LayoutIter.getRunReadonly

Gets the current run for read-only access.

When iterating by run, at the end of each line, there's a position with a null run, so this function can return null. The null run at the end of each line ensures that all lines have at least one run, even lines consisting of only a newline.

This is a faster alternative to [pango.layout_iter.LayoutIter.getRun], but the user is not expected to modify the contents of the run (glyphs, glyph widths, etc.).