Merge pull request #21 from Sumit-Sahu/master

adding comments

2 files changed, 339 insertions, 296 deletions

diff --git a/src/main/python/shapes/line.py b/src/main/python/shapes/line.py
index 516f34d..85c9274 100644
--- a/src/main/python/shapes/line.py
+++ b/src/main/python/shapes/line.py
@@ -13,15 +13,18 @@ class Grabber(QGraphicsPathItem):
 
     def __init__(self, annotation_line, index, direction):
         super(Grabber, self).__init__()
-        self.m_index = index
+        # store line to which it connects
         self.m_annotation_item = annotation_line
-        self._direction = direction
+        # index of first point of segment of above line
+        self.m_index = index
+        self.direction = direction
         self.setPath(Grabber.circle)
         # set graphical settings for this item
         self.setFlag(QGraphicsItem.ItemIsSelectable, True)
         self.setFlag(QGraphicsItem.ItemIsMovable, True)
         self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
         self.setAcceptHoverEvents(True)
+        # initially make invisible
         self.pen = QPen(Qt.white, -1, Qt.SolidLine)
         self.brush = QBrush(Qt.transparent)
 
@@ -29,7 +32,7 @@ class Grabber(QGraphicsPathItem):
         """ move position of grabber after resize"""
         if change == QGraphicsItem.ItemPositionChange and self.isEnabled():
             p = QPointF(self.pos())
-            if self._direction == Qt.Horizontal:
+            if self.direction == Qt.Horizontal:
                 p.setX(value.x())
                 if self.parentItem().refLine and self.m_index == len(self.parentItem().points) - 2:
                     points = self.parentItem().refLine.points
@@ -41,7 +44,7 @@ class Grabber(QGraphicsPathItem):
                         p.setX(min(point1.x(), point2.x()))
                     elif p.x() > max(point1.x(), point2.x()):
                         p.setX(max(point1.x(), point2.x()))
-            elif self._direction == Qt.Vertical:
+            elif self.direction == Qt.Vertical:
                 p.setY(value.y())
                 if self.parentItem().refLine and self.m_index == len(self.parentItem().points) - 2:
                     points = self.parentItem().refLine.points
@@ -69,18 +72,16 @@ class Grabber(QGraphicsPathItem):
         painter.setPen(self.pen)
         painter.drawPath(self.path())
 
-        # To paint path of shape
-        # color = Qt.red if self.isSelected() else Qt.black
-        # painter.setPen(QPen(Qt.blue, 1, Qt.SolidLine))
-        # painter.drawPath(self.shape())
-
     def shape(self):
         """Overrides shape method and set shape to segment on which grabber is located"""
         index = self.m_index
+        # take start and end point of segment
         startPoint = QPointF(self.parentItem().points[index])
         endPoint = QPointF(self.parentItem().points[index + 1])
+        # map in grabber's co-ordinate
         startPoint = self.mapFromParent(startPoint)
         endPoint = self.mapFromParent(endPoint)
+        # create path as line
         path = QPainterPath(startPoint)
         path.lineTo(endPoint)
         # generate outlines for path
@@ -91,15 +92,12 @@ class Grabber(QGraphicsPathItem):
     def boundingRect(self):
         return self.shape().boundingRect()
 
-    def mousePressEvent(self, event):
-        super(Grabber, self).mousePressEvent(event)
-
     def hoverEnterEvent(self, event):
         """
         Changes cursor to horizontal movement or vertical movement
          depending on the direction of the grabber on mouse enter
         """
-        if self._direction == Qt.Horizontal:
+        if self.direction == Qt.Horizontal:
             self.setCursor(QCursor(Qt.SplitHCursor))
         else:
             self.setCursor(QCursor(Qt.SplitVCursor))
@@ -113,10 +111,12 @@ class Grabber(QGraphicsPathItem):
         super(Grabber, self).hoverLeaveEvent(event)
 
     def show(self):
+        # set pen to show
         self.pen = QPen(Qt.black, 2, Qt.SolidLine)
         self.brush = QBrush(Qt.cyan)
 
     def hide(self):
+        # set pen to transparent
         self.pen = QPen(Qt.white, -1, Qt.SolidLine)
         self.brush = QBrush(Qt.transparent)
 
@@ -124,56 +124,68 @@ class Grabber(QGraphicsPathItem):
 class LineLabel(QGraphicsTextItem):
     def __init__(self, pos, parent=None):
         super(LineLabel, self).__init__()
+        # initial text
         self.setPlainText("abc")
+        # stores index of first point of segment
         self.index = None
+        # distance from line segment
         self.gap = None
+        # set graphical setting
         self.setFlags(QGraphicsItem.ItemIsMovable |
                       QGraphicsItem.ItemIsSelectable |
                       QGraphicsItem.ItemIsFocusable)
         self.setTextInteractionFlags(Qt.NoTextInteraction)
         self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
+        # set center of text label at mouse pos
         self.setPos(pos - self.boundingRect().center())
         self.setParentItem(parent)
+        # add line item to test label
         self.line = QGraphicsLineItem()
         self.line.setParentItem(self)
         self.line.setPen(QPen(Qt.black, 2, Qt.SolidLine))
         self.line.setFlag(QGraphicsItem.ItemStacksBehindParent)
+        # reset position of line
         self.resetPos()
 
     def paint(self, painter, option, widget):
-        painter.save()
-        painter.setPen(QPen(Qt.black, 2, Qt.SolidLine))
-        painter.setBrush(QBrush(Qt.white))
-
-        painter.drawEllipse(self.boundingRect())
-        painter.restore()
-        
+        # draw ellipse shape
+        painter.save()  # save painter
+        painter.setPen(QPen(Qt.black, 2, Qt.SolidLine))  # set pen to painter
+        painter.setBrush(QBrush(Qt.white))  # set brush
+        painter.drawEllipse(self.boundingRect())  # draw ellipse
+        painter.restore()  # restore painter as before drawing ellipse
         super(LineLabel, self).paint(painter, option, widget)
 
     def updateLabel(self):
-        offset = self.gap
-        points = self.parentItem().points
-        firstPoint = points[self.index]
-        endPoint = points[self.index + 1]
+        # finds new position on segment
+        offset = self.gap  # distance from segment
+        points = self.parentItem().points  # points of line
+        firstPoint = points[self.index]  # first point of segment on which label is attached
+        endPoint = points[self.index + 1]  # second point
         center = self.mapToParent(self.boundingRect().center())
         newPos = center
+        # if segment is vertical
         if firstPoint.x() == endPoint.x():
             newPos.setX(firstPoint.x() + self.gap)
             if min(firstPoint.y(), endPoint.y()) > newPos.y():
                 newPos.setY(min(firstPoint.y(), endPoint.y()))
             elif newPos.y() > max(firstPoint.y(), endPoint.y()):
                 newPos.setY(max(firstPoint.y(), endPoint.y()))
-
+        # segment is horizontal
         elif firstPoint.y() == endPoint.y():
             newPos.setY(firstPoint.y() + self.gap)
             if min(firstPoint.x(), endPoint.x()) > newPos.x():
                 newPos.setX(min(firstPoint.x(), endPoint.x()))
             elif newPos.x() > max(firstPoint.x(), endPoint.x()):
                 newPos.setX(max(firstPoint.x(), endPoint.x()))
+        # transfer center positon to top left
         newPos -= QPointF(self.boundingRect().width() / 2, self.boundingRect().height() / 2)
         self.setPos(newPos)
 
     def resetPos(self):
+        """ finds the segment of line on which mouse is clicked for adding label
+        and resets it's position on that segment
+        """
         points = self.parentItem().points
         min_A = QPointF()
         min_B = QPointF()
@@ -209,9 +221,10 @@ class LineLabel(QGraphicsTextItem):
             self.gap = -30 + self.boundingRect().height() / 2
 
     def itemChange(self, change, value):
+        # if position of label changes
         if change == QGraphicsItem.ItemPositionChange and self.scene():
-            newPos = QPointF(value)
-            newPos += QPointF(self.boundingRect().width() / 2, self.boundingRect().height() / 2)
+            newPos = QPointF(value)  # new position
+            newPos += QPointF(self.boundingRect().width() / 2, self.boundingRect().height() / 2)  # pos of center
             points = self.parentItem().points
             firstPoint = points[self.index]
             endPoint = points[self.index + 1]
@@ -225,7 +238,8 @@ class LineLabel(QGraphicsTextItem):
                     newPos.setX(min(firstPoint.x(), endPoint.x()))
                 elif newPos.x() > max(firstPoint.x(), endPoint.x()):
                     newPos.setX(max(firstPoint.x(), endPoint.x()))
-            newPos -= QPointF(self.boundingRect().width() / 2, self.boundingRect().height() / 2)
+            newPos -= QPointF(self.boundingRect().width() / 2,
+                              self.boundingRect().height() / 2)  # change center pos to top-left
             return newPos
         if change == QGraphicsItem.ItemPositionHasChanged and self.scene():
             self.updateGap()
@@ -234,6 +248,7 @@ class LineLabel(QGraphicsTextItem):
         return super(LineLabel, self).itemChange(change, value)
 
     def updateGap(self):
+        # updates distance of line from it's connection segment
         points = self.parentItem().points
         firstPoint = points[self.index]
         endPoint = points[self.index + 1]
@@ -246,6 +261,7 @@ class LineLabel(QGraphicsTextItem):
             self.gap = center.y() - firstPoint.y()
 
     def updateLine(self):
+        # updates line item of label
         points = self.parentItem().points
         firstPoint = points[self.index]
         endPoint = points[self.index + 1]
@@ -257,14 +273,15 @@ class LineLabel(QGraphicsTextItem):
             self.line.setLine(center.x(), center.y(), center.x(), point.y())
 
     def mouseDoubleClickEvent(self, event):
+        # set text editable
         self.setTextInteractionFlags(Qt.TextEditorInteraction)
         self.setFocus()
         super(LineLabel, self).mouseDoubleClickEvent(event)
 
     def focusOutEvent(self, event):
         super(LineLabel, self).focusOutEvent(event)
-        self.setTextInteractionFlags(Qt.NoTextInteraction)
-        
+        self.setTextInteractionFlags(Qt.NoTextInteraction)  # set text non interactive
+
     def __getstate__(self):
         return {
             "text": self.toPlainText(),
@@ -272,7 +289,7 @@ class LineLabel(QGraphicsTextItem):
             "gap": self.gap,
             "pos": (self.pos().x(), self.pos().y())
         }
-    
+
     def __setstate__(self, dict):
         self.setPlainText(dict['text'])
         self.index = dict['index']
@@ -280,11 +297,13 @@ class LineLabel(QGraphicsTextItem):
 
 
 def findIndex(line, pos):
+    # finds index of first point of segment of line which is nearer to given position
     points = line.points
     min_A = QPointF()
     min_B = QPointF()
     min_dis = math.inf
     index = -1
+    # iterating over points of line
     for i in range(len(points) - 1):
         A = points[i]
         B = points[i + 1]
@@ -293,7 +312,7 @@ def findIndex(line, pos):
         BAy = B.y() - A.y()
         CAx = C.x() - A.x()
         CAy = C.y() - A.y()
-        length = math.sqrt(BAx * BAx + BAy * BAy)
+        length = math.sqrt(BAx * BAx + BAy * BAy)  # length of segment
         if BAx == 0:
             if not min(A.y(), B.y()) <= C.y() <= max(A.y(), B.y()):
                 continue
@@ -317,10 +336,12 @@ class Line(QGraphicsPathItem):
 
     def __init__(self, startPoint, endPoint, **args):
         QGraphicsItem.__init__(self, **args)
+        # store startpoint and endpoint of line
         self.startPoint = startPoint
         self.endPoint = endPoint
         # stores all points of line
         self.points = []
+        # stores grips of line
         self.startGripItem = None
         self.endGripItem = None
         self.m_grabbers = []
@@ -334,32 +355,38 @@ class Line(QGraphicsPathItem):
         self.commonPathsCenters = []
         self.midLines = []
         self.label = []
-        self.arrowFlag = True
+        # if line point on rectangle grip
+        self.startGap = None # distance from center of start grip
+        self.endGap = None # distance from center of end grip
 
     def boundingRect(self):
+        # adjust bounding rect such that it contains intersection curve and arrow
         rect = self.shape().boundingRect()
-        rect.adjust(-10,-10,10,10)
+        rect.adjust(-10, -10, 10, 10)
         return rect
-    
+
     def advance(self, phase):
+        """ called by scene when item moves or updates on scene
+        """
         if not phase:
             return
-        # items colliding with line
-        # items = self.collidingItems(Qt.IntersectsItemShape)
+        # fine collision with line in ascending order
         items = self.scene().items(self.shape(), Qt.IntersectsItemShape, Qt.AscendingOrder)
-        self.commonPathsCenters = []
+        self.commonPathsCenters = [] # remove all previous interaction
         # if item is line and stacked above
         for item in items:
             if type(item) in [type(self)]:
                 if item == self:
                     break
-                shape = item.shape()
-                shape = self.mapFromItem(item, item.shape())
-                commonPath = self.shape().intersected(shape)
-                polygons = commonPath.toSubpathPolygons()
+                shape = item.shape() # shape of item
+                shape = self.mapFromItem(item, item.shape()) # map shape to self
+                commonPath = self.shape().intersected(shape) # find common path btw lines
+                polygons = commonPath.toSubpathPolygons() # chane common path to polygon
                 for polygon in polygons:
-                    center = polygon.boundingRect().center()
+                    center = polygon.boundingRect().center() # center of polygon
+                    # if collision is btw perpendicular line
                     if polygon.size() == 5:
+                        # ignore collision if other line has end point on this line
                         if item.refLine:
                             i = len(item.points) - 2
                             x1, y1 = item.points[i].x(), item.points[i].y()
@@ -378,8 +405,7 @@ class Line(QGraphicsPathItem):
     def paint(self, painter, option, widget):
         color = Qt.red if self.isSelected() else Qt.black
         painter.setPen(QPen(color, 2, Qt.SolidLine))
-        path = QPainterPath(self.startPoint)
-        arrowHead = QPolygonF()
+        path = QPainterPath(self.startPoint) # start path
         # iterating over all points of line
         for i in range(len(self.points) - 1):
             x1, y1 = self.points[i].x(), self.points[i].y()
@@ -409,7 +435,8 @@ class Line(QGraphicsPathItem):
                             path.arcTo(QRectF(x - 8, y - 8, 16, 16), 0, -180)
                             path.lineTo(point - QPointF(8, 0))
             path.lineTo(self.points[i + 1])
-            if i == len(self.points) - 2 and self.arrowFlag:
+            # draw arrow in last segment
+            if i == len(self.points) - 2:
                 arrow_size = 20.0
                 line = QLineF(self.points[i], self.points[i + 1])
                 if line.length() < 20:
@@ -429,13 +456,12 @@ class Line(QGraphicsPathItem):
                 arrowHead.append(line.p2())
                 arrowHead.append(arrow_p1)
                 arrowHead.append(arrow_p2)
-                # path.addPolygon(arrowHead)
                 painter.save()
                 painter.setBrush(Qt.black)
                 painter.drawPolygon(arrowHead)
                 painter.restore()
 
-        painter.drawPath(path)
+        painter.drawPath(path) # draw final path
 
     def createPath(self):
         """
@@ -449,6 +475,7 @@ class Line(QGraphicsPathItem):
         self.points = [self.startPoint, QPointF((x0 + x1) / 2, y0), QPointF((x0 + x1) / 2, y1), self.endPoint]
         # final path of line
         if self.refLine:
+            # line has end point on other line
             from .shapes import LineGripItem
             direction = "left"
             points = self.refLine.points
@@ -464,7 +491,7 @@ class Line(QGraphicsPathItem):
                     direction = "top"
                 else:
                     direction = "bottom"
-            self.endGripItem = LineGripItem(self, -1, direction, self)
+            self.endGripItem = LineGripItem(-1, [0, 0, direction], self)
             self.endGripItem.setPos(self.endPoint)
 
         if self.startGripItem and self.endGripItem:
@@ -490,8 +517,8 @@ class Line(QGraphicsPathItem):
                 pe = QPointF(self.endPoint.x() + offset, self.endPoint.y())
             start = self.startPoint
             end = self.endPoint
-            sitem = self.startGripItem.mapRectToScene(self.startGripItem.m_annotation_item.boundingRect())
-            eitem = self.endGripItem.mapRectToScene(self.endGripItem.m_annotation_item.boundingRect())
+            sitem = self.startGripItem.mapRectToScene(self.startGripItem.parentItem().boundingRect())
+            eitem = self.endGripItem.mapRectToScene(self.endGripItem.parentItem().boundingRect())
             if self.refLine:
                 eitem = self.endGripItem.mapRectToScene(QRectF(0, 0, 0, 0))
 
@@ -751,6 +778,7 @@ class Line(QGraphicsPathItem):
         self.setPath(path)
 
         if self.refLine:
+            # remove added grip
             self.scene().removeItem(self.endGripItem)
             self.endGripItem = None
             self.addGrabber()
@@ -767,9 +795,12 @@ class Line(QGraphicsPathItem):
             path.lineTo(self.points[i])
         path.lineTo(self.endPoint)
         self.setPath(path)
+        # update grabber of line
         self.updateGrabber()
+        # update labels connected to line
         for label in self.label:
             label.updateLabel()
+        # update line have end point on this line
         self.updateMidLines()
 
     def updatePoints(self):
@@ -848,6 +879,7 @@ class Line(QGraphicsPathItem):
 
     def itemChange(self, change, value):
         if change == QGraphicsItem.ItemSelectedHasChanged:
+            # on selection stack above to show curve on it
             if value == 1:
                 self.showGripItem()
                 items = self.collidingItems(Qt.IntersectsItemShape)
@@ -859,46 +891,63 @@ class Line(QGraphicsPathItem):
                 self.hideGripItem()
             return
         if change == QGraphicsItem.ItemSceneHasChanged and not self.scene():
+            # if line is removed from scene
             for line in self.midLines:
+                # remove lines connected to it
                 if line.scene():
                     line.scene().removeItem(line)
-            if self.startGripItem and self.startGripItem.line and not self.startGripItem.tempLine:
-                self.startGripItem.line = None
-                if self.endGripItem and self.endGripItem.line:
-                    self.endGripItem.line = None
+            if self.startGripItem and self.startGripItem.lines and not self.startGripItem.tempLine:
+                # remove line reference from grips
+                if self in self.startGripItem.lines: self.startGripItem.lines.remove(self)
+                if self.endGripItem and self.endGripItem.lines:
+                    if self in self.endGripItem.lines: self.endGripItem.lines.remove(self)
                 if self.refLine:
                     if self in self.refLine.midLines: self.refLine.midLines.remove(self)
 
         return super(Line, self).itemChange(change, value)
 
-    def updateLine(self, startPoint=None, endPoint=None):
+    def updateLine(self, endPoint=None):
 
         """This function is used to update connecting line when it add on
            canvas and when it's grip item  moves
         :return:
         """
-        self.prepareGeometryChange()
-        if startPoint:
-            self.startPoint = startPoint
         if endPoint:
             self.endPoint = endPoint
             self.createPath()
             self.updateGrabber()
             return
-
-        if self.startGripItem and self.endGripItem:
+        # update start point
+        if self.startGripItem:
             item = self.startGripItem
-            self.startPoint = item.parentItem().mapToScene(item.pos())
+            startPoint = item.parentItem().mapToScene(item.pos()) # center of grip
+            # end grip is rectangle
+            if item.size and item.m_location in ["top", "bottom"]:
+                startPoint.setX(startPoint.x() - self.startGap * item.boundingRect().width())
+            elif item.size:
+                startPoint.setY(
+                    startPoint.y() - self.startGap * item.boundingRect().height())
+            self.startPoint = startPoint
+        # end point on line
+        if self.endGripItem:
             item = self.endGripItem
-            self.endPoint = item.parentItem().mapToScene(item.pos())
+            endPoint = item.parentItem().mapToScene(item.pos()) # center of grip
+            # end grip is rectangle
+            if item.size and item.m_location in ["top", "bottom"]:
+                endPoint.setX(
+                    endPoint.x() - self.endGap * item.boundingRect().width())
+            elif item.size:
+                endPoint.setY(
+                    endPoint.y() - self.endGap * item.boundingRect().height())
+            self.endPoint = endPoint
             self.updatePath()
-
-        if self.startGripItem and self.refLine:
-            item = self.startGripItem
-            self.startPoint = item.parentItem().mapToScene(item.pos())
+        # end point on other line
+        elif self.refLine:
             self.updatePath()
 
     def updateMidLines(self):
+        """ Updates all lines connecting to it
+        """
         for line in self.midLines:
             points = line.refLine.points
             point1 = points[line.refIndex]
@@ -922,13 +971,6 @@ class Line(QGraphicsPathItem):
                     line.points[i - 1].setX(max(point1.x(), point2.x()))
             line.updatePath()
 
-    def removeFromCanvas(self):
-        """This function is used to remove connecting line from canvas
-        :return:
-        """
-        if self.scene():
-            self.scene().removeItem(self)
-
     def showGripItem(self):
         """shows grip items which contains line
         """
@@ -955,26 +997,14 @@ class Line(QGraphicsPathItem):
         """Pop up menu
         :return:
         """
+        # create a menu and add action
         contextMenu = QMenu()
-        addLableAction = contextMenu.addAction("add Label")
-        if self.arrowFlag is True:
-            str = "Hide Arrow"
-        else:
-            str = "Add Arrow"
-        changeArrowFlag = contextMenu.addAction(str)
+        addLableAction = contextMenu.addAction("Add Text Label")  # add action for text label
         action = contextMenu.exec_(event.screenPos())
+        # check for label action and add text label as child
         if action == addLableAction:
-            self.label.append(LineLabel(event.scenePos(), self))
-        if action == changeArrowFlag:
-            if str == "Hide Arrow":
-                self.arrowFlag =False
-            else:
-                self.arrowFlag =True
-            self.update()
-
-    def setPenStyle(self, style):
-        """change current pen style for line"""
-        self.penStyle = style
+            print(event.scenePos(), event.pos())
+            self.label.append(LineLabel(event.scenePos(), self))  # text label as child
 
     def __getstate__(self):
         return {
@@ -989,5 +1019,6 @@ class Line(QGraphicsPathItem):
             "label": [i for i in self.label],
             "id": hex(id(self))
         }
+
     def __setstate__(self, dict):
         self.points = [QPointF(x, y) for x, y in dict["points"]]
diff --git a/src/main/python/shapes/shapes.py b/src/main/python/shapes/shapes.py
index 6d06cba..117ffb8 100644
--- a/src/main/python/shapes/shapes.py
+++ b/src/main/python/shapes/shapes.py
@@ -14,24 +14,31 @@ from utils.app import fileImporter
 
 
 class ItemLabel(QGraphicsTextItem):
-    def __init__(self, pos, parent=None):
+    """Extends PyQt5's QGraphicsPathItem to create text label for svg item
+    """
+
+    def __init__(self, parent=None):
         super().__init__(parent=parent)
         self.setPlainText("abc")
+        # graphics setting for text label
         self.setFlags(QGraphicsItem.ItemIsMovable |
                       QGraphicsItem.ItemIsSelectable |
                       QGraphicsItem.ItemIsFocusable)
         self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
+        # set initial no text interaction
         self.setTextInteractionFlags(Qt.NoTextInteraction)
+        # set initial position just below parent
         self.setPos(self.parentItem().boundingRect().bottomLeft())
 
     def mouseDoubleClickEvent(self, event):
+        # make text editable
         self.setTextInteractionFlags(Qt.TextEditorInteraction)
-        self.setFocus()
+        self.setFocus()  # set focus to text
         super(ItemLabel, self).mouseDoubleClickEvent(event)
 
     def focusOutEvent(self, event):
         super(ItemLabel, self).focusOutEvent(event)
-        self.setTextInteractionFlags(Qt.NoTextInteraction)
+        self.setTextInteractionFlags(Qt.NoTextInteraction)  # make text not editable and thus movable
 
     def __getstate__(self):
         return {
@@ -69,26 +76,21 @@ class GripItem(QGraphicsPathItem):
         super(GripItem, self).mouseReleaseEvent(event)
 
 
-class SizeGripItem(GripItem):
+class SizeGripItem(QGraphicsPathItem):
     """
     Extends grip items for vertical and horizontal directions, with hover events and directional changes
     """
 
-    def __init__(self, annotation_item, index, direction=Qt.Horizontal, parent=None):
-        self.width = self.height = 0
-        if direction is Qt.Horizontal:
-            self.height = annotation_item.boundingRect().height()
-        else:
-            self.width = annotation_item.boundingRect().width()
-
-        path = QPainterPath()
-        path.addRect(QRectF(-self.width / 2, -self.height / 2, self.width, self.height))
-        super(SizeGripItem, self).__init__(annotation_item, path=path, parent=parent)
+    def __init__(self, index, direction=Qt.Horizontal, parent=None):
+        super(SizeGripItem, self).__init__(parent=parent)
+        # set graphical setting
         self.setFlag(QGraphicsItem.ItemIsSelectable, True)
         self.setFlag(QGraphicsItem.ItemIsMovable, True)
         self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
-        self.setPen(QPen(QColor("black"), -1))
+        self.setAcceptHoverEvents(True)
+        self.setPen(QPen(QColor("black"), 0))
         self.setZValue(2)
+        # property direction
         self._direction = direction
         self.m_index = index
 
@@ -99,21 +101,16 @@ class SizeGripItem(GripItem):
         """
         return self._direction
 
-    def paint(self, painter, option, widget):
-        if self.isSelected() and not self.parentItem().isSelected():
-            self.parentItem().setSelected(True)
-            self.parentItem().setFlag(QGraphicsSvgItem.ItemIsMovable, False)
-        super().paint(painter, option, widget)
-
     def updatePath(self):
         """updates path of size grip item
         """
-        if self._direction is Qt.Horizontal:
-            self.height = self.parentItem().boundingRect().height()
+        width = height = 0
+        if self.direction is Qt.Horizontal:
+            height = self.parentItem().boundingRect().height()
         else:
-            self.width = self.parentItem().boundingRect().width()
+            width = self.parentItem().boundingRect().width()
         path = QPainterPath()
-        path.addRect(QRectF(-self.width / 2, -self.height / 2, self.width, self.height))
+        path.addRect(QRectF(-width / 2, -height / 2, width, height))
         self.setPath(path)
 
     def updatePosition(self):
@@ -143,9 +140,7 @@ class SizeGripItem(GripItem):
         """
         Changes cursor to horizontal resize or vertical resize depending on the direction of the grip item on mouse enter
         """
-        # self.setPen(QPen(QColor("black"), 2))
-        # self.setBrush(QColor("red"))
-        if self._direction == Qt.Horizontal:
+        if self.direction == Qt.Horizontal:
             self.setCursor(QCursor(Qt.SizeHorCursor))
         else:
             self.setCursor(QCursor(Qt.SizeVerCursor))
@@ -155,8 +150,6 @@ class SizeGripItem(GripItem):
         """
         reverts cursor to default on mouse leave
         """
-        # self.setPen(QPen(Qt.transparent))
-        # self.setBrush(Qt.transparent)
         self.setCursor(QCursor(Qt.ArrowCursor))
         super(SizeGripItem, self).hoverLeaveEvent(event)
 
@@ -187,45 +180,71 @@ class SizeGripItem(GripItem):
         self.updatePosition()
         # Make parent item move able
         self.parentItem().setFlag(QGraphicsSvgItem.ItemIsMovable, True)
-        # If needed to reset transform of parent set it's position accordingly
+        # If needed, to reset transform of parent set it's position accordingly
         # self.parentItem().setPos(self.parentItem().x() + self.parentItem().transform().dx(), self.parentItem().y() + self.parentItem().transform().dy())
         # self.parentItem().resetTransform()
 
+    def show(self):
+        # make self visible
+        self.setPen(QPen(QColor("black"), 2))
+
+    def hide(self):
+        # hide self by setting pen to transparent
+        if not self.parentItem().isSelected():
+            self.setPen(QPen(Qt.transparent))
+            self.setBrush(Qt.transparent)
+
 
-class LineGripItem(GripItem):
+class LineGripItem(QGraphicsPathItem):
     """Extends grip items for connecting lines , with hover events and mouse events
     """
     circle = QPainterPath()
     circle.addEllipse(QRectF(-5, -5, 10, 10))
 
-    def __init__(self, annotation_item, index, grip, parent=None):
-        path = LineGripItem.circle
-
-        super(LineGripItem, self).__init__(annotation_item, path=path, parent=parent)
+    def __init__(self, index, grip, parent=None):
+        super(LineGripItem, self).__init__(parent=parent)
+        self.setPath(LineGripItem.circle)
+        # set it's index on item
         self.m_index = index
-        self.m_location = grip[2]
-        self.line = None
+        # store position of self
+        self.position = QPointF(grip[0], grip[1])
+        # set location
+        self._m_location = grip[2]
+        # set size in case of rectangle grip
+        self.size = grip[3] if len(grip) == 4 else None
         # stores current line which is in process
         self.tempLine = None
+        # stores lines conected to it
+        self.lines = []
         # keep previous hovered item when line drawing in process
         self.previousHoveredItem = None
+        # set graphical settings
         self.setFlag(QGraphicsItem.ItemIsSelectable, True)
         self.setPen(QPen(QColor("black"), -1))
-        self.grip = grip
+        self.setAcceptHoverEvents(True)
+        self.setCursor(QCursor(Qt.PointingHandCursor))
+
+    @property
+    def m_location(self):
+        return self._m_location
 
     def shape(self):
+        # return interactive path
         qp = QPainterPathStroker()
         qp.setWidth(8)
+        # create outline of path
         path = qp.createStroke(self.path())
         return path
 
-    def paint(self, painter,option, widget):
+    def paint(self, painter, option, widget):
+        # draw path with outline of interactive area(shape)
         painter.setPen(self.pen())
-        painter.drawPath(self.shape())
+        painter.drawPath(self.shape()) # draw outline
         painter.setBrush(self.brush())
-        if len(self.grip) ==4:
+        # if rectangle grip
+        if self.size:
             painter.save()
-            pen =self.pen()
+            pen = self.pen()
             pen.setWidth(-1)
             painter.setPen(pen)
             painter.drawPath(self.path())
@@ -238,47 +257,38 @@ class LineGripItem(GripItem):
         Moves position of grip item on resize
         """
         if change == QGraphicsItem.ItemSceneHasChanged and not self.scene():
-            if self.line and self.line.scene():
-                self.line.scene().removeItem(self.line)
+            # on removing from scene remove all lines connected to it
+            for line in self.lines:
+                if line.scene():
+                    line.scene().removeItem(line)
         return super(LineGripItem, self).itemChange(change, value)
 
-    def point(self, index):
-        """
-        yields a list of positions of grip items in a node item
-        """
-        width = self.parentItem().boundingRect().width()
-        height = self.parentItem().boundingRect().height()
-        if 0 <= index < 4:
-            return [
-                QPointF(0, -height / 2),
-                QPointF(-width / 2, 0),
-                QPointF(0, height / 2),
-                QPointF(width / 2, 0)
-            ][index]
-
     def updatePosition(self):
-        width = self.parentItem().boundingRect().width()
-        height = self.parentItem().boundingRect().height()
-        if len(self.grip) == 4:
+        width = self.parentItem().boundingRect().width() # width of parent
+        height = self.parentItem().boundingRect().height() # height of parent
+        # if grip item is rectangle change it's path
+        if self.size:
             rect_width = rect_height = 4
-            if self.grip[2] in ["left","right"]:
-                rect_height = (self.grip[3]*height)/100
+            if self.m_location in ["left", "right"]:
+                rect_height = (self.size * height) / 100
             else:
-                rect_width = (self.grip[3]*width)/100
-            path = QPainterPath()
-            path.addRect(QRectF(-rect_width / 2, -rect_height / 2, rect_width, rect_height))
-            self.setPath(path)
-
-        x = (self.grip[0] * width) / 100
-        y = (self.grip[1] * height) / 100
+                rect_width = (self.size * width) / 100
+            path = QPainterPath() # create path
+            path.addRect(QRectF(-rect_width / 2, -rect_height / 2, rect_width, rect_height)) # add rect to path
+            self.setPath(path) # set path to grip
+        # position according to svg co-ordinate
+        x = (self.position.x() * width) / 100
+        y = (self.position.y() * height) / 100
+        # change position into items coordinate
         x -= width / 2
         y -= height / 2
         y = -y
         self.setEnabled(False)
-        self.setPos(QPointF(x, y))
+        self.setPos(QPointF(x, y)) # set pos of grip
         self.setEnabled(True)
-        if self.line:
-            self.line.updateLine()
+        # update all lines connected to it
+        for line in self.lines:
+            line.updateLine()
 
     def mousePressEvent(self, mouseEvent):
         """Handle all mouse press for this item
@@ -286,10 +296,25 @@ class LineGripItem(GripItem):
         if mouseEvent.button() != Qt.LeftButton:
             return
         # initialize a line and add on scene
-        if not self.line:
-            startPoint = endPoint = self.parentItem().mapToScene(self.pos())
-            self.tempLine = Line(startPoint, endPoint)
-            self.scene().addItem(self.tempLine)
+        # restrict circle grip to one line
+        if self.size is None and len(self.lines) > 0:
+            pass
+        else:
+            startPoint = self.parentItem().mapToScene(self.pos()) # first point of line
+            mpos = self.mapToScene(mouseEvent.pos()) # position of mouse
+            gap = 0 # distance from center of grip
+            if self.size and self.m_location in ["top", "bottom"]:
+                gap = (startPoint.x() - mpos.x()) / self.boundingRect().width()
+                startPoint.setX(mpos.x())
+
+            elif self.size:
+                gap = (startPoint.y() - mpos.y()) / self.boundingRect().height()
+                startPoint.setY(mpos.y())
+
+            endPoint = startPoint
+            self.tempLine = Line(startPoint, endPoint) # create a line object
+            self.tempLine.startGap = gap # set gap to line
+            self.scene().addItem(self.tempLine) # add line on scene
         super().mousePressEvent(mouseEvent)
 
     def mouseMoveEvent(self, mouseEvent):
@@ -297,17 +322,17 @@ class LineGripItem(GripItem):
         """
         # if line get started then update it's end point
         if self.tempLine:
-            endPoint = mouseEvent.scenePos()
+            endPoint = mouseEvent.scenePos() # mouse position
             self.tempLine.updateLine(endPoint=endPoint)
-
+        # find item below cursor
         item = self.scene().itemAt(mouseEvent.scenePos().x(), mouseEvent.scenePos().y(),
                                    QTransform())
-
+        # hide grip of previous hovered item
         if self.previousHoveredItem and item != self.previousHoveredItem and \
                 item not in self.previousHoveredItem.lineGripItems:
             self.previousHoveredItem.hideGripItem()
         super().mouseMoveEvent(mouseEvent)
-
+        # show grip of current hoverde item
         if isinstance(item, NodeItem):
             self.previousHoveredItem = item
             item.showGripItem()
@@ -317,30 +342,51 @@ class LineGripItem(GripItem):
         super().mouseReleaseEvent(mouseEvent)
         # set final position of line
         if self.tempLine:
+            tag = 0
             items = self.scene().items(QPointF(mouseEvent.scenePos().x(), mouseEvent.scenePos().y()))
             for item in items:
+                # end point on grip
                 if type(item) == LineGripItem and item != self:
-                    if item.line:
+                    endPoint = item.parentItem().mapToScene(item.pos())
+                    gap = 0
+                    # restrict line to one grip
+                    if item.size is None and len(item.lines) > 0:
                         break
+                    # in case of rectangle grip
+                    if item.size and item.m_location in ["top", "bottom"]:
+                        mpos = self.mapToScene(mouseEvent.pos())
+                        gap = (endPoint.x() - mpos.x()) / item.boundingRect().width()
+                        endPoint.setX(mpos.x())
+                    elif item.size:
+                        mpos = self.mapToScene(mouseEvent.pos())
+                        gap = (endPoint.y() - mpos.y()) / item.boundingRect().height()
+                        endPoint.setY(mpos.y())
+
+                    self.tempLine.endGap = gap
                     self.tempLine.setStartGripItem(self)
                     self.tempLine.setEndGripItem(item)
-                    endPoint = item.parentItem().mapToScene(item.pos())
+                    # update line with end point so it sets final path
                     self.tempLine.updateLine(endPoint=endPoint)
-                    self.line = self.tempLine
-                    item.line = self.tempLine
+                    self.lines.append(self.tempLine)
+                    item.lines.append(self.tempLine)
+                    tag = 1
                     break
+                # end point on line
                 elif type(item) == Line and item != self.tempLine:
                     self.tempLine.setStartGripItem(self)
                     endPoint = mouseEvent.scenePos()
                     self.tempLine.refLine = item
                     self.tempLine.refIndex = findIndex(item, endPoint)
+                    # update line with end point so it sets final path
                     self.tempLine.updateLine(endPoint=endPoint)
-                    item.midLines.append(self.tempLine)
-                    self.line = self.tempLine
+                    item.midLines.append(self.tempLine) # stores temp line as mid line to other line
+                    self.lines.append(self.tempLine)
+                    tag = 1
                     break
-            self.scene().removeItem(self.tempLine)
-            if self.line:
-                self.scene().addItemPlus(self.line)
+            self.scene().removeItem(self.tempLine) # remove temp line from scene
+            # if line end point is on grip or line
+            if tag:
+                self.scene().addItemPlus(self.tempLine) # add line on scene
 
         self.tempLine = None
         self.previousHoveredItem = None
@@ -349,12 +395,12 @@ class LineGripItem(GripItem):
         """ shows line grip item
         """
         self.setPen(QPen(QColor("black"), 2))
-        self.setBrush(QColor("red"))
+        self.setBrush(QColor("cyan"))
 
     def hide(self):
         """ hides line grip item
         """
-        if (self.parentItem().isSelected() or self.isSelected()) is False:
+        if not self.parentItem().isSelected():
             self.setPen(QPen(Qt.transparent))
             self.setBrush(Qt.transparent)
 
@@ -364,26 +410,21 @@ class NodeItem(QGraphicsSvgItem):
         Extends PyQt5's QGraphicsSvgItem to create the basic structure of shapes with given unit operation type
     """
 
-    # set a common renderer for all svg
-    # renderer = QSvgRenderer(fileImporter(f'svg/ellipse.svg'))
-
     def __init__(self, unitOperationType=None, parent=None):
         QGraphicsSvgItem.__init__(self, parent)
         self.m_type = str(unitOperationType)
-        self.id = None
         self.m_renderer = QSvgRenderer(fileImporter(f'{unitOperationType}.svg'))
         self.setSharedRenderer(self.m_renderer)
         # set initial size of item
         self.width = self.m_renderer.defaultSize().width()
         self.height = self.m_renderer.defaultSize().height()
-        self.rect = QRectF(-self.width / 2, -self.height / 2, self.width, self.height)
         # set graphical settings for this item
         self.setFlags(QGraphicsSvgItem.ItemIsMovable |
                       QGraphicsSvgItem.ItemIsSelectable |
                       QGraphicsSvgItem.ItemSendsGeometryChanges)
         self.setAcceptHoverEvents(True)
         self.setZValue(2)
-        # grip items connected to this item
+        # items connected to this item
         self.lineGripItems = []
         self.sizeGripItems = []
         self.label = None
@@ -392,7 +433,7 @@ class NodeItem(QGraphicsSvgItem):
         """Overrides QGraphicsSvgItem's boundingRect() virtual public function and
         returns a valid bounding
         """
-        return self.rect
+        return QRectF(-self.width / 2, -self.height / 2, self.width, self.height)
 
     def paint(self, painter, option, widget):
         """
@@ -401,14 +442,11 @@ class NodeItem(QGraphicsSvgItem):
             :param option: QStyleOptionGraphicsItem instance
             :param widget: QWidget instance
         """
+        # check if render is set
         if not self.m_renderer:
             QGraphicsSvgItem.paint(self, painter, option, widget)
-        elif self.id:
-            self.m_renderer.render(painter, self.id, self.boundingRect())
         else:
-            self.m_renderer.render(painter, self.boundingRect())
-        if self.isSelected():
-            self.showGripItem()
+            self.m_renderer.render(painter, self.boundingRect())  # render svg using painter
 
     def resize(self, index, movement):
         """Move grip item with changing rect of node item
@@ -420,8 +458,6 @@ class NodeItem(QGraphicsSvgItem):
         else:
             self.width += movement.x()
             self.height += movement.y()
-
-        self.rect = QRectF(-self.width / 2, -self.height / 2, self.width, self.height)
         transform = QTransform()
         transform.translate(movement.x() / 2, movement.y() / 2)
         self.setTransform(transform, True)
@@ -431,7 +467,7 @@ class NodeItem(QGraphicsSvgItem):
         """adds grip items
         """
         if self.scene():
-            # add grip for resize it
+            # add grip for resizing
             for i, (direction) in enumerate(
                     (
                             Qt.Vertical,
@@ -440,19 +476,18 @@ class NodeItem(QGraphicsSvgItem):
                             Qt.Horizontal,
                     )
             ):
-                item = SizeGripItem(self, i, direction, parent=self)
+                item = SizeGripItem(i, direction, parent=self)
                 self.sizeGripItems.append(item)
             # add grip items for connecting lines
             for i in range(len(self.grips)):
                 grip = self.grips[i]
-                item = LineGripItem(self, i, grip, parent=self)
+                item = LineGripItem(i, grip, parent=self)
                 self.lineGripItems.append(item)
 
-    def updateLineGripItem(self, index_no_updates=None):
+    def updateLineGripItem(self):
         """
         updates line grip items
         """
-        # index_no_updates = index_no_updates or []
         for item in self.lineGripItems:
             item.updatePosition()
 
@@ -468,20 +503,27 @@ class NodeItem(QGraphicsSvgItem):
     def itemChange(self, change, value):
         """Overloads and extends QGraphicsSvgItem to also update grip items
         """
+        # check if item selected is changed
         if change == QGraphicsItem.ItemSelectedHasChanged:
+            # show grips if selected
             if value is True:
                 self.showGripItem()
             else:
                 self.hideGripItem()
             return
+        # check if transform changed
         if change == QGraphicsItem.ItemTransformHasChanged:
             self.updateLineGripItem()
             return
+        # check if position is changed
         if change == QGraphicsItem.ItemPositionHasChanged:
+            # update grips
             self.updateLineGripItem()
             self.updateSizeGripItem()
             return
+        # check if item is add on scene
         if change == QGraphicsItem.ItemSceneHasChanged and self.scene():
+            # add grips and update them
             self.addGripItem()
             self.updateLineGripItem()
             self.updateSizeGripItem()
@@ -504,32 +546,29 @@ class NodeItem(QGraphicsSvgItem):
         """shows grip items of svg item
         """
         for item in self.lineGripItems:
-            item.setPen(QPen(QColor("black"), 2))
-            item.setBrush(QColor("red"))
+            item.show()
         for item in self.sizeGripItems:
-            item.setPen(QPen(QColor("black"), 2))
+            item.show()
 
     def hideGripItem(self):
         """hide grip items of svg item
         """
         for item in self.lineGripItems:
-            if item.isSelected() is False:
-                item.setPen(QPen(Qt.transparent))
-                item.setBrush(Qt.transparent)
+            item.hide()
         for item in self.sizeGripItems:
-            item.setPen(QPen(Qt.transparent))
-            item.setBrush(Qt.transparent)
+            item.hide()
 
     def contextMenuEvent(self, event):
         """Pop up menu
         :return:
         """
+        # create a menu and add action
         contextMenu = QMenu()
-        addLabelAction = contextMenu.addAction("add Label")
-        # addLabelAction.triggered.connect(self.addLabel)
+        addLableAction = contextMenu.addAction("add Label")  # add action for text label
         action = contextMenu.exec_(event.screenPos())
-        if action == addLabelAction:
-            self.label = ItemLabel(event.scenePos(), self)
+        # check for label action and add text label as child
+        if action == addLableAction:
+            self.label = ItemLabel(self)  # text label as child
 
     def __getstate__(self):
         return {
@@ -545,7 +584,6 @@ class NodeItem(QGraphicsSvgItem):
         self.prepareGeometryChange()
         self.width = dict['width']
         self.height = dict['height']
-        self.rect = QRectF(-self.width / 2, -self.height / 2, self.width, self.height)
         self.updateSizeGripItem()
 
 
@@ -685,7 +723,7 @@ class Turbine(NodeItem):
         super(Turbine, self).__init__("svg/Compressors/Turbine")
         self.grips = [
             [18.06209745144267, 79.11931909160472, "top"],
-            [45.2091373550176,  91.385325275219, "top"],
+            [45.2091373550176, 91.385325275219, "top"],
             [18.06209745144267, 16.41537491819628, "bottom"],
             [45.2091373550176, 4.5725942986116, "bottom"]
         ]
@@ -693,13 +731,14 @@ class Turbine(NodeItem):
 
 class OilGasOrPulverizedFuelFurnace(NodeItem):
     def __init__(self):
-        super(OilGasOrPulverizedFuelFurnace, self).__init__("svg/Furnaces and Boilers/Oil Gas or Pulverized Fuel Furnace")
+        super(OilGasOrPulverizedFuelFurnace, self).__init__(
+            "svg/Furnaces and Boilers/Oil Gas or Pulverized Fuel Furnace")
         self.grips = [
-            [58.27673386073162,100,"top"],
-            [0,19.692723451106,"left"] ,
-            [17.2777337415748,33.3944873323144,"left",66.7889746646288],
-            [100,33.3944873323144,"right",66.7889746646288],
-            [57.9723659874,0,"bottom",81.389264491796]
+            [58.27673386073162, 100, "top"],
+            [0, 19.692723451106, "left"],
+            [17.2777337415748, 33.3944873323144, "left", 66.7889746646288],
+            [100, 33.3944873323144, "right", 66.7889746646288],
+            [57.9723659874, 0, "bottom", 81.389264491796]
         ]
 
 
@@ -707,62 +746,32 @@ class SolidFuelFurnace(NodeItem):
     def __init__(self):
         super(SolidFuelFurnace, self).__init__("svg/Furnaces and Boilers/Solid Fuel Furnace")
         self.grips = [
-            [50,100,"top"],
-            [0,33.39352642259468,"left",66.78705284518936],
-            [100,33.39352642259468,"right",66.78705284518936],
-            [50,0,"bottom",100]
+            [50, 100, "top"],
+            [0, 33.39352642259468, "left", 66.78705284518936],
+            [100, 33.39352642259468, "right", 66.78705284518936],
+            [50, 0, "bottom", 100]
         ]
 
 
-# class Exchanger(NodeItem):
-#     def __init__(self):
-#         super(Exchanger, self).__init__("svg/Heating or Cooling Arrangements/905Exchanger")
-#         self.grips = [
-#             [92.8093483, 70.60413752309337, "right"],
-#             [7.913824600849647, 70.60413752309337, "left"],
-#             [4.136894788615162, 86.9886362, "left"]
-#         ]
-
-
-# class KettleReboiler(NodeItem):
-#     def __init__(self):
-#         super(KettleReboiler, self).__init__("svg/Heating or Cooling Arrangements/907Kettle Reboiler")
-#         self.grips = [
-#             [41.316753407496, 89.824108247573, "top"],
-#             [62.0517030576456, 79.183192150093, "top"],
-#             [41.316753407496, 6.447877022097, "bottom"],
-#             [62.0517030576456, 16.14847772052, "bottom"]
-#         ]
-
-
 class Exchanger(NodeItem):
     def __init__(self):
         super(Exchanger, self).__init__("svg/Heating or Cooling Arrangements/Exchanger")
         self.grips = [
-            [100,31.74474612706027,"right"],
-            [100,62.70549343934227,"right"],
-            [33.68240920045628,100,"top"],
-            [33.68240920045628,0,"bottom"]
+            [100, 31.74474612706027, "right"],
+            [100, 62.70549343934227, "right"],
+            [33.68240920045628, 100, "top"],
+            [33.68240920045628, 0, "bottom"]
         ]
 
 
-# class Fan(NodeItem):
-#     def __init__(self):
-#         super(Fan, self).__init__("svg/Compressors/Fan")
-#         self.grips = [
-#             [41.4323581, 100, "top"],
-#             [61.1489583, 100, "top"]
-#         ]
-
-
 class HeatExchanger(NodeItem):
     def __init__(self):
         super(HeatExchanger, self).__init__("svg/Heating or Cooling Arrangements/Heat Exchanger")
         self.grips = [
-            [0,47.14356681569796,"left"],
-            [100,47.14356681569796,"right"],
-            [50.92839727035332,100,"top"],
-            [50.92839727035332,0,"bottom"]
+            [0, 47.14356681569796, "left"],
+            [100, 47.14356681569796, "right"],
+            [50.92839727035332, 100, "top"],
+            [50.92839727035332, 0, "bottom"]
         ]
 
 
@@ -770,8 +779,8 @@ class ImmersionCoil(NodeItem):
     def __init__(self):
         super(ImmersionCoil, self).__init__("svg/Heating or Cooling Arrangements/Immersion Coil")
         self.grips = [
-            [44.56276981957,100,"top"],
-            [88.232463407718,100,"top"]
+            [44.56276981957, 100, "top"],
+            [88.232463407718, 100, "top"]
         ]
 
 
@@ -779,36 +788,39 @@ class HorizontalVessel(NodeItem):
     def __init__(self):
         super(HorizontalVessel, self).__init__("svg/Process Vessels/Horizontal Vessel")
         self.grips = [
-            [50,100,"top",87.08554680344],
-            [0,50,"left"],
-            [100,50,"right"],
-            [50,0,"bottom",87.08554680344]
+            [50, 100, "top", 87.08554680344],
+            [0, 50, "left"],
+            [100, 50, "right"],
+            [50, 0, "bottom", 87.08554680344]
         ]
 
+
 class PackedVessel(NodeItem):
     def __init__(self):
         super(PackedVessel, self).__init__("svg/Process Vessels/Packed Vessel")
         self.grips = [
-            [50,100,"top"],
-            [0,50,"left",86.703566201060],
-            [100,50,"right",86.703566201060],
-            [50,0,"bottom"]
+            [50, 100, "top"],
+            [0, 50, "left", 86.703566201060],
+            [100, 50, "right", 86.703566201060],
+            [50, 0, "bottom"]
         ]
 
+
 class TraysOrPlates(NodeItem):
     def __init__(self):
         super(TraysOrPlates, self).__init__("svg/Process Vessels/Trays or plates")
         self.grips = [
         ]
 
+
 class VerticalVessel(NodeItem):
     def __init__(self):
         super(VerticalVessel, self).__init__("svg/Process Vessels/Vertical Vessel")
         self.grips = [
-            [50,100,"top"],
-            [0,50,"left",86.703566201060],
-            [100,50,"right",86.703566201060],
-            [50,0,"bottom"]
+            [50, 100, "top"],
+            [0, 50, "left", 86.703566201060],
+            [100, 50, "right", 86.703566201060],
+            [50, 0, "bottom"]
         ]
 
 
@@ -816,20 +828,21 @@ class Separators(NodeItem):
     def __init__(self):
         super(Separators, self).__init__("svg/Separators/Separators for Liquids, Decanter")
         self.grips = [
-            [50,100,"top",100],
-            [0,50,"left",100],
-            [100,50,"right",100],
-            [50,0,"bottom",100]
+            [50, 100, "top", 100],
+            [0, 50, "left", 100],
+            [100, 50, "right", 100],
+            [50, 0, "bottom", 100]
         ]
 
+
 class FixedRoofTank(NodeItem):
     def __init__(self):
         super(FixedRoofTank, self).__init__("svg/Storage Vessels Tanks/Fixed Roof Tank")
         self.grips = [
-            [50,100,"top"],
-            [0,50,"left",100],
-            [100,50,"right",100],
-            [50,0,"bottom",100]
+            [50, 100, "top"],
+            [0, 50, "left", 100],
+            [100, 50, "right", 100],
+            [50, 0, "bottom", 100]
         ]
 
 
@@ -837,19 +850,18 @@ class FloatingRoofTank(NodeItem):
     def __init__(self):
         super(FloatingRoofTank, self).__init__("svg/Storage Vessels Tanks/Floating Roof Tank")
         self.grips = [
-            [0,50,"left",100],
-            [100,50,"right",100],
-            [50,0,"bottom",100]
+            [0, 50, "left", 100],
+            [100, 50, "right", 100],
+            [50, 0, "bottom", 100]
         ]
 
+
 class SeparatorsForLiquidsDecanter(NodeItem):
     def __init__(self):
         super(SeparatorsForLiquidsDecanter, self).__init__("svg/Separators/Separators for Liquids, Decanter")
         self.grips = [
-            [50,100,"top",100],
-            [0,50,"left",100],
-            [100,50,"right",100],
-            [50,0,"bottom",100]
+            [50, 100, "top", 100],
+            [0, 50, "left", 100],
+            [100, 50, "right", 100],
+            [50, 0, "bottom", 100]
         ]
-
-