network: Reduce size of edge and fill the polygon.

src/view/network/GraphWidget.py

@@ -141,7 +141,7 @@ class EdgeItem(QGraphicsItem):
         elif not self.graph.graph.is_enable_edge(self.edge):
             color = Qt.darkGray
 
-        painter.setPen(QPen(color, 3, Qt.SolidLine, Qt.RoundCap,
+        painter.setPen(QPen(color, 2, Qt.SolidLine, Qt.RoundCap,
                             Qt.RoundJoin))
         # Draw the line
         painter.drawLine(line)
@@ -152,6 +152,10 @@ class EdgeItem(QGraphicsItem):
         )
 
         # Draw the arrows
+        brush = QBrush()
+        brush.setColor(color)
+        brush.setStyle(Qt.SolidPattern)
+
         angle = math.acos(line.dx() / line.length())
         if line.dy() >= 0:
             angle = (math.pi * 2.0) - angle
@@ -165,8 +169,12 @@ class EdgeItem(QGraphicsItem):
             math.sin(angle - math.pi + math.pi / 3) * size,
             math.cos(angle - math.pi + math.pi / 3) * size
         )
+        poly = QPolygonF([line_center, arrow_p1, arrow_p2])
+        path = QPainterPath()
+        path.addPolygon(poly)
 
-        painter.drawPolygon(QPolygonF([line_center, arrow_p1, arrow_p2]))
+        painter.drawPolygon(poly)
+        painter.fillPath(path, brush)
 
 class NodeText(QGraphicsTextItem):
     def __init__(self, node_item):