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ensure-gdiplus Function


Ensures GDI+ is present and running, or shuts it down. Needed only when writing FLI graphics code on Windows.




ensure-gdiplus &key event-func force shutdown => result

A function, or nil.
A boolean.
A boolean.
A boolean.

The function ensure-gdiplus checks that the GDI+ module gdiplus.dll is loaded and that GdiplusStartup has been called, or shuts down GDI+.

Most users will not need to call ensure-gdiplus. This is because when LispWorks itself uses GDI+, for instance via read-external-image, it calls ensure-gdiplus automatically, and never shuts GDI+ down.

However, if your code uses GDI+ directly (by calling it through the Foreign Language Interface), then you should call ensure-gdiplus instead of using GdiplusStartup directly. Then, LispWorks will know that GDI+ has already started. This is the only circumstance in which you need to call ensure-gdiplus.

Note: ensure-gdiplus is implemented only in LispWorks for Windows.

If shutdown is nil, ensure-gdiplus ensures GDI+ is started, by the following steps:

  1. Load the GDI+ module gdiplus.dll, if it is not already loaded.
  2. If GDI+ was already started by a previous call to ensure-gdiplus, force is nil, and event-func was either not passed or is cl:eq to the value that was passed in the previous call to ensure-gdiplus then ensure-gdiplus simply returns nil.
  3. If GDI+ was already started, shut it down.
  4. Start GDI+, and return the result of GdiplusStartup. This is 0 for success. For he meaning of other values, see the documentation of gpStatus in the MSDN.

If shutdown is true, then if GDI+ was started ensure-gdiplus shuts it down, and returns t, otherwise ensure-gdiplus returns nil. The default value of shutdown is nil.

The default value of both event-func and force is nil.

See also


CAPI User Guide and Reference Manual (Macintosh version) - 01 Dec 2021 19:31:44