RegisterScaleChangeNotifications function (shellscalingapi.h)

Registers a window to receive callbacks when scaling information changes.

Syntax

HRESULT RegisterScaleChangeNotifications(
  [in]  DISPLAY_DEVICE_TYPE displayDevice,
  [in]  HWND                hwndNotify,
  [in]  UINT                uMsgNotify,
  [out] DWORD               *pdwCookie
);

Parameters

[in] displayDevice

Type: DISPLAY_DEVICE_TYPE

The enum value that indicates which display device to receive notifications about.

[in] hwndNotify

Type: HWND

The handle of the window that will receive the notifications.

[in] uMsgNotify

Type: UINT

An application-defined message that is passed to the window specified by hwndNotify when scaling information changes. Typically, this should be set to WM_APP+x, where x is an integer value.

[out] pdwCookie

Type: DWORD*

Pointer to a value that, when this function returns successfully, receives a registration token. This token is used to revoke notifications by calling RevokeScaleChangeNotifications.

Return value

Type: STDAPI

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

This message specified by uMsgNotify is posted to the registered window through PostMessage. The wParam of the message can contain a combination of SCALE_CHANGE_FLAGS that describe the change that occurred.

Requirements

See also

GetScaleFactorForMonitor

RegisterScaleChangeEvent

UnregisterScaleChangeEvent