问题
I'm using Delphi XE2's TButtonedEdit but I would like to add a dropdown list for the history (like TComboBox). I know that TComboBox is a glorified TEdit, so is there a message I can send to TButtonedEdit to add this functionality please? Thanks.
回答1:
You can use the IAutoComplete2 interface to accomplish this task.
Check this sample code (adapted for TButtonedEdit and Delphi XE2), based on this answer (Auto append/complete from text file to an edit box delphi) from Ken White
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls, Winapi.ActiveX, Winapi.ShlObj,
Vcl.Mask, Vcl.ImgList;
type
IACList = interface(IUnknown)
['{77A130B0-94FD-11D0-A544-00C04FD7d062}']
function Expand(pszExpand : POLESTR) : HResult; stdcall;
end;
const
//options for IACList2
ACLO_NONE = 0; // don't enumerate anything
ACLO_CURRENTDIR = 1; // enumerate current directory
ACLO_MYCOMPUTER = 2; // enumerate MyComputer
ACLO_DESKTOP = 4; // enumerate Desktop Folder
ACLO_FAVORITES = 8; // enumerate Favorites Folder
ACLO_FILESYSONLY = 16; // enumerate only the file system
type
IACList2 = interface(IACList)
['{470141a0-5186-11d2-bbb6-0060977b464c}']
function SetOptions(dwFlag: DWORD): HResult; stdcall;
function GetOptions(var pdwFlag: DWORD): HResult; stdcall;
end;
IAutoComplete = interface(IUnknown)
['{00bb2762-6a77-11d0-a535-00c04fd7d062}']
function Init(hwndEdit: HWND; const punkACL: IUnknown;
pwszRegKeyPath, pwszQuickComplete: POLESTR): HResult; stdcall;
function Enable(fEnable: BOOL): HResult; stdcall;
end;
const
//options for IAutoComplete2
ACO_NONE = 0;
ACO_AUTOSUGGEST = $1;
ACO_AUTOAPPEND = $2;
ACO_SEARCH = $4;
ACO_FILTERPREFIXES = $8;
ACO_USETAB = $10;
ACO_UPDOWNKEYDROPSLIST = $20;
ACO_RTLREADING = $40;
type
IAutoComplete2 = interface(IAutoComplete)
['{EAC04BC0-3791-11d2-BB95-0060977B464C}']
function SetOptions(dwFlag: DWORD): HResult; stdcall;
function GetOptions(out pdwFlag: DWORD): HResult; stdcall;
end;
TEnumString = class(TInterfacedObject, IEnumString)
private
type
TPointerList = array[0..0] of Pointer; //avoid bug of Classes.pas declaration TPointerList = array of Pointer;
var
FStrings: TStringList;
FCurrIndex: integer;
public
//IEnumString
function Next(celt: Longint; out elt;
pceltFetched: PLongint): HResult; stdcall;
function Skip(celt: Longint): HResult; stdcall;
function Reset: HResult; stdcall;
function Clone(out enm: IEnumString): HResult; stdcall;
//VCL
constructor Create;
destructor Destroy;override;
end;
TACOption = (acAutoAppend, acAutoSuggest, acUseArrowKey);
TACOptions = set of TACOption;
TACSource = (acsList, acsHistory, acsMRU, acsShell);
TButtonedEdit = class(Vcl.ExtCtrls.TButtonedEdit)
private
FACList: TEnumString;
FAutoComplete: IAutoComplete;
FACEnabled: boolean;
FACOptions: TACOptions;
FACSource: TACSource;
function GetACStrings: TStringList;
procedure SetACEnabled(const Value: boolean);
procedure SetACOptions(const Value: TACOptions);
procedure SetACSource(const Value: TACSource);
procedure SetACStrings(const Value: TStringList);
protected
procedure CreateWnd; override;
procedure DestroyWnd; override;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
property ACEnabled: boolean read FACEnabled write SetACEnabled;
property ACOptions: TACOptions read FACOptions write SetACOptions;
property ACSource: TACSource read FACSource write SetACSource;
property ACStrings: TStringList read GetACStrings write SetACStrings;
end;
TForm1 = class(TForm)
ButtonedEdit1: TButtonedEdit;
ImageList1: TImageList;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm5;
implementation
{$R *.dfm}
uses
System.Win.ComObj;
procedure TForm1.FormCreate(Sender: TObject);
begin
ButtonedEdit1.ACEnabled:=True;
ButtonedEdit1.ACOptions:=[acAutoAppend, acAutoSuggest, acUseArrowKey];
ButtonedEdit1.ACSource:=acsList;
ButtonedEdit1.ACStrings.Add('string 1');
ButtonedEdit1.ACStrings.Add('string 2');
ButtonedEdit1.ACStrings.Add('string 3');
ButtonedEdit1.ACStrings.Add('string 4');
end;
{ TEnumString }
function TEnumString.Clone(out enm: IEnumString): HResult;
begin
Result := E_NOTIMPL;
Pointer(enm) := nil;
end;
constructor TEnumString.Create;
begin
inherited Create;
FStrings := TStringList.Create;
FCurrIndex := 0;
end;
destructor TEnumString.Destroy;
begin
FStrings.Free;
inherited;
end;
function TEnumString.Next(celt: Integer; out elt;
pceltFetched: PLongint): HResult;
var
I: Integer;
wStr: WideString;
begin
I := 0;
while (I < celt) and (FCurrIndex < FStrings.Count) do
begin
wStr := FStrings[FCurrIndex];
TPointerList(elt)[I] := CoTaskMemAlloc(2 * (Length(wStr) + 1));
StringToWideChar(wStr, TPointerList(elt)[I], 2 * (Length(wStr) + 1));
Inc(I);
Inc(FCurrIndex);
end;
if pceltFetched <> nil then
pceltFetched^ := I;
if I = celt then
Result := S_OK
else
Result := S_FALSE;
end;
function TEnumString.Reset: HResult;
begin
FCurrIndex := 0;
Result := S_OK;
end;
function TEnumString.Skip(celt: Integer): HResult;
begin
if (FCurrIndex + celt) <= FStrings.Count then
begin
Inc(FCurrIndex, celt);
Result := S_OK;
end
else
begin
FCurrIndex := FStrings.Count;
Result := S_FALSE;
end;
end;
{ TACEdit }
constructor TButtonedEdit.Create(AOwner: TComponent);
begin
inherited;
FACList := TEnumString.Create;
FACEnabled := True;
FACOptions := [acAutoAppend, acAutoSuggest, acUseArrowKey];
end;
procedure TButtonedEdit.CreateWnd;
var
Dummy: IUnknown;
Strings: IEnumString;
begin
inherited;
if HandleAllocated then
begin
try
Dummy := CreateComObject(CLSID_AutoComplete);
if (Dummy <> nil) and
(Dummy.QueryInterface(IID_IAutoComplete, FAutoComplete) = S_OK) then
begin
case FACSource of
acsHistory: Strings := CreateComObject(CLSID_ACLHistory) as
IEnumString;
acsMRU: Strings := CreateComObject(CLSID_ACLMRU) as
IEnumString;
acsShell: Strings := CreateComObject(CLSID_ACListISF) as
IEnumString;
else
Strings := FACList as IEnumString;
end;
if S_OK = FAutoComplete.Init(Handle, Strings, nil, nil) then
begin
SetACEnabled(FACEnabled);
SetACOptions(FACOptions);
end;
end;
except
//CLSID_IAutoComplete is not available
end;
end;
end;
destructor TButtonedEdit.Destroy;
begin
FACList := nil;
inherited;
end;
procedure TButtonedEdit.DestroyWnd;
begin
if (FAutoComplete <> nil) then
begin
FAutoComplete.Enable(False);
FAutoComplete := nil;
end;
inherited;
end;
function TButtonedEdit.GetACStrings: TStringList;
begin
Result := FACList.FStrings;
end;
procedure TButtonedEdit.SetACEnabled(const Value: Boolean);
begin
if (FAutoComplete <> nil) then
begin
FAutoComplete.Enable(FACEnabled);
end;
FACEnabled := Value;
end;
procedure TButtonedEdit.SetACOptions(const Value: TACOptions);
const
Options : array[TACOption] of integer = (ACO_AUTOAPPEND,
ACO_AUTOSUGGEST,
ACO_UPDOWNKEYDROPSLIST);
var
Option:TACOption;
Opt: DWORD;
AC2: IAutoComplete2;
begin
if (FAutoComplete <> nil) then
begin
if S_OK = FAutoComplete.QueryInterface(IID_IAutoComplete2, AC2) then
begin
Opt := ACO_NONE;
for Option := Low(Options) to High(Options) do
begin
if (Option in FACOptions) then
Opt := Opt or DWORD(Options[Option]);
end;
AC2.SetOptions(Opt);
end;
end;
FACOptions := Value;
end;
procedure TButtonedEdit.SetACSource(const Value: TACSource);
begin
if FACSource <> Value then
begin
FACSource := Value;
RecreateWnd;
end;
end;
procedure TButtonedEdit.SetACStrings(const Value: TStringList);
begin
if Value <> FACList.FStrings then
FACList.FStrings.Assign(Value);
end;
end.
And this is the result.
回答2:
I don't know about that specific control in XE2 (I'm on 2007 myself), but, assuming the Popup Menu property is one on your control, why not create a popup menu on the form and assign it to that property? then as you go through items on your control, you can have them get added to the popup menu with a common onclick handler to re-load the prior items as needed.
来源：https://stackoverflow.com/questions/11615336/is-it-possible-to-add-a-history-list-dropdown-to-delphis-tbuttonededit