Pango: The Rendering Pipeline (original) (raw)

The Rendering Pipeline

The Pango rendering pipeline takes a string of Unicode characters, converts them it into glyphs, and renders them on some output medium. This section describes the various stages of this pipeline and the APIs that implement them.

Itemization

breaks a piece of text into segments with consistent direction and shaping properties. Among other things, this determines which font to use for each character. Use pango_itemize() or pango_itemize_with_base_dir() to itemize text.

Shaping

converts characters into glyphs. Use pango_shape(),pango_shape_full() or pango_shape_item() to shape text.

Line Breaking

determines where line breaks should be inserted into a sequence of glyphs. The functions pango_default_break(), pango_tailor_break() andpango_attr_break() determine possible line breaks. The actual line breaking is done by PangoLayout.

Justification

adjusts inter-word spacing to form lines of even length. This is done byPangoLayout.

Rendering

takes a string of positioned glyphs, and renders them onto a surface. This is accomplished by a PangoRenderer object. The functionspango_cairo_show_glyph_string() and pango_cairo_show_layout() use aPangoRenderer to draw text onto a cairo surface.