cairo-text: Text

In RGtk2: R Bindings for Gtk 2.8.0 and Above

Description

Rendering text and glyphs

Methods and Functions

cairoSelectFontFace(cr, family, slant, weight)
cairoSetFontSize(cr, size)
cairoSetFontMatrix(cr, matrix)
cairoGetFontMatrix(cr, matrix)
cairoSetFontOptions(cr, options)
cairoGetFontOptions(cr)
cairoSetFontFace(cr, font.face)
cairoGetFontFace(cr)
cairoSetScaledFont(cr, scaled.font)
cairoGetScaledFont(cr)
cairoShowText(cr, utf8)
cairoShowGlyphs(cr, glyphs, num.glyphs)
cairoShowTextGlyphs(cr, utf8, glyphs, clusters, cluster.flags)
cairoFontExtents(cr)
cairoTextExtents(cr, utf8)
cairoGlyphExtents(cr, glyphs)
cairoToyFontFaceCreate(family, slant, weight)
cairoToyFontFaceGetFamily(font.face)
cairoToyFontFaceGetSlant(font.face)
cairoToyFontFaceGetWeight(font.face)

Detailed Description

Cairo has two sets of text rendering capabilities:

Structures

CairoGlyph

The CairoGlyph structure holds information about a single glyph when drawing or measuring text. A font is (in simple terms) a collection of shapes used to draw text. A glyph is one of these shapes. There can be multiple glyphs for a single character (alternates to be used in different contexts, for example), or a glyph can be a ligature of multiple characters. Cairo doesn't expose any way of converting input text into glyphs, so in order to use the Cairo interfaces that take arrays of glyphs, you must directly access the appropriate underlying font system.

Note that the offsets given by x and y are not cumulative. When drawing or measuring text, each glyph is individually positioned with respect to the overall origin CairoGlyph is a transparent-type.

index

[numeric] glyph index in the font. The exact interpretation of the glyph index depends on the font technology being used.

x

[numeric] the offset in the X direction between the origin used for drawing or measuring the string and the origin of this glyph.

y

[numeric] the offset in the Y direction between the origin used for drawing or measuring the string and the origin of this glyph.

CairoTextCluster

The CairoTextCluster structure holds information about a single text cluster. A text cluster is a minimal mapping of some glyphs corresponding to some UTF-8 text.

For a cluster to be valid, both num.bytes and num.glyphs should be non-negative, and at least one should be non-zero. Note that clusters with zero glyphs are not as well supported as normal clusters. For example, PDF rendering applications typically ignore those clusters when PDF text is being selected.

See cairoShowTextGlyphs for how clusters are used in advanced text operations. Since 1.8 CairoTextCluster is a transparent-type.

numBytes

[integer] the number of bytes of UTF-8 text covered by cluster

numGlyphs

[integer] the number of glyphs covered by cluster

Enums and Flags

CairoFontSlant

Specifies variants of a font face based on their slant.

normal

Upright font style

italic

Italic font style

oblique

Oblique font style

CairoFontWeight

Specifies variants of a font face based on their weight.

normal

Normal font weight

bold

Bold font weight

CairoTextClusterFlags

Specifies properties of a text cluster mapping. Since 1.8

backward

The clusters in the cluster list map to glyphs in the glyph list from end to start.

Author(s)

Derived by RGtkGen from GTK+ documentation

References

http://www.cairographics.org/manual/cairo-text.html

RGtk2 documentation built on Oct. 14, 2021, 5:08 p.m.