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.

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.

[Browsable(true)]
public override bool AllowShowFocusCues { get; set; }

Overrides: RadControl.AllowShowFocusCues

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.

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.

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.

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.

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.

[Browsable(true)]
public override bool AutoSize { get; set; }

Overrides: RadControl.AutoSize

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.

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.

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.

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.

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.

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.

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.

protected override Size DefaultSize { get; }

Overrides: Control.DefaultSize

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

public override bool EnableUIAutomation { get; set; }

Overrides: RadControl.EnableUIAutomation

Implements: ISupportRootUIAutomation.EnableUIAutomation

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.

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.

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.

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.

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.

public override Font Font { get; set; }

Overrides: RadControl.Font

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.

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.

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.

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.

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.

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.

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.

Gets or sets an object that implements 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

[Browsable(true)]
[Bindable(true)]
[SettingsBindable(true)]
public override string Text { get; set; }

Overrides: RadControl.Text

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.

public IRadRawElementProviderFragmentRoot UIAutomationProvider { get; }

Implements: ISupportRootUIAutomation.UIAutomationProvider

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.

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.

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.

Checks whether the element's theme is defined by the control.

public override bool ControlDefinesThemeForElement(RadElement element)

Overrides: RadControl.ControlDefinesThemeForElement(RadElement)

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

protected override AccessibleObject CreateAccessibilityInstance()

Overrides: Control.CreateAccessibilityInstance()

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.

protected override void CreateChildItems(RadElement parent)

Overrides: RadControl.CreateChildItems(RadElement)

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.

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.

Releases the resources used by the RadDropDownList control.

protected override void Dispose(bool disposing)

Overrides: RadControl.Dispose(bool)

Handles the key down event of the dropdown list element.

Handles the key press event of the dropdown list element.

Handles the key up event of the dropdown list element.

Handles the popup closed event of the dropdown list element.

Handles the popup closing event of the dropdown list element.

Handles the popup opened event of the dropdown list element.

Handles the popup opening event of the dropdown list element.

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.

public override void EndInit()

Overrides: RadControl.EndInit()

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.

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

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.

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.

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.

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.

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.

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.

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.

Raises the Enter event.

protected override void OnEnter(EventArgs e)

Overrides: Control.OnEnter(EventArgs)

Raises the GotFocus event.

protected override void OnGotFocus(EventArgs e)

Overrides: RadControl.OnGotFocus(EventArgs)

Raises the ItemDataBinding event.