org.osmdroid.samplefragments.data

Class HeatMap

java.lang.Object

org.osmdroid.samplefragments.BaseSampleFragment

org.osmdroid.samplefragments.data.HeatMap

All Implemented Interfaces:

Runnable, org.osmdroid.events.MapListener

public class HeatMap
extends BaseSampleFragment
implements org.osmdroid.events.MapListener, Runnable

EXPERIMENTAL!! https://github.com/osmdroid/osmdroid/issues/499

Demonstrates a way to generate heatmaps using osmdroid and a collection of data points. There's a lot of room for improvement but this class demonstrates two things

• How to load data asynchronously when the map moves/zooms
• How to generate a basic heat map

There's probably a many options to implement this. This example basically chops up the screen into cells, generates some random data, then iterates all of the data and increments up a counter based on the cell that it was rendered into. Finally the cells are converted into square polygons with a fill color based on the counter.

It's assumed that all required data is available on device for this example.

For future readers: other approaches

• if a server/network connection is available, it would be better to have the server generate a kml/kmz for the heat map, then use osmbonuspack to do the parsing. this will be much better at handling higher volumes of data
• use a server that generates slippy map tiles representing the overlay, then add a secondary TilesOverlay with that source.
• locally (on device) generate an image for the slippy map tiles representing the data, then add a secondary TilesOverlay with that source.
• make a custom Overlay class that has some custom onDraw logical to paint the image.

All of these other (and better) approaches really need some kind of geospatial index mechanism, such as this, only modified with some kind of running estimate algorithm.

created on 1/1/2017.

Since:

5.6.3

Field Summary

Fields

Modifier and Type	Field and Description
(package private) String	alpha
(package private) int	cellSizeInDp the size of the cell in density independent pixels a higher value = smoother image but higher processing and rendering times
(package private) DisplayMetrics	dm
(package private) org.osmdroid.views.overlay.FolderOverlay	heatmapOverlay
(package private) long	lastMovement
(package private) boolean	needsDataRefresh
(package private) String	orange
(package private) String	red
(package private) boolean	renderJobActive
(package private) boolean	running
(package private) String	TAG
(package private) String	yellow

Fields inherited from class org.osmdroid.samplefragments.BaseSampleFragment

mMapView

Constructor Summary

Constructors

Constructor and Description
HeatMap()

Method Summary

Modifier and Type	Method and Description
void	addOverlays() An appropriate place to override and add overlays.
String	getSampleTitle()
void	onPause()
void	onResume()
boolean	onScroll(org.osmdroid.events.ScrollEvent event) handles the map movement rendering portions, prevents more than one render at a time, waits for the user to stop moving the map before triggering the render
boolean	onZoom(org.osmdroid.events.ZoomEvent event) handles the map movement rendering portions, prevents more than one render at a time, waits for the user to stop moving the map before triggering the render
void	run() handles the map movement rendering portions, prevents more than one render at a time, waits for the user to stop moving the map before triggering the render
void	runTestProcedures() optional place to put automated test procedures, used during the connectCheck tests this is called OFF of the UI thread.

Methods inherited from class org.osmdroid.samplefragments.BaseSampleFragment

getmMapView, onActivityCreated, onCreate, onCreateOptionsMenu, onCreateView, onDestroy, onDestroyView, onOptionsItemSelected, onPrepareOptionsMenu, skipOnCiTests

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TAG

String TAG

dm

DisplayMetrics dm

renderJobActive

boolean renderJobActive

running

boolean running

lastMovement

long lastMovement

needsDataRefresh

boolean needsDataRefresh

cellSizeInDp

int cellSizeInDp

the size of the cell in density independent pixels a higher value = smoother image but higher processing and rendering times

alpha

String alpha

red

String red

orange

String orange

yellow

String yellow

heatmapOverlay

org.osmdroid.views.overlay.FolderOverlay heatmapOverlay

Constructor Detail

HeatMap

public HeatMap()

Method Detail

getSampleTitle

public String getSampleTitle()

Specified by:

getSampleTitle in class BaseSampleFragment

addOverlays

public void addOverlays()

Description copied from class: BaseSampleFragment

An appropriate place to override and add overlays.

Overrides:

addOverlays in class BaseSampleFragment

onPause

public void onPause()

onResume

public void onResume()

onScroll

public boolean onScroll(org.osmdroid.events.ScrollEvent event)

handles the map movement rendering portions, prevents more than one render at a time, waits for the user to stop moving the map before triggering the render

Specified by:

onScroll in interface org.osmdroid.events.MapListener

onZoom

public boolean onZoom(org.osmdroid.events.ZoomEvent event)

handles the map movement rendering portions, prevents more than one render at a time, waits for the user to stop moving the map before triggering the render

Specified by:

onZoom in interface org.osmdroid.events.MapListener

run

public void run()

handles the map movement rendering portions, prevents more than one render at a time, waits for the user to stop moving the map before triggering the render

Specified by:

run in interface Runnable

runTestProcedures

public void runTestProcedures()
                       throws Exception

optional place to put automated test procedures, used during the connectCheck tests this is called OFF of the UI thread. block this method call util the test is done

Overrides:

runTestProcedures in class BaseSampleFragment

Throws:

Exception