gui_timebartriangle.py

from PyQt4 import QtCore, QtGui

class TimeBarTriangle(QtGui.QGraphicsPolygonItem):
    SIZE = 20

    def __init__(self, top, parent = None):
        super(TimeBarTriangle, self).__init__(parent)
        self.top = top
        self.height = 0
        self.setCursor(QtCore.Qt.SizeHorCursor)

        # Setup pens.
        self.normalPen = QtGui.QPen()
        self.normalPen.setWidth(3)
        self.selectedPen = QtGui.QPen()
        self.selectedPen.setWidth(5)
        self.setPen(self.normalPen)

    def setHeight(self, height):
        if self.height == height:
            return
        self.height = height

        # Create polygon.
        poly = QtGui.QPolygonF()
        if self.top:
            poly.append(QtCore.QPointF(-self.SIZE / 2, 0))
            poly.append(QtCore.QPointF(self.SIZE / 2, 0))
            poly.append(QtCore.QPointF(0, self.SIZE))
        else:
            poly.append(QtCore.QPointF(-self.SIZE / 2, height))
            poly.append(QtCore.QPointF(self.SIZE / 2, height))
            poly.append(QtCore.QPointF(0, height - self.SIZE))
        self.setPolygon(poly)

    def setSelectedPen(self, selected):
        if selected:
            self.setPen(self.selectedPen)
        else:
            self.setPen(self.normalPen)

    def setColor(self, color):
        # Color normal pen
        np = self.normalPen
        np.setColor(color)
        self.normalPen = np
        # Color selection pen
        sp = self.selectedPen
        sp.setColor(color)
        self.selectedPen = sp
        # Color current pen
        p = self.pen()
        p.setColor(color)
        self.setPen(p)

    def itemChange(self, change, value):
        """
        This virtual function is called by QGraphicsItem to notify custom 
        items that some part of the item's state changes.
        """
        # Set proper cursor for enabled and disabled item.
        if change == self.ItemEnabledChange:
            if self.isEnabled(): # means it will became disabled now
                self.setCursor(QtCore.Qt.ArrowCursor)
            else: # means it will became enabled now
                self.setCursor(QtCore.Qt.SizeHorCursor)

        return super(TimeBarTriangle, self).itemChange(change, value)