Tile splitting diagonal length criterion

[cdeil]

@tboch - At https://github.com/hipspy/hips/blame/71e593ab7e60767be70d9b2b13398016c35db09a/docs/drawing_algo.rst#L73 you wrote

To overcome this problem, Aladin Desktop and Aladin Lite use the following recursive strategy: for tiles either too large (one edge is >300 pixels or diagonal is > 150 pixels when projected) or too distorted (ratio of smaller diagonal on larger diagonal is smaller than 0.7)

and by now @adl1995 has implemented that criterion in a helper function in draw.py.

I think maybe that is a typo and really the diagonal length limit should be 350 or 450 pix instead of 150 as written? My reasoning is that one of the two diagonals is always longer than any of the edges, so as written the "one edge is > 300 pixels" criterion is superfluous, because the "diagonal is > 150 pix" criterion would already always be true in those cases, no?

[tboch]

Actually, after re-checking, the criterion to use to determine if a file is too large is as follow:

• either one edge is > 300 pixels when projected
• or the tile is considered as distorted (ratio of smaller diagonal on larger diagonal < 0.7) AND one of the diagonal is > 150 pixels when projected

I have updated the document accordingly

[cdeil]

@adl1995 - Please update the implementation (and possibly tests) to match the description.

[adl1995]

Fixed in #101.