Корретная отрисовка в Canvas

Canvas.cpp

@@ -84,26 +84,29 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 			current_line = nullptr;
 			mode = Mode::None;
 			obj_count++;
+		}
 			update();
 			return;
 		}	
-	}
 
 	else if (mode == Mode::Parallel) {
 		Line* found = findAt(scene);
 
 		if (!found) {
 			current_line = nullptr;
+			update();
 			return;
 		}
 
 		if (!current_line) {
 			current_line = found;
+			update();
 			return;
 		}
 
 		if (found == current_line){
 			current_line = nullptr;
+			update();
 			return;
 		}
 
@@ -111,9 +114,9 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 			sys.addConstraintParallel(*found, *current_line, constraints_count++);
 			parallelPairs.insert(makeOrderedPair(found, current_line));
 			current_line = nullptr;
+			update();
 			mode = Mode::None;
 		}
-
 		else {
 			
 		#ifdef _DEBUG
@@ -125,6 +128,7 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 				QMessageBox::Ok
 			);
 			current_line = nullptr;
+			update();
 			return;
 		}
 
@@ -136,16 +140,19 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 
 		if (!clickedPoint) {
 			firstPoint = nullptr;
+			update();
 			return;
 		}
 
 		if (!firstPoint) {
 			firstPoint = clickedPoint;
+			update();
 			return;
 		}
 
 		if (clickedPoint == firstPoint) {
 			firstPoint = nullptr;
+			update();
 			return;
 		}
 
@@ -158,6 +165,7 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 		if (l1 == l2) {
 			QMessageBox::warning(this, QString("NO!"), QString("P2P failed"));
 			firstPoint = nullptr;
+			update();
 			return;
 		}
 
@@ -172,23 +180,66 @@ void Canvas::mousePressEvent(QMouseEvent* event)
 void Canvas::paintEvent(QPaintEvent*)
 {
 	QPainter p(this);
-	p.setRenderHint(QPainter::Antialiasing);
+	p.setRenderHint(QPainter::Antialiasing, true);
+
+	// === Решаем систему один раз ===
 	if (!params.empty()) {
 		int res = sys.solve(params);
-		if (res == SolveStatus::Success) {
+		if (res == SolveStatus::Success || res == SolveStatus::Converged) {
 			sys.applySolution();
 		}
 		else {
-		#ifdef _DEBUG
-			qDebug() << "INVAILD LAST CONSTRAINT. REMOVE HIM";
-		#endif
 			sys.removeConstraint(sys.get_last_constraint());
+			constraints_count--;
 		}
 	}
+
 	for (Line* line : lines) {
-		line->draw(p);
+		bool isSelected = (mode == Mode::Parallel && line == current_line);
+
+		QPen linePen = isSelected ? QPen(Qt::red, 4) : QPen(Qt::black, 2);
+		p.setPen(linePen);
+
+		// Рисуем саму линию
+		p.drawLine(QPointF(*line->p1.x, *line->p1.y),
+			QPointF(*line->p2.x, *line->p2.y));
+
+		// Рисуем концы — с учётом выделения
+		QBrush pointBrush = isSelected ? QBrush(Qt::red) : QBrush(Qt::darkBlue);
+		p.setBrush(pointBrush);
+		p.setPen(Qt::NoPen);  // убираем обводку у кружков
+
+		p.drawEllipse(QPointF(*line->p1.x, *line->p1.y), 5, 5);
+		p.drawEllipse(QPointF(*line->p2.x, *line->p2.y), 5, 5);
+	}
+
+	// === Подсветка выбранной точки в режиме Coincident ===
+	if (mode == Mode::Coincedent && firstPoint) {
+		QPointF pt(*firstPoint->x, *firstPoint->y);
+		p.setPen(Qt::NoPen);
+		p.setBrush(Qt::red);
+		p.drawEllipse(pt, 12, 12);
+		p.setBrush(Qt::white);
+		p.drawEllipse(pt, 8, 8);
+		p.setBrush(Qt::red);
+		p.drawEllipse(pt, 4, 4);  // маленький центр
+	}
+
+	// === Текущая рисуемая линия (DrawingLine) ===
+	if (current_line && mode == Mode::DrawingLine) {
+		QPen pen(Qt::blue, 3, Qt::DashLine);
+		p.setPen(pen);
+		p.setBrush(Qt::transparent);
+
+		p.drawLine(QPointF(*current_line->p1.x, *current_line->p1.y),
+			QPointF(*current_line->p2.x, *current_line->p2.y));
+
+		// Концы текущей линии — синие точки
+		p.setBrush(Qt::blue);
+		p.setPen(Qt::NoPen);
+		p.drawEllipse(QPointF(*current_line->p1.x, *current_line->p1.y), 6, 6);
+		p.drawEllipse(QPointF(*current_line->p2.x, *current_line->p2.y), 6, 6);
 	}
-	return;
 }
 
 Canvas::Canvas(QWidget *parent)