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Fri Sep 19 04:45:07 2014

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Using Python and MapInfo with Callbacks

The other day I posted an entry about using MapInfo with Python and Qt (see http://woostuff.wordpress.com/2011/03/05/mapinfo-map-control-into-qt-python-form/), one big thing that I missed was support for callbacks, which if you want to do anything related to integrated mapping is a must for map tool support.

Turns out it is pretty easy, and today I worked out how.

You will need to create a class in python that looks something like this:

class Callback():
    _public_methods_ = ['SetStatusText']
    _reg_progid_ = "MapInfo.PythonCallback"
    _reg_clsid_ = "{14EF8D30-8B00-4B14-8891-36B8EF6D51FD}"
    def SetStatusText(self,status):
        print status

This will be our callback object that we will need to create for MapInfo.

First I will explain what some of the funny stuff is:

  • _public_methods_ is a Python array of all the methods that you would like to expose to COM eg MapInfo in this case. This attribute is a must for creating a COM object.
  • _reg_progid_ is the name of your COM application or object.  This can be anything you would like.
  • _reg_clsid_ is the GUID, or unique id, for the object or app.  Do not use the one I have, call the following in a Python shell to create your own.
             import pythoncom
             pythoncom.CreateGuid()
             
  • SetStatusText is the MapInfo callback method that is called when the status bar changes in MapInfo.

In order to use the class as a COM object we have two more steps to complete, one is registering the COM object and the other is creating it.

First, in oder to register the object we call the following code from our main Python method:

if __name__ == "__main__":
    print "Registering COM server..."
    import win32com.server.register
    win32com.server.register.UseCommandLine(Callback)
    main()

This will register the COM object which will mean it can then be creating for use by MapInfo.

In order to create our callback in Python we call:

callback = win32com.client.Dispatch("MapInfo.PythonCallback")

and set it as our callback object for MapInfo:

mapinfo.SetCallback(callback)

So after all that the final code looks like this:

def main():
    from PyQt4.QtCore import *
    from PyQt4.QtGui import *
    from win32com.client import Dispatch
    import sys

    app = QApplication(sys.argv)
    app.setAttribute(Qt.AA_NativeWindows,True)
    wnd = QMainWindow()
    wnd.resize(400, 400)
    widget = QWidget()
    wnd.setCentralWidget(widget)
    wnd.show()

    handle = int(widget.winId())
    mapinfo = Dispatch("MapInfo.Application")
    callback = win32com.client.Dispatch("MapInfo.PythonCallback")
    mapinfo.SetCallback(callback)
    mapinfo.do('Set Next Document Parent %s Style 1' % handle)
    mapinfo.do('Open Table "D:\GIS\MAPS\Property.TAB"')
    mapinfo.do('Map from Property')

    app.exec_()

class Callback():
    """ Callback class for MapInfo """
    _public_methods_ = ['SetStatusText']
    _reg_progid_ = "MapInfo.PythonCallback"
    _reg_clsid_ = "{14EF8D30-8B00-4B14-8891-36B8EF6D51FD}"
    def SetStatusText(self,status):
        print status

if __name__ == "__main__":
    print "Registering COM server..."
    import win32com.server.register
    win32com.server.register.UseCommandLine(Callback)
    main()

and the result is a map window and information printed to the console.

Information from MapInfo callback

I think Python could be a good language to prototype MapInfo based app, or even build a whole app itself. If you do end up making something of it let me know I am quite interested with what people could come up with.


Filed under: MapInfo, Mapinfo Programming, Open Source Tagged: gis, Mapbasic, mapinfo, mapinfo interop, mapinfo ole, MapInfo Professional, mapping, Open Source, python

MapInfo map control into Qt Python form

Tonight for a bit of fun, or shits and jiggles as we say here, I thought I would try and embed a MapInfo map control into a Qt python widget (although I should be studying, but it’s Saturday night) .

Turns out it is pretty easy!

pls send me teh codez? OK here you go.

from PyQt4.QtCore import *
from PyQt4.QtGui import *
from win32com.client import Dispatch
import sys

app = QApplication(sys.argv)
app.setAttribute(Qt.AA_NativeWindows,True)
wnd = QMainWindow()
wnd.resize(400, 400)
widget = QWidget()
wnd.setCentralWidget(widget)
wnd.show()

handle = int(widget.winId())
mapinfo = Dispatch("MapInfo.Application")
mapinfo.do('Set Next Document Parent %s Style 1' % handle)
mapinfo.do('Open Table "D:\GIS\MAPS\Property.TAB"')
mapinfo.do('Map from Property')

app.exec_()

The above code will load MapInfo and open the property layer into the Qt Widget control, with the result below.

MapInfo map in python Qt based form

So this means you don’t “always” have to write your MapInfo based apps in C# or C++; of course I already knew this as anything that can use OLE and provide a native window handle to MapInfo will work, I just never tried it.


Filed under: MapInfo, Mapinfo Programming, Open Source Tagged: gis, mapinfo, mapinfo interop, mapinfo ole, MapInfo Professional, mapping, Open Source, python

MapInfo .Net Wrapper – The End…

Well it was a good project while it lasted, but I’m sorry to say that I will not be continuing work on it. For now anyway. Very sorry to those who were waiting for me to release v2.

Over the last couple of months, the amount of time I have spent on the project has decreased dramatically due to full-time work, part-time uni, other projects and family life.

My reasons for ending the project are: (1) I don’t have to the time to spend on it. My current work has me doing less development and more surveying and map work. (2) full-time work and part-time uni leaves very little time for anything else. (3) Having recently rediscovered QGIS, I feel my programming efforts are better spent on that project and helping develop and promote it more especially in Australia .  (4) Being a lone developer is hard, especially on a large library type project.  I was not able to keep the code coming, examples clean and up to date, and docs written.

I will however be continuing my other MapInfo based applications which can be found on: http://code.google.com/p/nathansmapinfoprojects/ I have no intentions of ending those.  I know a lot [few] of people use them so I am quite happy to continue support and features.

So, again, very sorry that it has ended but everything must come to an end at some stage.   The code is up on http://code.google.com/p/mapinfodotnetwrapper/ if anyone else would like to continue with it I am quite happy to give you full write access to the repository.


Filed under: Mapinfo Programming

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