cairo-scaled-font: cairo_scaled_font_t
Description
Font face at particular size and optionsMethods and Functions
cairoScaledFontCreate(font.face, font.matrix, ctm, option)
cairoScaledFontStatus(scaled.font)
cairoScaledFontExtents(scaled.font)
cairoScaledFontTextExtents(scaled.font, utf8)
cairoScaledFontGlyphExtents(scaled.font, glyphs, num.glyphs)
cairoScaledFontTextToGlyphs(scaled.font, x, y, utf8, utf8.len = -1)
cairoScaledFontGetFontFace(scaled.font)
cairoScaledFontGetFontOptions(scaled.font)
cairoScaledFontGetFontMatrix(scaled.font)
cairoScaledFontGetCtm(scaled.font)
cairoScaledFontGetScaleMatrix(scaled.font)
cairoScaledFontGetType(scaled.font)
cairoScaledFontSetUserData(scaled.font, key, user.data)
cairoScaledFontGetUserData(scaled.font, key)
cairoScaledFont(font.face, font.matrix, ctm, option)Detailed Description
CairoScaledFont represents a realization of a font face at a particular
size and transformation and a certain set of font options.Structures
CairoScaledFont-
A
CairoScaledFont is a font scaled to a particular size and device
resolution. A CairoScaledFont is most useful for low-level font
usage where a library or application wants to cache a reference
to a scaled font to speed up the computation of metrics. There are various types of scaled fonts, depending on the
font backend they use. The type of a
scaled font can be queried using cairoScaledFontGetType. Memory management of CairoScaledFont is done with
cairoScaledFontReference() and cairoScaledFontDestroy(). CairoFontExtents-
The
CairoFontExtents structure stores metric information for
a font. Values are given in the current user-space coordinate
system. Because font metrics are in user-space coordinates, they are
mostly, but not entirely, independent of the current transformation
matrix. If you call cairo_scale(cr, 2.0, 2.0),
text will be drawn twice as big, but the reported text extents will
not be doubled. They will change slightly due to hinting (so you
can't assume that metrics are independent of the transformation
matrix), but otherwise will remain unchanged.
CairoFontExtents is a transparent-type.
ascent- [numeric] the distance that the font extends above the baseline.
Note that this is not always exactly equal to the maximum
of the extents of all the glyphs in the font, but rather
is picked to express the font designer's intent as to
how the font should align with elements above it.
descent- [numeric] the distance that the font extends below the baseline.
This value is positive for typical fonts that include
portions below the baseline. Note that this is not always
exactly equal to the maximum of the extents of all the
glyphs in the font, but rather is picked to express the
font designer's intent as to how the the font should
align with elements below it.
height- [numeric] the recommended vertical distance between baselines when
setting consecutive lines of text with the font. This
is greater than
ascent+descent by a
quantity known as the line spacing
or external leading. When space
is at a premium, most fonts can be set with only
a distance of ascent+descent between lines. maxXAdvance- [numeric] the maximum distance in the X direction that
the the origin is advanced for any glyph in the font.
maxYAdvance- [numeric] the maximum distance in the Y direction that
the the origin is advanced for any glyph in the font.
this will be zero for normal fonts used for horizontal
writing. (The scripts of East Asia are sometimes written
vertically.)
CairoTextExtents-
The
CairoTextExtents structure stores the extents of a single
glyph or a string of glyphs in user-space coordinates. Because text
extents are in user-space coordinates, they are mostly, but not
entirely, independent of the current transformation matrix. If you call
cairo_scale(cr, 2.0, 2.0), text will
be drawn twice as big, but the reported text extents will not be
doubled. They will change slightly due to hinting (so you can't
assume that metrics are independent of the transformation matrix),
but otherwise will remain unchanged.
xBearing- [numeric] the horizontal distance from the origin to the
leftmost part of the glyphs as drawn. Positive if the
glyphs lie entirely to the right of the origin.
yBearing- [numeric] the vertical distance from the origin to the
topmost part of the glyphs as drawn. Positive only if the
glyphs lie completely below the origin; will usually be
negative.
width- [numeric] width of the glyphs as drawn
height- [numeric] height of the glyphs as drawn
xAdvance- [numeric] distance to advance in the X direction
after drawing these glyphs
yAdvance- [numeric] distance to advance in the Y direction
after drawing these glyphs. Will typically be zero except
for vertical text layout as found in East-Asian languages.