Presenting use of Maps, distance calculation, geolocation. Code examples.

1. Google Maps API
Brief introduction
Maksim Golivkin
www.androidaalto.org
www.mobileguild.eu
Twitter: MaksimGolivkin
13.11.2010 Android Aalto Community

2. Plan
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Intro to Google Maps API
MapView & MapActivity
Overlays
Distances
Balloons
Geocoding
UI update with handlers

3. Intro to maps API: New Project
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Target build and emulator have to use Google API for
platform you have chosen.
For instance, Google API for 1.6

4. Intro to maps API : AndroidManifest.xml
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Things to remember:
uses-library declaration for runtime;
permissions to access Internet and location services.

5. MapView: Layout
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If inappropriate API key is used, map isn't displayed.
For one Google account one can generate several keys.
How to generate your own:
http://code.google.com/android/add-ons/google-apis/mapkey.html

6. MapActivity onCreate
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7. Overlays
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Each overlay is information layer on the map.
Google Maps has 3 overlay classes (main purpose below):
Overlay - drawing complex figures on the map and
capturing touch moves.
ItemizedOverlay - abstract, extends Overlay, for drawing
of multiple markers.
MyLocationOverlay - to display user location on the map.

8. Overlays: hierarchy
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9. Overlays: ItemizedOverlay #1
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Most important thing:
on every content change call protected populate method;
include populate call in constructor
Reference:
http://code.google.com/p/android/issues/detail?id=2035

10. Overlays: ItemizedOverlay #2
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11. Overlays: ItemizedOverlay usage
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12. Overlays: MyLocationOverlay
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Convenient to display user location on map.
Most important thing: call disableMyLocation and
disableCompass (if enabled), when activity goes to
background.

13. Overlays: MyLocationOverlay usage
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14. Distance
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Note:
Google Maps API uses (int) micro-degrees for
coordinates;
Android Location package uses (double) degrees for
coordinates;
microdegrees = degrees * 1000 000; or
microdegrees = degress * 1E6;
degrees = microdegrees / (double)1E6;

15. Distance calculation
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16. Balloons : usage
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17. Balloons
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Nice small existing library.
Available at:
https://github.com/jgilfelt/android-
mapviewballoons

18. Geocoding
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Geocoding - translating coordinates to address.
Reverse geocoding - translating address from coordinates.
GeoCoder class.
Do geocoding in background thread!

19. UI update with Handler
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Nested anonymous classes are ugly!
Alternative: Handler + Message + Bundle.
Note: when updating UI, be sure to instantiate Handler (or
Handler child class) in UI thread. For example, in onCreate
method.

20. Thank you!
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Example code can be found at:
http://mobileguild.eu/code/FindHackatron.zip