Fuchs Maps

Sometime ago after I finished my tutorials for Android offline map app I spent some time adding more features to the simple app, I guess I should share the code since many of those features are expected from any map application.

The post here won’t contain detailed explanation about how each feature is implemented since each feature might require it’s own post. Anyway if you’ve been reading my previous tutorials everything here should be straightforward and easy to understand, consider the source code provided here as some sort of raw data that someone might benefit from 🙂 .

This code is built upon the offline version of the app, so it doesn’t have web tiles support and the mapView cannot be created in xml (these can be changed easily by following the previous two tutorials).

The code isn’t perfect either, it does the job though 🙂 .

Here’s the features list:

• Points of interest (POI).
• GPS tracking service.
• Compass.
• Location sharing.
• Map selection at runtime.
• Changing tiles size at runtime.
• Importing\Exporting points and tracks.
• Source code.

The post will contain lots of images so please be cautious :).

Points of Interest:

Points of interest
(in green)

These are points that can be created/modified at runtime, just by long touching the map a button with options will appear.

Each point when touched will create a toast showing it’s name.

com.fuchs.poi/ POI:
Each poi has an Id (for database storage), name, gps coordinates, and a visibility flag.

com.fuchs.poi/ POIProvider:
class with static methods used to get\insert\modify points in the database.

com.fuchs.maps.views.overlays/ MapOverlay
A MapOverlay is a layer drawn on the mapView after the mapView has done rendering the tiles.

The class mapView now contains a list of MapOverlay objects, a MapOverlay is a simple class that gets notified when changes occur to the mapView it is connected to.

com.fuchs.maps.views.overlays/ POIOverlay
This class contains a list of POI objects called points (added using POIOverlay.addPoint), now in order to draw each point at the right location we need to convert the gps coordinates of the point to map pixel coordinates which is done by calling tilesManager.lonLatToPixelXY , to avoid calling this function on each draw, we call it once per zoom level and save the result for later use in the list absPoints.
If the zoom level of the mapView changes then we’ll have to recalculate the pixel coordinates.

GPS Tracking Service:

Two different tracks

With this feature you can track and record your location and view it while recording or later after the recording is done.

The recording is done using a service, so if you start it and put the app in the background it will still be running.

Tracks are rendered using an overlay called TracksOverlay.

com.fuchs.tracking/ Track
A Track is simply a list of TrackPoint objects along with an id and a visibility flag.

com.fuchs.tracking/ TrackPoints
Each TrackPoint contains gps coordinates and the time it was recorded at.

com.fuchs.tracking/ TracksProvider:
Contains some static methods to handle creating/modifying tracks in the tracks database.

com.fuchs.maps.views.overlays/ TracksOverlay:
To draw a track we simply convert its TrackPoints to map pixel coordinates and then draw a line between each pair of points, point i and point i+1 where i goes from 0 to number of points -2.

Just for optimization we calculate the pixel coordinates for each point and store it in an instance of TracksOverlay.AbsTrack which can later be used for rendering.

com.fuchs.tracking/ TrackerService:
The service when started creates a LocationListener which updates the static Track object in the TrackerService whenever a new location is available.

Compass:

For the compass I modified the code here a little bit and put it in com.fuchs.util.CompassSensor.java, the class takes a Handler in the constructor, this handler will be sent a message whenever a new value is available.

To draw the compass I added a drawable of a compass to the layout, then I rotated the image of the compass according to the values passed to the Handler.

This Handler can be found in the main activity FMapsActivity and it’s called compassHandler.

Location Sharing:

When you long-touch the map a button will appear and you can choose to share the location of the place you touched, the app will show a list of apps you can share the location with, the format of the shared coordinates as simply latitude,longitude , you can change the format as you like.

The sharing is done in FMapsActivity at btnShareLocationOnClick.

One thing I should mention here is the button that appears on the map, the FMapsActivity implements the IMapViewEventListener interface which contains the method onLongPress, now when you long-press the mapView this will notify the activity and it will show the button called btnOptions and set the coordinates of the pressed point in the tag of btnOptions.

Map selection at runtime:

This can be done by pressing the menu button and selecting Maps.

You must make sure that the folder name of the maps is valid, this folder name can be changed in the settings.
By default the app expects to have a folder named something like this /mnt/sdcard/Fuchs Maps/ that contains the maps. Please make sure the path contains the last slash.

Changing tiles size at runtime:

This can be done in the settings, the tiles size is passed to both MapView and TilesManager.

The smaller the tile size is the more tiles can be fit in the view which in turn will result in more memory usage and of course rendering will take more time.

Click to enlarge
Warning: 585KB 😀
Left: 256 (100%)
Center: 512 (200%)
Right: 128 (50%)

You can use filtering to make the tiles look smoother when you select a tile size larger than the actual size of the tile image, just uncomment the line bitmapPaint.setFilterBitmap(true); in the constructor of MapView, note that enabling filtering will affect performance.

Importing\Exporting points and tracks:

Since the classes Track, TrackPoint, POI are all serializable we can write them into files, the export/import functionality is in both TracksProvider class and POIProvider class.

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Source Code:

FuchsMaps.zip (176KB) – Eclipse project, Android 2.2+

If you want something explained more please use the comments bellow, if you’re new at this please read the previous tutorials or none of the above will make sense.

One final note: try adding features to your existing app and don’t try to add the features of your app here, it’s easier and better to use your own code design instead of trying to understand a full project like this one.