Re: [XBoard-devel] Promotion and piece menus

[h.g. muller]

Indeed, there is an XBoard version with a graphical promotion
and edit-position popups, basically displaying the pieces you
can select on a small board with the same square size as
the normal board. But I was not very happy with it. It was
unwieldly large, escpecially in Edit Position when I wanted
to show both black and white pieces simultaneously,
(I have always hated the XBoard way of using the middle
mouse button, as my laptop doesn't have one), and especially
in variants with a large number as piece types. It would also
be a lot of work to port that to WinBoard. For these reasons
I was looking for a more elegant alternative.

My experience so far is that you really have to try it out; what
looked good to me on paper was really awful when I tried it.

I do have a solution that I like ery much now, though:
the detour "under-promotion". It cycles through the choices,
but not on a board square, but while you are dragging the piece.
This works very smoothly:

When you click the Pawn, it stays a Pawn. But when you start
dragging it (i.e. as soon as it umps to the mouse pointer),
it gets represented by the default promotion piece (usually Queen).
As soon as you drag it forward, (which you cannot avoid to reach
the promotion square), it is fixed to this representation, and will
promote to it when you release it on the promotion-square.
So you see what you get; no way to make a mistake even if
you are suffering from Parkinson. But if you start pulling the
mouse backwards, it starts cycling through the pieces,
Q -> N -> B -> R -> Q. Because you started with the transition
P->Q immediately, you have to drag it back more than a marginal
amount to get the Knight as first under-promotion option.
Even if you are so inept to do that, you will see that it happened,
and can refrain from dropping the Knight on the promotion square.
There is no way to cycle through the pieces backward, but you
can recover by continuing to drag the Pawn backwards until
you get the Queen in the next cycle.

If you release after pulling backwards, it counts as a first click
on the Pawn, which reverts to Pawn as it jumps back to the
from square, but the promotion choice is remembered, until
you click another piece, and you can finish a click-click move
by clicking the promoton square (but no preview then), or
do a drag-drop move that now starts with the selected piece
as soon as you 'lift' the Pawn.

To solve the beginners issue, the message field will display
"Pull pawn backwards to under-promote", which should be
enough of a hint to figure it out.

It also integrates reasonably well in the one-click schem
we used: a click on a 7th-rank Pawn will not be considered
a unique move even when the Pawn has only one target
square, because of the promotion choice. In the old way
you would get the promotion popup requiring a second click,
now you can drag to the to-square, possibly through a detour,
which should not be slower. Clicking the to-square will promote
auto-queen fashion, as in the old scheme.

I also pushed this to hgm.nubati.net now (the WinBoard version
also works!). It also has to be run with -sweepPromotions true.
So far it is my favorite solution.