A Sample Recognizer

This section describes a simple recognizer called SREC that demonstrates some of the information given in this chapter. The text describes the most interesting parts of the program and illustrates with code fragments. The complete source listing for SREC.C resides in the SAMPLES\PEN\SREC subdirectory.

SREC is used by the PENAPP application described in Chapter 7, "A Sample Pen Application." To see how SREC works, you must create both PENAPP.EXE and SREC.DLL using the supplied MAKE files, then run PENAPP.

When using the SREC recognizer, PENAPP specifies that a stroke ends when the pen leaves the tablet. Therefore, SREC recognizes only one stroke at a time. SREC takes the beginning and ending points of the stroke and calculates the nearest compass direction of the line formed by these endpoints.

For its HRC object, SREC creates a structure that contains an HPENDATA handle to the input data, the module handle returned from InstallRecognizer, and recognition results. The following typedef statements define the HRC and HRCRESULT objects for SREC. Notice that SREC keeps its HRCRESULT within the HRC.

typedef struct // HRCRESULT object


DWORD reserved; // Reserve top DWORD

SYG syg; // Recognition results

} HRCRESULTinternal, FAR *LPHRCRESULTinternal;

typedef struct // HRC object


DWORD reserved; // Reserve top DWORD

HPENDATA hpendata; // Raw pen data to be recognized

HREC hrec; // Module handle for SREC

HRCRESULTinternal hrcresult; // HRCRESULT structure

} HRCinternal, FAR *LPHRCinternal;

When it finishes recognizing a stroke, SREC fills out a SYG symbol graph structure. The structure holds one of the symbol values listed here:

Symbol value
Single tap

The following sections describe the functions that SREC exports. These functions appear under the same categories described earlier in this chapter, in the section "List of Exported Functions." This allows for quick cross-referencing between a general description of a function and its actual implementation in SREC.

Although defined by the Pen API, the function names below appear in monospace font rather than bold because the names refer to routines in the SREC.C source file.

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