Update line with last point and current coordinates.

def mouseMoveEvent(self, ev):
        """Update line with last point and current coordinates."""
        pos = self.transformPos(ev.pos())

        # Update coordinates in status bar if image is opened
        window = self.parent().window()
        if window.filePath is not None:
            self.parent().window().labelCoordinates.setText(
                'X: %d; Y: %d' % (pos.x(), pos.y()))

        # Polygon drawing.
        if self.drawing():
            self.overrideCursor(CURSOR_DRAW)
            if self.current:
                color = self.drawingLineColor
                if self.outOfPixmap(pos):
                    # Don't allow the user to draw outside the pixmap.
                    # Project the point to the pixmap's edges.
                    pos = self.intersectionPoint(self.current[-1], pos)
                elif len(self.current) > 1 and self.closeEnough(pos, self.current[0]):
                    # Attract line to starting point and colorise to alert the
                    # user:
                    pos = self.current[0]
                    color = self.current.line_color
                    self.overrideCursor(CURSOR_POINT)
                    self.current.highlightVertex(0, Shape.NEAR_VERTEX)

                if self.drawSquare:
                    initPos = self.current[0]
                    minX = initPos.x()
                    minY = initPos.y()
                    min_size = min(abs(pos.x() - minX), abs(pos.y() - minY))
                    directionX = -1 if pos.x() - minX < 0 else 1
                    directionY = -1 if pos.y() - minY < 0 else 1
                    self.line[1] = QPointF(minX + directionX * min_size, minY + directionY * min_size)
                else:
                    self.line[1] = pos

                self.line.line_color = color
                self.prevPoint = QPointF()
                self.current.highlightClear()
            else:
                self.prevPoint = pos
            self.repaint()
            return

        # Polygon copy moving.
        if Qt.RightButton & ev.buttons():
            if self.selectedShapeCopy and self.prevPoint:
                self.overrideCursor(CURSOR_MOVE)
                self.boundedMoveShape(self.selectedShapeCopy, pos)
                self.repaint()
            elif self.selectedShape:
                self.selectedShapeCopy = self.selectedShape.copy()
                self.repaint()
            return

        # Polygon/Vertex moving.
        if Qt.LeftButton & ev.buttons():
            if self.selectedVertex():
                self.boundedMoveVertex(pos)
                self.shapeMoved.emit()
                self.repaint()
            elif self.selectedShape and self.prevPoint:
                self.overrideCursor(CURSOR_MOVE)
                self.boundedMoveShape(self.selectedShape, pos)
                self.shapeMoved.emit()
                self.repaint()
            return

        # Just hovering over the canvas, 2 posibilities:
        # - Highlight shapes
        # - Highlight vertex
        # Update shape/vertex fill and tooltip value accordingly.
        self.setToolTip("Image")
        for shape in reversed([s for s in self.shapes if self.isVisible(s)]):
            # Look for a nearby vertex to highlight. If that fails,
            # check if we happen to be inside a shape.
            index = shape.nearestVertex(pos, self.epsilon)
            if index is not None:
                if self.selectedVertex():
                    self.hShape.highlightClear()
                self.hVertex, self.hShape = index, shape
                shape.highlightVertex(index, shape.MOVE_VERTEX)
                self.overrideCursor(CURSOR_POINT)
                self.setToolTip("Click & drag to move point")
                self.setStatusTip(self.toolTip())
                self.update()
                break
            elif shape.containsPoint(pos):
                if self.selectedVertex():
                    self.hShape.highlightClear()
                self.hVertex, self.hShape = None, shape
                self.setToolTip(
                    "Click & drag to move shape '%s'" % shape.label)
                self.setStatusTip(self.toolTip())
                self.overrideCursor(CURSOR_GRAB)
                self.update()
                break
        else:  # Nothing found, clear highlights, reset state.
            if self.hShape:
                self.hShape.highlightClear()
                self.update()
            self.hVertex, self.hShape = None, None
            self.overrideCursor(CURSOR_DEFAULT)