Coincedent points

Canvas.cpp

@@ -1,5 +1,9 @@
 #include "Canvas.h"
 
+static double dist_P2P(QPointF p1, QPointF p2) {
+	return sqrt(pow(p2.x() - p1.x(), 2) + pow(p2.y() - p1.y(), 2));
+}
+
 void Canvas::changeMode(Mode _mode)
 {
 	mode = _mode;
@@ -16,6 +20,20 @@ Line* Canvas::findAt(QPointF& pos)
 	return nullptr;
 }
 
+Point* Canvas::findPointAt(QPointF pos, qreal tolerance)
+{
+	for (Line* line : lines) {
+		QPointF p1(*line->p1.x, *line->p1.y);
+		QPointF p2(*line->p2.x, *line->p2.y);
+
+		if (dist_P2P(p1, pos) <= tolerance)
+			return &line->p1;
+		else if (dist_P2P(p2, pos) <= tolerance)
+			return &line->p2;
+	}
+	return nullptr;
+}
+
 LinePair Canvas::makeOrderedPair(Line* l1, Line* l2)
 {
 	return (l1 < l2) ? std::make_pair(l1, l2) : std::make_pair(l2, l1);
@@ -102,7 +120,7 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 		#ifdef _DEBUG
 			qDebug() << "Line" << first << "and" << found << "are parallel. Abort!";
 		#endif
-			QMessageBox::information(this,
+			QMessageBox::warning(this,
 				QString("Wrong"),
 				QString("Parallel lines can not be more parallel!"),
 				QMessageBox::Ok
@@ -113,6 +131,43 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 
 		update();
 	}
+
+	else if (mode == Mode::Coincedent) {
+		Point* clickedPoint = findPointAt(scene);
+
+		if (!clickedPoint) {
+			firstPoint = nullptr;
+			return;
+		}
+
+		if (!firstPoint) {
+			firstPoint = clickedPoint;
+			return;
+		}
+
+		if (clickedPoint == firstPoint) {
+			firstPoint = nullptr;
+			return;
+		}
+
+		Line *l1 = nullptr, *l2 = nullptr;
+		for (Line* l : lines) {
+			if (&l->p1 == firstPoint || &l->p2 == firstPoint) l1 = l;
+			if (&l->p1 == clickedPoint || &l->p2 == clickedPoint) l2 = l;
+		}
+
+		if (l1 == l2) {
+			QMessageBox::warning(this, QString("NO!"), QString("P2P failed"));
+			firstPoint = nullptr;
+			return;
+		}
+
+		sys.addConstraintP2PCoincident(*firstPoint, *clickedPoint, constraints_count++);
+		firstPoint = nullptr;
+		mode = Mode::None;
+		update();
+		return;
+	}
 }
 
 void Canvas::paintEvent(QPaintEvent*)
@@ -163,5 +218,7 @@ Canvas::~Canvas()
 
 	if (current_line) 
 		delete current_line;
+	if (firstPoint)
+		delete firstPoint;
 }