检测屏幕锁定 - Win32 中的 FMX

Question

我希望我的应用程序在屏幕锁定时运行一些代码（Win 7 和 10）。当用户锁定屏幕时，我的应用程序也可能在后台。

有人指出我正确的方向吗？

谢谢你， 接力人

Answer 1

使用WTSRegisterSessionNotification() 注册HWND 以通过WM_WTSSESSION_CHANGE 窗口消息接收WTS_SESSION_(UN)LOCK 通知。

您可以使用 FMX 的FormToHWND() 函数来获取您的表单的HWND。但是，FireMonkey 控件（包括 Forms）没有可覆盖的 WndProc() 方法来处理窗口消息，就像 VCL 一样，因此您必须使用 Win32 API 的 SetWindowLongPtr() 或 SetWindowSubclass() 函数（请参阅 MSDN 上的 Subclassing Controls ) 接收WM_WTSSESSION_CHANGE 窗口消息：

class TMyForm : public TForm
{
    ...
#ifdef _Windows
private:
    bool MonitoringWTS;
    static LRESULT CALLBACK SubclassWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData);
protected:
    virtual void __fastcall CreateHandle();
#endif
    ...
};

#ifdef _Windows

#include <FMX.Platform.Win.hpp>
#include <commctrl.h>
#include <wtsapi32.h>

void __fastcall TMyForm::CreateHandle()
{
    MonitoringWTS = false;

    TForm::CreateHandle();

    // depending on which version of C++Builder you are using...
    HWND hWnd = FormToHWND(this);
    //HWND hWnd = WindowHandleToPlatform(Handle)->Wnd;
    //HWND hWnd = FmxHandleToHWND(Handle);

    if (!SetWindowSubclass(hWnd, &SubclassWndProc, 1, reinterpret_cast<DWORD_PTR>(this)))
        throw Exception(_D("Could not subclass window"));

    MonitoringWTS = WTSRegisterSessionNotification(hWnd, NOTIFY_FOR_THIS_SESSION);
    if (!MonitoringWTS)
        RaiseLastOSError();
}

LRESULT CALLBACK TMyForm::SubclassWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
    switch (uMsg)
    {
        case WM_NCDESTROY:
        {
            WTSUnRegisterSessionNotification(hWnd);
            reinterpret_cast<TMyForm*>(dwRefData)->MonitoringWTS = false;

            RemoveWindowSubclass(hWnd, &SubclassWndProc, uIdSubclass);
            break;
        }

        case WM_WTSSESSION_CHANGE:
        {
            TMyForm *pThis = reinterpret_cast<TMyForm*>(dwRefData);

            switch (wParam)
            {
                case WTS_SESSION_LOCK:
                    // do something ...
                    break;

                case WTS_SESSION_UNLOCK:
                    // do something ...
                    break;
            }

            return 0;
        }
    }

    return DefSubclassProc(hWnd, uMsg, wParam, lParam);
}

#endif

或者，您可以使用 RTL 的 AllocateHWnd() 函数创建隐藏的 HWND 并为其提供自定义 WndProc() 方法：

class TMyForm : public TForm
{
    ...
#ifdef _Windows
private:
    HWND WndForWTS;
    bool MonitoringWTS;
    void __fastcall WndProcForWTS(TMessage &Message);
public:
    __fastcall TMyForm(TComponent *Owner);
    __fastcall ~TMyForm();
#endif
    ...
};

#ifdef _Windows

#include <wtsapi32.h>

__fastcall TMyForm::TMyForm(TComponent *Owner)
    : TForm(Owner)
{
    WndForWTS = AllocateHWnd(&WndProcForWTS);

    MonitoringWTS = WTSRegisterSessionNotification(WndForWTS, NOTIFY_FOR_THIS_SESSION);
    if (!MonitoringWTS)
    {
        int err = GetLastError();
        DeallocateHWnd(WndForWTS);
        RaiseLastOSError(err);
    }
}

__fastcall ~TMyForm();
{
    DeallocateHWnd(WndForWTS);
}

void __fastcall TMyForm::WndProcForWTS(TMessage &Message)
{
    switch (Message.Msg)
    {
        case WM_NCDESTROY:
        {
            if (MonitoringWTS)
            {
                WTSUnRegisterSessionNotification(WndForWTS);
                MonitoringWTS = false;
            }
            WndForWTS = NULL;
            break;
        }

        case WM_WTSSESSION_CHANGE:
        {
            switch (Message.WParam)
            {
                case WTS_SESSION_LOCK:
                    // do something ...
                    break;

                case WTS_SESSION_UNLOCK:
                    // do something ...
                    break;
            }

            return;
        }
    }

    Message.Result = DefWindowProc(WndForWTS, Message.Msg, Message.WParam, Message.LParam);
}

#endif