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try to fix text vertical alignment again

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This commit is contained in:
Matthew Flatt 2010-09-17 21:53:20 -06:00
parent 158d119b12
commit 57c963c045
1 changed files with 20 additions and 13 deletions
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33
collects/racket/draw/dc.rkt
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@ -1233,7 +1233,8 @@
(let ([glyph-string (make-PangoGlyphString len
glyph-infos
log-clusters)])
;; Move into position and draw the glyphs
;; Move into position (based on the recorded Pango-units baseline)
;; and draw the glyphs
(cairo_move_to cr
(align-x/delta x 0)
(align-y/delta (+ y (/ (vector-ref first-v 4) (->fl PANGO_SCALE))) 0))
@ -1246,37 +1247,43 @@
(for/fold ([w 0.0][h 0.0][d 0.0][a 0.0])
([ch (in-string s)])
(let ([layout (vector-ref (hash-ref layouts (char->integer ch)) 0)])
(let-values ([(lw lh ld la)
(let-values ([(lw lh ld la flh)
(let ([v (and cache (hash-ref cache (char->integer ch) #f))])
(if v
;; Used cached size:
(values (vector-ref v 0)
(vector-ref v 1)
(vector-ref v 2)
(vector-ref v 3))
(vector-ref v 3)
(vector-ref v 6))
;; Query and record size:
(begin
(pango_layout_get_extents layout #f logical)
(let ([baseline (pango_layout_get_baseline layout)]
[orig-h (PangoRectangle-height logical)])
;; We keep an integer width to pixel-align each individual character,
;; We keep integer width & height to pixel-align each individual character,
;; but we keep non-integral lh & ld to pixel-align the baseline.
(let ([lw (integral (/ (PangoRectangle-width logical)
(exact->inexact PANGO_SCALE)))]
[lh (/ orig-h (exact->inexact PANGO_SCALE))]
[flh (/ orig-h (exact->inexact PANGO_SCALE))]
[ld (/ (- orig-h baseline) (exact->inexact PANGO_SCALE))]
[la 0.0])
(when cache
(hash-set! cache (char->integer ch)
(vector lw lh ld la baseline
;; rounded width in Pango units:
(inexact->exact
(floor (* lw (->fl PANGO_SCALE)))))))
(values lw lh ld la))))))])
(let ([lh (ceiling flh)])
(when cache
(hash-set! cache (char->integer ch)
(vector lw lh ld la
;; baseline in Pango units; for fast path
baseline
;; rounded width in Pango units; for fast path
(inexact->exact
(floor (* lw (->fl PANGO_SCALE))))
;; unrounded height, for slow-path alignment
flh)))
(values lw lh ld la flh)))))))])
(when draw?
(cairo_move_to cr
(align-x/delta (+ x w) 0)
(let ([bl (- lh ld)])
(let ([bl (- flh ld)])
(- (align-y/delta (+ y bl) 0)
(align-y/delta bl 0))))
;; Here's the draw command, which uses most of the time in this mode: