B4A Class Open Street Map viewer - GPS

spsp · Feb 19, 2021

Hi,

This b4Xlib contains a custom view (cvMap) which can display Open Street Map.

View attachment 109081

The tiles are retrieved from the internet and cached in a database. You can add shapes and images on the map.

UI :
- Lat/lng Center of the map
- Zoom Level
- Compass Direction with rotation
- Scale
- Button Menu
- Grid
- Center
- GPS position and bearing

Event :
- ready
- Lat/lng changed
- Zoom Level Changed
- Compass Direction Changed
- Shape Clicked
- Map Clicked
- Center Lat/lng clicked
- Button Menu clicked
- Scale clicked
- Compass Clicked
- GPS Clicked

Tile Server
2 new properties :

tileServer : Choose your tile server (see https://wiki.openstreetmap.org/wiki/Tile_servers), default : https://a.tile.openstreetmap.org/
userAgent : request to the tile server requires a user agent in the header. You can now set your own user Agent : default : Mozilla/5.0 (Windows NT 6.1; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0

This 2 properties are available in the designer or with setter/getter from the cvmap : userAgent, tileServer

Dependencies :
- Core
- SQL
- OKHttpUtils2
- XUI
- XUI views

Other files in the b4xlib :
- coMapUtilities : code module with Types, functions, helpers
- clTileManager : standard class module to load tile from database and/or internet and save them into the database
- clMapShapeCirgle : standard class to draw circle on the map
- clMapShapeLine : standard class to draw line on the map
- clMapShapePolygon : standard class to draw polygon on the map
- clMapShapeImage : standard class to draw image on the map
- layout cvmap.bal and cvmap.bjl
- images for the compass and gps

How to use it :
- Just add the cvMap custom view with the designer
- create sub to handle events if necessary
- set options (lat/lng, zoom.....)

B4A example and B4J example included

spsp

papajds · Dec 12, 2023

Hi,

OK, not knowing B4A, I discover its possibilities every day thank you, I'll try, (it's not won)

MbedAndroid · Dec 29, 2023

cvmap giving crashes. Got one of them during the exercises.
firebase output:
Fatal Exception: java.lang.RuntimeException
Object should first be initialized (B4XView).

anywheresoftware.b4a.AbsObjectWrapper.getObject (AbsObjectWrapper.java:67)

anywheresoftware.b4a.objects.B4XViewWrapper.getTag (B4XViewWrapper.java:600)

com.TrainingApp.cvmap._latlngtopoint (cvmap.java:1013)

com.TrainingApp.cvmap._update_gps (cvmap.java:1778)

com.TrainingApp.cvmap._gps_locationchanged (cvmap.java:970)

com.TrainingApp.main._updatechart (main.java:9304)

java.lang.reflect.Method.invoke (Method.java)

anywheresoftware.b4a.keywords.Common.CallSubNew2 (Common.java:1069)

com.TrainingApp.tracker._gps_locationchanged (tracker.java:205)

java.lang.reflect.Method.invoke (Method.java)

com.android.internal.os.ZygoteInit.main (ZygoteInit.java:947)

trying to solve it in this way:

B4X:

public Sub LatLngToPoint(aLatLng As TMapLatLng) As TMapPoint
    Try
    'https://www.netzwolf.info/osm/tilebrowser.html?marker.x=12&marker.y=189&tx=1&ty=0&tz=1&ts=256#tile
    Dim v As B4XView=PointToTile(0,0)
    If v.IsInitialized=False Then  'from here
        Dim pp As TMapPoint
        pp.Initialize
        pp.fX=0
        pp.fY=0
        Return pp
    End If 'to here
    Dim txy As TMapTileXY=v.tag
    Dim gpx As Double=(txy.fX+(-v.Left/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim gpy As Double=(txy.fy+(-v.top/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim tx As TMapTileNumberOffset=LngToTileX(aLatLng.fLng,fMap.fZoomLevel)
    Dim ty As TMapTileNumberOffset=LatToTileY(aLatLng.fLat,fMap.fZoomLevel)
    Dim ppx As Double=(tx.fTile+(tx.fOffset/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim ppy As Double=(ty.fTile+(ty.fOffset/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim p As TMapPoint=coMapUtilities.initPoint(fTilesCount*coMapUtilities.cTileSize*(ppx-gpx),fTilesCount*coMapUtilities.cTileSize*(ppy-gpy))
    Return p

End Sub

miladfakhrizade · Feb 29, 2024

how to zoom in map with multitouch or pinchzoom?

@spsp

spsp · Mar 1, 2024

miladfakhrizade said:
how to zoom in map with multitouch or pinchzoom?

@spsp

Hi,

Add a gesture library and detect action.

spsp

MbedAndroid · Mar 16, 2024

found another crash
Fatal Exception: java.lang.RuntimeException: Object should first be initialized (B4XView).
at anywheresoftware.b4a.AbsObjectWrapper.getObject(AbsObjectWrapper.java:67)
at anywheresoftware.b4a.objects.B4XViewWrapper.asViewWrapper(B4XViewWrapper.java:91)
at anywheresoftware.b4a.objects.B4XViewWrapper.getTag(B4XViewWrapper.java:600)
at com.TrainingApp.cvmap._latlngtopoint(cvmap.java:1013)
at com.TrainingApp.cvmap._update_gps(cvmap.java:1781)
at com.TrainingApp.cvmap._gps_locationchanged(cvmap.java:970)
at com.TrainingApp.main._updatechart(main.java:9488)
at java.lang.reflect.Method.invoke(Method.java)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:221)
hope this solves the bug in the same way as post #122

B4X:

public Sub LatLngToPoint(aLatLng As TMapLatLng) As TMapPoint
    'https://www.netzwolf.info/osm/tilebrowser.html?marker.x=12&marker.y=189&tx=1&ty=0&tz=1&ts=256#tile
    Dim v As B4XView=PointToTile(0,0)
    If v.IsInitialized Then '<----add
    Dim txy As TMapTileXY=v.tag
    Dim gpx As Double=(txy.fX+(-v.Left/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim gpy As Double=(txy.fy+(-v.top/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim tx As TMapTileNumberOffset=LngToTileX(aLatLng.fLng,fMap.fZoomLevel)
    Dim ty As TMapTileNumberOffset=LatToTileY(aLatLng.fLat,fMap.fZoomLevel)
    Dim ppx As Double=(tx.fTile+(tx.fOffset/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim ppy As Double=(ty.fTile+(ty.fOffset/coMapUtilities.cTileSize))/Power(2,fMap.fZoomLevel)
    Dim p As TMapPoint=coMapUtilities.initPoint(fTilesCount*coMapUtilities.cTileSize*(ppx-gpx),fTilesCount*coMapUtilities.cTileSize*(ppy-gpy))
    Else 'add from here
Dim p As TMapPoint
        p.Initialize
        p.fX=0
        p.fY=0
    End If 'to here
    Return p

      
End Sub

Lucas Siqueira · Sep 16, 2024

How can I get a tooltip using B4XMAP?

fungms · Nov 2, 2025

Hi, for today is your app with this lib working normally? I'm looking for resolve problem of

or is there other working solution than changing UserAgent? Maybe own server?

aminoacid · Nov 2, 2025

fungms said:
Hi, for today is your app with this lib working normally? I'm looking for resolve problem of
View attachment 168095
or is there other working solution than changing UserAgent? Maybe own server?

Check this out... works great ...

jSD_OpenMaps

As many currently know Googlemaps' Webapi do not work correctly on the webview because the latest versions use webgl I decided to do a new library that uses OpenMap and Leaflet with the same methods and events of the Googlemaps bookshop. I also created a second OpenMapext class that adds some...

www.b4x.com

fungms · Nov 2, 2025

aminoacid said:
Check this out... works great ...

jSD_OpenMaps

As many currently know Googlemaps' Webapi do not work correctly on the webview because the latest versions use webgl I decided to do a new library that uses OpenMap and Leaflet with the same methods and events of the Googlemaps bookshop. I also created a second OpenMapext class that adds some...

www.b4x.com

How come I didn't find by myself, I've checked many many many old libs and apps, even became to an google developer and wrote down my credit card to them ... going to test it. THX

fungms · Nov 2, 2025

fungms said:
How come I didn't find by myself, I've checked many many many old libs and apps, even became to an google developer and wrote down my credit card to them ... going to test it. THX

I know why I didn't find - its only B4J and @Star-Dust has no B4A version

Maybe someone's fired up own server like https://github.com/Overv/openstreetmap-tile-server ? Any clue or direction will be appreciated for not loosing time

aminoacid · Nov 3, 2025

fungms said:
I know why I didn't find - its only B4J and @Star-Dust has no B4A version

Maybe someone's fired up own server like https://github.com/Overv/openstreetmap-tile-server ? Any clue or direction will be appreciated for not loosing time

When StarDust was developing his library, many of us made a few donations towards his efforts and he graciously gave the contributors a copy of the source code. Perhaps you can approach him and see if he would be willing to do the same for you so you can maybe revise it for Android?

mw71 · Nov 3, 2025

fungms said:
Hi, for today is your app with this lib working normally? I'm looking for resolve problem of
View attachment 168095
or is there other working solution than changing UserAgent? Maybe own server?

Hello,

I encountered the same issue with a PHP/JS project. At the time, it occurred during testing due to too many requests being made in too short a time. Waiting 24 hours resolved the issue.

Having your own tile server would certainly help, too — although I don't know anything about that.

B4A Class Open Street Map viewer - GPS

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