From 79be66bdf1ad1bc58231402579d59a8b7189c95e Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Sun, 1 May 2016 01:27:13 +0200
Subject: [PATCH] Let getPosNearX take horizontal scrolling into account

If we do not do that, it is not possible to position the cursor after
a long inset with the mouse.

To do this, it is necessary to add the pit information to the Row
object. This is a good idea in any case, and will allow to simplify
some code later on.

Fixes bug #10094.
(cherry picked from commit 8851645799ef67015e49fd75b9dfeed65d685e85)
---
 src/Row.cpp         |  3 ++-
 src/Row.h           |  6 ++++++
 src/TextMetrics.cpp | 15 ++++++++++++++-
 src/TextMetrics.h   |  2 +-
 status.22x          |  3 +++
 5 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/Row.cpp b/src/Row.cpp
index d0694f7d2e..58a23805f2 100644
--- a/src/Row.cpp
+++ b/src/Row.cpp
@@ -148,7 +148,8 @@ Row::Row()
 	: separator(0), label_hfill(0), left_margin(0), right_margin(0),
 	  sel_beg(-1), sel_end(-1),
 	  begin_margin_sel(false), end_margin_sel(false),
-	  changed_(false), crc_(0), pos_(0), end_(0), right_boundary_(false)
+	  changed_(false), crc_(0),
+	  pit_(0), pos_(0), end_(0), right_boundary_(false)
 {}
 
 
diff --git a/src/Row.h b/src/Row.h
index f0c5b72ca1..0bd4597746 100644
--- a/src/Row.h
+++ b/src/Row.h
@@ -144,6 +144,10 @@ public:
 	void setSelectionAndMargins(DocIterator const & beg,
 		DocIterator const & end) const;
 
+	///
+	void pit(pit_type p) { pit_ = p; }
+	///
+	pit_type pit() const { return pit_; }
 	///
 	void pos(pos_type p) { pos_ = p; }
 	///
@@ -286,6 +290,8 @@ private:
 	mutable bool changed_;
 	/// CRC of row contents.
 	mutable size_type crc_;
+	/// Index of the paragraph that contains this row
+	pit_type pit_;
 	/// first pos covered by this row
 	pos_type pos_;
 	/// one behind last pos covered by this row
diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 816f4bacd6..fdf0da6926 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -443,6 +443,7 @@ bool TextMetrics::redoParagraph(pit_type const pit)
 		if (row_index == pm.rows().size())
 			pm.rows().push_back(Row());
 		Row & row = pm.rows()[row_index];
+		row.pit(pit);
 		row.pos(first);
 		breakRow(row, right_margin, pit);
 		setRowHeight(row, pit);
@@ -1113,6 +1114,16 @@ pos_type TextMetrics::getPosNearX(Row const & row, int & x,
 	int const xo = origin_.x_;
 	x -= xo;
 
+	int offset = 0;
+	CursorSlice rowSlice(const_cast<InsetText &>(text_->inset()));
+	rowSlice.pit() = row.pit();
+	rowSlice.pos() = row.pos();
+
+	// Adapt to cursor row scroll offset if applicable.
+	if (bv_->currentRowSlice() == rowSlice)
+		offset = bv_->horizScrollOffset();
+	x += offset;
+
 	pos_type pos = row.pos();
 	boundary = false;
 	if (row.empty())
@@ -1166,8 +1177,10 @@ pos_type TextMetrics::getPosNearX(Row const & row, int & x,
 		else
 			boundary = row.right_boundary();
 	}
-	x += xo;
+
+	x += xo - offset;
 	//LYXERR0("getPosNearX ==> pos=" << pos << ", boundary=" << boundary);
+
 	return pos;
 }
 
diff --git a/src/TextMetrics.h b/src/TextMetrics.h
index f0abcb5201..6f5cf68733 100644
--- a/src/TextMetrics.h
+++ b/src/TextMetrics.h
@@ -150,7 +150,7 @@ private:
 public:
 	/// returns the position near the specified x-coordinate of the row.
 	/// x is an absolute screen coord, it is set to the real beginning
-	/// of this column.
+	/// of this column. This takes in account horizontal cursor row scrolling.
 	pos_type getPosNearX(Row const & row, int & x, bool & boundary) const;
 
 	/// returns pos in given par at given x coord.
diff --git a/status.22x b/status.22x
index 4321008e0e..cfe0a4de62 100644
--- a/status.22x
+++ b/status.22x
@@ -57,6 +57,9 @@ What's new
 - Fix horizontal scrolling feature when inside a collapsable inset
   with several paragraphs.
 
+- Fix selection of large formula with the mouse when horizontal
+  scrolling kicks in (but 10094).
+
 - Fix display of collapsable insets when the same document is shown in
   two views with different width (bug 9756).