Google Maps APIBrief introduction

Maksim Golivkin

www.androidaalto.orgwww.mobileguild.eu

Twitter: MaksimGolivkin

13.11.2010 Android Aalto Community

Plan

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Intro to Google Maps API MapView & MapActivityOverlaysDistancesBalloons

GeocodingUI update with handlers

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

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.

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

MapActivity onCreate

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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.

Overlays: hierarchy

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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

Overlays: ItemizedOverlay #2

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Overlays: ItemizedOverlay usage

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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.

Overlays: MyLocationOverlay usage

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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; ormicrodegrees = degress * 1E6;

degrees = microdegrees / (double)1E6;

Distance calculation

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Balloons : usage

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Balloons

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Nice small existing library. Available at:https://github.com/jgilfelt/android-mapviewballoons

Geocoding

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Geocoding - translating coordinates to address.Reverse geocoding - translating address from coordinates.

GeoCoder class.

Do geocoding in background thread!

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.

Thank you!

13.11.2010 Android Aalto Community

Example code can be found at:http://mobileguild.eu/code/FindHackatron.zip