Delphi XE3探索：Winapi.Functiondiscovery （三）

Demo程序

现在使用以上的实现过程就可以接收到设备通知了，下面的代码用于测试USB设备的插入和移除通知。

type  
 TNotifier=class
    procedure  OnUpdate(enumQueryUpdateAction: QueryUpdateAction; fdqcQueryContext: FDQUERYCONTEXT;
      pIFunctionInstance: IFunctionInstance);
  end;

procedure NotificationDemo;
Const
  Timeout = 20000;
var
  hr : HResult;
  pIFunctionDiscoveryNotification : TFunctionDiscoveryNotificationSync;
  LNotifier : TNotifier;
begin
 LNotifier:=TNotifier.Create;
 try
   pIFunctionDiscoveryNotification:=TFunctionDiscoveryNotificationSync.Create;
   try
       //set the callback
       pIFunctionDiscoveryNotification.OnUpdateEvent:=LNotifier.OnUpdate;
       Writeln(Format('Waiting for %d ms, to plug in a PnP device',[Timeout]));
       pIFunctionDiscoveryNotification.WaitFor(Timeout, FCTN_CATEGORY_PNP, QUA_ADD);
       Writeln('Done');
   finally
     pIFunctionDiscoveryNotification:=nil;
   end;

   pIFunctionDiscoveryNotification:=TFunctionDiscoveryNotificationSync.Create;
   try
       //set the callback
       pIFunctionDiscoveryNotification.OnUpdateEvent:=LNotifier.OnUpdate;
       Writeln(Format('Waiting for %d ms, to remove a PnP device',[Timeout]));
       pIFunctionDiscoveryNotification.WaitFor(Timeout, FCTN_CATEGORY_PNP, QUA_REMOVE);
       Writeln('Done');
   finally
     pIFunctionDiscoveryNotification:=nil;
   end;
 finally
     LNotifier.Free;
 end;
end;

{ TNotifier }
procedure TNotifier.OnUpdate(enumQueryUpdateAction: QueryUpdateAction;
  fdqcQueryContext: FDQUERYCONTEXT; pIFunctionInstance: IFunctionInstance);
var
  ppIPropertyStore  : IPropertyStore;
  pv : TPropVariant;
begin
  case enumQueryUpdateAction of
    QUA_ADD    : Writeln(Format('Action : %s',['Add']));
    QUA_REMOVE : Writeln(Format('Action : %s',['Remove']));
    QUA_CHANGE : Writeln(Format('Action : %s',['Change']));
  end;
  if Succeeded(pIFunctionInstance.OpenPropertyStore(STGM_READ, ppIPropertyStore)) then
    if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_DeviceDesc, pv)) then
      Writeln(Format('Device Desc. %s',[pv.pwszVal]));
    if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_Class, pv)) then
      Writeln(Format('Class        %s',[pv.pwszVal]));
    if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_Manufacturer, pv)) then
      Writeln(Format('Manufacturer %s',[pv.pwszVal]));
end;

begin
 try
   ReportMemoryLeaksOnShutdown:=True;
   if (Win32MajorVersion >= 6) then  // available on Vista (or later)
   begin
    if Succeeded(CoInitializeEx(nil, COINIT_MULTITHREADED)) then
    try
     NotificationDemo;
    finally
      CoUninitialize;
    end;
   end
   else
   Writeln('Windows version not compatible');
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;
end.

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