WM_DEVICECHANGE message

msdn:http://msdn.microsoft.com/en-us/library/windows/desktop/aa363480%28v=vs.85%29.aspx

otifies an application of a change to the hardware configuration of a device or the computer.

A window receives this message through its WindowProc function.

C++

LRESULT CALLBACK WindowProc(HWND   hwnd,     // handle to window                            UINT   uMsg,     // WM_DEVICECHANGE                            WPARAM wParam,   // device-change event                            LPARAM lParam ); // event-specific data

Parameters

hwnd

A handle to the window.

uMsg

The WM_DEVICECHANGE identifier.

wParam

The event that has occurred. This parameter can be one of the following values from the Dbt.h header file.

ValueMeaning

DBT_CONFIGCHANGECANCELED

0x0019

A request to change the current configuration (dock or undock) has been canceled.

DBT_CONFIGCHANGED

0x0018

The current configuration has changed, due to a dock or undock.

DBT_CUSTOMEVENT

0x8006

A custom event has occurred.

DBT_DEVICEARRIVAL

0x8000

A device or piece of media has been inserted and is now available.

DBT_DEVICEQUERYREMOVE

0x8001

Permission is requested to remove a device or piece of media. Any application can deny this request and cancel the removal.

DBT_DEVICEQUERYREMOVEFAILED

0x8002

A request to remove a device or piece of media has been canceled.

DBT_DEVICEREMOVECOMPLETE

0x8004

A device or piece of media has been removed.

DBT_DEVICEREMOVEPENDING

0x8003

A device or piece of media is about to be removed. Cannot be denied.

DBT_DEVICETYPESPECIFIC

0x8005

A device-specific event has occurred.

DBT_DEVNODES_CHANGED

0x0007

A device has been added to or removed from the system.

DBT_QUERYCHANGECONFIG

0x0017

Permission is requested to change the current configuration (dock or undock).

DBT_USERDEFINED

0xFFFF

The meaning of this message is user-defined.

 

lParam

A pointer to a structure that contains event-specific data. Its format depends on the value of thewParam parameter. For more information, refer to the documentation for each event.

Return value

Return TRUE to grant the request.

Return BROADCAST_QUERY_DENY to deny the request.

Remarks

For devices that offer software-controllable features, such as ejection and locking, the system typically sends aDBT_DEVICEREMOVEPENDING message to let applications and device drivers end their use of the device gracefully. If the system forcibly removes a device, it may not send aDBT_DEVICEQUERYREMOVE message before doing so.

Requirements

Minimum supported client

Windows XP

Minimum supported server

Windows Server 2003

Header

Winuser.h (include Windows.h or Dbt.h)

See also

DBT_CONFIGCHANGECANCELED

DBT_CONFIGCHANGED

DBT_CUSTOMEVENT

DBT_DEVICEARRIVAL

DBT_DEVICEQUERYREMOVE

DBT_DEVICEQUERYREMOVEFAILED

DBT_DEVICEREMOVECOMPLETE

DBT_DEVICEREMOVEPENDING

DBT_DEVICETYPESPECIFIC

DBT_DEVNODES_CHANGED

DBT_QUERYCHANGECONFIG

DBT_USERDEFINED