From 91b4e8038435021c4f177a9eef11dc60bbe2f389 Mon Sep 17 00:00:00 2001
From: Eberhard Graether <egraether@gmail.com>
Date: Sat, 21 Apr 2018 04:30:55 +0200
Subject: [PATCH] ui: adapt scroll target value in code single file mode as
 workaround when view scrolls below last line

---
 src/lib_gui/qt/element/QtCodeArea.cpp       |  3 +--
 src/lib_gui/qt/element/QtCodeField.cpp      |  5 +++++
 src/lib_gui/qt/element/QtCodeField.h        |  2 ++
 src/lib_gui/qt/element/QtCodeFileSingle.cpp | 13 +++++++++++++
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/lib_gui/qt/element/QtCodeArea.cpp b/src/lib_gui/qt/element/QtCodeArea.cpp
index 3e23b6b4..a884594c 100644
--- a/src/lib_gui/qt/element/QtCodeArea.cpp
+++ b/src/lib_gui/qt/element/QtCodeArea.cpp
@@ -274,8 +274,7 @@ void QtCodeArea::lineNumberAreaPaintEvent(QPaintEvent *event)
 
 int QtCodeArea::lineNumberDigits() const
 {
-	int max = qMax(1, int(getStartLineNumber()) + blockCount());
-	return utility::digits(max);
+	return utility::digits(getEndLineNumber());
 }
 
 int QtCodeArea::lineNumberAreaWidth() const
diff --git a/src/lib_gui/qt/element/QtCodeField.cpp b/src/lib_gui/qt/element/QtCodeField.cpp
index 963591cb..2d778e53 100644
--- a/src/lib_gui/qt/element/QtCodeField.cpp
+++ b/src/lib_gui/qt/element/QtCodeField.cpp
@@ -130,6 +130,11 @@ uint QtCodeField::getEndLineNumber() const
 	return m_startLineNumber + blockCount() - 1;
 }
 
+int QtCodeField::totalLineHeight() const
+{
+	return blockBoundingRect(firstVisibleBlock()).height() * blockCount();
+}
+
 std::string QtCodeField::getCode() const
 {
 	return m_code;
diff --git a/src/lib_gui/qt/element/QtCodeField.h b/src/lib_gui/qt/element/QtCodeField.h
index 4e72027d..c2663fb0 100644
--- a/src/lib_gui/qt/element/QtCodeField.h
+++ b/src/lib_gui/qt/element/QtCodeField.h
@@ -35,6 +35,8 @@ public:
 	uint getStartLineNumber() const;
 	uint getEndLineNumber() const;
 
+	int totalLineHeight() const;
+
 	std::string getCode() const;
 
 	std::shared_ptr<SourceLocationFile> getSourceLocationFile() const;
diff --git a/src/lib_gui/qt/element/QtCodeFileSingle.cpp b/src/lib_gui/qt/element/QtCodeFileSingle.cpp
index 2ef8e18f..fa3e9697 100644
--- a/src/lib_gui/qt/element/QtCodeFileSingle.cpp
+++ b/src/lib_gui/qt/element/QtCodeFileSingle.cpp
@@ -195,6 +195,19 @@ bool QtCodeFileSingle::requestScroll(
 	double percentA = double(lineNumber - 1) / m_area->getEndLineNumber();
 	double percentB = endLineNumber ? double(endLineNumber - 1) / m_area->getEndLineNumber() : 0.0f;
 
+	// fix percentages wrong when code area is scrollable beyond last line due to some unknown bug
+	{
+		int totalHeight = m_area->sizeHint().height();
+		int totalLineHeight = m_area->totalLineHeight();
+
+		if (std::abs(totalHeight - totalLineHeight) > 100)
+		{
+			double factor = totalLineHeight / double(totalHeight);
+			percentA *= factor;
+			percentB *= factor;
+		}
+	}
+
 	ensurePercentVisibleAnimated(percentA, percentB, animated, target);
 
 	m_scrollRequested = true;