From dbf644fb03a25f7370d1e893f38cb5dc15a53dde Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Wed, 22 Sep 2021 15:09:26 +0200
Subject: [PATCH] Improve row flushing

Add new row flags Flush and FlushBefore to let insets indicate whether
they cause flushing of current row (eg. newline) or of previous row
(e.g. display insets).
---
 src/RowFlags.h              | 20 ++++++++++++--------
 src/TextMetrics.cpp         |  6 ++++--
 src/insets/InsetNewline.cpp |  9 +++++++++
 src/insets/InsetNewline.h   |  2 +-
 src/insets/InsetSeparator.h |  2 +-
 5 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/RowFlags.h b/src/RowFlags.h
index f94f0c62d5..01c4dd24ed 100644
--- a/src/RowFlags.h
+++ b/src/RowFlags.h
@@ -32,22 +32,26 @@ enum RowFlags {
 	BreakBefore = 1 << 0,
 	// Avoid breaking row before this element
 	NoBreakBefore = 1 << 1,
+	// flush the row before this element (useful with BreakBefore)
+	FlushBefore = 1 << 2,
 	// force new (maybe empty) row after this element
-	AlwaysBreakAfter = 1 << 2,
+	AlwaysBreakAfter = 1 << 3,
 	// break row after this element if there are more elements
-	BreakAfter = 1 << 3,
+	BreakAfter = 1 << 4,
 	// break row whenever needed after this element
-	CanBreakAfter = 1 << 4,
+	CanBreakAfter = 1 << 5,
 	// Avoid breaking row after this element
-	NoBreakAfter = 1 << 5,
+	NoBreakAfter = 1 << 6,
 	// The contents of the row may be broken in two (e.g. string)
-	CanBreakInside = 1 << 6,
+	CanBreakInside = 1 << 7,
+	// Flush the row that ends with this element
+	Flush = 1 << 8,
 	// specify an alignment (left, right) for a display element
 	// (default is center)
-	AlignLeft = 1 << 7,
-	AlignRight = 1 << 8,
+	AlignLeft = 1 << 9,
+	AlignRight = 1 << 10,
 	// A display element breaks row at both ends
-	Display = BreakBefore | BreakAfter,
+	Display = FlushBefore | BreakBefore | BreakAfter,
 	// Flags that concern breaking after element
 	AfterFlags = AlwaysBreakAfter | BreakAfter | CanBreakAfter | NoBreakAfter
 };
diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 14dc7051ef..2b1ee5adbe 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -1068,7 +1068,6 @@ void cleanupRow(Row & row, bool at_end)
 	}
 
 	row.endpos(row.back().endpos);
-	row.flushed(at_end);
 	// remove trailing spaces on row break
 	if (!at_end)
 		row.back().rtrim();
@@ -1118,8 +1117,11 @@ RowList TextMetrics::breakParagraph(Row const & bigrow) const
 		int const f2 = (fcit == end) ? (end_label ? Inline : NoBreakBefore)
 		                             : fcit->row_flags;
 		if (rows.empty() || needsRowBreak(f1, f2)) {
-			if (!rows.empty())
+			if (!rows.empty()) {
 				cleanupRow(rows.back(), false);
+				// Flush row as requested by row flags
+				rows.back().flushed((f1 & Flush) || (f2 & FlushBefore));
+			}
 			pos_type pos = rows.empty() ? 0 : rows.back().endpos();
 			rows.push_back(newRow(*this, bigrow.pit(), pos, is_rtl));
 			// the width available for the row.
diff --git a/src/insets/InsetNewline.cpp b/src/insets/InsetNewline.cpp
index f5fcd42ac6..ecfacf47ce 100644
--- a/src/insets/InsetNewline.cpp
+++ b/src/insets/InsetNewline.cpp
@@ -39,6 +39,15 @@ InsetNewline::InsetNewline() : Inset(nullptr)
 {}
 
 
+int InsetNewline::rowFlags() const
+{
+	if (params_.kind == InsetNewlineParams::LINEBREAK)
+		return AlwaysBreakAfter;
+	else
+	    return AlwaysBreakAfter | Flush;
+}
+
+
 void InsetNewlineParams::write(ostream & os) const
 {
 	switch (kind) {
diff --git a/src/insets/InsetNewline.h b/src/insets/InsetNewline.h
index 1ef0ae52fb..c85a97df66 100644
--- a/src/insets/InsetNewline.h
+++ b/src/insets/InsetNewline.h
@@ -47,7 +47,7 @@ public:
 	explicit InsetNewline(InsetNewlineParams par) : Inset(0)
 	{ params_.kind = par.kind; }
 	///
-	int rowFlags() const override { return AlwaysBreakAfter; }
+	int rowFlags() const override;
 	///
 	static void string2params(std::string const &, InsetNewlineParams &);
 	///
diff --git a/src/insets/InsetSeparator.h b/src/insets/InsetSeparator.h
index 9352bdf0df..0c12d95686 100644
--- a/src/insets/InsetSeparator.h
+++ b/src/insets/InsetSeparator.h
@@ -65,7 +65,7 @@ public:
 		return docstring();
 	}
 	///
-	int rowFlags() const override { return BreakAfter; }
+	int rowFlags() const override { return BreakAfter | Flush; }
 private:
 	///
 	InsetCode lyxCode() const override { return SEPARATOR_CODE; }
-- 
2.39.5