ui: panning in code view

* Implemented horizontal panning for code snippets by dragging the mouse left and right.

src/app/qt/element/QtCodeArea.cpp

@@ -5,6 +5,7 @@
 #include <QPainter>
 #include <QPushButton>
 #include <QToolTip>
+#include <qscrollbar.h>
 
 #include "utility/messaging/type/MessageActivateTokenLocations.h"
 #include "utility/messaging/type/MessageShowFile.h"
@@ -55,6 +56,7 @@ QtCodeArea::QtCodeArea(
 	, m_locationFile(locationFile)
 	, m_hoveredAnnotation(nullptr)
 	, m_digits(0)
+	, m_panningValue(-1)
 {
 	setObjectName("code_area");
 	setReadOnly(true);
@@ -229,10 +231,19 @@ void QtCodeArea::leaveEvent(QEvent* event)
 	setHoveredAnnotation(nullptr);
 }
 
+void QtCodeArea::mousePressEvent(QMouseEvent* event)
+{
+	if (event->button() == Qt::LeftButton)
+	{
+		m_panningValue = event->pos().x();
+	}
+}
+
 void QtCodeArea::mouseReleaseEvent(QMouseEvent* event)
 {
 	if (event->button() == Qt::LeftButton)
 	{
+		m_panningValue = -1;
 		QTextCursor cursor = this->cursorForPosition(event->pos());
 		std::vector<Id> locationIds = findLocationIdsForPosition(cursor.position());
 
@@ -253,6 +264,19 @@ void QtCodeArea::mouseDoubleClickEvent(QMouseEvent* event)
 
 void QtCodeArea::mouseMoveEvent(QMouseEvent* event)
 {
+	if (m_panningValue!= -1)
+	{
+		int panningCurrentPosition = event->pos().x();
+		int deltaPos = panningCurrentPosition - m_panningValue;
+		m_panningValue = panningCurrentPosition;
+
+		QScrollBar* scrollbar = horizontalScrollBar();
+		int visibleContentWidth = width() - lineNumberAreaWidth();
+		float deltaPosRatio = float(deltaPos) / (visibleContentWidth);
+		scrollbar->setValue(scrollbar->value() - utility::roundToInt(deltaPosRatio * scrollbar->pageStep()));
+	}
+
+
 	QTextCursor cursor = this->cursorForPosition(event->pos());
 
 	m_hoveredLocationIds = findLocationIdsForPosition(cursor.position());

src/app/qt/element/QtCodeArea.h

@@ -8,6 +8,7 @@
 
 #include "utility/types.h"
 
+class QDragMoveEvent;
 class QPaintEvent;
 class QResizeEvent;
 class QSize;
@@ -34,7 +35,7 @@ public:
 		QSize sizeHint() const;
 
 	protected:
-		void paintEvent(QPaintEvent* event);
+		virtual void paintEvent(QPaintEvent* event);
 
 	private:
 		QtCodeArea *m_codeArea;
@@ -73,6 +74,7 @@ protected:
 	virtual void leaveEvent(QEvent* event);
 	virtual void mouseReleaseEvent(QMouseEvent* event);
 	virtual void mouseDoubleClickEvent(QMouseEvent* event);
+	virtual void mousePressEvent(QMouseEvent* event);
 	virtual void mouseMoveEvent(QMouseEvent* event);
 
 private slots:
@@ -131,6 +133,7 @@ private:
 	std::vector<Id> m_hoveredLocationIds;
 
 	int m_digits;
+	int m_panningValue; // just for horizontal panning
 };
 
 #endif // QT_CODE_AREA_H

src/lib/utility/utility.cpp

@@ -73,3 +73,8 @@ size_t utility::digits(size_t n)
 
 	return digits;
 }
+
+int utility::roundToInt(float n)
+{
+	return (n > 0.0f) ? (n + 0.5f) : (n - 0.5f);
+}

src/lib/utility/utility.h

@@ -39,6 +39,8 @@ namespace utility
 	bool intersectionPoint(Vec2f a1, Vec2f b1, Vec2f a2, Vec2f b2, Vec2f* i);
 
 	size_t digits(size_t n);
+
+	int roundToInt(float n);
 }
 
 template<typename T>