The ComboBox component combines functions of the ListBox and EditBox components.
This component allows to select a value from the list or set user's own value.
The difference of the ComboBox from the similar ListBox component is the following:
ComboBox allows a user to enter his own values.
ComboBox can be expanded as well as collapsed (ListBox is always expanded).
ComboBox does not allow multiple selection.
The main property of the component is Items. You can fill this list when a form is being developed (designed). To do so, click a button with ellipsis next to a property in the Objects Inspector window or select the Elements option from the context menu of the component.
The main event of the OnChange component occurs when a text in the edit window is changed as a result of direct editing or selecting from the list.
Component style depends on the Style property.
The choice of a user or the text, entered by him, can be found out by the value of the Text property.
The index of the item, selected by a user, can be found out by the value of the ItemIndex property.
| Property name | Brief description | |
| Align | The Align property determines the behavior of the component, when the size of its parent component is changed. | |
| AllowDrag | The AllowDrag property determines whether an object can be dragged from the component. | |
| AllowDrop | The AllowDrop property determines whether the component can accept a dragged object. | |
| Anchors | The Anchors property returns settings that determine the percentage of the size change for the current component when the parent component is resized. | |
| Brush | The Brush property specifies the brush used to fill the component area. | |
| ClientHeight | The ClientHeight property is used to receive or specify the height of the component’s client space. | |
| ClientWidth | The ClientWidth property is used to receive or specify the width of the component’s client space. | |
| Color | The Color property determines the background color of a component. | |
| ComponentCount | The ComponentCount property returns the number of child components. | |
| Components | The Components property returns the child component. | |
| Cursor | The Cursor property determines the look of the cursor over the component. | |
| Data | The Data property is used to store any custom data. | |
| DropDownCount | The DropDownCount property determines the maximum number of items, simultaneously displayed in a drop-down list. | |
| DroppedDown | The DroppedDown property returns True, if the drop-down menu of a component is expanded. | |
| Enabled | The Enabled property determines whether the component is available for the user. | |
| Focused | The Focused property returns True, if the focus is set on the component. | |
| Font | The Font property determines the set of characteristics, describing the font, used to display text. | |
| Height | The Height property determines the component height. | |
| HelpContext | The HelpContext property determines a unique index for the context help section for this component. | |
| Hint | The Hint property determines the hint text for the component. | |
| ItemCount | The ItemCount property returns the number of rows in a drop-down menu. | |
| ItemHeight | The ItemHeight property returns the height of elements (rows) of a drop-down menu. | |
| ItemIndex | The ItemIndex property determines the index of the selected element of the list. | |
| Items | The Items property returns the component rows collection. | |
| Left | The Left property determines the coordinate of the left border of the component. | |
| MaxLength | The MaxLength property determines the maximum length of the entered text. | |
| Name | The Name property determines the component name. | |
| Parent | The Parent property determines the parent component. | |
| ParentColor | The ParentColor property determines whether the component inherits the color of the parent component. | |
| ParentFont | The ParentFont property determines whether the component should use the font of the parent component. | |
| ParentShowHint | The ParentShowHint property determines when a tooltip is displayed. | |
| PopupMenu | The PopupMenu property determines the context menu to be displayed on right-click. | |
| Scrolls | The Scrolls property returns parameters of component's scrollbars. | |
| SelLength | The SelLength property determines the number of characters selected in the component text. | |
| SelStart | The SelStart property determines the position of the cursor from which to start text selection in the component. | |
| SelText | The SelText property determines text, selected in the component. | |
| ShowHint | The ShowHint property enables and disables showing a hint for the component. | |
| Sorted | The Sorted property determines, whether the rows in the drop-down menu must be automatically sorted in alphabetical order. | |
| Style | The Style property determines the display style of the component. | |
| TabOrder | The TabOrder property determines the component position in the tab order. | |
| TabStop | The TabStop property determines whether the focus is set to a component when the TAB button is pressed. | |
| Tag | The Tag property is not used by the compiler. A user can change the value of the Tag property and use it as he wishes. | |
| Text | The Text property determines the row identifying a component for user. | |
| Top | The Top property determines the coordinate of the top border of the component. | |
| Visible | The Visible property determines the visibility of the component during execution. | |
| Width | The Width property determines the component width. |
| Method name | Brief description | |
| BringToFront | The BringToFront method brings a component to front. | |
| ClearEdit | The ClearEdit method allows to clear the input field. | |
| ClientToScreen | The ClientToScreen method converts point coordinates relative to component coordinates into display coordinates. | |
| DoDragDrop | The DoDragDrop method allows to start drag-and-drop operation. | |
| GetImage | The GetImage method returns the image of the component with all the child components. | |
| SelectAll | The SelectAll method allows to select all component items. | |
| ScreenToClient | The ScreenToClient method converts screen coordinates of a point to coordinates specified relative to the component coordinate system. | |
| SendToBack | The SendToBack method sends a component to back. | |
| SetFocus | The SetFocus method sets focus to this component. |
| Event name | Brief description | |
| OnBeginDrag | The OnBeginDrag event occurs for a component, when a user starts to drag an object from the component. | |
| OnChange | The OnChange event occurs when the text in the component edit field is changed. | |
| OnClick | The OnClick event occurs if a user clicks a component area using the main mouse button. | |
| OnDblClick | The OnDblClick event occurs if a user double-clicks a component area using the mouse button. | |
| OnDragDrop | The OnDragDrop event occurs for a component if a user drops a dragged object over it. | |
| OnDragEnter | The OnDragEnter event occurs when a dragged object crosses the borders of this component. | |
| OnDragLeave | The OnDragLeave event occurs when a dragged object leaves the borders of this component. | |
| OnDragOver | The OnDragOver event occurs for this component when a user drags a dragged object over it. | |
| OnDropDown | The OnDropDown event occurs when a drop-down menu appears. | |
| OnEnter | The OnEnter event occurs when a component receives focus. | |
| OnExit | The OnExit event occurs when a component loses focus. | |
| OnHScroll | The OnHScroll event occurs when the horizontal scrollbar slider changes its position. | |
| OnItemSelect | The OnItemSelect event occurs, when an element is selected from the list. | |
| OnKeyDown | The OnKeyDown event occurs if a component is focused and a keyboard key is pressed. | |
| OnKeyPress | The OnKeyPress event occurs if a component is focused when a user presses a character key. | |
| OnKeyPreview | The OnKeyPreview event occurs prior to each event requiring clicking. | |
| OnKeyUp | The OnKeyUp event occurs if a component is focused and a user releases any button previously pressed. | |
| OnMouseDown | The OnMouseDown event occurs when the pointer is in component area and a mouse button is pressed. | |
| OnMouseEnter | The OnMouseEnter event occurs when mouse cursor enters the component area. | |
| OnMouseHover | The OnMouseHover event occurs when mouse cursor is held in the component area. | |
| OnMouseLeave | The OnMouseLeave event occurs when mouse cursor leaves the component area. | |
| OnMouseMove | The OnMouseMove event occurs on moving the cursor over component. | |
| OnMouseUp | The OnMouseUp event occurs on releasing mouse button when the cursor is in component area. | |
| OnMouseWheel | The OnMouseWheel event occurs if the component has focus when the mouse wheel is rotated. | |
| OnVScroll | The OnVScroll event occurs when the vertical scrollbar slider changes its position. |
See also: