int CALLBACK EnumFontFamProc(lpnlf, lpntm, FontType, lParam) | |||||
LOGFONT FAR* lpnlf; | /* address of structure with logical-font data | */ | |||
TEXTMETRIC FAR* lpntm; | /* address of structure with physical-font data | */ | |||
int FontType; | /* type of font, */ | ||||
LPARAM lParam; | /* address of application-defined data | */ |
The EnumFontFamProc function is an application-defined callback function that retrieves information about available fonts.
lpnlf
Points to a NEWLOGFONT structure that contains information about the logical attributes of the font. This structure is locally-defined and is identical to the Windows LOGFONT structure except for two new members. The NEWLOGFONT structure has the following form:
struct tagNEWLOGFONT { /* nlf */
int lfHeight;
int lfWidth;
int lfEscapement;
int lfOrientation;
int lfWeight;
BYTE lfItalic;
BYTE lfUnderline;
BYTE lfStrikeOut;
BYTE lfCharSet;
BYTE lfOutPrecision;
BYTE lfClipPrecision;
BYTE lfQuality;
BYTE lfPitchAndFamily;
BYTE lfFaceName[LF_FACESIZE];
BYTE lfFullName[2 * LF_FACESIZE]; /* TrueType only */
BYTE lfStyle[LF_FACESIZE]; /* TrueType only */
} NEWLOGFONT;
The lfFullName and lfStyle members are appended to a LOGFONT structure when a TrueType font is enumerated in the EnumFontFamProc function.
The lfFullName member is a character array specifying the full name for the font. This name contains the font name and style name.
The lfStyle member is a character array specifying the style name for the font.
For example, when bold italic Arial̉ is enumerated, the last three members of the NEWLOGFONT structure contain the following strings:
lfFaceName = “Arial”; lfFullName = “Arial Bold Italic”; lfStyle = “Bold Italic”;
For a full description of the LOGFONT structure, see the Microsoft Windows Programmer's Reference, Volume 3.
lpntm
Points to a NEWTEXTMETRIC structure that contains information about the physical attributes of the font, if the font is a TrueType font. If the font is not a TrueType font, this parameter points to a TEXTMETRIC structure.
The NEWTEXTMETRIC structure has the following form:
typedef struct tagNEWTEXTMETRIC { /* ntm */
int tmHeight;
int tmAscent;
int tmDescent;
int tmInternalLeading;
int tmExternalLeading;
int tmAveCharWidth;
int tmMaxCharWidth;
int tmWeight;
BYTE tmItalic;
BYTE tmUnderlined;
BYTE tmStruckOut;
BYTE tmFirstChar;
BYTE tmLastChar;
BYTE tmDefaultChar;
BYTE tmBreakChar;
BYTE tmPitchAndFamily;
BYTE tmCharSet;
int tmOverhang;
int tmDigitizedAspectX;
int tmDigitizedAspectY;
DWORD ntmFlags;
UINT ntmSizeEM;
UINT ntmCellHeight;
UINT ntmAvgWidth;
} NEWTEXTMETRIC;
The TEXTMETRIC structure is identical to NEWTEXTMETRIC except that it does not include the last four members. For a full description of these structures, see the Microsoft Windows Programmer's Reference, Volume 3.
FontType
Specifies the type of the font. This parameter can be a combination of the following masks:
DEVICE_FONTTYPE RASTER_FONTTYPE TRUETYPE_FONTTYPE
lParam
Points to the application-defined data passed by EnumFontFamilies.
This function must return a nonzero value to continue enumeration; to stop enumeration, it must return zero.
An application must register this callback function by passing its address to the EnumFontFamilies function. The EnumFontFamProc function is a placeholder for the application-defined function name. The actual name must be exported by including it in an EXPORTS statement in the application's module-definition (.DEF) file.
The AND (&) operator can be used with the RASTER_FONTTYPE, DEVICE_FONTTYPE, and TRUETYPE_FONTTYPE constants to determine the font type. If the RASTER_FONTTYPE bit is set, the font is a raster font. If the TRUETYPE_FONTTYPE bit is set, the font is a TrueType font. If neither bit is set, the font is a vector font. A third mask, DEVICE_FONTTYPE, is set when a device (for example, a laser printer) supports downloading TrueType fonts; it is zero if the font is not a device font. (Any device can support device fonts, including display adapters and dot-matrix printers.) An application can also use the DEVICE_FONTTYPE mask to distinguish GDI-supplied raster fonts from device-supplied fonts. GDI can simulate bold, italic, underline, and strikeout attributes for GDI-supplied raster fonts, but not for device-supplied fonts.