Mapping Hacks

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Chapter 5, Mapping with Gadgets

#63 Build Your Own Car Navigation System with GpsDrive

HACK

self.map.zoom_in( )

self.draw_map( )

def draw_map(self):

"""Remove all drawing objects from the Tk canvas, and re-draw them

with new coordinates"""

# delete old drawing items

self.canvas.delete("all")

# show the current viewing position and zoom

self.canvas.create_text(10,10,text="Location Lat=%f Lon=%f Zoom=%f"

% (self.map.lat, self.map.lon, self.map.zoom), anchor="nw")

self.wpt.draw(self.map, self.canvas)

self.track.draw(self.map, self.canvas)

# place a crosshair in the middle of the screen

self.canvas.create_line(self.width/2-5, self.height/2, self.width

/2+5, self.height/2)

self.canvas.create_line(self.width/2, self.height/2-5, self.width/2,

self.height/2+5)

self.canvas.pack( )

from Tkinter import *

root = Tk( )

app = App(root)

root.mainloop( )

Since this application only displays data stored in a file, it does not take

advantage of a mobile computer with a live GPS feed. In order to display live

updates, the previous code would need an additional thread to populate

new data into the GUI. If you are interested in adding this functionality, see

http://www.mappinghacks.com/projects/carcomputer and the next hack,

“Build Your Own Car Navigation System with GpsDrive”

[Hack #63].

—Thomas Hargrove

HACK

#63

Build Your Own Car Navigation System with

GpsDrive Hack #63

Watch your position on a map move as you move. ...