factor/basis/ui/baseline-alignment/baseline-alignment.factor

84 lines
2.4 KiB
Factor

! Copyright (C) 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays kernel locals math math.functions math.order math.vectors
sequences ui.gadgets accessors combinators ;
IN: ui.baseline-alignment
SYMBOL: +baseline+
GENERIC: baseline ( gadget -- y )
M: gadget baseline drop f ;
GENERIC: cap-height ( gadget -- y )
M: gadget cap-height drop f ;
<PRIVATE
! Text has ascent/descent/cap-height slots, graphics does not.
TUPLE: gadget-metrics height ascent descent cap-height ;
: <gadget-metrics> ( gadget dim -- metrics )
second swap [ baseline ] [ cap-height ] bi
[ dup [ 2dup - ] [ f ] if ] dip
gadget-metrics boa ; inline
: ?supremum ( seq -- n/f )
sift [ f ] [ supremum ] if-empty ;
: max-ascent ( seq -- n )
[ ascent>> ] map ?supremum ;
: max-cap-height ( seq -- n )
[ cap-height>> ] map ?supremum ;
: max-descent ( seq -- n )
[ descent>> ] map ?supremum ;
: max-text-height ( seq -- y )
[ ascent>> ] filter [ height>> ] map ?supremum ;
: max-graphics-height ( seq -- y )
[ ascent>> not ] filter [ height>> ] map ?supremum 0 or ;
:: combine-metrics ( graphics-height ascent descent cap-height -- ascent' descent' )
ascent [
cap-height 2 / :> mid-line
graphics-height 2 /
[ ascent mid-line - max mid-line + floor >integer ]
[ descent mid-line + max mid-line - ceiling >integer ] bi
] [ f f ] if ;
: (measure-metrics) ( children sizes -- graphics-height ascent descent cap-height )
[ <gadget-metrics> ] 2map
{
[ max-graphics-height ]
[ max-ascent ]
[ max-descent ]
[ max-cap-height ]
} cleave ;
PRIVATE>
:: align-baselines ( gadgets -- ys )
gadgets [ dup pref-dim <gadget-metrics> ] map
dup max-ascent 0 or :> max-ascent
dup max-cap-height 0 or :> max-cap-height
dup max-graphics-height :> max-graphics-height
max-cap-height max-graphics-height + 2 /i :> critical-line
critical-line max-ascent [-] :> text-leading
max-ascent critical-line [-] :> graphics-leading
[
dup ascent>>
[ ascent>> max-ascent swap - text-leading ]
[ height>> max-graphics-height swap - 2/ graphics-leading ] if +
] map ;
: measure-metrics ( children sizes -- ascent descent )
(measure-metrics) combine-metrics ;
: measure-height ( children sizes -- height )
(measure-metrics) dup [ combine-metrics + ] [ 3drop ] if ;