在Delphi中使用IVirtualDesktopManager

Question

我想在Windows 10的Turbo Delphi中使用IVirtualDesktopManager。 我没有得到任何错误，但IsWindowOnCurrentVirtualDesktop和GetWindowDesktopId不返回任何有用的东西。有谁知道我在这里做错了吗？谢谢。

unit VDMUnit; 

interface 

uses ActiveX, Comobj; 

Const 
IID_VDM: TGUID ='{A5CD92FF-29BE-454C-8D04-D82879FB3F1B}'; 
CLSID_VDM: TGUID ='{AA509086-5CA9-4C25-8F95-589D3C07B48A}'; 

type 
    {$EXTERNALSYM IVirtualDesktopManager} 
    IVirtualDesktopManager = interface(IUnknown) 
    ['{A5CD92FF-29BE-454C-8D04-D82879FB3F1B}'] 
    function IsWindowOnCurrentVirtualDesktop(Wnd:cardinal; var IsTrue: boolean): HResult; stdcall; 
    function GetWindowDesktopId(Wnd:cardinal; pDesktopID: PGUID): HResult; stdcall; 
    function MoveWindowToDesktop(Wnd:cardinal; DesktopID: PGUID): HResult; stdcall; 
    end; 

function IsOnCurrentDesktop(wnd:cardinal):boolean; 
procedure GetWindowDesktopId(Wnd:cardinal; pDesktopID: PGUID); 
procedure MoveWindowToDesktop(Wnd:cardinal; DesktopID: PGUID); 

implementation 

var 
    vdm:IVirtualDesktopManager; 

function IsOnCurrentDesktop(wnd:cardinal):boolean; 
begin 
    CoInitialize(nil); 
    OleCheck(CoCreateInstance(CLSID_VDM, nil, CLSCTX_INPROC_SERVER,IVirtualDesktopManager,vdm)); 
    OleCheck(vdm.IsWindowOnCurrentVirtualDesktop(wnd,result)); 
    CoUninitialize; 
end; 

procedure GetWindowDesktopId(Wnd:cardinal; pDesktopID: PGUID); 
begin 
    CoInitialize(nil); 
    OleCheck(CoCreateInstance(CLSID_VDM, nil, CLSCTX_INPROC_SERVER ,IVirtualDesktopManager,vdm)); 
    OleCheck(vdm.GetWindowDesktopId(wnd,pDesktopID)); 
    CoUninitialize; 
end; 

procedure MoveWindowToDesktop(Wnd:cardinal; DesktopID: PGUID); 
begin 
    CoInitialize(nil); 
    OleCheck(CoCreateInstance(CLSID_VDM, nil, CLSCTX_INPROC_SERVER,IVirtualDesktopManager,vdm)); 
    OleCheck(vdm.MoveWindowToDesktop(wnd,DesktopID)); 
    CoUninitialize; 
end; 

end. 

好的，下面是一个简单的例子：这个项目只是一个TMemo和一个Ttimer的表单。 它显示Form1.handle不能用于检查窗口是否在当前桌面上。但是，如果您检查Application.Handle，那么如果您切换到另一个桌面并再次返回，则会正确返回false，以便检查备注中的内容。 我觉得这很了不起，因为我认为一个应用程序可以有多个窗口显示在不同的桌面上？

unit Unit1; 

interface 

uses 
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
    Dialogs, ActiveX, Comobj, StdCtrls, ExtCtrls; 

const 
IID_VDM: TGUID = '{A5CD92FF-29BE-454C-8D04-D82879FB3F1B}'; 
CLSID_VDM: TGUID ='{AA509086-5CA9-4C25-8F95-589D3C07B48A}'; 

type 
    IVirtualDesktopManager = interface(IUnknown) 
    ['{A5CD92FF-29BE-454C-8D04-D82879FB3F1B}'] 
    function IsWindowOnCurrentVirtualDesktop(Wnd: HWND; out IsTrue: BOOL): HResult; stdcall; 
    function GetWindowDesktopId(Wnd: HWND; out DesktopID: TGUID): HResult; stdcall; 
    function MoveWindowToDesktop(Wnd: HWND; const DesktopID: TGUID): HResult; stdcall; 
    end; 

type 
    TForm1 = class(TForm) 
    Memo1: TMemo; 
    Timer1: TTimer; 
    procedure Timer1Timer(Sender: TObject); 
    private 
    { Private declarations } 
    public 
    { Public declarations } 
    end; 

var 
    Form1: TForm1; 

implementation 

{$R *.dfm} 

function GetVDM: IVirtualDesktopManager; 
begin 
    Result := nil; 
    OleCheck(CoCreateInstance(CLSID_VDM, nil, CLSCTX_INPROC_SERVER, IVirtualDesktopManager, Result)); 
end; 

function IsOnCurrentDesktop(wnd: HWND): Boolean; 
var 
    value: BOOL; 
begin 
    OleCheck(GetVDM.IsWindowOnCurrentVirtualDesktop(Wnd, value)); 
    Result := value; 
end; 

procedure TForm1.Timer1Timer(Sender: TObject); 
begin 
    if IsOnCurrentDesktop(Form1.Handle) then 
    Memo1.Lines.Add('Yes') 
    else 
    Memo1.Lines.Add('No'); 
end; 



end. 

Answer 1

您所有的接口方法的声明有误，但IsWindowOnCurrentVirtualDesktop()尤其是麻烦，因为它的第二个参数需要一个指向一个BOOL，而不是一个指针Boolean。 BOOL和Boolean是很不同的数据类型。 BOOL是LongBool的别名，其大小为4个字节，而Boolean的大小为1个字节。

除此之外，您应该使用HWND而不是Cardinal作为Wnd参数。我还建议使用out和const代替原始指针DesktopID参数。

此外，你真的需要摆脱Co(Un)Initialize()调用，他们根本不属于你的功能。 调用者负责（不）初始化COM，因为它必须决定访问COM时要使用的COM线程模型。个人功能不应该代表主叫方作出决定。 COM必须基于每个线程进行初始化，因此在调用函数之前调用CoInitialize()是各个应用程序线程的责任，并且在终止之前调用CoUninitialize()。

由于您的vdm变量，这一点尤其重要。该变量属于每个函数的内部，而不是全局内存。在编译器试图在已经调用CoUninitialize()之后的单元终止期间释放该接口时，您冒着崩溃风险。

与所述所有这一切，尝试一些更喜欢这个：

unit VDMUnit; 

interface 

uses 
    Windows; 

function IsOnCurrentDesktop(wnd: HWND): Boolean; 
function GetWindowDesktopId(Wnd: HWND): TGUID; 
procedure MoveWindowToDesktop(Wnd: HWND; const DesktopID: TGUID); 

implementation 

uses 
    ActiveX, Comobj; 

const 
IID_VDM: TGUID = '{A5CD92FF-29BE-454C-8D04-D82879FB3F1B}'; 
CLSID_VDM: TGUID ='{AA509086-5CA9-4C25-8F95-589D3C07B48A}'; 

type 
    IVirtualDesktopManager = interface(IUnknown) 
    ['{A5CD92FF-29BE-454C-8D04-D82879FB3F1B}'] 
    function IsWindowOnCurrentVirtualDesktop(Wnd: HWND; out IsTrue: BOOL): HResult; stdcall; 
    function GetWindowDesktopId(Wnd: HWND; out DesktopID: TGUID): HResult; stdcall; 
    function MoveWindowToDesktop(Wnd: HWND; const DesktopID: TGUID): HResult; stdcall; 
    end; 

function GetVDM: IVirtualDesktopManager; 
begin 
    Result := nil; 
    OleCheck(CoCreateInstance(CLSID_VDM, nil, CLSCTX_INPROC_SERVER, IVirtualDesktopManager, Result)); 
end; 

function IsOnCurrentDesktop(wnd: HWND): Boolean; 
var 
    value: BOOL; 
begin 
    OleCheck(GetVDM.IsWindowOnCurrentVirtualDesktop(Wnd, value)); 
    Result := value; 
end; 

function GetWindowDesktopId(Wnd: HWND): TGUID; 
being 
    OleCheck(GetVDM.GetWindowDesktopId(Wnd, Result)); 
end; 

procedure MoveWindowToDesktop(Wnd: HWND; const DesktopID: TGUID); 
begin 
    OleCheck(GetVDM.MoveWindowToDesktop(Wnd, DesktopID)); 
end; 

end. 

最后，注意IVirtualDesktopManager仅适用于Windows 10及更高版本，所以如果你不想让你的代码崩溃上早期版本的Windows，你应该更优雅去除OleCheck()上CoCreateInstance()这样你就可以处理错误，如：

uses 
    Classes; 

type 
    TFakeVirtualDesktopManager = class(TInterfacedObject, IVirtualDesktopManager) 
    public 
    function IsWindowOnCurrentVirtualDesktop(Wnd: HWND; out IsTrue: BOOL): HResult; stdcall; 
    function GetWindowDesktopId(Wnd: HWND; out DesktopID: TGUID): HResult; stdcall; 
    function MoveWindowToDesktop(Wnd: HWND; const DesktopID: TGUID): HResult; stdcall; 
    end; 

function TFakeVirtualDesktopManager.IsWindowOnCurrentVirtualDesktop(Wnd: HWND; out IsTrue: BOOL): HResult; stdcall; 
begin 
    IsTrue := False; 
    Result := S_OK; 
end; 

function TFakeVirtualDesktopManager.GetWindowDesktopId(Wnd: HWND; out DesktopID: TGUID): HResult; stdcall; 
begin 
    DesktopID := GUID_NULL; 
    Result := S_OK; 
end; 

function TFakeVirtualDesktopManager.MoveWindowToDesktop(Wnd: HWND; const DesktopID: TGUID): HResult; stdcall; 
begin 
    Result := S_OK; 
end; 

function GetVDM: IVirtualDesktopManager; 
var 
    hr: HResult; 
begin 
    Result := nil; 
    hr := CoCreateInstance(CLSID_VDM, nil, CLSCTX_INPROC_SERVER, IVirtualDesktopManager, Result); 
    if Failed(hr) then 
    begin 
    if hr = REGDB_E_CLASSNOTREG then 
     Result := TFakeVirtualDesktopManager.Create as IVirtualDesktopManager 
    else 
     OleCheck(hr); 
    end; 
end;