The first order of business in supporting IMEs on Windows NT 3.5 is to add code that responds to messages sent by the active IME DLL. An IME-aware application traps the message WM_IME_REPORT. When an IME sends a WM_IME_REPORT message, it sets wParam to one of the values listed in Figure 7-19. The IME might send your application an entire string at once, in which case it sets wParam to IR_STRING, or the IME might send characters 1 byte at a time, in which case it sets wParam to IR_STRINGSTART to signal that the next WM_CHAR message will contain the beginning of a string. After the IME has transmitted the entire string, it will send another WM_IME_REPORT message, with wParam set to IR_STRINGEND.
| wParam Value | Description |
| IR_CHANGECONVERT | Reports that the conversion window will change in status |
| IR_CLOSECONVERT | Reports that the conversion window will close |
| IR_FULL_CONVERT | Reports that the conversion window will overflow the bounding rectangle |
| IR_OPENCONVERT | Reports that the conversion window will open |
| IR_STRING | Reports a determined string |
| IR_STRINGEND | Reports the end of determined-string transmission |
| IR_STRINGSTART | Reports the start of determined-string transmission |
| IR_BASE_UI | Reports the user interface |
| IR_ENHANCED_UI | Reports the character-window–based user interface |
Figure 7-19 Possible wParam values for the message WM_IME_REPORT under the Windows NT 3.5 IME model.
The Japanese Win32 SDK ships with sample code, called USEIME, that you can study for further details on implementing IME support for Windows NT 3.5.
On Windows NT 3.5, the standard IMEs are based on the appropriate local character set, such as Shift-JIS, rather than on Unicode. The operating system automatically converts strings into Unicode if necessary. (See the section titled "Unicode on Windows NT" in Chapter 3.)