From 824d1c993a138d051c79149fc4b27e1c002736a4 Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Tue, 5 Jan 2021 14:53:15 +0100
Subject: [PATCH] Fixup 294e4884: center correctly Abstract label when
 paragraph is empty

When a paragraph is empty, it was not possible to query what the left
margin would be for an hypothetical second row.

Modify TextMetrics::leftMargin so that it does not test
whether position is after the last position of the paragraph.

Cosmetics: set the size of label to "small" for Abstract layout in
standard classes and reduce the spacing between label and text.

Fixes remainder of #11939.
---
 lib/layouts/stdstruct.inc |  3 +--
 src/TextMetrics.cpp       | 12 ++++++++----
 src/TextMetrics.h         |  4 +++-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/lib/layouts/stdstruct.inc b/lib/layouts/stdstruct.inc
index b611b53da1..a0a9750711 100644
--- a/lib/layouts/stdstruct.inc
+++ b/lib/layouts/stdstruct.inc
@@ -27,13 +27,12 @@ Style Abstract
 	Align                 Block
 	LabelType             Centered
 	LabelString           "Abstract"
-	LabelBottomSep        0.5
+	LabelBottomSep        0.2
 	Font
 	  Size                Small
 	EndFont
 	LabelFont
 	  Series              Bold
-	  Size                Large
 	EndFont
 	HTMLLabelFirst        1
 	HTMLForceCSS          1
diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 214fe89238..89e8699077 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -1598,7 +1598,8 @@ void TextMetrics::deleteLineForward(Cursor & cur)
 
 int TextMetrics::leftMargin(pit_type pit) const
 {
-	return leftMargin(pit, text_->paragraphs()[pit].size());
+	// the + 1 is useful when the paragraph is empty
+	return leftMargin(pit, text_->paragraphs()[pit].size() + 1);
 }
 
 
@@ -1610,7 +1611,10 @@ int TextMetrics::leftMargin(pit_type const pit, pos_type const pos) const
 	LASSERT(pit < int(pars.size()), return 0);
 	Paragraph const & par = pars[pit];
 	LASSERT(pos >= 0, return 0);
-	LASSERT(pos <= par.size(), return 0);
+	// We do not really care whether pos > par.size(), since we do not
+	// access the data. It can be actially useful, when querying the
+	// margin without indentation (see leftMargin(pit_type).
+
 	Buffer const & buffer = bv_->buffer();
 	//lyxerr << "TextMetrics::leftMargin: pit: " << pit << " pos: " << pos << endl;
 	DocumentClass const & tclass = buffer.params().documentClass();
@@ -1764,8 +1768,8 @@ int TextMetrics::leftMargin(pit_type const pit, pos_type const pos) const
 	    && !text_->inset().neverIndent()
 	    // display style insets do not need indentation
 	    && !(!par.empty()
-	         && par.isInset(pos)
-	         && par.getInset(pos)->rowFlags() & Inset::Display)
+	         && par.isInset(0)
+	         && par.getInset(0)->rowFlags() & Inset::Display)
 	    && (!(tclass.isDefaultLayout(par.layout())
 	        || tclass.isPlainLayout(par.layout()))
 	        || buffer.params().paragraph_separation
diff --git a/src/TextMetrics.h b/src/TextMetrics.h
index d65618fc0c..0ae802aca5 100644
--- a/src/TextMetrics.h
+++ b/src/TextMetrics.h
@@ -123,12 +123,14 @@ public:
 	int height() const { return dim_.height(); }
 
 	/**
-	 * Returns the left beginning of the text.
+	 * Returns the left beginning of a row starting at \c pos.
 	 * This information cannot be taken from the layout object, because
 	 * in LaTeX the beginning of the text fits in some cases
 	 * (for example sections) exactly the label-width.
 	 */
 	int leftMargin(pit_type pit, pos_type pos) const;
+	/// Return the left beginning of a row which is not the first one.
+	/// This is the left margin when there is no indentation.
 	int leftMargin(pit_type pit) const;
 
 	///
-- 
2.39.2