unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, StrUtils, ExtCtrls;
type
TComboBox = class(StdCtrls.TComboBox)
private
CtrlLoad : Boolean;
UnFlicker : Boolean;
UpDown : Boolean;
AuxText : String;
HistoryName : String;
StoredItems : TStringList;
CountItems : Byte;
procedure FilterItems;
procedure StoredItemsChange(Sender: TObject);
procedure LoadHistory(FileHistory : String = ''; CountHistory : Byte = 10);
procedure ComboExit(Sender: TObject);
procedure ComboCloseUp(Sender: TObject);
procedure ComboKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
procedure CNCommand(var Message: TWMCommand); Message CN_COMMAND;
protected
public
constructor Create(Owner: TComponent); override;
destructor Destroy; override;
end;
type
TForm1 = class(TForm)
ComboBox1 : TComboBox;
ComboBox2: TComboBox;
ComboBox3: TComboBox;
ComboBox4: TComboBox;
Button1 : TButton;
ComboBox5: TComboBox;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
public
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
constructor TComboBox.Create(Owner: TComponent);
begin
inherited;
AutoComplete := False;
StoredItems := TStringList.Create;
StoredItems.OnChange := StoredItemsChange;
Self.OnExit := ComboExit;
Self.OnCloseUp := ComboCloseUp;
Self.OnKeyDown := ComboKeyDown;
UnFlicker := False;
CtrlLoad := False;
end;
destructor TComboBox.Destroy;
begin
StoredItems.Free;
inherited;
end;
procedure TComboBox.LoadHistory(FileHistory : String = ''; CountHistory : Byte = 10);
begin
CtrlLoad := True;
Self.DropDownCount := CountHistory;
CountItems := CountHistory;
if FileHistory = EmptyStr then
HistoryName := 'History_' + Self.Name + '.txt'
else
HistoryName := FileHistory;
if FileExists(HistoryName) then
Self.StoredItems.LoadFromFile(HistoryName);
end;
procedure TComboBox.CNCommand(var Message: TWMCommand);
begin
inherited;
if Message.NotifyCode = CBN_EDITUPDATE then
FilterItems;
end;
procedure TComboBox.FilterItems;
var
i : Integer;
StartPos, EndPos : Integer;
begin
SendMessage(Handle, CB_GETEDITSEL, WPARAM(@StartPos), LPARAM(@EndPos));
AuxText := Text;
if Text <> EmptyStr then
begin
Items.Clear;
for i := 0 to StoredItems.Count - 1 do
begin
if PosEx(LowerCase(Text), LowerCase(StoredItems[i])) > 0 then
Items.Add(StoredItems[i]);
end;
end
else
Items.Assign(StoredItems);
if UnFlicker then
SendMessage(Handle, CB_SHOWDROPDOWN, Integer(True), 0);
Text := AuxText;
SendMessage(Handle, CB_SETEDITSEL, 0, MakeLParam(StartPos, EndPos));
UnFlicker := True;
end;
procedure TComboBox.StoredItemsChange(Sender: TObject);
begin
if Assigned(StoredItems) then
FilterItems;
end;
procedure TComboBox.ComboExit(Sender: TObject);
var
i : Integer;
begin
if (Items.IndexOf(Text) = -1) and (Text <> EmptyStr) and CtrlLoad then
begin
StoredItems.Insert(0,Text);
for i := StoredItems.Count - 1 downto CountItems do
StoredItems.Delete(i);
StoredItems.SaveToFile(HistoryName);
Self.ItemIndex := 0;
end;
end;
procedure TComboBox.ComboCloseUp(Sender: TObject);
begin
If (AuxText <> EmptyStr) and (UpDown = False) then
begin
Text := AuxText;
end;
UpDown := False;
end;
procedure TComboBox.ComboKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
if (Key = VK_UP) or (Key = VK_DOWN) then
UpDown := True;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
i : Integer;
begin
for i := 0 to ComponentCount - 1 do
begin
if Components[i] is TComboBox then
begin
if TComboBox(Components[i]).Text <> EmptyStr then
ShowMessage(TComboBox(Components[i]).Text);
end;
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
// Archivo Histórico definido por el usuario y por defecto 10 items por archivo
ComboBox1.LoadHistory('History_1.txt');
// Archivo Histórico definido por el usuario y 12 items por archivo
ComboBox2.LoadHistory('History_2.txt',12);
// Archivo Histórico definido por defecto ('History_' + Self.Name + '.txt') y 10 items por archivo
ComboBox3.LoadHistory;
// Archivo Histórico definido por defecto ('History_' + Self.Name + '.txt') y 5 items por archivo
ComboBox4.LoadHistory('',5);
// ComboBox5 no usa el método LoadHistory y por lo tanto se comporta como un Combobox Estándar
end;
end.
