Советы по Delphi




Как отловить PnP изменения в системе?


Олег Кулабухов делится своим опытом:

Нужно просто отловить сообщение WM_DEVICECHANGE

    type
TForm1 = class(TForm)
Button1: TButton;
private
{ Private declarations }
procedure WMDeviceChange(var Message: TMessage);
message WM_DEVICECHANGE;
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.DFM}

const DBT_DEVICEARRIVAL = $8000;
const DBT_DEVICEQUERYREMOVE = $8001;
const DBT_DEVICEQUERYREMOVEFAILED = $8002;
const DBT_DEVICEREMOVEPENDING = $8003;
const DBT_DEVICEREMOVECOMPLETE = $8004;
const DBT_DEVICETYPESPECIFIC = $8005;
const DBT_CONFIGCHANGED = $0018;

procedure TForm1.WMDeviceChange(var Message: TMessage);
var
s : string;
begin
{Do Something here}
case Message.wParam of
DBT_DEVICEARRIVAL :
s := 'A device has been inserted and is now available';
DBT_DEVICEQUERYREMOVE: begin
s := 'Permission to remove a device is requested';
ShowMessage(s);
{True grants premission}
Message.Result := integer(true);
exit;
end;
DBT_DEVICEQUERYREMOVEFAILED :
s := 'Request to remove a device has been canceled';
DBT_DEVICEREMOVEPENDING :
s := 'Device is about to be removed';
DBT_DEVICEREMOVECOMPLETE :
s := 'Device has been removed';
DBT_DEVICETYPESPECIFIC :
s := 'Device-specific event';
DBT_CONFIGCHANGED :
s:= 'Current configuration has changed'
else s := 'Unknown Device Message';
end;
ShowMessage(s);
inherited;
end;

[001908]




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