QGIS » QGIS Application

Here is the code of my custom QgsMapCanvasItem:

class QgsPositionMarker(QgsMapCanvasItem):
Graphic = QPolygon([QPoint(-20, 0), QPoint(20, 15), QPoint(10, 0), QPoint(20, -15)])

def init(self, canvas):
        QgsMapCanvasItem.__init__(self, canvas)
        self.x, self.y, self.r = 0, 0, 0

def update_position(self, x, y, r):
        self.x, self.y, self.r = x, y, r

def paint(self, painter, option, widget):
        painter.setPen(QPen(QColor(0, 0, 0), 2))
        painter.setBrush(QColor(255, 0, 0))
        painter.setRenderHint(QPainter.Antialiasing)

point = self.toCanvasCoordinates(QgsPoint(self.x, self.y))

painter.translate(point.x(), point.y())
        painter.rotate(self.r)
        painter.drawPolygon(QgsPositionMarker.Graphic)

I tested, and the transformed points from toCanvasCoordinates method are calculated correctly (ie. i center the position marker in the middle of map canvas, and i get the same resulting point, regardless whether the map is rotated or not) When i update map canvas like this:

self.map.setRotation(r)
        self.marker.update_position(x, y, r)

self.map.setExtent(myextents)
        self.map.refresh()

Position of the marker is correct only if map rotation is zero, otherwise not, even though the point returned from toCanvasCoordinates is always correct.Error persists if i reverse the order of setRotation and marker.update_position calls.