Text layout is a loose hierarchy of segmentation.

A complete account of text layout would be at least a small book. Since there’s no way I can write that now, this blog post is a small step towards that – in particular, an attempt to describe the “big picture,” using the conceptual framework of a “loose hierarchy.” Essentially, a text layout engine breaks the input into finer and finer grains, then reassembles the results into a text layout object suitable for drawing, measurement, and hit testing.