The Clipboard and the WM_RENDERFORMAT Message

• Microsoft Windows Software Development Kit (SDK) versions 3.0 and 3.1
• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT versions 3.5 and 3.51
      - Microsoft Windows 95 version 4.0
  

The clipboard sends a WM_RENDERFORMAT message to an application to request that application format the data last copied to the clipboard in the specified format, and then pass a handle to the formatted data to the clipboard.

If an application cannot supply the requested data, it should return a NULL handle. Because most applications provide access to the actual data (not rendered) through the CF_TEXT format, applications that use the clipboard can get the applicable data when rendering fails.

If the application cannot render the data because the system is out of memory, the application can call GlobalCompact(-1) to discard and compress memory, then try the memory allocation request again.

If this fails to provide enough memory, the application can render the data into a file. However, applications that use this technique must cooperate in order to know that the information is in a file, the name of the file, and the format of the data.