Your application passes a glyph bounds constant in the iTypeOfBounds parameter of the functionATSUGetGlyphBounds to indicate whether the width of the resulting typographic glyph bounds will be determined using the caret origin, glyph origin in device space, or glyph origin in fractional absolute positions.
enum {
kATSUseCaretOrigins = 0,
kATSUseDeviceOrigins = 1,
kATSUseFractionalOrigins = 2
};
Constant descriptions
kATSUseCaretOrigins
Specifies that the width of the typographic glyph bounds will be determined using the caret origin. The caret origin is halfway between two characters.
kATSUseDeviceOrigins
Specifies that the width of the typographic glyph bounds will be determined using the glyph origin in device space. This is useful for adjusting text on the screen.
kATSUseFractionalOrigins
Specifies that the width of the typographic glyph bounds will be determined using the glyph origin in fractional absolute positions, which are uncorrected for device display. This provides the ideal position of laid-out text and is useful for scaling text on the screen. This origin is also used to get the width of the typographic bounding rectangle when you call ATSUMeasureText.
