From 0cc684aec5f86416bffe3a3fd3b6281f659e6511 Mon Sep 17 00:00:00 2001
From: Juergen Spitzmueller <spitz@lyx.org>
Date: Tue, 9 Jul 2019 14:48:11 +0200
Subject: [PATCH] Truncate long citation label in the middle rather than the
 end.

Fixes: #10769
---
 src/BiblioInfo.cpp           | 15 ++++++++++-----
 src/insets/InsetCitation.cpp |  4 ++--
 src/support/lstrings.cpp     | 16 ++++++++++++----
 src/support/lstrings.h       |  5 ++++-
 4 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/src/BiblioInfo.cpp b/src/BiblioInfo.cpp
index 80cafeb359..b0f64bd0e3 100644
--- a/src/BiblioInfo.cpp
+++ b/src/BiblioInfo.cpp
@@ -1326,9 +1326,15 @@ docstring const BiblioInfo::getLabel(vector<docstring> keys,
 	LASSERT(max_size >= 16, max_size = 16);
 
 	// we can't display more than 10 of these, anyway
+	// but since we truncate in the middle,
+	// we need to split into two halfs.
 	bool const too_many_keys = keys.size() > 10;
-	if (too_many_keys)
-		keys.resize(10);
+	vector<docstring> lkeys;
+	if (too_many_keys) {
+		lkeys.insert(lkeys.end(), keys.end() - 5, keys.end());
+		keys.resize(5);
+		keys.insert(keys.end(), lkeys.begin(), lkeys.end());
+	}
 
 	CiteEngineType const engine_type = buf.params().citeEngineType();
 	DocumentClass const & dc = buf.params().documentClass();
@@ -1353,9 +1359,8 @@ docstring const BiblioInfo::getLabel(vector<docstring> keys,
 		ret = data.getLabel(xrefptrs, buf, ret, ci, key + 1 != ken, i == 1);
 	}
 
-	if (too_many_keys)
-		ret.push_back(0x2026);//HORIZONTAL ELLIPSIS
-	support::truncateWithEllipsis(ret, max_size);
+	support::truncateWithEllipsis(ret, max_size, true);
+
 	return ret;
 }
 
diff --git a/src/insets/InsetCitation.cpp b/src/insets/InsetCitation.cpp
index ba45f691a3..6d5c381df8 100644
--- a/src/insets/InsetCitation.cpp
+++ b/src/insets/InsetCitation.cpp
@@ -458,8 +458,8 @@ void InsetCitation::updateBuffer(ParIterator const &, UpdateType)
 	cache.recalculate = false;
 	cache.generated_label = glabel;
 	unsigned int const maxLabelChars = 45;
-	cache.screen_label = glabel.substr(0, maxLabelChars + 1);
-	support::truncateWithEllipsis(cache.screen_label, maxLabelChars);
+	cache.screen_label = glabel;
+	support::truncateWithEllipsis(cache.screen_label, maxLabelChars, true);
 }
 
 
diff --git a/src/support/lstrings.cpp b/src/support/lstrings.cpp
index 68eabd9d26..e2f3d9c084 100644
--- a/src/support/lstrings.cpp
+++ b/src/support/lstrings.cpp
@@ -1233,13 +1233,21 @@ docstring const protectArgument(docstring & arg, char const l,
 }
 
 
-bool truncateWithEllipsis(docstring & str, size_t const len)
+bool truncateWithEllipsis(docstring & str, size_t const len, bool const mid)
 {
 	if (str.size() <= len)
 		return false;
-	str.resize(len);
-	if (len > 0)
-		str[len - 1] = 0x2026;// HORIZONTAL ELLIPSIS
+	if (mid && len > 0) {
+		size_t const hlen = len / 2;
+		docstring suffix = str.substr(str.size() - hlen);
+		str.resize(hlen);
+		str[hlen - 1] = 0x2026;// HORIZONTAL ELLIPSIS
+		str += suffix;
+	} else {
+		str.resize(len);
+		if (len > 0)
+			str[len - 1] = 0x2026;// HORIZONTAL ELLIPSIS
+	}
 	return true;
 }
 
diff --git a/src/support/lstrings.h b/src/support/lstrings.h
index dde06e5454..ff0ce1d207 100644
--- a/src/support/lstrings.h
+++ b/src/support/lstrings.h
@@ -276,6 +276,8 @@ docstring const protectArgument(docstring & arg, char const l = '[',
 /// Truncates a string with an ellipsis at the end.  Leaves str unchanged and
 /// returns false if it is shorter than len. Otherwise resizes str to len, with
 /// U+2026 HORIZONTAL ELLIPSIS at the end, and returns true.
+/// If mid is true, the ellipsis will be put to the mid of the string, and the first
+/// and last half is appended/prepended. 
 ///
 /// Warning (Unicode): The cases where we want to truncate the text and it does
 /// not end up converted into a QString for UI display must be really
@@ -294,7 +296,8 @@ docstring const protectArgument(docstring & arg, char const l = '[',
 ///
 /// FIXME: apply those principles in the current code.
 ///
-bool truncateWithEllipsis(docstring & str, size_t const len);
+bool truncateWithEllipsis(docstring & str, size_t const len,
+			  bool const mid = false);
 
 /// Word-wraps the provided docstring, returning a line-broken string
 /// of width no wider than width, with the string broken at spaces.
-- 
2.39.5