Test struts on paragraph with offset middle box.
Add paragraphLines to Rich ParagraphLayout.
BREAKING: The paragraphLines field of ParagraphLayout must be preserved
for pagination.
BREAKING: The width of a rich text ParagraphLayout will now remain
unchanged after pagination.
BREAKING: Empty space at the top of the first line and at the bottom
of the last line in a ParagraphLayout will now be preserved.
Add manual test for mixed vertical alignment.
Test mixed line height with varied alignment.
Store parent text options in ResolvedBox.
This is required for vertically aligning the box with its parent.
Add content rect to Fragment.
Add helper function to strut empty boxes.
Test preservation of lines with boxes.
Test boxes with no text or only a space.
Allow trimmed whitespace to generate empty fragments.
BREAKING: Output may now contain more fragments with zero glyphs,
representing runs of whitespace that was trimmed away. These runs may
also start a box at the end of a line, instead of the beginning of the
next line.
BREAKING: Trimmed whitespace now affects line height.
Test paragraphSafeWidth on LTR paragraphs.
Allow generating an empty run.
Store default level in BiDiLevels.
This will be required for handling empty text sequences.
Test with AlignStart by default.
Test right-aligned paragraph.
Internally mark hard line breaks.
Internally allow splitting texts at endpoints.
This is required in order to preserve a hard line break at the end of
the input.
Test handling of empty lines.