'Return a rectangle in local coordinates containing the cell
at `row` and `column`.'

def cell_rect(self, row, column):

    size = self.__pixmap.size()
    if (not ((0 <= column < size.width()) or (0 <= row < size.height()))):
        return QRectF()
    topleft = QPointF(column, row)
    bottomright = QPointF((column + 1), (row + 1))
    t = self.heatmap_item.pixmapTransform()
    rect = t.mapRect(QRectF(topleft, bottomright))
    rect.translated(self.heatmap_item.pos())
    return rect
