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# -*- coding: utf-8 -*-
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# Copyright (c) 2004 - 2007 Detlev Offenbach <detlev@die-offenbachs.de>
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Module implementing a graphics item for an association between two items.
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from PyQt4.QtCore import *
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from PyQt4.QtGui import *
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from E4Graphics.E4ArrowItem import E4ArrowItem, NormalArrow, WideArrow
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class AssociationItem(E4ArrowItem):
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Class implementing a graphics item for an association between two items.
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The association is drawn as an arrow starting at the first items and
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def __init__(self, itemA, itemB, type = Normal, parent = None, scene = None):
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@param itemA first widget of the association
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@param itemB second widget of the association
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@param type type of the association. This must be one of
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<li>Normal (default)</li>
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<li>Generalisation</li>
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@keyparam parent reference to the parent object (QGraphicsItem)
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@keyparam scene reference to the scene object (QGraphicsScene)
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arrowType = NormalArrow
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arrowType = NormalArrow
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elif type == Generalisation:
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E4ArrowItem.__init__(self, QPointF(0, 0), QPointF(100, 100),
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arrowFilled, arrowType, parent, scene)
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self.setFlag(QGraphicsItem.ItemIsMovable, False)
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self.setFlag(QGraphicsItem.ItemIsSelectable, False)
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## self.calculateEndingPoints = self.__calculateEndingPoints_center
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self.calculateEndingPoints = self.__calculateEndingPoints_rectangle
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self.regionA = NoRegion
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self.regionB = NoRegion
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self.calculateEndingPoints()
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self.itemA.addAssociation(self)
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self.itemB.addAssociation(self)
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def __mapRectFromItem(self, item):
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Private method to map item's rectangle to this item's coordinate system.
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@param item reference to the item to be mapped (QGraphicsRectItem)
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@return item's rectangle in local coordinates (QRectF)
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tl = self.mapFromItem(item, rect.topLeft())
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return QRectF(tl.x(), tl.y(), rect.width(), rect.height())
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def __calculateEndingPoints_center(self):
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Private method to calculate the ending points of the association item.
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The ending points are calculated from the centers of the
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if self.itemA is None or self.itemB is None:
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self.prepareGeometryChange()
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rectA = self.__mapRectFromItem(self.itemA)
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rectB = self.__mapRectFromItem(self.itemB)
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midA = QPointF(rectA.x() + rectA.width() / 2.0,
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rectA.y() + rectA.height() / 2.0)
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midB = QPointF(rectB.x() + rectB.width() / 2.0,
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rectB.y() + rectB.height() / 2.0)
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startP = self.__findRectIntersectionPoint(self.itemA, midA, midB)
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endP = self.__findRectIntersectionPoint(self.itemB, midB, midA)
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if startP.x() != -1 and startP.y() != -1 and \
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endP.x() != -1 and endP.y() != -1:
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self.setPoints(startP.x(), startP.y(), endP.x(), endP.y())
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def __calculateEndingPoints_rectangle(self):
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Private method to calculate the ending points of the association item.
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The ending points are calculated by the following method.
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For each item the diagram is divided in four Regions by its diagonals
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Region 1 | /\ | Region 3
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Each diagonal is defined by two corners of the bounding rectangle
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To calculate the start point we have to find out in which
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region (defined by itemA's diagonals) is itemB's TopLeft corner
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(lets call it region M). After that the start point will be
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the middle point of rectangle's side contained in region M.
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To calculate the end point we repeat the above but in the opposite direction
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(from itemB to itemA)
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if self.itemA is None or self.itemB is None:
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self.prepareGeometryChange()
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rectA = self.__mapRectFromItem(self.itemA)
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rectB = self.__mapRectFromItem(self.itemB)
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xA = rectA.x() + rectA.width() / 2.0
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yA = rectA.y() + rectA.height() / 2.0
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xB = rectB.x() + rectB.width() / 2.0
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yB = rectB.y() + rectB.height() / 2.0
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rc = QRectF(xA, yA, rectA.width(), rectA.height())
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oldRegionA = self.regionA
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self.regionA = self.__findPointRegion(rc, xB, yB)
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# move some regions to the standard ones
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if self.regionA == NorthWest:
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elif self.regionA == NorthEast:
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elif self.regionA == SouthEast:
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elif self.regionA == SouthWest:
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elif self.regionA == Center:
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self.__updateEndPoint(self.regionA, True)
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# now do the same for itemB
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rc = QRectF(xB, yB, rectB.width(), rectB.height())
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oldRegionB = self.regionB
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self.regionB = self.__findPointRegion(rc, xA, yA)
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# move some regions to the standard ones
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if self.regionB == NorthWest:
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elif self.regionB == NorthEast:
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elif self.regionB == SouthEast:
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elif self.regionB == SouthWest:
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elif self.regionB == Center:
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self.__updateEndPoint(self.regionB, False)
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def __findPointRegion(self, rect, posX, posY):
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Private method to find out, which region of rectangle rect contains the point
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(PosX, PosY) and returns the region number.
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@param rect rectangle to calculate the region for (QRectF)
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@param posX x position of point (float)
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@param posY y position of point (float)
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@return the calculated region number<br />
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West = Region 1<br />
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North = Region 2<br />
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East = Region 3<br />
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South = Region 4<br />
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NorthWest = On diagonal 2 between Region 1 and 2<br />
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NorthEast = On diagonal 1 between Region 2 and 3<br />
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SouthEast = On diagonal 2 between Region 3 and 4<br />
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SouthWest = On diagonal 1 between Region4 and 1<br />
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Center = On diagonal 1 and On diagonal 2 (the center)<br />
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b1 = x + w / 2.0 - y * slope1
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b2 = x + w / 2.0 - y * slope2
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eval1 = slope1 * posY + b1
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eval2 = slope2 * posY + b2
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if eval1 > posX and eval2 > posX:
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elif eval1 > posX and eval2 < posX:
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elif eval1 < posX and eval2 < posX:
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elif eval1 < posX and eval2 > posX:
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elif eval1 == posX and eval2 < posX:
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elif eval1 < posX and eval2 == posX:
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elif eval1 == posX and eval2 > posX:
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elif eval1 > posX and eval2 == posX:
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elif eval1 == posX and eval2 == posX:
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def __updateEndPoint(self, region, isWidgetA):
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Private method to update an endpoint.
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@param region the region for the endpoint (integer)
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@param isWidgetA flag indicating update for itemA is done (boolean)
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if region == NoRegion:
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rect = self.__mapRectFromItem(self.itemA)
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rect = self.__mapRectFromItem(self.itemB)
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elif region == North:
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elif region == South:
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elif region == Center:
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self.setStartPoint(px, py)
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self.setEndPoint(px, py)
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def __findRectIntersectionPoint(self, item, p1, p2):
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Private method to find the intersetion point of a line with a rectangle.
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@param item item to check against
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@param p1 first point of the line (QPointF)
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@param p2 second point of the line (QPointF)
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@return the intersection point (QPointF)
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rect = self.__mapRectFromItem(item)
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QLineF(rect.topLeft(), rect.topRight()),
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QLineF(rect.topLeft(), rect.bottomLeft()),
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QLineF(rect.bottomRight(), rect.bottomLeft()),
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QLineF(rect.bottomRight(), rect.topRight())
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intersectLine = QLineF(p1, p2)
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intersectPoint = QPointF(0, 0)
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if intersectLine.intersect(line, intersectPoint) == \
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QLineF.BoundedIntersection:
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return intersectPoint
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return QPointF(-1.0, -1.0)
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def __findIntersection(self, p1, p2, p3, p4):
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Method to calculate the intersection point of two lines.
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The first line is determined by the points p1 and p2, the second
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line by p3 and p4. If the intersection point is not contained in
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the segment p1p2, then it returns (-1.0, -1.0).
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For the function's internal calculations remember:<br />
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QT coordinates start with the point (0,0) as the topleft corner
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and x-values increase from left to right and y-values increase
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from top to bottom; it means the visible area is quadrant I in
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the regular XY coordinate system
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Quadrant II | Quadrant I
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-----------------|-----------------
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Quadrant III | Quadrant IV
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In order for the linear function calculations to work in this method
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we must switch x and y values (x values become y values and viceversa)
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@param p1 first point of first line (QPointF)
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@param p2 second point of first line (QPointF)
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@param p3 first point of second line (QPointF)
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@param p4 second point of second line (QPointF)
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@return the intersection point (QPointF)
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# line 1 is the line between (x1, y1) and (x2, y2)
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# line 2 is the line between (x3, y3) and (x4, y4)
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no_line1 = True # it is false, if line 1 is a linear function
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no_line2 = True # it is false, if line 2 is a linear function
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slope1 = (y2 - y1) / (x2 - x1)
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b1 = y1 - slope1 * x1
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slope2 = (y4 - y3) / (x4 - x3)
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b2 = y3 - slope2 * x3
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# if either line is not a function
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if no_line1 and no_line2:
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# if the lines are not the same one
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return QPointF(-1.0, -1.0)
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# if the lines are the same ones
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if y3 <= y1 and y1 <= y4:
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return QPointF(y1, x1)
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return QPointF(y2, x2)
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if y4 <= y1 and y1 <= y3:
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return QPointF(y1, x1)
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return QPointF(y2, x2)
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pt.setX(slope2 * x1 + b2)
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if not (y2 <= pt.x() and pt.x() <= y1):
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if not (y1 <= pt.x() and pt.x() <= y2):
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pt.setX(slope1 * x3 + b1)
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if not (y4 <= pt.x() and pt.x() <= y3):
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if not (y3 <= pt.x() and pt.x() <= y4):
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pt.setY((b2 - b1) / (slope1 - slope2))
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pt.setX(slope1 * pt.y() + b1)
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# the intersection point must be inside the segment (x1, y1) (x2, y2)
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if x2 >= x1 and y2 >= y1:
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if not ((x1 <= pt.y() and pt.y() <= x2) and (y1 <= pt.x() and pt.x() <= y2)):
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elif x2 < x1 and y2 >= y1:
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if not ((x2 <= pt.y() and pt.y() <= x1) and (y1 <= pt.x() and pt.x() <= y2)):
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elif x2 >= x1 and y2 < y1:
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if not ((x1 <= pt.y() and pt.y() <= x2) and (y2 <= pt.x() and pt.x() <= y1)):
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if not ((x2 <= pt.y() and pt.y() <= x1) and (y2 <= pt.x() and pt.x() <= y1)):
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def widgetMoved(self):
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Public method to recalculate the association after a widget was moved.
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self.calculateEndingPoints()
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def unassociate(self):
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Public method to unassociate from the widgets.
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self.itemA.removeAssociation(self)
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self.itemB.removeAssociation(self)
added
removed
eric/Graphics/AssociationItem.py
