TMS doesn't work with L.CRS.Simple in 1.0

[hyperknot]

As provided by a user in #4333 using L.CRS.Simple with tms: true results in an exception where this._globalTileRange is uninitialised in tileLayer / getTileUrl.

Leaflet/src/layer/tile/TileLayer.js

Line 77 in b60e18d

getTileUrl: function (coords) {

http://playground-leaflet.rhcloud.com/jac/1/edit?html,output

It works untouched in 0.7, but is broken in 1.0

Related issue: #2298

cc: @perliedman

[perliedman]

The problem is that L.CRS.Simple is an so called "infinite" CRS (https://github.com/Leaflet/Leaflet/blob/master/src/geo/crs/CRS.Simple.js#L24), which means it does not have any bounds.

TMS, on the other hand, needs an upper bound for the CRS's Y coordinate, to be able to flip the tile row.

This means that TMS will not work with L.CRS.Simple out of the box in 1.0. On the other hand, the only reason it worked in 0.7 was that L.CRS.Simple had implicit bounds, and from what I remember a lot of people ran into weird problems because those implicit bounds were rarely the same as the actual limits.

If you want to use TMS and a CRS that resembles L.CRS.Simple, you should extend it, set infinite: false and give it the bounds you want. This could, of course, be made clearer with a tutorial or some kind of warning in the docs.

[jieter]

Regarding #4337, should we not try to replace {-y} if map.crs.infinite === true to prevent this error ?

[perliedman]

@jieter yes, sounds like a good plan. In general it would of course be very nice to provide a better error message than that some internal variable is undefined!

[balciseri]

Yes at the moment if i reference the master version with the {-y} fix i can't use crs: L.CRS.Simple,
because it will not work.

[jieter]

Hang on, working on it...

[jieter]

@perliedman Leaflet doesn't seem to do much explaining in error messages. I've added an example of the error produced by a small L.CRS.Simple-example to the description of #4344 .