使用CreateDesktop / SwitchDesktop在新桌面内创build表单

我需要为应用程序创build一个系统模式表单，该表单应该阻止整个窗口，直到input特定值。 所以我正在尝试创build桌面和切换。 到目前为止，创build一个桌面切换到它，并返回正常工作对我来说。

但是， 当我尝试创build表单时，从新线程中，表单不显示，但应用程序保留在新创build的空白桌面，因此永远屏蔽屏幕，直到我注销。

我在这里find的代码中创build它：

System Modal Dialog

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// ScreenLocker.h #pragma once using namespace System; using namespace System::Windows::Forms; namespace Developex { public ref class ScreenLocker { private: String ^_desktopName; Form ^_form; void DialogThread(void); public: static void ShowSystemModalDialog (String ^desktopName, Form ^form); }; } // ScreenLocker.cpp #include "stdafx.h" #include "ScreenLocker.h" using namespace System::Threading; using namespace System::Runtime::InteropServices; namespace Developex { void ScreenLocker::DialogThread() { // Save the handle to the current desktop HDESK hDeskOld = GetThreadDesktop(GetCurrentThreadId()); // Create a new desktop IntPtr ptr = Marshal::StringToHGlobalUni(_desktopName); HDESK hDesk = CreateDesktop((LPCWSTR)ptr.ToPointer(), NULL, NULL, 0, GENERIC_ALL, NULL); Marshal::FreeHGlobal(ptr); // Switch to the new deskop SwitchDesktop(hDesk); // Assign new desktop to the current thread SetThreadDesktop(hDesk); // Run the dialog Application::Run(_form); // Switch back to the initial desktop SwitchDesktop(hDeskOld); CloseDesktop(hDesk); } void ScreenLocker::ShowSystemModalDialog(String ^desktopName, Form ^form) { // Create and init ScreenLocker instance ScreenLocker ^locker = gcnew ScreenLocker(); locker->_desktopName = desktopName; locker->_form = form; // Create a new thread for the dialog (gcnew Thread(gcnew ThreadStart(locker, &Developex::ScreenLocker::DialogThread)))->Start(); } } 

那么，现在我试图“翻译”到Delphi，到目前为止，这是我的：

 unit Utils; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ADODB, Grids, DBGrids, ExtCtrls, ComCtrls, SyncObjs, ShellApi, AddTimeU; type TFormShowThread = class(TThread) HDesktopglobal: HDESK; hDeskOld: HDESK; UHeapSize: ULong; tempDword: DWORD; frm : TfrmBlockScreen; private protected procedure Execute; override; public constructor Create(form : TfrmBlockScreen); destructor Destroy; override; end; implementation constructor TFormShowThread.Create(form : TfrmBlockScreen); begin FreeOnTerminate := True; inherited Create(True); frm := form; end; destructor TFormShowThread.Destroy; begin inherited; end; procedure TFormShowThread.Execute; begin hDeskOld := GetThreadDesktop(GetCurrentThreadId()); HDesktopglobal := CreateDesktop('Z', nil, nil, 0, GENERIC_ALL, nil); SwitchDesktop(HDesktopglobal); SetThreadDesktop(HDesktopglobal); // tried this Application.CreateForm(TfrmBlockScreen, frm); // also tried this with same result //frm := TfrmBlockScreen.Create(nil); //frm.Show(); SwitchDesktop(hDeskOld); CloseDesktop(HDesktopglobal); end; end. 

我用这个代码运行：

 var frmBlockScreen : TfrmBlockScreen; frmShowThread : TFormShowThread; begin frmShowThread := TFormShowThread.Create(frmBlockScreen); frmShowThread.Priority := tpNormal; frmShowThread.OnTerminate := ThreadDone; frmShowThread.Start(); 

我不明白为什么这不起作用，C ++，据说应该工作，它在同一个应用程序中创build一个新的forms。

这就是我如何结束的：

我把我想要显示的表单移动到一个新的项目中，并将其编译为timeup.exe。 我使用下面显示的过程创build了一个进程，发送桌面作为参数，以便我可以将进程分配给该桌面。 这样，我甚至不需要创build一个新的线程…它的工作到目前为止。

这有什么缺点吗？

 var HDesktopglobal: HDESK; hDeskOld: HDESK; sDesktopName : String; begin Application.Initialize; Application.MainFormOnTaskbar := True; try hDeskOld := GetThreadDesktop(GetCurrentThreadId()); sDesktopName := 'TimeUpDesktop'; HDesktopglobal := CreateDesktop(PWideChar(sDesktopName), nil, nil, 0, GENERIC_ALL, nil); SwitchDesktop(HDesktopglobal); SetThreadDesktop(HDesktopglobal); ExecNewProcess('TimeUp.exe', sDesktopName); SwitchDesktop(hDeskOld); CloseDesktop(HDesktopglobal); finally SwitchDesktop(hDeskOld); CloseDesktop(HDesktopglobal); end; Application.Run; end. procedure ExecNewProcess(ProgramName : String; Desktop : String); var StartInfo : TStartupInfo; ProcInfo : TProcessInformation; CreateOK : Boolean; begin { fill with known state } FillChar(StartInfo,SizeOf(TStartupInfo),#0); FillChar(ProcInfo,SizeOf(TProcessInformation),#0); StartInfo.cb := SizeOf(TStartupInfo); StartInfo.lpDesktop := PChar(Desktop); CreateOK := CreateProcess(PChar(ProgramName),nil, nil, nil,False, CREATE_NEW_PROCESS_GROUP+NORMAL_PRIORITY_CLASS, nil, nil, StartInfo, ProcInfo); { check to see if successful } if CreateOK then //may or may not be needed. Usually wait for child processes WaitForSingleObject(ProcInfo.hProcess, INFINITE); end;