typedef struct tagTEXTMETRIC { /* tm */
LONG tmHeight;
LONG tmAscent;
LONG tmDescent;
LONG tmInternalLeading;
LONG tmExternalLeading;
LONG tmAveCharWidth;
LONG tmMaxCharWidth;
LONG tmWeight;
LONG tmOverhang;
LONG tmDigitizedAspectX;
LONG tmDigitizedAspectY;
BYTE tmFirstChar;
BYTE tmLastChar;
BYTE tmDefaultChar;
BYTE tmBreakChar;
BYTE tmItalic;
BYTE tmUnderlined;
BYTE tmStruckOut;
BYTE tmPitchAndFamily;
BYTE tmCharSet;
} TEXTMETRIC;
The TEXTMETRIC structure contains basic information about a physical font. All sizes are given in logical units; that is, they depend on the current mapping mode of the display context.
tmHeight
Specifies the height (ascent + descent) of characters.
tmAscent
Specifies the ascent (units above the baseline) of characters.
tmDescent
Specifies the descent (units below the baseline) of characters.
tmInternalLeading
Specifies the amount of leading (space) inside the bounds set by the tmHeight member. Accent marks and other foreign characters may occur in this area. The designer may set this member to zero.
tmExternalLeading
Specifies the amount of extra leading (space) that the application adds between rows. Since this area is outside the font, it contains no marks and will not be altered by text output calls in either OPAQUE or TRANSPARENT mode. The designer may set this member to zero.
tmAveCharWidth
Specifies the average width of characters in the font (loosely defined as the width of the letter x). This value does not include overhang required for bold or italic characters.
tmMaxCharWidth
Specifies the width of the widest character in the font.
tmWeight
Specifies the weight of the font.
tmOverhang
Specifies the per-string extra width that may be added to some synthesized fonts. When synthesizing some attributes, such as bold or italic, GDI or a device may have to add width to a string on both a per-character and per-string basis. For example, GDI makes a string bold by expanding the intracharacter spacing and overstriking by an offset value; it italicizes a font by skewing the string. In either case, there is an overhang past the basic string. For bold strings, the overhang is the distance by which the overstrike is offset. For italic strings, the overhang is the amount the top of the font is skewed past the bottom of the font.
The tmOverhang member allows the application to determine how much of the character width returned by a GetTextExtentPoint function call on a single character is the actual character width and how much is the per-string extra width. The actual width is the extent minus the overhang.
tmDigitizedAspectX
Specifies the horizontal aspect of the device for which the font was designed.
tmDigitizedAspectY
Specifies the vertical aspect of the device for which the font was designed. The ratio of the tmDigitizedAspectX and tmDigitizedAspectY members is the aspect ratio of the device for which the font was designed.
tmItalic
Specifies an italic font if it is nonzero.
tmUnderlined
Specifies an underlined font if it is nonzero.
tmStruckOut
Specifies a struckout font if it is nonzero.
tmFirstChar
Specifies the value of the first character defined in the font.
tmLastChar
Specifies the value of the last character defined in the font.
tmDefaultChar
Specifies the value of the character that will be substituted for characters that are not in the font.
tmBreakChar
Specifies the value of the character that will be used to define word breaks for text justification.
tmPitchAndFamily
Specifies the pitch and family of the selected font. The low-order bit specifies the pitch of the font. If it is 1, the font is variable pitch. If it is 0, the font is fixed pitch.
The four high-order bits designate the font family. The tmPitch-AndFamily member can be combined with the hexadecimal value 0xF0 by using the bitwise AND operator, and then be compared with the font family names for an identical match. For a description of the font families, see the LOGFONT structure, earlier in this chapter.
tmCharSet
Specifies the character set of the font.
GetTextMetrics