QGIS/python/plugins/sextante/modeler/ModelerArrowItem.py

from PyQt4 import QtCore, QtGui
import math
from sextante.modeler.ModelerGraphicItem import ModelerGraphicItem
from sextante.core.GeoAlgorithm import GeoAlgorithm

#portions of this code have been taken and adapted from PyQt examples, released under the following license terms

#############################################################################
##
## Copyright (C) 2010 Riverbank Computing Limited.
## Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
## All rights reserved.
##
## This file is part of the examples of PyQt.
##
## $QT_BEGIN_LICENSE:BSD$
## You may use this file under the terms of the BSD license as follows:
##
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## modification, are permitted provided that the following conditions are
## met:
##   * Redistributions of source code must retain the above copyright
##     notice, this list of conditions and the following disclaimer.
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##     the documentation and/or other materials provided with the
##     distribution.
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##     the names of its contributors may be used to endorse or promote
##     products derived from this software without specific prior written
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## $QT_END_LICENSE$
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#############################################################################

class ModelerArrowItem(QtGui.QGraphicsPathItem):

    def __init__(self, startItem, outputIndex, endItem, paramIndex ,parent=None, scene=None):
        super(ModelerArrowItem, self).__init__(parent, scene)
        self.arrowHead = QtGui.QPolygonF()
        self.paramIndex = paramIndex
        self.outputIndex = outputIndex
        self.myStartItem = startItem
        self.myEndItem = endItem
        self.setFlag(QtGui.QGraphicsItem.ItemIsSelectable, False)
        self.myColor = QtCore.Qt.gray
        self.setPen(QtGui.QPen(self.myColor, 1, QtCore.Qt.SolidLine,
                QtCore.Qt.RoundCap, QtCore.Qt.RoundJoin))
        self.setZValue(0)


    def startItem(self):
        return self.myStartItem

    def endItem(self):
        return self.myEndItem

    def paint(self, painter, option, widget=None):
        startItem = self.myStartItem
        endItem = self.myEndItem
        myPen = self.pen()
        myPen.setColor(self.myColor)
        painter.setPen(myPen)
        painter.setBrush(self.myColor)

        controlPoints = []
        endPt = self.endItem().getLinkPointForParameter(self.paramIndex)
        startPt = self.startItem().getLinkPointForOutput(self.outputIndex)
        if isinstance(self.startItem().element, GeoAlgorithm):
            if self.startItem().element.outputs:
                controlPoints.append(startItem.pos() + startPt)
                controlPoints.append(startItem.pos() + startPt + QtCore.QPointF(ModelerGraphicItem.BOX_WIDTH /2,0))
                controlPoints.append(endItem.pos() + endPt - QtCore.QPointF(ModelerGraphicItem.BOX_WIDTH /2, 0))
                controlPoints.append(endItem.pos() + endPt)
                pt = QtCore.QPointF(startItem.pos() + startPt + QtCore.QPointF(-3, -3))
                painter.drawEllipse(pt.x(), pt.y(), 6, 6)
                pt = QtCore.QPointF(endItem.pos() + endPt + QtCore.QPointF(-3, -3))
                painter.drawEllipse(pt.x(), pt.y(), 6, 6)
            else: # case where there is a dependency on an algorithm not on an output
                controlPoints.append(startItem.pos() + startPt)
                controlPoints.append(startItem.pos() + startPt + QtCore.QPointF(ModelerGraphicItem.BOX_WIDTH /2,0))
                controlPoints.append(endItem.pos() + endPt - QtCore.QPointF(ModelerGraphicItem.BOX_WIDTH /2, 0))
                controlPoints.append(endItem.pos() + endPt)
        else:
            controlPoints.append(startItem.pos())
            controlPoints.append(startItem.pos() + QtCore.QPointF(ModelerGraphicItem.BOX_WIDTH /2,0))
            controlPoints.append(endItem.pos() + endPt - QtCore.QPointF(ModelerGraphicItem.BOX_WIDTH /2, 0))
            controlPoints.append(endItem.pos() + endPt)
            pt = QtCore.QPointF(endItem.pos() + endPt + QtCore.QPointF(-3, -3))
            painter.drawEllipse(pt.x(), pt.y(), 6, 6)

        path = QtGui.QPainterPath()
        path.moveTo(controlPoints[0])
        path.cubicTo(*controlPoints[1:])
        painter.strokePath(path, painter.pen())
        self.setPath(path)