try to speed text drawing by working at the glyph level
This commit is contained in:
Matthew Flatt
parent
ff617c4bf2
commit
d57f72136d
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@ -17,7 +17,11 @@
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"dc-intf.ss"
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"dc-path.ss"
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"point.ss"
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"local.ss")
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"local.ss"
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racket/flonum
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ffi/unsafe
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"bstr.rkt")
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(provide dc-mixin
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dc-backend<%>
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@ -1046,10 +1050,18 @@
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(let ([desc (get-pango font)]
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[attrs (send font get-pango-attrs)]
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[integral round]
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[x (if rotate? 0.0 x)]
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[y (if rotate? 0.0 y)])
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[x (if rotate? 0.0 (exact->inexact x))]
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[y (if rotate? 0.0 (exact->inexact y))])
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;; We have two ways to draw text:
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;; - If `combine?' (to enable kerning etc.), then we create a Pango layout
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;; and draw it. This is the slow but pretty way (bt not used for editors,
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;; where the text needs to draw the same if it's drawn all together or
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;; in pieces).
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;; - If not `combine' or if combining isn't supported (e.g., because the scale
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;; is too small, so that it would look bad), then we draw character by character.
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(if (and combine?
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(can-combine-text? (* effective-scale-y (send font get-point-size))))
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;; This is combine mode.
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(let loop ([s s] [w 0.0] [h 0.0] [d 0.0] [a 0.0])
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(cond
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[(not s)
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@ -1105,6 +1117,8 @@
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(exact->inexact PANGO_SCALE)))]
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[na 0.0])
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(loop next-s (+ w nw) (max h nh) (max d nd) (max a na))))])))]))
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;; This is character-by-character mode. It uses a cached per-character+font layout
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;; object.
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(let ([logical (make-PangoRectangle 0 0 0 0)]
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[cache (if (or combine?
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(not (= 1.0 effective-scale-x))
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@ -1120,51 +1134,134 @@
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(hash-set! attr-layouts attrs layouts)
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layouts)))]
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[xform current-xform])
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;; First, ensure that all layout records are ready:
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(for ([ch (in-string s)])
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(let* ([layout-info
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(or (hash-ref layouts (char->integer ch) #f)
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(let ([layout (pango_layout_new context)])
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(pango_layout_set_font_description layout desc)
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(when attrs (pango_layout_set_attributes layout attrs))
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(pango_layout_set_text layout (string ch))
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(unless (or (not substitute-fonts?)
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(zero? (pango_layout_get_unknown_glyphs_count layout)))
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;; No good glyph; look for an alternate face
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(install-alternate-face ch layout font desc attrs context))
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(let ([run (extract-only-run layout)])
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(let ([layout-info (vector layout xform run)])
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(hash-set! layouts (char->integer ch) layout-info)
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layout-info))))]
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[layout (vector-ref layout-info 0)])
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(unless (equal? xform (vector-ref layout-info 1))
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(pango_cairo_update_layout cr layout)
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(vector-set! layout-info 1 xform)
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(vector-set! layout-info 2 (extract-only-run layout)))))
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;; At this point, we have two options for dealing with the layouts.
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;; If layouts all use the same font and a single glyph, then
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;; build a glyph string with the right offsets and draw all the
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;; characters at once. That's faster, but it only works if there
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;; are no font substitions or other fancy glyph transformations.
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;; We try the fast way, and bail out to the low way if it doesn't
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;; work. Also, we don't bother with the fast way if there's just one
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;; character or if we're just measuring text.
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(begin0
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(for/fold ([w 0.0][h 0.0][d 0.0][a 0.0])
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([ch (in-string s)])
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(let* ([layout+xform
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(or (hash-ref layouts (char->integer ch) #f)
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(let ([layout (pango_layout_new context)])
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(pango_layout_set_font_description layout desc)
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(when attrs (pango_layout_set_attributes layout attrs))
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(pango_layout_set_text layout (string ch))
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(unless (or (not substitute-fonts?)
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(zero? (pango_layout_get_unknown_glyphs_count layout)))
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;; No good glyph; look for an alternate face
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(install-alternate-face ch layout font desc attrs context))
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(let ([layout+xform (mcons layout xform)])
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(hash-set! layouts (char->integer ch) layout+xform)
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layout+xform)))]
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[layout (mcar layout+xform)])
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(unless (equal? xform (mcdr layout+xform))
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(pango_cairo_update_layout cr layout)
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(set-mcdr! layout+xform xform))
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(when (and draw? (or (not (eq? ch #\space))
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attrs))
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(cairo_move_to cr (align-x/delta (+ x w) 0) (align-y/delta y 0))
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;; Here's the draw command, which uses most of the time:
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(pango_cairo_show_layout cr layout))
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(let ([v (and cache
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(hash-ref cache (char->integer ch) #f))])
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(if v
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(values (if blank? 0.0 (+ w (vector-ref v 0)))
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(max h (vector-ref v 1))
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(max d (vector-ref v 2))
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(max a (vector-ref v 3)))
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(begin
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(pango_layout_get_extents layout #f logical)
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(let ([lw (integral (/ (PangoRectangle-width logical) (exact->inexact PANGO_SCALE)))]
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[lh (integral (/ (PangoRectangle-height logical) (exact->inexact PANGO_SCALE)))]
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[ld (integral (/ (- (PangoRectangle-height logical)
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(pango_layout_get_baseline layout))
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(exact->inexact PANGO_SCALE)))]
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[la 0.0])
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(when cache
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(hash-set! cache (char->integer ch) (vector lw lh ld la)))
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(values (if blank? 0.0 (+ w lw)) (max h lh) (max d ld) (max a la))))))))
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(unless (and
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draw?
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cache
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((string-length s) . > . 1)
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(let ([len (string-length s)]
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[first-v (hash-ref cache (char->integer (string-ref s 0)) #f)])
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;; Check whether the fast way applies...
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(let ([glyph-infos (malloc len _PangoGlyphInfo 'raw)] ;; assuming atomic until `free' below
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[log-clusters (malloc len _int 'raw)]
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[first-font (let* ([run (vector-ref (hash-ref layouts (char->integer (string-ref s 0))) 2)])
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(and run
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(PangoItem-font (PangoGlyphItem-item run))))]
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[first-ascent (and first-v (fl- (vector-ref first-v 1) (vector-ref first-v 2)))])
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(and
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(let loop ([i 0][dx 0.0])
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(or (= i len)
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(let* ([ch (string-ref s i)]
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[layout-info (hash-ref layouts (char->integer ch))]
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[run (vector-ref layout-info 2)]
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[v (hash-ref cache (char->integer ch) #f)])
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(and run
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v
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(fl= first-ascent
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(fl- (vector-ref v 1) (vector-ref v 2)))
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(ptr-equal? first-font
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(PangoItem-font (PangoGlyphItem-item run)))
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;; Assume that the rect of the characters will pan out,
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;; and start filling in the glyph-info array:
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(let ([dest-info (cast (ptr-add glyph-infos i _PangoGlyphInfo)
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_pointer
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_PangoGlyphInfo-pointer)])
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(memcpy dest-info
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(PangoGlyphString-glyphs (PangoGlyphItem-glyphs run))
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1
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_PangoGlyphInfo)
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(ptr-set! log-clusters _int i i)
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;; Adjust width to be consistent with integral widths
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;; used when drawing individual characters.
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(let ([w (vector-ref v 0)])
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(set-PangoGlyphInfo-width! dest-info
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(inexact->exact
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(flfloor
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(fl* w (->fl PANGO_SCALE)))))
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(loop (add1 i) (fl+ dx w))))))))
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;; If we get here, we can use the fast way:
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(let ([glyph-string (make-PangoGlyphString len
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glyph-infos
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log-clusters)])
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;; Move into position and draw the glyphs
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(cairo_move_to cr
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(align-x/delta x 0)
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(+ (align-y/delta y 0)
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(/ (vector-ref first-v 4) (->fl PANGO_SCALE))))
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(pango_cairo_show_glyph_string cr first-font glyph-string)
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(free glyph-infos)
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(free log-clusters)
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#t)))))
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;; We use the slower, per-layout way:
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(for/fold ([w 0.0][h 0.0][d 0.0][a 0.0])
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([ch (in-string s)])
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(let ([layout (vector-ref (hash-ref layouts (char->integer ch)) 0)])
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(when (and draw? (or (not (eq? ch #\space))
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attrs))
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(cairo_move_to cr (align-x/delta (+ x w) 0) (align-y/delta y 0))
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;; Here's the draw command, which uses most of the time in this mode:
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(pango_cairo_show_layout cr layout))
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(let ([v (and cache
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(hash-ref cache (char->integer ch) #f))])
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(if v
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(values (if blank? 0.0 (+ w (vector-ref v 0)))
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(max h (vector-ref v 1))
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(max d (vector-ref v 2))
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(max a (vector-ref v 3)))
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(begin
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(pango_layout_get_extents layout #f logical)
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(let ([baseline (pango_layout_get_baseline layout)]
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[orig-h (PangoRectangle-height logical)])
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(let ([lw (integral (/ (PangoRectangle-width logical) (exact->inexact PANGO_SCALE)))]
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[lh (integral (/ orig-h (exact->inexact PANGO_SCALE)))]
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[ld (integral (/ (- orig-h baseline) (exact->inexact PANGO_SCALE)))]
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[la 0.0])
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(when cache
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(hash-set! cache (char->integer ch) (vector lw lh ld la baseline)))
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(values (if blank? 0.0 (+ w lw)) (max h lh) (max d ld) (max a la))))))))))
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(when rotate? (cairo_restore cr))))))))
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(define/private (extract-only-run layout)
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(let* ([iter (pango_layout_get_iter layout)]
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[run (pango_layout_iter_get_run_readonly iter)]
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[done? (or (not (pango_layout_iter_next_run iter))
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(and (not (pango_layout_iter_get_run_readonly iter))
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(not (pango_layout_iter_next_run iter))))])
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(pango_layout_iter_free iter)
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(and run
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done?
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(= 1 (PangoGlyphString-num_glyphs (PangoGlyphItem-glyphs run)))
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run)))
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(define/private (install-alternate-face ch layout font desc attrs context)
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(or
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(for/or ([face (in-list
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@ -66,6 +66,47 @@
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PangoRectangle-width
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PangoRectangle-height)
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(define-cstruct _PangoItem
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([offset _int]
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[length _int]
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[num_chars _int]
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;; Inline PangoAnalysis:
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[shape_engine _pointer]
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[lang_engine _pointer]
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[font PangoFont]
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[level _uint8]
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[gravity _uint8]
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[flags _uint8]
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[script _uint8]
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[language _pointer]
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[extra_attrs _pointer]))
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(provide (struct-out PangoItem)
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_PangoItem _PangoItem-pointer)
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(define-cstruct _PangoGlyphInfo
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([glyph _uint32]
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[width _uint32]
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[dx _uint32]
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[dy _uint32]
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[is_cluster_start _uint]))
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(provide (struct-out PangoGlyphInfo)
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_PangoGlyphInfo _PangoGlyphInfo-pointer)
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(define-cstruct _PangoGlyphString
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([num_glyphs _int]
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[glyphs _pointer]
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[log_clusters _pointer]))
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(provide (struct-out PangoGlyphString)
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_PangoGlyphString)
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(define-cstruct _PangoGlyphItem ([item _PangoItem-pointer]
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[glyphs _PangoGlyphString-pointer]))
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(provide (struct-out PangoGlyphItem))
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(define-glib g_object_unref (_fun _pointer -> _void)
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#:wrap (deallocator))
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@ -100,12 +141,16 @@
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(define-pangocairo pango_cairo_update_layout (_fun _cairo_t PangoLayout -> _void))
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(define-pango pango_layout_set_text (_fun PangoLayout [s : _string] [_int = -1] -> _void))
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(define-pangocairo pango_cairo_show_layout (_fun _cairo_t PangoLayout -> _void))
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(define-pangocairo pango_cairo_show_glyph_item (_fun _cairo_t _string _PangoGlyphItem-pointer -> _void))
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(define-pangocairo pango_cairo_show_glyph_string (_fun _cairo_t PangoFont _PangoGlyphString-pointer -> _void))
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(define-pango pango_layout_iter_free (_fun PangoLayoutIter -> _void)
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#:wrap (deallocator))
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(define-pango pango_layout_get_iter (_fun PangoLayout -> PangoLayoutIter)
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#:wrap (allocator pango_layout_iter_free))
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(define-pango pango_layout_iter_get_baseline (_fun PangoLayoutIter -> _int))
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(define-pango pango_layout_iter_next_run (_fun PangoLayoutIter -> _bool))
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(define-pango pango_layout_iter_get_run_readonly (_fun PangoLayoutIter -> (_or-null _PangoGlyphItem-pointer)))
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(define-pango pango_layout_get_context (_fun PangoLayout -> PangoContext)) ;; not an allocator
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(define-pango pango_layout_get_extents (_fun PangoLayout _pointer _PangoRectangle-pointer -> _void))
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@ -117,6 +162,7 @@
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(begin0
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(pango_layout_iter_get_baseline iter)
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(pango_layout_iter_free iter))))))
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(define-pango pango_layout_get_spacing (_fun PangoLayout -> _int))
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(define-pango pango_layout_new (_fun PangoContext -> PangoLayout)
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#:wrap (allocator g_object_unref))
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