Rtftype.h

Rtftype.h begins by declaring a sample set of character, paragraph, section, and document properties. These structures are present to demonstrate how the dispatch routines can modify any particular property and are not actually used to format text.

For example, the following enumeration describes which destination text should be routed to:

typedef enum { rdsNorm, rdsSkip } RDS;

Because this is just a sample RTF reader, there are only two destinations; a more complicated reader would add an entry to this enumeration for each destination supported [for example, headers, footnotes, endnotes, comments (annotations), bookmarks, and pictures].

The following enumeration describes the internal state of the RTF parser:

typedef enum { risNorm, risBin, risHex } RIS;

This is entirely separate from the state of the dispatch routines and the destination state; other RTF readers may not necessarily have anything similar to this.

The following structure encapsulates the state that must be saved at a group start and restored at a group end:

typedef struct save
{
struct save *pNext;
CHP chp;
PAP pap;
SEP sep;
DOP dop;
RDS rds;
RIS ris;
} SAVE;

The following enumeration describes a set of classes for RTF controls:

typedef enum {kwdChar, kwdDest, kwdProp, kwdSpec} KWD;

Use kwdChar for controls that represent special characters (such as \-, \{, or \}).

Use kwdDest for controls that introduce RTF destinations.

Use kwdProp for controls that modify some sort of property.

Use kwdSpec for controls that need to run some specialized code.

The following enumeration defines the number of PROP structures (described below) that will be used. There will typically be an iprop for every field in the character, paragraph, section, and document properties.

typedef enum {ipropBold, ipropItalic, ipropUnderline, ipropLeftInd,
ipropRightInd, ipropFirstInd, ipropCols, ipropPgnX, ipropPgnY,
ipropXaPage, ipropYaPage, ipropXaLeft, ipropXaRight,
ipropYaTop, ipropYaBottom, ipropPgnStart, ipropSbk, 
ipropPgnFormat, ipropFacingp, ipropLandscape, ipropJust,
ipropPard, ipropPlain,
ipropMax} IPROP;

The following structure is a very compact way to describe how to locate the address of a particular value in one of the property structures:

typedef enum {actnSpec, actnByte, actnWord} ACTN;
typedef enum {propChp, propPap, propSep, propDop} PROPTYPE;

typedef struct propmod
{
ACTN actn;
PROPTYPE prop;
int offset;
} PROP;

The actn field describes the width of the value being described: if the value is a byte, then actn is actnByte; if the value is a word, then actn is actnWord; if the value is neither a byte nor a word, then you can use actnSpec to indicate that some C code needs to be run to set the value. The prop field indicates which property structure is being described; propChp indicates that the value is located within the CHP structure; propPap indicates that the value is located within the PAP structure, and so on. Finally, the offset field contains the offset of the value from the start of the structure. The offsetof() macro is usually used to initialize this field.

The following structure describes how to parse a particular RTF control:

typedef enum {ipfnBin, ipfnHex, ipfnSkipDest } IPFN;
typedef enum {idestPict, idestSkip } IDEST;

typedef struct symbol
{
char *szKeyword;
int dflt;
bool fPassDflt;
KWD kwd;
int idx;
} SYM;

szKeyword points to the RTF control being described; kwd describes the class of the particular RTF control (described above); dflt is the default value for this control, and fPassDflt should be nonzero if the value in dflt should be passed to the dispatch routine. (fPassDflt is only nonzero for control words that normally set a particular value. For example, the various section break controls typically have nonzero fPassDflt controls, but controls that take parameters should not.)

Idx is a generalized index; its use depends on the kwd being used for this control.

• If kwd is kwdChar, then idx is the character that should be output.
  
  
• If kwd is kwdDest, then idx is the idest for the new destination.
  
  
• If kwd is kwdProp, then idx is the iprop for the appropriate property.
  
  
• If kwd is kwdSpec, then idx is an ipfn for the appropriate function.

With this structure, it is very simple to dispatch an RTF control word. Once the reader isolates the RTF control word and its (possibly associated) value, the reader then searches an array of SYM structures to find the RTF control word. If the control word is not found, the reader ignores it, unless the previous control was \*, in which case the reader must scan past an entire group.

If the control word is found, the reader then uses the kwd value from the SYM structure to determine what to do. This is, in fact, exactly what the function ecTranslateKeyword in the file RTFACTN.C does.