FONTINFO

typedef struct tagFONTINFO {

short dfType;

short dfPoints;

short dfVertRes;

short dfHorizRes;

short dfAscent;

short dfInternalLeading;

short dfExternalLeading;

char dfItalic;

char dfUnderline;

char dfStrikeOut;

short dfWeight;

char dfCharSet;

short dfPixWidth;

short dfPixHeight;

char dfPitchAndFamily;

short dfAvgWidth;

short dfMaxWidth;

char dfFirstChar;

char dfLastChar;

char dfDefaultChar;

char dfBreakChar;

short dfWidthBytes;

long dfDevice;

long dfFace;

long dfBitsPointer;

long dfBitsOffset;

char dfReserved;

/* The following fields present only for Windows 3.x fonts */

long dfFlags;

short dfAspace;

short dfBspace;

short dfCspace;

long dfColorPointer;

long dfReserved1[4];

} FONTINFO;

The FONTINFO structure contains information about a physical font. Depending on whether the font is realized by GDI or by a device driver, the FONTINFO structure may be immediately followed by a character width table and by font bitmap or vector information.

The FONTINFO structure contains optional members (dfFlags through dfReserved1) that are present only if the font has been designed for Windows 3.x. If GDI realizes a font for a driver, the font's corresponding FONTINFO structure will not include these optional members unless the RC_BIGFONT bit is set in the dpRaster member of the driver's GDIINFO structure.

Members

dfType

Specifies font type. The low-order byte, reserved for exclusive GDI use, is a combination of the following values.

All other values in the low-order byte are reserved. In particular, the value 0x0008 in the dfType member is reserved for use with Asian fonts.

The high-order byte is reserved for device use. GDI never inspects the high byte. If GDI realizes the font, it sets this byte to zero. If the device driver realizes the font, it can set this byte to any value.

dfPoints

Specifies the point size at which this character set looks best.

dfVertRes

Specifies the vertical resolution (dots-per-inch) at which this character set was digitized.

dfHorizRes

Specifies the horizontal resolution (dots-per-inch) at which this character set was digitized.

dfAscent

Specifies the distance from the top of a character definition cell to the baseline of the typographical font. It is useful for aligning the baseline of fonts of different heights.

dfInternalLeading

Specifies the amount of leading inside the bounds set by the dfPixHeight member. Accent marks may occur in this area.

dfExternalLeading

Specifies the amount of extra leading that the designer requests the application add between rows. Since this area is outside of the font proper, it contains no marks and will not be altered by text output calls in either the OPAQUE or TRANSPARENT mode.

dfItalic

Specifies whether the character-definition data represents an italic font. The low-order bit is 1 if the flag is set. All other bits are zero.

dfUnderline

Specifies whether the character-definition data represents an underlined font. The low-order bit is 1 if the flag is set. All other bits are zero.

dfStrikeOut

Specifies whether the character definition data represents a struck-out font. The low-order bit is 1 if the flag is set. All other bits are zero.

dfWeight

Specifies the weight of the characters in the character definition data, on a scale from 1–1000. A value of 400 specifies regular weight type; 700 is bold; and so on.

dfCharSet

Specifies the character set defined by this font. It can be one of the following values.

dfPixWidth

Specifies the width of all characters in the font.

For vector fonts, the dfPixWidth member is the width of the grid on which the font was digitized.

For raster fonts, dfPixWidth is the width (in pixels) of each character bitmap. If that member is zero, the font has variable-width characters and these widths are specified in the character-width table immediately following this structure.

dfPixHeight

Specifies the height of all characters in the font.

For vector fonts, the dfPixHeight member is the height of the grid on which the font was digitized.

For raster fonts, dfPixHeight is the height (in scan lines) of each character bitmap.

dfPitchAndFamily

Specifies the pitch and font family. The pitch specifies whether the characters in the font have the same width or variable widths. The font family indicates, in a general way, the look of a font.

The dfPitchAndFamily member can be a combination of the following values.

If the high-order 4 bits is set to FF_DONTCARE (0x00), the font belongs to no specific family.

dfAvgWidth

Specifies the width of characters in the font. For fixed-pitch fonts, this is the same as dfPixWidth. For variable-pitched fonts, this is the width of the character “X.”

dfMaxWidth

Specifies the maximum pixel width of any character in the font. For fixed-pitch fonts, this is simply dfPixWidth.

dfFirstChar

Specifies the first character code defined by this font. Character definitions are stored only for the characters actually present in a font, so this field should be used when calculating indexes into the character-width table following this structure.

dfLastChar

Specifies the last character code defined by this font. Notice that all the characters with codes between the dfFirstChar and dfLastChar member must be present in the character-width table.

dfDefaultChar

Specifies the default character. A device driver uses this character as a substitute for any character in a string that is out of the range of the dfFirstChar through dfLastChar members. The character is given relative to dfFirstChar so that the actual value of the default character is the sum of dfDefaultChar and dfFirstChar. Ideally, the dfDefaultChar member should be a visible character in the current font, for example, a period (.).

dfBreakChar

Specifies the word-break character. Applications use this character the separate words when wrapping or justifying lines of text. The character is given relative to dfFirstChar so that the actual value of the word-break character is the sum of the dfBreakChar and dfFirstChar members. In many fonts, dfBreakChar is zero and dfFirstChar is 32. This means that the word-break character value is 32, an ASCII space.

dfWidthBytes

Specifies the number of bytes in each row of the font bitmap (raster fonts). This field is not used for vector fonts. The dfWidthBytes member is always an even quantity so that rows of the bitmap start on 16-bit boundaries.

dfDevice

Specifies the offset from the beginning of the segment containing the FONTINFO structure to the null-terminated ASCII string specifying the device name. For a generic font, this value will be NULL.

dfFace

Specifies the offset from the beginning of the segment containing the FONTINFO structure to the null-terminated ASCII string specifying the name of the font face.

dfBitsPointer

Specifies the absolute machine address of the bitmap. This is set by GDI. The dfBitsPointer member is guaranteed to be even.

dfBitsOffset

Specifies the offset from the beginning of the segment containing the FONTINFO structure to the beginning of the bitmap information.

If the PF_BITS_IS_ADDRESS bit is set in dfType, dfBitsOffset is an absolute address of the bitmap or vector information. For example, this bit is set if the font bitmap or vector information is in ROM.

For raster fonts, dfBitsOffset points to a sequence of bytes that make up the bitmaps for each character in the font.

For vector fonts, dfBitsOffset points to a string of bytes or words (depending on the size of the grid on which the font was digitized) that specifies the strokes for each character of the font. The dfBitsOffset member must be even.

dfReserved

Reserved; do not use. This member is present only for raster fonts. In Windows 2.x fonts, this member ensures that the character-width table (which immediately follows this member) starts on a 16-bit boundary.

dfFlags

Specifies the format of the font bitmap information. It can be one of the following values.

This member is present only for Windows 3.x fonts.

dfAspace

Specifies the global A space, if any. The dfAspace member is the distance from the current position to the left edge of the bitmap. This member is present only for Windows 3.x fonts.

dfBspace

Specifies the global B space, if any. The dfBspace member is the width of the character. This member is present only for Windows 3.x fonts.

dfCspace

Specifies the global C space, if any. The dfCspace member is the distance from the right edge of the bitmap to the new current position. This member is present only for Windows 3.x fonts.

dfColorPointer

Specifies the offset to the color table (if any) for color fonts. This member is present only for Windows 3.x fonts, however, it is not presently used and should always be set to NULL.

dfReserved1

This member is not used. This member is present only for Windows 3.x fonts.

Comments

The FONTINFO structure may be immediately followed by one or more of the following items.

All device drivers must support Windows 2.x fonts. If a device driver supports Windows 3.x fonts, it must set the RC_BIGFONT bit in the dpRaster member of its GDIINFO structure. Printer drivers can call the GetDeviceCaps function (GDI.80), and check for the RC_BIGFONT bit in the raster capabilities to determine whether the display driver uses Windows 3.x fonts.

When a device driver realizes a font using the RealizeObject function, the dfFace and dfDevice members must point to valid character strings containing the font and device names.

Windows 2.x Fonts

For Windows 2.x fonts the character-width table is either an array of integer values or an array of glyph-entry structures. The number of elements in the array is equal to:

dfLastChar - dfFirstChar + 2

That is, there is always one more element than the number of characters in the font. The extra entry is available for storing the size in bytes of the last character in a vector font. Although this extra entry applies only to vector fonts, it is present for all fonts.

For fixed-pitch vector fonts, the character-width table is an array of integer values. In this case, each element of the array is an offset (relative to the start of the segment containing the FONTINFO structure) to the first byte or 16 bits of vector information for the given character. The number of bytes or words for a particular character is calculated by subtracting its character-width table entry from the entry for the next character.

For variable-pitch vector fonts, the character width table is an array of VECTORGLYPHENTRY structures. The VECTORGLYPHENTRY structure has the following form:

typedef struct tagVECTORGLYPHENTRY {

short vgeOffset; /* offset to vectors relative to segment start */

short vgeWidth; /* width of character in pixels */

} VECTORGLYPHENTRY;

The vgeOffset member specifies the offset (relative to the start of the segment containing the FONTINFO structure) to the first byte or 16 bits of vector information for the given character. The vgeWidth member specifies the width for the character.

For raster fonts, the character-width table is an array of RASTERGLYPHENTRY structures.

The rgeWidth member specifies the width (in pixels) of the bitmap for the given character. The member also specifies the advance width for the given character. The rgeOffset member specifies the offset (relative to the start of the segment containing the FONTINFO structure) to the first byte of bitmap information for the character.

Windows 2.x fonts cannot exceed 64K bytes.

Windows 3.x Fonts

Windows 3.x fonts are primarily designed for use on systems with more than average memory and a microprocessor (such as an 80386) that has instructions that use 32-bit address offsets.

For Windows 3.x fonts, the format of the character-width table is dependent on the value of the dfFlags member.

Windows presently supports only the DFF_FIXED and DFF_PROPORTIONAL values.

The rgeWidth member specifies the width (in pixels) of the bitmap for the given character. The member also specifies the width for the character. The rgeOffset member specifies the offset (relative to the start of the segment containing the FONTINFO structure) to the first byte of bitmap information for the character.

The ABCGLYPHENTRY structure has the following form:

typedef struct tagABCGLYPHENTRY {

short ageWidth; /* width of character bitmap in pixels */

long ageOffset; /* pointer to the bits */

FIXED ageAspace; /* A space in fractional pixels (16.16) */

FIXED ageBspace; /* B space in fractional pixels (16.16) */

FIXED ageCspace; /* C space in fractional pixels (16.16) */

} ABCGLYPHENTRY;

The ageWidth member specifies the width (in pixels) of the bitmap for the given character. The ageOffset member specifies the offset (relative to the start of the segment containing the FONTINFO structure) to the first byte of bitmap information for the character. The sum of the ageAspace, ageBspace, and ageCspace members specify the width of the character.

The COLORGLYPHENTRY structure has the following form:

typedef struct tagCOLORGLYPHENTRY {

short cgeWidth; /* width of character bitmap in pixels */

long cgeOffset; /* pointer to the bits */

short cgeHeight; /* height of character bitmap in pixels */

FIXED cgeAspace; /* A space in fractional pixels (16.16) */

FIXED cgeBspace; /* B space in fractional pixels (16.16) */

FIXED cgeCspace; /* C space in fractional pixels (16.16) */

} COLORGLYPHENTRY;

The cgeWidth member specifies the width (in pixels) of the bitmap for the given character. The cgeOffset member specifies the offset (relative to the start of the segment containing the FONTINFO structure) to the first byte of bitmap information for the character. The cgeHeight member specifies the height (in scan lines) of the bitmap. The sum of the cgeAspace, cgeBspace, and cgeCspace members specify the width of the character.

The number of bits for each pixel in a character bitmap depends on the value of the dfFlags member.

All other font formats use 1 bit per pixel.

Windows 3.x fonts can exceed 64K bytes.

See Also

ExtTextOut, RealizeObject, StrBlt