Add setAlignment(content, start, end, align) and alignmentAt(...) ops to
RichTextEditing with paragraph-range bookkeeping (mirroring toggleBlock).
setAlignment marks every line the selection touches, leaves untouched
paragraphs alone, and stores START as "no alignment" (dropping the range) so
an otherwise-plain paragraph stays plaintext-only; CENTER/END become explicit
ranges. It emits the same canonical form RichTextHtml.fromHtml returns — one
merged range per run of adjacent same-aligned lines, and blank paragraphs
anchor no range (the HTML model can't pin text-align to an empty <p>) — so the
model, its HTML, and the editor's ParagraphStyle rendering never drift.
alignmentAt returns the shared alignment (START default for plain paragraphs,
null when mixed), driving a three-state control directly.
Add ParagraphAlignmentControl (start/center/end glyph buttons) and append it —
plus the existing FontSizePicker — at the END of the toolbar, after the block
and link buttons. Per the #73 lesson, nothing may shift the bullet/numbered/
quote buttons rightward or the compose E2E's no-scroll performClick on "•" (and
siblings) misses.
Editor renders alignment via the existing ParagraphStyle(textAlign) path
(applyAlignment routes through it, preserving the selection since alignment
never changes the text).
Tests: setAlignment/alignmentAt covered thoroughly at the JVM layer (caret,
multi-paragraph merge, mid-block split, untouched paragraphs, blank lines,
empty document, mixed selections) plus a serialize->parse round-trip fixpoint
on setAlignment output; applyAlignment covered in RichTextEditorTest; a
compile-only androidTest drives the control in isolation.
Closes#76
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8
df5c1aa2f9