Python MapScript Appendix¶
- Author:
Sean Gillies
- Author:
Seth Girvin
- Contact:
sethg at geographika.co.uk
- Last Updated:
2021-05-24
Introduction¶
The Python MapScript module contains some class extension methods that have not yet been implemented for other languages.
Classes¶
References to sections below will be added here as the documentation grows.
imageObj¶
Pillow (a fork of the Python Imaging Library), https://pillow.readthedocs.io/, is an
indispensable tool for image manipulation. The extensions to imageObj
are
all geared towards better integration of Pillow in MapScript applications.
imageObj Extended Methods¶
imageObj.write()
- write image data to a Python file-like object. Default is stdout.
url = urllib.urlopen('https://mapserver.org/_static/banner.png')
ms_image = imageObj(url, 'AGG/JPEG')
See MapScript Image Generation for further examples.
pointObj¶
pointObj Methods¶
- __str__()string
Return a string formatted like
{ 'x': %f , 'y': %f, 'z': %f }
with the coordinate values substituted appropriately. Usage example:
>>> p = mapscript.pointObj(1, 1, 1) >>> str(p) { 'x': 1 , 'y': 1, 'z': 1 }
Note that the return value can be conveniently eval’d into a Python dictionary:
>>> p_dict = eval(str(p)) >>> p_dict['x'] 1
rectObj¶
rectObj Methods¶
- __contains__( pointObj point )boolean
Returns True if point is inside the rectangle, otherwise returns False.
>>> r = mapscript.rectObj(0, 0, 1, 1) >>> p = mapscript.pointObj(2, 0) # outside >>> p in r False >>> p not in r True
- __str__()string
Return a string formatted like
{ 'minx': %f , 'miny': %f , 'maxx': %f , 'maxy': %f }
with the bounding values substituted appropriately. Usage example:
>>> r = mapscript.rectObj(0, 0, 1, 1) >>> str(r) { 'minx': 0 , 'miny': 0 , 'maxx': 1 , 'maxy': 1 }
Note that the return value can be conveniently eval’d into a Python dictionary:
>>> r_dict = eval(str(r)) >>> r_dict['minx'] 0
Exception Handling¶
The Python MapScript module maps a few MapServer errors into Python exceptions. Attempting to load a non-existent Mapfile raises an “IOError”, for example
>>> import mapscript
>>> mapfile = '/no/such/file.map'
>>> m = mapscript.mapObj(mapfile)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.3/site-packages/mapscript.py", line 799, in __init__
newobj = _mapscript.new_mapObj(*args)
IOError: msLoadMap(): Unable to access file. (/no/such/file.map)
>>>
The message of the error is written by “msSetError” and so is the same message that CGI mapserv users see in error logs.