fit the map area to show the road between two points

[jesussmile]

I was just working with your new method limitAreaMap and with it I am able to fit the map with the selection of roads,
First I took the coordinates of the two roads and then found a midpoint. Then using BoundingBox I am able to resize the map to fit the road

getMidPointLatLong(GeoPoint latLng1, GeoPoint latLng2) async {
    double midLat, midLong;

    int coefficient = 1;

    if ((latLng1.latitude > 90 && latLng2.latitude < -90) ||
        (latLng2.latitude > 90 && latLng1.latitude < -90)) {
      midLat = 180 - ((latLng1.latitude - latLng2.latitude) / 2).abs();

      if ((latLng1.latitude < 0 &&
              latLng1.latitude.abs() < latLng2.latitude.abs()) ||
          (latLng2.latitude < 0 &&
              latLng2.latitude.abs() < latLng1.latitude.abs()))
        coefficient = -1;

      midLat *= coefficient;
    } else
      midLat = (latLng2.latitude + latLng1.latitude) / 2;

    coefficient = 1;

    if ((latLng1.longitude > 90 && latLng2.longitude < -90) ||
        (latLng2.longitude > 90 && latLng1.longitude < -90)) {
      midLong =
          180 - ((latLng1.longitude.abs() - latLng2.longitude.abs()) / 2).abs();

      if ((latLng1.longitude < 0 &&
              latLng1.longitude.abs() < latLng2.longitude.abs()) ||
          (latLng2.longitude < 0 &&
              latLng2.longitude.abs() < latLng1.longitude.abs()))
        coefficient = -1;

      midLong *= coefficient;
    } else
      midLong = (latLng2.longitude + latLng1.longitude) / 2;

    print("middle ${GeoPoint(latitude: midLat, longitude: midLong)}");
    
    await osmController.limitAreaMap(BoundingBox(
        north: midLat, east: midLong, south: midLat, west: midLong));
    await osmController.zoom(-4);
    await osmController.removeLimitAreaMap();
  }

Not sure if its anyuseful to this project but still thought I would share,
if you want to be more precise than zooming out and control then use this
it based on distance i.e Kilometers

kmInDegree(lat, long) {
    const pi = Math.pi;
    const eSq = 0.00669437999014;
    const a = 6378137.0; //equatorial radius in metres
    lat = lat * pi / 180; //convert to radians
    long = long * pi / 180; //convert radians

    var latLength = (pi * a * (1 - eSq)) /
        (180 * Math.pow((1 - eSq * Math.pow(Math.sin(lat), 2)), 3 / 2));

    var longLength = (pi * a * Math.cos(long)) /
        (180 * Math.sqrt((1 - (eSq * Math.pow(Math.sin(long), 2)))));

    return (latLength, longLength);
  }

My.Video1.mp4

[liodali]

thanks for sharing, it will be usefull we can add it as completary function
i will add it soon
for kmInDegree can explain utility of it ?

[jesussmile]

kmInDegree will convert kilometers to degrees, you will use it before sending it to BoundingBox, after getting the midpoint. for example, if you return this

return {
    lat: 1000 / latLength,
    long: 1000 / longLength
  };

It will add 1 km in degrees to east, west north, and south. For smaller distances, the zoom method of your plugin will work fine but if the distance is large or very small then you need to add the kminDegree value to it so that the road will fit in the map, or you can fit anything like multiple Geopoint, etc, This will guarantee 100% that all markers, location or road is visible in the screen. I hope it makes sense.

[liodali]

also you should know that i will add zoomToBoundingBox ( available in all platform ) that it will get all area visibile

[jesussmile]

Great! That would be much better. Right now everything works fine for me but I am stuck on two things. Rotate the icon and replace the default icon. Any update on this ?

[liodali]

for now I'm little bit focing on making ios support stable and i started adding the web support (still prototyping) but i will add rotate static point this weekend and i will add default icon next weekend

[renehw]

This recurse was avaliable in the last version?

[liodali]

i will add fit area camera method in general soon i will add it in 0.28+

[renehw]

Fine, thanks for this. For now, I implemented the solution that Jesus send for the get the midle point, but I can't getter the currect zoom, you may help me with this?

[liodali]

for the zoom it's tricky you can for example base on distance to calculate it
for example for each level in the zoom there are specific number distnce for each tile

• example for zoom level 18 we have distance of 0.5m/pixel (https://wiki.openstreetmap.org/wiki/Zoom_levels)
  so you can make approximatly if distance > X km zoom = 8 etc ..

this implementation of zoomToboundingbox in osmdroid

• https://github.com/osmdroid/osmdroid/blob/4094f3869a72215e5f7fb5ead78c21674b60ab07/osmdroid-android/src/main/java/org/osmdroid/views/MapView.java#L536
• https://github.com/osmdroid/osmdroid/blob/4094f3869a72215e5f7fb5ead78c21674b60ab07/osmdroid-android/src/main/java/org/osmdroid/util/TileSystem.java#L410

[renehw]

I Understand, I will try implement this, thank you!