Maintain an old Delphi project recently, want to customize a control, dynamic filtering based on user input data, because ability is limited, and nearly ten years have not used the Delphi, feeling a little overwhelmed, for help here, can filter the current control, but can only enter one character at a time, problems should be input character popup list after Edit lost focus, warrior please help solve, thank you so much!

TFilterEdit expanded the TButtonEdit,, TButtonEdit expanded the TCustomEdit just integrates a Button without other extensions, so it can replace with TCustomEdit TButtonEdit, because must maintain the project is based on the object, so that defines a class TBaseItem, controls a TBaseItem list, according to user input from the list to filter the data, display the drop-down ListBox in the form, then can use the cursor keys to select,

Code for reference some examples downloaded from the Internet,

 
The unit FilterEdit; 

Interface 

USES Classes, Controls, Messages, Windows, Forms, StdCtrls, ButtonEdit; 

Type 
TBaseItem=class 
Private 
FInCode: string; 
FDispCode: string; 
FDispName: string; 
FHintCode: string; 
Public 
The function MatchItem (const value: string) : Boolean; 
The property InCode: string read FInCode write FInCode; 
The property DispCode: string read FDispCode write FDispCode; 
The property DispName: string read FDispName write FDispName; 
The property HintCode: string read FHintCode write FHintCode; 
end; 

TDropWindow=class; 

TFilterEdit=class (TButtonEdit) 
Private 
FDropDown: Boolean; 
FDropWindow: TDropWindow; 
FWindowHeight: integer; 
FWindowWidth: integer; 
FItemList: TStrings; 
FFilterItemList: TStrings; 
FSelectedItem: TBaseItem; 

Procedure SetWindowWidth (const value: integer); 
Procedure SetWindowHeight (const value: integer); 
Procedure SetWindowPosition (var point: TPoint); 
Procedure SetSelectedItem (value: TBaseItem); 
Procedure SetItemList (const value: TStrings); 
The function GetItemCount: integer; 
Protected 
//procedure Change. Override. 
Procedure DropDown can; Virtual; 
Procedure CloseUp; Virtual; 
Procedure WMKillFocus (var Msg: TWMKillFocus); The message WM_KILLFOCUS; 
Procedure WMChar (var Msg: TWMChar); The message WM_CHAR; 
Procedure MouseDown (Button: TMouseButton; Shift: TShiftState; X: Integer; Y: Integer); Override. 
//
Procedure RefreshFilterList (filter: string); 
Public 
The constructor Create (AOwner: TComponent); Override. 
The destructor Destroy; Override. 
The property SelectedItem: TBaseItem read FSelectedItem write SetSelectedItem; 
The property ItemCount: integer read GetItemCount; 
The property Items: TStrings read FItemList write SetItemList; 
Published 
The property DropWindowWidth: integer read FWindowWidth write SetWindowWidth; 
The property DropWindowHeight: integer read FWindowHeight write SetWindowHeight; 
end; 

TDropWindow=class (TCustomForm) 
Private 
FListBox: TListBox; 
Procedure WMMouseActivate (var Msg: TMessage); The message WM_MOUSEACTIVATE; 
Procedure WMActivate (var Msg: TWMActivate); The message WM_ACTIVATE; 
The function GetForm: TWinControl; 
Procedure ListBoxKeyPress (Sender: TObject; Var Key: Char); 
Procedure SelectData (Sender: TObject); 
Procedure RefreshList; 
The function GetEdit: TFilterEdit; 
Protected 
Procedure CreateParams (var Params: TCreateParams); Override. 
Procedure DoShow; Override. 
Public 
The constructor Create (AOwner: TComponent); Override. 
The destructor Destroy; Override. 
The property ListBox: TListBox read FListBox write FListBox; 
The property Edit: TFilterEdit read GetEdit; 
end; 

Procedure Register; 

Implementation 

Procedure Register; 
The begin 
RegisterComponents (' DYF, [TFilterEdit]); 
//RegisterPropertyEditor (TypeInfo (string), TButtonEdit, 'SelectField, TSelectFieldEditer); 
end; 

{TBaseItem} 

The function TBaseItem. MatchItem (const value: string) : Boolean; 
The begin 
Result:=(Pos (value, self. FDispCode) & gt; 0) or (Pos (value, self. FHintCode) & gt; 0) 
Or (Pos (value, self. FDispName) & gt; 0); 
end; 

{TFilterEdit} 

The constructor TFilterEdit. Create (AOwner: TComponent); 
The begin 
Inherited; 

Self. FItemList:=TStringList. Create; 
Self. FFilterItemList:=TStringList. Create; 

Self. FDropWindow:=TDropWindow. Create (self); 
Self. FWindowWidth:=200; 
Self. FWindowHeight:=80; 
Self. FDropWindow. Width:=200; 
Self. FDropWindow. Height:=80; 
Self. FDropDown:=false; 
end; 

Destructor TFilterEdit. Destroy; 
The begin 
Self. FDropWindow. Free; 
Self. FFilterItemList. The Clear; 
Self. FFilterItemList. Free; 
Self. FItemList. The Clear; 
Self. FItemList. Free; 

Inherited; 
end; 

Procedure TFilterEdit. DropDown can; 
Var 
P: TPoint; 
The begin 
Self. FDropWindow. Color: Color=; 
Self. FDropWindow. The Font. The Assign (Font); 
P:=Parent ClientToScreen (Point (self. Left, the self. The Top + self. Height)); 
SetWindowPosition (p); 

Self. FDropWindow. Top:=p.Y; 
Self. FDropWindow. Left:=p.X; 
Self. FDropWindow. Show; 
Invalidate. 
//Windows. SetFocus (self. FDropWindow. Handle). 
Self. FDropDown:=true; 
//self. SetFocus; 
end; 

Procedure TFilterEdit. CloseUp; 
The begin 
Self. FDropWindow. Hide; nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull