GdiplusStartupOutput type

The two functions that GDI+ returns when it is started without its background thread.

When SuppressBackgroundThread is True, GDI+ runs no thread of its own for its background work, and the program must call a hook function before it enters its message loop and an unhook function after it leaves it. GDI+ returns the two functions in a GdiplusStartupOutput, which the GdiPlusUser constructor fills in. It mirrors the GdiplusStartupOutput structure of GDI+ and has two fields and no methods.

A program that leaves the background thread on never needs this type.

Fields

NotificationHook

A NotificationHookProc. 0 until GDI+ has been started with the output.

NotificationUnhook

A NotificationUnhookProc. 0 until GDI+ has been started with the output.

Delegates

NotificationHookProc

Function( token As ULONG ) As GpStatus. Starts the background work and returns a token.

NotificationUnhookProc

Sub( token As ULONG ). Stops it. Pass the token that the hook returned.

Warning 0.9.45.0

The token is declared as a 32-bit Long, and in a 64-bit program GDI+ writes a 64-bit value into it. NotificationHookProc overwrites the four bytes after the variable. Use the module functions NotificationHook and NotificationUnhook below, whose token is a LongPtr.

Module functions

Syntax: NotificationHook( token As LongPtr ) As GpStatus
Syntax: NotificationUnhook( token As LongPtr )

Call the two functions of GDI+ directly. They work only after GDI+ has been started with a GdiplusStartupInput whose SuppressBackgroundThread is True, through the constructor that takes an output.

Dim settings As GdiplusStartupInput
settings.GdiplusVersion = 1
settings.SuppressBackgroundThread = True
Dim output As GdiplusStartupOutput
Dim user As GdiPlusUser = GdiPlusUser(settings, output)
Debug.Print user.LastResult                                      ' 0
Debug.Print output.NotificationHook <> 0                         ' True
Debug.Print output.NotificationUnhook <> 0                       ' True
Dim token As LongPtr
Dim status As GpStatus = NotificationHook(token)
' ... the program's message loop runs here ...
NotificationUnhook token