Fix bug #8242: undo fails for longest label width

In the existing code for setting layout of pragraph parameters,
Text::undoSpan is used to "guess" which paragraphs should be saved in Undo.
With this patch the approach is more precise: before every explicit change
to a paragraph, a Cursor::recordUndo call is inserted. This is much more robust than trying to guess.

In particular, we do not look at depth changes at all, since they are now
handled in updateBuffer since #8159 has been fixed.

src/Text.cpp

@@ -700,8 +700,7 @@ void Text::breakParagraph(Cursor & cur, bool inverse_logic)
 		return;
 	}
 
-	// a layout change may affect also the following paragraph
-	recUndo(cur, cur.pit(), undoSpan(cur.pit()) - 1);
+	cur.recordUndo();
 
 	// Always break behind a space
 	// It is better to erase the space (Dekel)

src/Text.h

@@ -82,8 +82,8 @@ public:
 	/// set layout over selection
 	void setLayout(pit_type start, pit_type end,
 		docstring const & layout);
-	/// Set given layout to current cursor position.
-	/// FIXME: replace Cursor with DocIterator.
+	/// Set given layout to current cursor position or selection.
+	/// Handles undo.
 	void setLayout(Cursor & cur, docstring const & layout);
 
 	/// what type of depth change to make
@@ -343,10 +343,6 @@ private:
 	/// The InsetText owner shall have access to everything.
 	friend class InsetText;
 
-	/// return past-the-last paragraph influenced by a layout
-	/// change on pit
-	pit_type undoSpan(pit_type pit);
-
 	// fix the cursor `cur' after a characters has been deleted at `where'
 	// position. Called by deleteEmptyParagraphMechanism
 	static void fixCursorAfterDelete(CursorSlice & cur, CursorSlice const & where);
@@ -375,7 +371,7 @@ private:
 	void readParagraph(Paragraph & par, Lexer & lex, ErrorList & errorList);
 	/// Set Label Width string to all paragraphs of the same layout
     /// and depth in a sequence.
-	void setLabelWidthStringToSequence(pit_type const par_offset, docstring const & s);
+	void setLabelWidthStringToSequence(Cursor const & cur, docstring const & s);
 
 	/// Owner Inset.
 	InsetText * owner_;

src/Text2.cpp

@@ -183,25 +183,6 @@ void Text::setInsetFont(BufferView const & bv, pit_type pit,
 }
 
 
-// return past-the-last paragraph influenced by a layout change on pit
-pit_type Text::undoSpan(pit_type pit)
-{
-	pit_type const end = paragraphs().size();
-	pit_type nextpit = pit + 1;
-	if (nextpit == end)
-		return nextpit;
-	//because of parindents
-	if (!pars_[pit].getDepth())
-		return boost::next(nextpit);
-	//because of depth constrains
-	for (; nextpit != end; ++pit, ++nextpit) {
-		if (!pars_[pit].getDepth())
-			break;
-	}
-	return nextpit;
-}
-
-
 void Text::setLayout(pit_type start, pit_type end,
 		     docstring const & layout)
 {
@@ -227,8 +208,7 @@ void Text::setLayout(Cursor & cur, docstring const & layout)
 
 	pit_type start = cur.selBegin().pit();
 	pit_type end = cur.selEnd().pit() + 1;
-	pit_type undopit = undoSpan(end - 1);
-	recUndo(cur, start, undopit - 1);
+	cur.recordUndoSelection();
 	setLayout(start, end, layout);
 	cur.forceBufferUpdate();
 }
@@ -431,31 +411,31 @@ docstring Text::getStringToIndex(Cursor const & cur)
 }
 
 
-void Text::setLabelWidthStringToSequence(pit_type const par_offset,
+void Text::setLabelWidthStringToSequence(Cursor const & cur,
 		docstring const & s)
 {
-	pit_type offset = par_offset;
+	Cursor c = cur;
 	// Find first of same layout in sequence
-	while (!isFirstInSequence(offset)) {
-		offset = depthHook(offset, pars_[offset].getDepth());
+	while (!isFirstInSequence(c.pit())) {
+		c.pit() = depthHook(c.pit(), c.paragraph().getDepth());
 	}
 
 	// now apply label width string to every par
 	// in sequence
-	pit_type const end = pars_.size();
-	depth_type const depth = pars_[offset].getDepth();
-	Layout const & layout = pars_[offset].layout();
-	for (pit_type pit = offset; pit != end; ++pit) {
-		while (pars_[pit].getDepth() > depth) {
-			++pit;
-			if (pit == end)
+	depth_type const depth = c.paragraph().getDepth();
+	Layout const & layout = c.paragraph().layout();
+	for ( ; c.pit() <= c.lastpit() ; ++c.pit()) {
+		while (c.paragraph().getDepth() > depth) {
+			++c.pit();
+			if (c.pit() > c.lastpit())
 				return;
 		}
-		if (pars_[pit].getDepth() < depth)
+		if (c.paragraph().getDepth() < depth)
 			return;
-		if (pars_[pit].layout() != layout)
+		if (c.paragraph().layout() != layout)
 			return;
-		pars_[pit].setLabelWidthString(s);
+		c.recordUndo();
+		c.paragraph().setLabelWidthString(s);
 	}
 }
 
@@ -463,26 +443,25 @@ void Text::setLabelWidthStringToSequence(pit_type const par_offset,
 void Text::setParagraphs(Cursor & cur, docstring arg, bool merge) 
 {
 	LASSERT(cur.text(), /**/);
-	// make sure that the depth behind the selection are restored, too
-	pit_type undopit = undoSpan(cur.selEnd().pit());
-	recUndo(cur, cur.selBegin().pit(), undopit - 1);
 
 	//FIXME UNICODE
 	string const argument = to_utf8(arg);
 	depth_type priordepth = -1;
 	Layout priorlayout;
-	for (pit_type pit = cur.selBegin().pit(), end = cur.selEnd().pit();
-	     pit <= end; ++pit) {
-		Paragraph & par = pars_[pit];
+	Cursor c(cur.bv());
+	c.setCursor(cur.selectionBegin());
+	for ( ; c <= cur.selectionEnd() ; ++c.pit()) {
+		Paragraph & par = c.paragraph();
 		ParagraphParameters params = par.params();
 		params.read(argument, merge);
 		// Changes to label width string apply to all paragraphs
 		// with same layout in a sequence.
 		// Do this only once for a selected range of paragraphs
 		// of the same layout and depth.
-		if (par.getDepth() != priordepth || par.layout() != priorlayout)
-			setLabelWidthStringToSequence(pit, params.labelWidthString());
+		cur.recordUndo();
 		par.params().apply(params, par.layout());
+		if (par.getDepth() != priordepth || par.layout() != priorlayout)
+			setLabelWidthStringToSequence(c, params.labelWidthString());
 		priordepth = par.getDepth();
 		priorlayout = par.layout();
 	}
@@ -495,23 +474,22 @@ void Text::setParagraphs(Cursor & cur, docstring arg, bool merge)
 void Text::setParagraphs(Cursor & cur, ParagraphParameters const & p) 
 {
 	LASSERT(cur.text(), /**/);
-	// make sure that the depth behind the selection are restored, too
-	pit_type undopit = undoSpan(cur.selEnd().pit());
-	recUndo(cur, cur.selBegin().pit(), undopit - 1);
 
 	depth_type priordepth = -1;
 	Layout priorlayout;
-	for (pit_type pit = cur.selBegin().pit(), end = cur.selEnd().pit();
-	     pit <= end; ++pit) {
-		Paragraph & par = pars_[pit];
+	Cursor c(cur.bv());
+	c.setCursor(cur.selectionBegin());
+	for ( ; c < cur.selectionEnd() ; ++c.pit()) {
+		Paragraph & par = c.paragraph();
 		// Changes to label width string apply to all paragraphs
 		// with same layout in a sequence.
 		// Do this only once for a selected range of paragraphs
 		// of the same layout and depth.
-		if (par.getDepth() != priordepth || par.layout() != priorlayout)
-			setLabelWidthStringToSequence(pit,
-				par.params().labelWidthString());
+		cur.recordUndo();
 		par.params().apply(p, par.layout());
+		if (par.getDepth() != priordepth || par.layout() != priorlayout)
+			setLabelWidthStringToSequence(c,
+				par.params().labelWidthString());
 		priordepth = par.getDepth();
 		priorlayout = par.layout();
 	}

status.20x

@@ -109,14 +109,17 @@ What's new
 - Fix various crashes when single document is edited in more windows
   (bug 8203).
 
-- Fix crash when using undo in a paragraph with layout Bibliography (bug 7111).
-
 - Fix crash when renaming a child buffer.
 
-- Replace current selection when pasting (bug 8027).
+- Fix crash when using undo in a paragraph with layout Bibliography (bug 7111).
 
 - Make sure that undo restores environment depth correctly (bug 8159).
 
+- Make sure that undo restores paragraph longest label width correctly
+  (bug 8242).
+
+- Replace current selection when pasting (bug 8027).
+
 - Fix enumitem module translation (bug #8201).
 
 - Set math display format when showing XHTML in View>Source.