From 9230b2cf1a95c50e2bf0b4ca8e214bddd45cf65f Mon Sep 17 00:00:00 2001
From: Christoph Egger <siccegge@faui49man12.informatik.uni-erlangen.de>
Date: Thu, 4 Dec 2014 19:56:15 +0100
Subject: [PATCH] Add support for backward edges

---
 src/gui/widgets/BasicBlockWidget.hxx |  8 ++---
 src/gui/widgets/CFGScene.cxx         | 47 ++++++++++++++++++++++------
 src/gui/widgets/CFGScene.hxx         |  2 +-
 3 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/src/gui/widgets/BasicBlockWidget.hxx b/src/gui/widgets/BasicBlockWidget.hxx
index dd2fa30..5fda53e 100644
--- a/src/gui/widgets/BasicBlockWidget.hxx
+++ b/src/gui/widgets/BasicBlockWidget.hxx
@@ -30,10 +30,10 @@ public:
 		return mapToScene(QPointF(width/2, 0));
 	}
 
-    std::tuple<QPointF, QPointF, QPointF> getExits() const {
-        return std::make_tuple(mapToScene(QPointF(  width/3, height)),
-                               mapToScene(QPointF(  width/2, height)),
-                               mapToScene(QPointF(2*width/3, height)));
+    std::array<QPointF, 3> getExits() const {
+        return { {  mapToScene(QPointF(  width/3, height)),
+					mapToScene(QPointF(  width/2, height)),
+					mapToScene(QPointF(2*width/3, height)) } };
     }
 
     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
diff --git a/src/gui/widgets/CFGScene.cxx b/src/gui/widgets/CFGScene.cxx
index 81c9735..75a39f0 100644
--- a/src/gui/widgets/CFGScene.cxx
+++ b/src/gui/widgets/CFGScene.cxx
@@ -6,7 +6,7 @@ void CFGScene::drawBackground(QPainter* painter, const QRectF & rect) {
     spaceWidgets();
 
     for (BasicBlockWidget * widget : widgets) {
-        QPointF kopf = widget->getEntry();
+		QPointF kopf = widget->getEntry();
         painter->setPen(QColor(0x00, 0xff, 0x00, 0xff));
         painter->drawLine(kopf, kopf - QPointF(0, 20));
 
@@ -16,25 +16,52 @@ void CFGScene::drawBackground(QPainter* painter, const QRectF & rect) {
             if (NULL != next[1]) {
                 painter->setPen(QColor(0xff, 0x00, 0x00, 0xff));
                 painter->drawLine(std::get<0>(tails), std::get<0>(tails) + QPointF(0, 20));
-                drawLine(painter, std::get<0>(tails) + QPointF(0, 20), next[1]->getEntry() - QPointF(0, 20));
+                drawLine(painter, widget, next[1], -1);
+
                 painter->setPen(QColor(0x00, 0xff, 0x00, 0xff));
                 painter->drawLine(std::get<2>(tails), std::get<2>(tails) + QPointF(0, 20));
-                drawLine(painter, std::get<2>(tails) + QPointF(0, 20), next[0]->getEntry() - QPointF(0, 20));
+                drawLine(painter, widget, next[0], 1);
             } else {
                 painter->setPen(QColor(0x00, 0x00, 0x00, 0xff));
                 painter->drawLine(std::get<1>(tails), std::get<1>(tails) + QPointF(0, 20));
-                drawLine(painter, std::get<1>(tails) + QPointF(0, 20), next[0]->getEntry() - QPointF(0, 20));
+                drawLine(painter, widget, next[0], 0);
             }
         }
     }
 }
 
-void CFGScene::drawLine(QPainter* painter, QPointF from, QPointF to, bool left) {
-    if ((to - from).y() > 0) {
-        QPointF angle1(from + QPointF(0, (to - from).y())), angle2(to - QPointF(0, (to - from).y() / 2));
-        painter->drawLine(from,   angle1);
-        painter->drawLine(angle1, to);
-    }
+void CFGScene::drawLine(QPainter* painter, BasicBlockWidget * from, BasicBlockWidget * to, int8_t side) {
+	QPointF from_p = from->getExits()[side+1] + QPointF(0, 20);
+	QPointF to_p = to->getEntry() - QPointF(0, 20);
+    if ((to_p - from_p).y() > 0) {
+		/* Forward Edge */
+        QPointF angle1(from_p + QPointF(0, (to_p - from_p).y()));
+        painter->drawLine(from_p,   angle1);
+        painter->drawLine(angle1, to_p);
+    } else {
+		/* Backward Edge */
+		QRectF from_r(from->boundingRect()), to_r(to->boundingRect());
+		from_r.moveTo(from->scenePos());
+		to_r.moveTo(to->scenePos());
+		QRectF bound = from_r | to_r;
+		if (std::abs(bound.right() - from_p.x()) > std::abs(bound.left() - to_p.x())) {
+			/* we go left */
+			QPointF middle1 = from_p + QPointF(bound.left() - from_p.x() - 20, 0);
+			QPointF middle2 = to_p   + QPointF(bound.left() - to_p.x()   - 20, 0);
+
+			painter->drawLine(from_p, middle1);
+			painter->drawLine(middle1, middle2);
+			painter->drawLine(middle2, to_p);
+		} else {
+			/* we go right */
+			QPointF middle1 = from_p - QPointF(from_p.x() - bound.right() - 20, 0);
+			QPointF middle2 = to_p   - QPointF(to_p.x()   - bound.right() - 20, 0);
+
+			painter->drawLine(from_p, middle1);
+			painter->drawLine(middle1, middle2);
+			painter->drawLine(middle2, to_p);
+		}
+	}
 }
 
 void CFGScene::spaceWidgets() {
diff --git a/src/gui/widgets/CFGScene.hxx b/src/gui/widgets/CFGScene.hxx
index 6baa618..fb395f7 100644
--- a/src/gui/widgets/CFGScene.hxx
+++ b/src/gui/widgets/CFGScene.hxx
@@ -22,7 +22,7 @@ public:
 private:
     std::vector<BasicBlockWidget*> widgets;
 
-    void drawLine(QPainter* painter, QPointF from, QPointF to, bool left = true);
+    void drawLine(QPainter* painter, BasicBlockWidget * from, BasicBlockWidget * to, int8_t side = 0);
 
     void spaceWidgets();
 };
-- 
2.39.2