Getting different bounds compare to leaflet using CrsSimple()

[Pinkal7600]

I am using the northEast and southWest LatLng to set bounds and it's working perfectly. But, as I compare to the leaflet by doing the same process. I get different bounds in output. How can I make them similar?

flutter_map:

MapOptions mapOptions = MapOptions(
  center: LatLng(0, 0),
  onTap: _handleTap,
  minZoom: 1,
  maxZoom: 4,
  crs: CrsSimple(),
);

LatLng northEast = MapState(mapOptions)
    .unproject(CustomPoint(imageWidth, 0), mapOptions.maxZoom);
LatLng southWest = MapState(mapOptions)
    .unproject(CustomPoint(0, imageHeight), mapOptions.maxZoom); 

LatLngBounds latLngBonds = LatLngBounds(southWest, northEast);
mapOptions.bounds = latLngBonds;

leaflet:

this.previewMap = L.map('previewMap', {
  minZoom: 1,
  maxZoom: 4,
  center: [0, 0],
  crs: L.CRS.Simple,
})

const northEast = this.previewMap.unproject([width, 0], this.previewMap.getMaxZoom())
const southWest = this.previewMap.unproject([0, height], this.previewMap.getMaxZoom())

const bounds = new L.LatLngBounds(southWest, northEast)

Output:

flutter_map:
northEast Lat : -0.0, Lng : 0.5986328125
southWest Lat : -0.626953125, Lng : 0.0

leaflet:
northEast Lat : -0.0, Lng : 153.25
southWest Lat : -160.5, Lng : 0.0

I want to make the output bonds similar for flutter_map and leaflet

[ibrierley]

You can convert between them with project/unproject, you may have to look at /map/map.dart to see if you have access to those methods, or copy them and use if you don't maybe.

[Pinkal7600]

@ibrierley, I am not getting any idea about what things need to be changed to get a similar output of LatLngBounds. I checked project/unproject in map.dart but it will use the current CRS pointToLatLng method. Can you please help me with which things I can look in detail and modify to get similar output?

[ibrierley]

Apologies, I hadn't looked through the code, and assumed leaflet was converted to a different format, but probably not, so ignore my prev reply.... Just out of interest, can you dump out the maxzooms/image width/heights, just to prove what they are when the unproject happens... Ian

…

On Thu, Aug 13, 2020 at 8:43 AM Pinkal Patel ***@***.***> wrote: @ibrierley <https://github.com/ibrierley>, I am not getting any idea about what things need to be changed to get a similar output of LatLngBounds. I checked project/unproject in map.dart but it will use the current CRS pointToLatLng method. Can you please help me with which things I can look in detail and modify to get similar output? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#725 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA5YN5KJALCAPGF3C6K5FHTSAOKSXANCNFSM4PZYPIQQ> .

[Pinkal7600]

If I remove max zoom, I get below output:

northEast Lat : -0.0, Lng : 0.0011692047119140625
southWest Lat : -0.001224517822265625, Lng : 0.0

We cannot dump CustomPoint which I use with image height and width.

[ibrierley]

Should be able to dump the custom points params (x,y or whatever). I just think you need to prove the data you are entering into each is exactly the same if you are getting different outputs first. Ian

…

On Thu, Aug 13, 2020 at 10:07 AM Pinkal Patel ***@***.***> wrote: If I remove max zoom, I get below output: northEast Lat : -0.0, Lng : 0.0011692047119140625 southWest Lat : -0.001224517822265625, Lng : 0.0 We cannot dump CustomPoint which I use with image height and width. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#725 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA5YN5LVM7BYEANA67QZKRLSAOUNPANCNFSM4PZYPIQQ> .

[Pinkal7600]

When I pass 0 as height, width, and max zoom for flutter_map and leaflet. I get the same output as below for LatLngBounds.

northwest :: lat : -0.0, lng : 0.0
southEast :: lat : -0.0, lng : 0.0

Should be able to dump the custom points params (x,y or whatever). I just think you need to prove the data you are entering into each is exactly the same if you are getting different outputs first. Ian
…
On Thu, Aug 13, 2020 at 10:07 AM Pinkal Patel @.***> wrote: If I remove max zoom, I get below output: northEast Lat : -0.0, Lng : 0.0011692047119140625 southWest Lat : -0.001224517822265625, Lng : 0.0 We cannot dump CustomPoint which I use with image height and width. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#725 (comment)>, or unsubscribe https://github.com/notifications/unsubscribe-auth/AA5YN5LVM7BYEANA67QZKRLSAOUNPANCNFSM4PZYPIQQ .

[ibrierley]

Think I'm lost on what you're trying to actually achieve here, why you are entering in 0 as width/height.

If it was me, main thing I would be testing for, with a different output, is if the inputs are exactly the same. What is the imageWidth/Height in the flutter_map version, what is the width/height in the leaflet version. Also just print the zoomlevels you use before calling the sub, just to be 100% sure all the variables are the same going in.

After that though, I'm not sure what the problem is you are actually having and if this is a redherring...what problem are you actually having ? Is it code afterwards which relies on those bounds that doesn't like those numbers ?

[Pinkal7600]

@ibrierley Apologies, I misunderstand the thing you want it.

I used below height and width and the max zoom is already defined in the first post message which is 4 for both flutter_map and leaflet.

double imageHeight = 2568;
double imageWidth = 2452;

[Pinkal7600]

@ibrierley , I found the solution. As compared to the leaflet we were missing something. So, I have made some changes as below and also remove the latlong: ^0.6.1 package and used maps_toolkit: ^1.1.0+2 package for LatLng and some maths function for latlng as latlong packages is not maintained. But in maps_toolkit it also required modification in maps_toolkit.dart as we need to add export 'src/math_util.dart'; to use math function for latlng.

Added below to override function in CrsSimple class.

@override
num scale(double zoom) {
  return math.pow(2, zoom);
}

@override
num zoom(double scale) {
  return math.log(scale) / math.ln2;
}

And modify the return of unproject of _LonLat class as below

@override
LatLng unproject(CustomPoint point) {
  return LatLng(point.y, point.x);
//    return LatLng(inclusiveLat(point.y), inclusiveLng(point.x)); // old return 
}