Edytuj

Udostępnij za pośrednictwem

LOGFONTA structure (dimm.h)

  • Artykuł

Defines the attributes of a font.

Syntax

typedef struct __MIDL___MIDL_itf_dimm_0000_0000_0003 {
  LONG lfHeight;
  LONG lfWidth;
  LONG lfEscapement;
  LONG lfOrientation;
  LONG lfWeight;
  BYTE lfItalic;
  BYTE lfUnderline;
  BYTE lfStrikeOut;
  BYTE lfCharSet;
  BYTE lfOutPrecision;
  BYTE lfClipPrecision;
  BYTE lfQuality;
  BYTE lfPitchAndFamily;
  CHAR lfFaceName[32];
} LOGFONTA;

Members

lfHeight

Type: LONG

Specifies the height, in logical units, of the font's character cell or character. The character height value (also known as the em height) is the character cell height value minus the internal-leading value. The font mapper interprets the value specified in lfHeight in the following manner.

Value Description
> 0 The font mapper transforms this value into device units and matches it against the cell height of the available fonts.
0 The font mapper uses a default height value when it searches for a match.
< 0 The font mapper transforms this value into device units and matches its absolute value against the character height of the available fonts.
 

For all height comparisons, the font mapper looks for the largest font that does not exceed the requested size.

This mapping occurs when the font is used for the first time.

For the MM_TEXT mapping mode, you may use the following formula to specify a height for a font with a given point size.

lfHeight = -MulDiv(PointSize, GetDeviceCaps(hDC, LOGPIXELSY), 72);

where MulDiv is defined as follows:

#define MulDiv(a,b,c)    (((a)*(b))/(c))

lfWidth

Type: LONG

Specifies the average width, in logical units, of characters in the font. If lfWidth is not zero, the aspect ratio of the device is matched against the digitization aspect ratio of the available fonts to find the closest match, determined by the absolute value of the difference.

lfEscapement

Type: LONG

Specifies the angle, in tenths of degrees, between the escapement vector and the x-axis of the device. The escapement vector is parallel to the base line of a row of text.

The lfEscapement member specifies both the escapement and orientation. You should set lfEscapement and lfOrientation to the same value.

lfOrientation

Type: LONG

Specifies the angle, in tenths of degrees, between each character's base line and the x-axis of the device.

lfWeight

Type: LONG

Specifies the weight of the font in the range 0 through 1000. For example, 400 is normal and 700 is bold. If this value is zero, a default weight is used.

The following values are defined in Wingdi.h for convenience.

Value Weight
FW_DONTCARE 0
FW_THIN 100
FW_EXTRALIGHT 200
FW_ULTRALIGHT 200
FW_LIGHT 300
FW_NORMAL 400
FW_REGULAR 400
FW_MEDIUM 500
FW_SEMIBOLD 600
FW_DEMIBOLD 600
FW_BOLD 700
FW_EXTRABOLD 800
FW_ULTRABOLD 800
FW_HEAVY 900
FW_BLACK 900

lfItalic

Type: BYTE

TRUE to specify an italic font.

lfUnderline

Type: BYTE

TRUE to specify an underlined font.

lfStrikeOut

Type: BYTE

TRUE to specify a strikeout font.

lfCharSet

Type: BYTE

Specifies the character set. The following values are predefined:

ANSI_CHARSET BALTIC_CHARSET
CHINESEBIG5_CHARSET DEFAULT_CHARSET
EASTEUROPE_CHARSET GB2312_CHARSET
GREEK_CHARSET HANGUL_CHARSET
MAC_CHARSET OEM_CHARSET
RUSSIAN_CHARSET SHIFTJIS_CHARSET
SYMBOL_CHARSET TURKISH_CHARSET
 
Korean Windows
JOHAB_CHARSET
 
Middle-Eastern Windows
HEBREW_CHARSET
ARABIC_CHARSET
 
Thai Windows
THAI_CHARSET
 

The OEM_CHARSET value specifies a character set that is operating-system dependent.

DEFAULT_CHARSET is set to a value based on the current system locale. For example, when the system locale is English (United States), the value is ANSI_CHARSET.

Fonts with other character sets may exist in the operating system. If an application uses a font with an unknown character set, it should not attempt to translate or interpret strings that are rendered with that font.

This member is important in the font mapping process. To ensure consistent results, specify a specific character set. If you specify a typeface name in the lfFaceName member, make sure that the lfCharSet value matches the character set of the typeface specified in lfFaceName.

lfOutPrecision

Type: BYTE

Specifies the output precision. The output precision defines how closely the output must match the requested font's height, width, character orientation, escapement, pitch, and font type. It can be one of the following values defined in Wingdi.h:

Value Description
OUT_DEFAULT_PRECIS Specifies the default font mapper behavior.
OUT_RASTER_PRECIS Instructs the font mapper to choose a raster font when the system contains multiple fonts with the same name.
OUT_STRING_PRECIS This value is not used by the font mapper, but it is returned when raster fonts are enumerated.

lfClipPrecision

Type: BYTE

Specifies the clipping precision. The clipping precision defines how to clip characters that are partially outside the clipping region. It can be one or more of the following values defined in Wingdi.h:

Value Description
CLIP_DEFAULT_PRECIS Specifies default clipping behavior.
CLIP_CHARACTER_PRECIS Not used.
CLIP_STROKE_PRECIS Not used by the font mapper, but is returned when raster, vector, or TrueType fonts are enumerated.

lfQuality

Type: BYTE

Specifies the output quality. The output quality defines how carefully the GDI must attempt to match the logical-font attributes to those of an actual physical font. It can be one of the following values defined in Wingdi.h:

Value Description
ANTIALIASED_QUALITY Enables antialiasing for the font. The display driver must support antialiased text for this setting to work.
NONANTIALIASED_QUALITY Forces use of draft quality when the HKEY_LOCAL_MACHINE\System\GDI\Fontsmoothing registry subkey is present.
CLEARTYPE_COMPAT_QUALITY Enables ClearType text for the font using compatible widths. A compatible width produces text that has the same spacing as non-ClearType text.
CLEARTYPE_QUALITY Enables ClearType text for the font. The display driver must support ClearType text for this setting to work.
DEFAULT_QUALITY Appearance of the font does not matter.
DRAFT_QUALITY For GDI raster fonts, scaling is enabled, which means that more font sizes are available, but the quality may be lower. Bold, italic, underline, and strikeout fonts are synthesized if necessary.

lfPitchAndFamily

Type: BYTE

Specifies the pitch and group of the font. The two low-order bits specify the pitch of the font and can be one of the following values defined in Wingdi.h:

  • DEFAULT_PITCH
  • FIXED_PITCH
  • MONO_FONT
  • VARIABLE_PITCH
Bits 4 through 7 of the member specify the font group and can be one of the following values defined in Wingdi.h:
  • FF_DECORATIVE
  • FF_DONTCARE
  • FF_MODERN
  • FF_ROMAN
  • FF_SCRIPT
  • FF_SWISS
The proper value can be obtained by using the Boolean OR operator to join one pitch constant with one family constant.

Font families describe the look of a font in a general way. They are intended for specifying fonts when the exact typeface desired is not available. The values for font families are as follows:

Value Description
FF_DECORATIVE Novelty fonts, for example, Old English.
FF_DONTCARE Do not care or do not know.
FF_MODERN Fonts with constant stroke width (monospace), with or without serifs. Monospace fonts are usually modern, for example, Pica, Elite, and Courier New.
FF_ROMAN Fonts with variable stroke width (proportional) and with serifs, for example, Serif.
FF_SCRIPT Fonts designed to look like handwriting, for example, Script and Cursive.
FF_SWISS Fonts with variable stroke width (proportional) and without serifs, for example, Sans Serif.

lfFaceName[32]

Type: TCHAR[LF_FACESIZE]

Specifies a null-terminated string that specifies the typeface name of the font. The length of this string must not exceed 32 characters, including the terminating null character. The EnumFontFamilies function can be used to enumerate the typeface names of all currently available fonts. If lfFaceName is an empty string, GDI uses the first font that matches the other specified attributes.

Remarks

The following situations do not support ClearType antialiasing:

  • Text is rendered on a printer.
  • Display set for 256 colors or less.
  • Text is rendered to a terminal server client.
  • The font is not a TrueType font or an Microsoft OpenType font with TrueType outlines. For example, the following do not support ClearType antialiasing: Type 1 fonts, Postscript OpenType fonts without TrueType outlines, bitmap fonts, vector fonts, and device fonts.
  • The font has tuned embedded bitmaps, for any font sizes that contain the embedded bitmaps. For example, this occurs commonly in East Asian fonts.
This structure first appeared in Shtypes.idl and Shtypes.h in Windows Vista, for ease of use with members of the IVisualProperties interface. However, the identical structure is defined in Wingdi.h and Windows.h in earlier versions of Windows.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Header dimm.h (include Shtypes.h, Dimm.h)

See also

IVisualProperties::GetFont

IVisualProperties::SetFont