From 7be177e9ab51f3b33fd60833ee3a7dd0aa30522b Mon Sep 17 00:00:00 2001
From: Lirusaito <inusaito@gmail.com>
Date: Tue, 26 Mar 2019 05:09:21 -0400
Subject: [PATCH] Fix a text editor bug with selection being lost when url
 segments updated

By doing it the right way, and calculating where the selection should be
after the change is applied.
Also no longer consider text editor modified if nothing was changed.
Also update cursor position so it doesn't move to the wrong place on update
---
 indra/llui/lltexteditor.cpp | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/indra/llui/lltexteditor.cpp b/indra/llui/lltexteditor.cpp
index 3996470be..e2e34538b 100644
--- a/indra/llui/lltexteditor.cpp
+++ b/indra/llui/lltexteditor.cpp
@@ -4477,9 +4477,22 @@ void LLTextEditor::replaceUrl(const std::string &url,
 		{
 			S32 start = seg->getStart();
 			S32 end = seg->getEnd();
-			text = text.substr(0, start) + wlabel + text.substr(end, text.size() - end + 1);
-			seg->setEnd(start + wlabel.size());
-			modified = true;
+			const auto& old_label = text.substr(start, end - start);
+			if (wlabel != old_label)
+			{
+				const auto difference = std::abs((S32)wlabel.length() - (S32)old_label.length());
+				if (mSelectionEnd >= end) // Selection stays at/after end
+				{
+					mSelectionEnd += difference;
+					if (mSelectionStart >= end)
+						mSelectionStart += difference;
+				}
+				if (mCursorPos >= end) // Cursor stays at/after end
+					mCursorPos += difference;
+				text.replace(start, end - start, wlabel);
+				seg->setEnd(start + wlabel.size());
+				modified = true;
+			}
 		}
 
 		/* Singu TODO: Icons with Urls?
@@ -4508,7 +4521,6 @@ void LLTextEditor::replaceUrl(const std::string &url,
 	{
 		mWText = text;
 		mTextIsUpToDate = FALSE;
-		deselect();
 		setCursorPos(mCursorPos);
 		needsReflow();
 	}