Как правильно определять координаты по указателю мыши

// x, y - в пикселях из QDMapView::SignalMouseMove(int x, int y, int modkeys)
void QGISWidget::updateCurrentCoordinates(int x, int y)
{
    HMAP mapHandle = map->GetMapHandle();
    int mapX, mapY;
    map->GetMapLeftTop(&mapX, &mapY);
    mapX += x;
    mapY += y;

    ppPicturePlane->SetPlaceIn(PP_PICTURE);
    ppPicturePlane->SetPlaceOut(PP_PLANE);
    ppPicturePlane->SetPoint(x, y);
    ppPicturePlane->GetPoint(&pointInPlane.X, &pointInPlane.Y);

    double height = mapGetPrecisionHeightTriangle(mapHandle, pointInPlane.x, pointInPlane.y);
    HANDLE egmMatrixHandle = 0;
    if (height > ERRORHEIGHT)
        egmMatrixHandle = mapOpenEgmPro(0, 0);

    mapSetCurrentPointFormat(mapHandle, CoordinatesType);

    WCHAR coordinatesStringWide[128];   coordinatesStringWide[0] = 0;
    mapPlaneToPointFormatStringPro(mapHandle, &pointInPlane.x, &pointInPlane.y, &height, egmMatrixHandle,
                                   coordinatesStringWide, sizeof(coordinatesStringWide));

    QString coordinatesQString = WcharToQString(coordinatesStringWide);
    ui->text2->setText(coordinatesQString);
}