FormatInfo

Gets or sets an object that implements the IFormatProvider interface. This object is used when formatting items displayed in the dropdown list. The default provider is CultureInfo.CurrentCulture, which formats items according to the current system locale settings.

Declaration
public virtual IFormatProvider FormatInfo { get; set; }
Property Value
System.IFormatProvider

FormatString

Gets or sets a format string that will be used for visual item formatting if FormattingEnabled is set to true. The format string follows the .NET formatting syntax (like "{0:C}") and applies to the display value of each item, allowing for custom formatting of numeric values, dates, or other data types.

Declaration
public virtual string FormatString { get; set; }
Property Value
System.String

FormattingEnabled

Gets or sets a value that determines whether text formatting is enabled for the visual items. When enabled, the control applies the format specified by FormatString to the display values, allowing for custom formatting such as currency symbols, date formats, or numeric precision.

Declaration
[RadDescription("FormattingEnabled", typeof(RadDropDownListElement))]
public virtual bool FormattingEnabled { get; set; }
Property Value
System.Boolean

IsFilterActive

Gets a value indicating whether there is either a Filter predicate or a FilterExpression string currently set and active. This property helps determine if the items in the dropdown are being filtered by any mechanism.

Declaration
public bool IsFilterActive { get; }
Property Value
System.Boolean

IsPopupVisible

Gets a value indicating whether the dropdown popup portion of the control is currently visible. This read-only property can be used to determine if the dropdown list is open or closed.

Declaration
public virtual bool IsPopupVisible { get; }
Property Value
System.Boolean

ItemHeight

Gets or sets the height in pixels for all items in the dropdown list. This property determines the uniform height of each item in the list, affecting the overall appearance and spacing. Note that this property is ignored when AutoSizeItems is set to true.

Declaration
public int ItemHeight { get; set; }
Property Value
System.Int32

Items

Gets the collection of RadListDataItem objects that represent the items displayed in this dropdown list. This collection can be modified directly to add, remove, or modify items in the dropdown.

Declaration
public virtual RadListDataItemCollection Items { get; }
Property Value
RadListDataItemCollection

ItemsSortComparer

Gets or sets an object that implements System.Collections.Generic.IComparer<T> which is used when sorting items. This property allows you to define a custom sorting algorithm for the items displayed in the drop-down list, providing greater flexibility than the default alphabetical sorting.

Declaration
public IComparer<RadListDataItem> ItemsSortComparer { get; set; }
Property Value
System.Collections.Generic.IComparer<RadListDataItem>

ListElement

Gets or sets the RadListElement that manages the list portion of this dropdown control. This element is responsible for displaying, arranging, and managing the list items in the dropdown.

Declaration
public RadListElement ListElement { get; set; }
Property Value
RadListElement

MaxDropDownItems

Gets or sets the maximum number of items to be shown in the drop-down portion of the RadDropDownList without requiring scrolling. A value of 0 means that all items will be shown without a scrollbar if space permits; otherwise, the dropdown will display the specified number of items and provide scrolling for additional items.

Declaration
public virtual int MaxDropDownItems { get; set; }
Property Value
System.Int32

MaxLength

Gets or sets the maximum number of characters the user can type or paste into the text box portion of the RadDropDownList control. This property primarily affects the control when using DropDown style, as it limits the length of text that can be manually entered. Has no effect when the control is in DropDownList mode.

Declaration
public virtual int MaxLength { get; set; }
Property Value
System.Int32

NullText

Gets or sets the text that is displayed when RadDropDownList has no text set. This placeholder text appears in a grayed-out font when the control has focus but no value has been entered or selected, providing users with guidance on what to enter or select.

Declaration
[RadDefaultValue("NullText", typeof(RadTextBoxItem))]
[RadDescription("NullText", typeof(RadTextBoxItem))]
public string NullText { get; set; }
Property Value
System.String

Popup

Gets a reference to the drop-down popup form associated with this RadDropDownList. This property provides access to the actual popup control, allowing you to customize its appearance, behavior, and content at runtime or during design.

Declaration
public virtual RadEditorPopupControlBase Popup { get; }
Property Value
RadEditorPopupControlBase

ReadOnly

Gets or sets a value indicating whether the dropdown list is read-only. When set to true, users can view the content but cannot change the selection or edit the text in the control. This is useful for display-only scenarios where user interaction should be prevented.

Declaration
public virtual bool ReadOnly { get; set; }
Property Value
System.Boolean

SelectedIndex

Gets or sets the zero-based index of the currently selected item in the dropdown list. A value of -1 indicates that no item is selected. Setting this property will cause the SelectedIndexChanging and SelectedIndexChanged events to fire and will update the displayed text to match the newly selected item.

Declaration
public virtual int SelectedIndex { get; set; }
Property Value
System.Int32

SelectedItem

Gets or sets the currently selected RadListDataItem in the dropdown list. This is the actual item object rather than just its value or index. Setting this property will trigger the selection changed events and update the displayed text.

Declaration
public virtual RadListDataItem SelectedItem { get; set; }
Property Value
RadListDataItem

SelectedItems

Provides a read-only collection of the currently selected items in the dropdown list. While the RadDropDownList typically allows only single selection, this property maintains interface compatibility with other list controls.

Declaration
public IReadOnlyCollection<RadListDataItem> SelectedItems { get; }
Property Value
IReadOnlyCollection<RadListDataItem>

SelectedText

Gets or sets the text that is currently selected in the editable portion of the DropDownList. This property is only applicable when the control has an editable text portion. Setting this property replaces the selected text with the specified value.

Declaration
public string SelectedText { get; set; }
Property Value
System.String

SelectedValue

Gets or sets the value of the currently selected item in the dropdown list. This corresponds to the value of the property specified by ValueMember. Setting this property to a value that is shared by multiple items will select the first matching item. Setting this property will trigger the selection changed events.

Declaration
public virtual object SelectedValue { get; set; }
Property Value
System.Object

SelectionLength

Gets or sets the number of characters selected in the editable portion of the drop-down list. This property allows you to determine or control the length of the current text selection. A value of 0 indicates that no text is selected (the caret is positioned without selection).

Declaration
public int SelectionLength { get; set; }
Property Value
System.Int32

SelectionStart

Gets or sets the starting character position of the current text selection in the editable portion of the drop-down list. The index is zero-based, meaning the first character position is 0, not 1. This property is only applicable when the control has an editable text portion.

Declaration
public int SelectionStart { get; set; }
Property Value
System.Int32

SelectNextOnDoubleClick

Gets or sets a value indicating whether the control should automatically select the next item when the user double-clicks in the edit box area. When enabled, this feature allows users to cycle through available options without opening the dropdown, providing a quick way to browse through sequential items in the list.

Declaration
[RadDescription("SelectNextOnDoubleClick", typeof(RadDropDownListElement))]
public virtual bool SelectNextOnDoubleClick { get; set; }
Property Value
System.Boolean

ShowImageInEditorArea

Gets or sets a value indicating whether the RadListDataItem image will be displayed in the editor element when DropDownStyle is set to DropDownList. When enabled, images associated with list items will be shown alongside text in the main control area.

Declaration
public virtual bool ShowImageInEditorArea { get; set; }
Property Value
System.Boolean

SortStyle

Gets or sets the sort style for items in the dropdown list. It can be Ascending, Descending, or None. When sorting is enabled, items are ordered based on the property specified by DisplayMember. This affects how items appear in the dropdown portion of the control.

Declaration
public virtual SortStyle SortStyle { get; set; }
Property Value
SortStyle

TabStop

Gets or sets a value indicating whether the user can give the focus to this control using the TAB key. The behavior varies based on the current DropDownStyle: when set to DropDownList, the focus applies to the text box element, otherwise it applies to the control itself.

Declaration
public bool TabStop { get; set; }
Property Value
System.Boolean

true if the user can give the focus to the control using the TAB key; otherwise, false.

Text

Gets or sets the text associated with this control. The text represents the content displayed in the editable portion of the drop-down list control.

Declaration
public override string Text { get; set; }
Property Value
System.String

Overrides

UIAutomationProvider

Gets the UI Automation Provider that exposes this control to UI Automation clients. This property is used by accessibility technologies to interact with the control.

Declaration
public IRadRawElementProviderFragmentRoot UIAutomationProvider { get; }
Property Value
IRadRawElementProviderFragmentRoot

Implements

ValueMember

Gets or sets the property name used to determine the underlying value of each item in the dropdown list. When the control is bound to a data source, this property specifies which field from the data source should be used as the value when an item is selected. This value is accessible through the SelectedValue property. Cannot be set to null - will be converted to an empty string.

Declaration
[RadDescription("ValueMember", typeof(RadListElement))]
public string ValueMember { get; set; }
Property Value
System.String

Methods

BeginUpdate()

Suspends visual updates of the control. Call this method before making multiple changes to the control to prevent flickering and improve performance. Each call to BeginUpdate must be paired with a corresponding call to EndUpdate.

Declaration
public virtual void BeginUpdate()
See Also

CloseDropDown()

Programmatically hides the drop-down popup if it is currently displayed on the screen. This method allows you to close the list programmatically without user interaction, which is useful in scenarios where you need to dismiss the popup based on custom logic.

Declaration
public virtual void CloseDropDown()

ControlDefinesThemeForElement(RadElement)

Declaration
public override bool ControlDefinesThemeForElement(RadElement element)
Parameters
RadElement element

Returns
System.Boolean

Overrides

CreateAccessibilityInstance()

Creates and returns an accessibility object for this control. This method is used by accessibility technologies like screen readers to interact with the control.

Declaration
protected override AccessibleObject CreateAccessibilityInstance()
Returns
System.Windows.Forms.AccessibleObject

An System.Windows.Forms.AccessibleObject representing this control for accessibility purposes.

CreateChildItems(RadElement)

Creates and initializes the child elements of the RadDropDownList control. This method creates a new RadDropDownListElement, adds it to the control's element hierarchy, and wires up the necessary events.

Declaration
protected override void CreateChildItems(RadElement parent)
Parameters
RadElement parent

The parent element that will contain the child items.
Overrides

CreateDropDownListElement()

Creates a new instance of the RadDropDownListElement class that will be used as the core element of this dropdown list control. Override this method in derived classes to provide custom dropdown element implementations.

Declaration
protected virtual RadDropDownListElement CreateDropDownListElement()
Returns
RadDropDownListElement

A new instance of the RadDropDownListElement class.

CreateRootElement()

Declaration
protected override RootRadElement CreateRootElement()
Returns
RootRadElement

Overrides

DeferRefresh()

Defers the visual refresh of the control until the returned IDisposable object is disposed. This method provides a convenient way to use the using statement to temporarily suspend updates during a block of code that makes multiple changes to the control.

Declaration
public virtual IDisposable DeferRefresh()
Returns
System.IDisposable

An IDisposable object that, when disposed, will resume visual updates and refresh the control.

Dispose(Boolean)

Releases the resources used by the RadDropDownList control.

Declaration
protected override void Dispose(bool disposing)
Parameters
System.Boolean disposing

true to release both managed and unmanaged resources; false to release only unmanaged resources.
Overrides

dropDownListElement_KeyDown(Object, KeyEventArgs)

Handles the key down event of the dropdown list element.

Declaration
protected virtual void dropDownListElement_KeyDown(object sender, KeyEventArgs e)
Parameters
System.Object sender

The source of the event.
System.Windows.Forms.KeyEventArgs e

The key event data.

dropDownListElement_KeyPress(Object, KeyPressEventArgs)

Handles the key press event of the dropdown list element.

Declaration
protected virtual void dropDownListElement_KeyPress(object sender, KeyPressEventArgs e)
Parameters
System.Object sender

The source of the event.
System.Windows.Forms.KeyPressEventArgs e

The key press event data.

dropDownListElement_KeyUp(Object, KeyEventArgs)

Handles the key up event of the dropdown list element.

Declaration
protected virtual void dropDownListElement_KeyUp(object sender, KeyEventArgs e)
Parameters
System.Object sender

The source of the event.
System.Windows.Forms.KeyEventArgs e

The key event data.

element_PopupClosed(Object, RadPopupClosedEventArgs)

Handles the popup closed event of the dropdown list element.

Declaration
protected virtual void element_PopupClosed(object sender, RadPopupClosedEventArgs args)
Parameters
System.Object sender

The source of the event.
RadPopupClosedEventArgs args

The popup closed event data.

element_PopupClosing(Object, RadPopupClosingEventArgs)

Handles the popup closing event of the dropdown list element.

Declaration
protected virtual void element_PopupClosing(object sender, RadPopupClosingEventArgs args)
Parameters
System.Object sender

The source of the event.
RadPopupClosingEventArgs args

The popup closing event data.

element_PopupOpened(Object, EventArgs)

Handles the popup opened event of the dropdown list element.

Declaration
protected virtual void element_PopupOpened(object sender, EventArgs e)
Parameters
System.Object sender

The source of the event.
System.EventArgs e

The event data.

element_PopupOpening(Object, CancelEventArgs)

Handles the popup opening event of the dropdown list element.

Declaration
protected virtual void element_PopupOpening(object sender, CancelEventArgs e)
Parameters
System.Object sender

The source of the event.
System.ComponentModel.CancelEventArgs e

The event data that allows cancellation of the opening.

EndInit()

Resumes layout operations after initialization of the RadDropDownList is complete. Applies the binding context to ensure proper data binding between the control and its data source.

Declaration
public override void EndInit()
Overrides

EndUpdate()

Resumes visual updates of the control after a call to BeginUpdate. Call this method after completing multiple changes to the control to resume visual updates and apply all pending changes at once. Each call to EndUpdate must be preceded by a corresponding call to BeginUpdate.

Declaration
public virtual void EndUpdate()
See Also

FindItemExact(String, Boolean)

Searches for an item in the list that exactly matches the specified text.

Declaration
public RadListDataItem FindItemExact(string text, bool caseSensitive)
Parameters
System.String text

The text to search for in the list items.
System.Boolean caseSensitive

A value indicating whether the search should be case-sensitive.
Returns
RadListDataItem

The RadListDataItem that exactly matches the specified text, or null if no match is found.

FindString(String)

Searches for an item in the list that matches the specified string according to the current FindStringComparer. By default, the FindStringComparer uses the System.String.StartsWith() method for string comparison. This method starts searching from index 0, and if it reaches the end of the Items collection, it wraps to the beginning and continues until it has searched the entire collection.

Declaration
public int FindString(string s)
Parameters
System.String s

The string to search for in the list items.
Returns
System.Int32

The zero-based index of the first matching item, or -1 if no match is found.

FindString(String, Int32)

Searches for an item in the list that matches the specified string according to the current FindStringComparer. By default, the FindStringComparer uses the System.String.StartsWith() method for string comparison. This method starts searching from the specified index, and if it reaches the end of the Items collection, it wraps to the beginning and continues until it reaches one position before the starting index.

Declaration
public int FindString(string s, int startIndex)
Parameters
System.String s

The string to search for in the list items.
System.Int32 startIndex

The zero-based index at which to start the search.
Returns
System.Int32

The zero-based index of the first matching item, or -1 if no match is found.

FindStringExact(String)

Searches for an item in the list that exactly matches the specified string. Unlike FindString, this method requires an exact match rather than a partial match. The search starts from index 0 and searches the entire list.

Declaration
public int FindStringExact(string s)
Parameters
System.String s

The string to search for in the list items.
Returns
System.Int32

The zero-based index of the first exactly matching item, or -1 if no exact match is found.

FindStringExact(String, Int32)

Searches for an item in the list that exactly matches the specified string. Unlike FindString, this method requires an exact match rather than a partial match. This method starts searching from the specified index, and if it reaches the end of the Items collection, it wraps to the beginning and continues until it reaches one position before the starting index.

Declaration
public int FindStringExact(string s, int startIndex)
Parameters
System.String s

The string to search for in the list items.
System.Int32 startIndex

The zero-based index at which to start the search.
Returns
System.Int32

The zero-based index of the first exactly matching item, or -1 if no exact match is found.

FindStringNonWrapping(String)

Searches for an item in the list that matches the specified string according to the current FindStringComparer, but unlike FindString, it does not wrap around to the beginning when the end of the list is reached. The search starts from index 0 and continues until the end of the list.

Declaration
public int FindStringNonWrapping(string s)
Parameters
System.String s

The string to search for in the list items.
Returns
System.Int32

The zero-based index of the first matching item, or -1 if no match is found.

FindStringNonWrapping(String, Int32)

Searches for an item in the list that matches the specified string according to the current FindStringComparer, but unlike FindString, it does not wrap around to the beginning when the end of the list is reached. The search starts from the specified index and continues until the end of the list.

Declaration
public int FindStringNonWrapping(string s, int startIndex)
Parameters
System.String s

The string to search for in the list items.
System.Int32 startIndex

The zero-based index at which to start the search.
Returns
System.Int32

The zero-based index of the first matching item, or -1 if no match is found.

IsInputChar(Char)

Declaration
protected override bool IsInputChar(char charCode)
Parameters
System.Char charCode

Returns
System.Boolean

IsInputKey(Keys)

Declaration
protected override bool IsInputKey(Keys keyData)
Parameters
System.Windows.Forms.Keys keyData

Returns
System.Boolean

Overrides

OnBindingContextChanged(EventArgs)

Declaration
protected override void OnBindingContextChanged(EventArgs e)
Parameters
System.EventArgs e

Overrides

OnCreatingVisualItem(Object, CreatingVisualListItemEventArgs)

Declaration
protected virtual void OnCreatingVisualItem(object sender, CreatingVisualListItemEventArgs args)
Parameters
System.Object sender

CreatingVisualListItemEventArgs args

OnDataBindingComplete(Object, ListBindingCompleteEventArgs)

Raises the DataBindingComplete event. This method is called after a data binding operation completes, allowing derived classes to handle this event without attaching a delegate.

Declaration
protected virtual void OnDataBindingComplete(object sender, ListBindingCompleteEventArgs e)
Parameters
System.Object sender

The source of the event.
ListBindingCompleteEventArgs e

An ListBindingCompleteEventArgs instance that contains information about the binding operation.
See Also

OnEnter(EventArgs)

Raises the System.Windows.Forms.Control.Enter event.

Declaration
protected override void OnEnter(EventArgs e)
Parameters
System.EventArgs e

An System.EventArgs that contains the event data.

OnGotFocus(EventArgs)

Raises the System.Windows.Forms.Control.GotFocus event.

Declaration
protected override void OnGotFocus(EventArgs e)
Parameters
System.EventArgs e

An System.EventArgs that contains the event data.
Overrides

OnItemDataBinding(Object, ListItemDataBindingEventArgs)

Raises the ItemDataBinding event.

Declaration
protected virtual void OnItemDataBinding(object sender, ListItemDataBindingEventArgs args)
Parameters
System.Object sender

The source of the event.
ListItemDataBindingEventArgs args

A ListItemDataBindingEventArgs that contains the event data.

OnItemDataBound(Object, ListItemDataBoundEventArgs)

Raises the ItemDataBound event.

Declaration
protected virtual void OnItemDataBound(object sender, ListItemDataBoundEventArgs args)
Parameters
System.Object sender

The source of the event.
ListItemDataBoundEventArgs args

A ListItemDataBoundEventArgs that contains the event data.

OnLeave(EventArgs)

Raises the System.Windows.Forms.Control.Leave event.

Declaration
protected override void OnLeave(EventArgs e)
Parameters
System.EventArgs e

An System.EventArgs that contains the event data.

OnLostFocus(EventArgs)

Raises the System.Windows.Forms.Control.LostFocus event.

Declaration
protected override void OnLostFocus(EventArgs e)
Parameters
System.EventArgs e

An System.EventArgs that contains the event data.
Overrides

OnRightToLeftChanged(EventArgs)

Raises the System.Windows.Forms.Control.RightToLeftChanged event. This method is called when the System.Windows.Forms.Control.RightToLeft property value changes, allowing the control to update its appearance and layout for right-to-left languages.

Declaration
protected override void OnRightToLeftChanged(EventArgs e)
Parameters
System.EventArgs e

An System.EventArgs that contains the event data.
Overrides

OnSelectedIndexChanged(Object, Int32)

Declaration
protected virtual void OnSelectedIndexChanged(object sender, int newIndex)
Parameters
System.Object sender

System.Int32 newIndex

OnSelectedIndexChanging(Object, Int32)

Declaration
protected virtual bool OnSelectedIndexChanging(object sender, int newIndex)
Parameters
System.Object sender

System.Int32 newIndex

Returns
System.Boolean

OnSelectedValueChanged(Object, Int32, Object, Object)

Declaration
protected virtual void OnSelectedValueChanged(object sender, int newIndex, object oldValue, object newValue)
Parameters
System.Object sender

System.Int32 newIndex

System.Object oldValue

System.Object newValue

OnSortStyleChanged(SortStyle)

Raises the SortStyleChanged event.

Declaration
protected virtual void OnSortStyleChanged(SortStyle sortStyle)
Parameters
SortStyle sortStyle

The new sort style that was applied to the dropdown list.

OnVisualItemFormatting(RadListVisualItem)

Raises the VisualItemFormatting event.

Declaration
protected virtual void OnVisualItemFormatting(RadListVisualItem item)
Parameters
RadListVisualItem item

The RadListVisualItem being formatted.

ProcessAutoSizeChanged(Boolean)

Declaration
protected override void ProcessAutoSizeChanged(bool value)
Parameters
System.Boolean value

Overrides

ProcessCodedUIMessage(ref IPCMessage)

Declaration
protected override void ProcessCodedUIMessage(ref IPCMessage request)
Parameters
IPCMessage request

Overrides

Rebind()

Forces a re-evaluation and refresh of the current data source. This method is useful when the underlying data in the data source has changed and you need the control to reflect these changes without explicitly reassigning the DataSource property.

Declaration
public void Rebind()

ResetBackColorThemeOverrides()

Declaration
protected override void ResetBackColorThemeOverrides()
Overrides

ResetForeColorThemeOverrides()

Declaration
protected override void ResetForeColorThemeOverrides()
Overrides

SelectAll()

Selects all items in the drop-down list if the SelectionMode property allows multiple selection. This method can be used to quickly select all available options in the list when working with multi-select drop-down lists.

Declaration
public void SelectAll()
Exceptions
System.InvalidOperationException

Thrown when attempting to select all items in a selection mode that doesn't support multiple selection.

SelectAllText()

Selects all the text in the editable portion of the RadDropDownList. This is only applicable when DropDownStyle is set to DropDown. This method provides a convenient way to select the entire text content for quick editing or replacement.

Declaration
public void SelectAllText()

SelectText(Int32, Int32)

Selects a range of text in the editable portion of the RadDropDownList. This is only applicable when DropDownStyle is set to DropDown. Use this method to programmatically select text in the control for operations like cut, copy, or deletion.

Declaration
public void SelectText(int start, int length)
Parameters
System.Int32 start

The position of the first character to be selected within the text box (zero-based index).
System.Int32 length

The number of characters to select.

SetBackColorThemeOverrides()

Declaration
protected override void SetBackColorThemeOverrides()
Overrides

SetForeColorThemeOverrides()

Declaration
protected override void SetForeColorThemeOverrides()
Overrides

ShowDropDown()

Programmatically displays the drop-down popup on the screen, showing the list of available items. This method is equivalent to clicking the drop-down button with the mouse. It allows you to open the list programmatically without user interaction.

Declaration
public virtual void ShowDropDown()

WndProc(ref Message)

Declaration
protected override void WndProc(ref Message m)
Parameters
System.Windows.Forms.Message m

Overrides

Events

CreatingVisualListItem

Occurs when the control needs to create visual items to represent data items in the view. This event provides the opportunity to create custom visual representations of list items, allowing for advanced visual customization beyond the standard appearance. The event fires both during initial rendering and when the control is resized.

Declaration
public event CreatingVisualListItemEventHandler CreatingVisualListItem
Event Type
CreatingVisualListItemEventHandler

DataBindingComplete

Occurs when a data binding operation on the control has been completed. This event provides an opportunity to perform additional processing after items have been loaded from the data source, such as selecting a default item or performing custom filtering.

Declaration
public event ListBindingCompleteEventHandler DataBindingComplete
Event Type
ListBindingCompleteEventHandler

See Also

ItemDataBinding

Occurs before each RadListDataItem is bound to a data item from the data source. This event is raised once for each item in the data source during the data binding process, allowing you to customize how each item is created and initialized before it appears in the list. You can provide your own custom RadListDataItem implementation through the event arguments.

Declaration
public event ListItemDataBindingEventHandler ItemDataBinding
Event Type
ListItemDataBindingEventHandler

ItemDataBound

Occurs after each RadListDataItem has been bound to a data item from the data source. This event is raised once for each item in the data source after the initial binding process is complete, allowing you to perform additional customization or formatting of the list item based on the bound data.

Declaration
public event ListItemDataBoundEventHandler ItemDataBound
Event Type
ListItemDataBoundEventHandler

KeyDown

Occurs when a key is pressed while the control has focus. This event is raised before the KeyPress event and can be used to detect and handle special keys such as function keys, arrow keys, and other non-character keys.

Declaration
public event KeyEventHandler KeyDown
Event Type
System.Windows.Forms.KeyEventHandler

KeyPress

Occurs when a character key is pressed while the control has focus. This event can be used to intercept and handle specific character inputs before they are processed by the control, enabling custom input validation or special key handling.

Declaration
public event KeyPressEventHandler KeyPress
Event Type
System.Windows.Forms.KeyPressEventHandler

KeyUp

Occurs when a key is released while the control has focus. This event is useful for detecting when the user releases a keyboard key, which can be used for implementing custom keyboard navigation or shortcuts.

Declaration
public event KeyEventHandler KeyUp
Event Type
System.Windows.Forms.KeyEventHandler

PopupClosed

Occurs when the drop-down popup has been fully closed. This event is raised after the popup is no longer visible to the user. The event arguments contain information about the cause of the closing action, which can be used to perform different operations based on how the popup was closed.

Declaration
public virtual event RadPopupClosedEventHandler PopupClosed
Event Type
RadPopupClosedEventHandler

PopupClosing

Occurs just before the drop-down popup is about to be closed. This event provides an opportunity to cancel the closing operation or to perform cleanup operations before the popup disappears. The event arguments contain information about the cause of the closing action.

Declaration
public virtual event RadPopupClosingEventHandler PopupClosing
Event Type
RadPopupClosingEventHandler

PopupOpened

Occurs when the drop-down popup has been fully opened and displayed to the user. This event can be used to perform initialization tasks after the popup becomes visible, such as adjusting scroll position or focusing specific items.

Declaration
public virtual event EventHandler PopupOpened
Event Type
System.EventHandler

PopupOpening

Occurs just before the drop-down popup is displayed to the user. This event can be used to cancel the opening of the popup or to perform last-minute modifications to the items displayed in the list before they become visible.

Declaration
public virtual event CancelEventHandler PopupOpening
Event Type
System.ComponentModel.CancelEventHandler

SelectedIndexChanged

Occurs when the index of the currently selected item in the drop-down list changes. This event is raised when the user selects a new item from the list or when the SelectedIndex property is programmatically changed. The event arguments provide information about the previous and current selection position.

Declaration
public event PositionChangedEventHandler SelectedIndexChanged
Event Type
PositionChangedEventHandler

SelectedIndexChanging

Occurs just before the selected index in the drop-down list is about to change. This event allows you to cancel the selection change by setting the Cancel property of the event arguments to true, providing a way to validate or restrict item selection based on custom business logic.

Declaration
public event PositionChangingEventHandler SelectedIndexChanging
Event Type
PositionChangingEventHandler

SelectedValueChanged

Occurs when the value of the currently selected item in the drop-down list changes. Unlike the SelectedIndexChanged event, this event only fires when the actual value changes, not just the index. For example, if two different items in the list have the same value, selecting between them will not trigger this event.

Declaration
public event EventHandler SelectedValueChanged
Event Type
System.EventHandler

SortStyleChanged

Occurs when the sorting style of the drop-down list items changes. This event allows you to respond to changes in how items are sorted in the list, which can be useful for performing additional operations after the sort order has changed.

Declaration
public event SortStyleChangedEventHandler SortStyleChanged
Event Type
SortStyleChangedEventHandler

TextChanged

Occurs when the Text property value changes. This event is raised after the text displayed in the control is modified either by user input or programmatically.

Declaration
public event EventHandler TextChanged
Event Type
System.EventHandler

VisualListItemFormatting

Occurs when a visual list item needs to be formatted. This event fires when a property of a visible data item changes or when a visual item is associated with a new data item (such as during scrolling). It provides the opportunity to customize the appearance of list items based on their content or state.

Declaration
public event VisualListItemFormattingEventHandler VisualListItemFormatting
Event Type
VisualListItemFormattingEventHandler

Explicit Interface Implementations

ISupportRootUIAutomation.DisposeUIAutomationProvider()

Declaration
void ISupportRootUIAutomation.DisposeUIAutomationProvider()
Implements

ISupportRootUIAutomation.InitializeUIAutomationProvider()

Declaration
void ISupportRootUIAutomation.InitializeUIAutomationProvider()
Implements

ISupportRootUIAutomation.RootUIAutomationManager

Gets the UI Automation Manager.

Declaration
IRootUIAutomationManager ISupportRootUIAutomation.RootUIAutomationManager { get; }
Returns
IRootUIAutomationManager

Implements

Extension Methods