def updateMatrix(self):
        matrix = QtGui.QMatrix()
        power = float(self.currentScale - self.scaleMax/2 - self.scaleOffset
                      )/self.scaleRatio
        scale = pow(2.0, power)
        matrix.scale(scale, scale)
        self.setMatrix(matrix)
Increment the key by the given amount.
dataset/ETHPy150Open VisTrails/VisTrails/vistrails/gui/graphics_view.py/QInteractiveGraphicsView.updateMatrix--crossover with--dataset/ETHPy150Open coleifer/walrus/walrus/containers.py/Hash.incr_float