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跨進程獲取 ListBox 與 ComboBox 內容：Win32 API 實戰

編輯：Delphi

在自動化測試、螢幕閱讀器、資料擷取等場景中，常需從其他進程的視窗控制項讀取列表內容。本文提供基於 SendMessage 的完整實作，支援 ListBox 與 ComboBox，經 Windows 2000 + Delphi 6 測試通過。

核心函數：GetListBoxText

function GetListBoxText(mHandle: THandle; mStrings: TStrings): Boolean;
var vItemCount, I: Integer; S: string;
begin
  Result := False;
  if not Assigned(mStrings) then Exit;
  mStrings.BeginUpdate;
  try
    mStrings.Clear;
    vItemCount := SendMessage(mHandle, LB_GETCOUNT, 0, 0);
    for I := 0 to vItemCount - 1 do begin
      SetLength(S, SendMessage(mHandle, LB_GETTEXTLEN, I, 0));
      SendMessage(mHandle, LB_GETTEXT, I, Integer(@S[1]));
      mStrings.Add(S);
    end;
    SetLength(S, 0);
  finally mStrings.EndUpdate; end;
  Result := True;
end;

核心函數：GetComboBoxText

function GetComboBoxText(mHandle: THandle; mStrings: TStrings): Boolean;
var vItemCount, I: Integer; S: string;
begin
  Result := False;
  if not Assigned(mStrings) then Exit;
  mStrings.BeginUpdate;
  try
    mStrings.Clear;
    vItemCount := SendMessage(mHandle, CB_GETCOUNT, 0, 0);
    for I := 0 to vItemCount - 1 do begin
      SetLength(S, SendMessage(mHandle, CB_GETLBTEXTLEN, I, 0));
      SendMessage(mHandle, CB_GETLBTEXT, I, Integer(@S[1]));
      mStrings.Add(S);
    end;
    SetLength(S, 0);
  finally mStrings.EndUpdate; end;
  Result := True;
end;

關鍵 API 對照

功能	ListBox 訊息	ComboBox 訊息
取得項目數	`LB_GETCOUNT`	`CB_GETCOUNT`
取得項目文字長度	`LB_GETTEXTLEN`	`CB_GETLBTEXTLEN`
取得項目文字	`LB_GETTEXT`	`CB_GETLBTEXT`

實戰範例：熱鍵觸發滑鼠下控制項讀取

procedure TForm1.FormCreate(Sender: TObject);
begin
  RegisterHotKey(Handle, 1, MOD_WIN, VK_F2); // Win+F2 讀 ListBox
  RegisterHotKey(Handle, 2, MOD_WIN, VK_F3); // Win+F3 讀 ComboBox
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  UnRegisterHotKey(Handle, 1); UnRegisterHotKey(Handle, 2);
end;

procedure TForm1.WMHOTKEY(var Msg: TWMHOTKEY);
var hWnd: THandle;
begin
  hWnd := WindowFromPoint(Point(Mouse.CursorPos.X, Mouse.CursorPos.Y));
  case Msg.HotKey of
    1: GetListBoxText(hWnd, MemoText.Lines);
    2: GetComboBoxText(hWnd, MemoText.Lines);
  end;
end;

注意事項與限制

✅ 適用於標準 Win32 ListBox/ComboBox 控制項
❌ **不適用**於：Owner-draw 且無文字資料、虛擬模式、WPF/WinForms/Qt 等非原生控制項
❌ **權限限制**：目標進程若為高權限（系統管理員），低權限進程無法發送訊息（UIPI）
⚠️ **64 位元相容**：Delphi 6 為 32 位元，若目標為 64 位元進程需 64 位元編譯器
🔧 **編碼問題**：舊版 Delphi 字串為 ANSI，Unicode 內容需 WideString + LB_GETTEXT 配合 WM_GETTEXT 變體

進階：支援 Unicode 的版本

function GetListBoxTextW(mHandle: THandle; mStrings: TStrings): Boolean;
var cnt, i, len: Integer; ws: WideString;
begin
  Result := False; if not Assigned(mStrings) then Exit;
  mStrings.BeginUpdate;
  try
    mStrings.Clear;
    cnt := SendMessage(mHandle, LB_GETCOUNT, 0, 0);
    for i := 0 to cnt - 1 do begin
      len := SendMessage(mHandle, LB_GETTEXTLEN, i, 0);
      SetLength(ws, len);
      SendMessage(mHandle, LB_GETTEXT, i, LPARAM(@ws[1]));
      mStrings.Add(ws);
    end;
  finally mStrings.EndUpdate; end;
  Result := True;
end;