MicroStation^® Python: Grouped Hole Classes

class AreaData ():
    '''
    Area Data holds data harvested from shape and complex shape elements.

    '''
    def __init__(self, eh: ElementHandle):
        self._id = eh.GetElementId()
        #  Make the area positive, irrespective of the measured value
        self._area = abs(get_shape_area(eh))
        self._perim = get_shape_perimeter(eh)
        self._outer = IsSolid(eh)
        self._level_id = get_element_level(eh)

    @property
    def id(self)->int:
        return self._id

    @property
    def level_id(self)->int:
        return self._level_id

    @property
    def area(self)->float:
        return self._area

    @property
    def perimeter(self)->float:
        return self._perim

    @property
    def outer(self)->bool:
        return self._outer

    def __str__(self):
        if self.outer:
            return f"Solid [{self._id}] Perimeter {format_distance_value(self._perim)} Area {format_area_value(self._area)} level {self._level_id}"
        else:
            return f"Hole [{self._id}] Perimeter {format_distance_value(self._perim)} Area {format_area_value(self._area)} level {self._level_id}"

Helper Functions

Functions get_shape_area and get_shape_perimeter use the CurveVector API to mensurate the DGN elements …

get_shape_area function

def get_shape_area(eh: ElementHandle)->float:
    """
    Compute area of a planar closed CurveVector using CentroidAreaXY.
    Returns area (float) or None on failure.
    """
    curve_vector = get_shape_curvevector(eh)
    if curve_vector is None:
        return 0.0

    area = 0.0
    try:
        success, centroid, area = curve_vector.CentroidAreaXY()
    except Exception as e:
        print(f"Element [{eh.GetElementId()}] error computing area with CentroidAreaXY: {e}", file=sys.stderr)
        return 0.0

    if not success or area is None:
        print(f"Element [{eh.GetElementId()}] CentroidAreaXY failed to compute area.", file=sys.stderr)
        return 0.0

    return area

get_shape_perimeter function

def get_shape_perimeter(eh: ElementHandle)->float:
    """
    Compute perimeter (length) of a CurveVector.
    """
    perimeter = 0.0
    curve_vector = get_shape_curvevector(eh)
    if curve_vector is None:
        return 0.0
    try:
        perimeter = curve_vector.Length()
    except Exception as e:
        print(f"Element [{eh.GetElementId()}] error computing perimeter: {e}", file=sys.stderr)
        return 0.0
    return perimeter

get_shape_curvevector function

The function that converts an ElementHandle to a CurveVector is quite lengthy because it performs several tests to ensure that the result is valid …

def get_shape_curvevector(eh: ElementHandle)->CurveVector:
    """
    Returns CurveVector if it is a closed, planar region-like shape. Otherwise returns None.
    """
    curve_vector = get_curvevector(eh)
    if curve_vector is None:
        return None

    # Must be closed
    try:
        if not curve_vector.IsClosedPath():
            print(f"Element [{eh.GetElementId()}] is not a closed path", file=sys.stderr)
            return None
    except Exception as e:
        print(f"Element [{eh.GetElementId()}] error checking IsClosedPath: {e}", file=sys.stderr)
        return None

    # Must be planar
    try:
        localToWorld = Transform()
        worldToLocal = Transform()
        drange = DRange3d()
        is_planar = curve_vector.IsPlanar(localToWorld, worldToLocal, drange)
        if not is_planar:
            print(f"Element [{eh.GetElementId()}] is not planar", file=sys.stderr)
            return None
    except Exception as e:
        print(f"Element [{eh.GetElementId()}] error checking planarity: {e}", file=sys.stderr)
        return None

    return curve_vector

Formatting Measurements

Python, like the C++ MicroStationAPi and C# MicroStationNET, measure using MicroStation units-of-resolution (UORs). UORs are not human-friendly because they tend to be large numbers, several orders of magnitude bigger than measurements you might expect in feet, metres, square feet or metres². The Python API supplies formatters that convert UORs into human-friendly numbers

You can read more about the formatters.

The grouped holes example provides distance_formatter and area_formatter classes. They handle the shape perimeter and area values into something more reasonable than UORs.

Acknowledgements

Thanks go to MicroStation Programming Forum regulars …

• Jan Šlegr
• YongAn Fu
• Leonard Jones

They each provided help or suggestions that made my Python life easier.

Download Grouped Hole Example

Visit the Grouped Holes Download page.

Use MicroStation's Python Manager to find and execute the script.

Questions

Post questions about MicroStation programming to the MicroStation Programming Forum.