533 lines
16 KiB
C++
533 lines
16 KiB
C++
/*
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* Copyright © 2011,2012 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#include "hb-ot-shape-normalize-private.hh"
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#include "hb-ot-shape-private.hh"
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/*
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* HIGHLEVEL DESIGN:
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*
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* This file exports one main function: _hb_ot_shape_normalize().
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*
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* This function closely reflects the Unicode Normalization Algorithm,
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* yet it's different.
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*
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* Each shaper specifies whether it prefers decomposed (NFD) or composed (NFC).
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* The logic however tries to use whatever the font can support.
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*
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* In general what happens is that: each grapheme is decomposed in a chain
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* of 1:2 decompositions, marks reordered, and then recomposed if desired,
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* so far it's like Unicode Normalization. However, the decomposition and
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* recomposition only happens if the font supports the resulting characters.
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*
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* The goals are:
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*
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* - Try to render all canonically equivalent strings similarly. To really
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* achieve this we have to always do the full decomposition and then
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* selectively recompose from there. It's kinda too expensive though, so
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* we skip some cases. For example, if composed is desired, we simply
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* don't touch 1-character clusters that are supported by the font, even
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* though their NFC may be different.
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*
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* - When a font has a precomposed character for a sequence but the 'ccmp'
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* feature in the font is not adequate, use the precomposed character
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* which typically has better mark positioning.
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*
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* - When a font does not support a combining mark, but supports it precomposed
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* with previous base, use that. This needs the itemizer to have this
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* knowledge too. We need to provide assistance to the itemizer.
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*
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* - When a font does not support a character but supports its decomposition,
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* well, use the decomposition (preferring the canonical decomposition, but
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* falling back to the compatibility decomposition if necessary). The
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* compatibility decomposition is really nice to have, for characters like
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* ellipsis, or various-sized space characters.
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*
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* - The complex shapers can customize the compose and decompose functions to
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* offload some of their requirements to the normalizer. For example, the
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* Indic shaper may want to disallow recomposing of two matras.
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*
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* - We try compatibility decomposition if decomposing through canonical
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* decomposition alone failed to find a sequence that the font supports.
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* We don't try compatibility decomposition recursively during the canonical
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* decomposition phase. This has minimal impact. There are only a handful
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* of Greek letter that have canonical decompositions that include characters
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* with compatibility decomposition. Those can be found using this command:
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*
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* egrep "`echo -n ';('; grep ';<' UnicodeData.txt | cut -d';' -f1 | tr '\n' '|'; echo ') '`" UnicodeData.txt
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*/
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static hb_bool_t
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decompose_func (hb_unicode_funcs_t *unicode,
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hb_codepoint_t ab,
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hb_codepoint_t *a,
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hb_codepoint_t *b)
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{
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/* XXX FIXME, move these to complex shapers and propagage to normalizer.*/
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switch (ab) {
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case 0x0AC9 : return false;
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case 0x0931 : return false;
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case 0x0B94 : return false;
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/* These ones have Unicode decompositions, but we do it
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* this way to be close to what Uniscribe does. */
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case 0x0DDA : *a = 0x0DD9; *b= 0x0DDA; return true;
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case 0x0DDC : *a = 0x0DD9; *b= 0x0DDC; return true;
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case 0x0DDD : *a = 0x0DD9; *b= 0x0DDD; return true;
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case 0x0DDE : *a = 0x0DD9; *b= 0x0DDE; return true;
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case 0x0F77 : *a = 0x0FB2; *b= 0x0F81; return true;
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case 0x0F79 : *a = 0x0FB3; *b= 0x0F81; return true;
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case 0x17BE : *a = 0x17C1; *b= 0x17BE; return true;
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case 0x17BF : *a = 0x17C1; *b= 0x17BF; return true;
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case 0x17C0 : *a = 0x17C1; *b= 0x17C0; return true;
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case 0x17C4 : *a = 0x17C1; *b= 0x17C4; return true;
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case 0x17C5 : *a = 0x17C1; *b= 0x17C5; return true;
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case 0x1925 : *a = 0x1920; *b= 0x1923; return true;
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case 0x1926 : *a = 0x1920; *b= 0x1924; return true;
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case 0x1B3C : *a = 0x1B42; *b= 0x1B3C; return true;
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case 0x1112E : *a = 0x11127; *b= 0x11131; return true;
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case 0x1112F : *a = 0x11127; *b= 0x11132; return true;
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#if 0
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case 0x0B57 : *a = 0xno decomp, -> RIGHT; return true;
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case 0x1C29 : *a = 0xno decomp, -> LEFT; return true;
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case 0xA9C0 : *a = 0xno decomp, -> RIGHT; return true;
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case 0x111BF : *a = 0xno decomp, -> ABOVE; return true;
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#endif
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}
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return unicode->decompose (ab, a, b);
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}
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static hb_bool_t
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compose_func (hb_unicode_funcs_t *unicode,
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hb_codepoint_t a,
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hb_codepoint_t b,
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hb_codepoint_t *ab)
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{
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/* XXX, this belongs to indic normalizer. */
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if ((FLAG (unicode->general_category (a)) &
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(FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
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FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
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FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK))))
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return false;
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/* XXX, add composition-exclusion exceptions to Indic shaper. */
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if (a == 0x09AF && b == 0x09BC) { *ab = 0x09DF; return true; }
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/* XXX, these belong to the hebew / default shaper. */
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/* Hebrew presentation-form shaping.
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* https://bugzilla.mozilla.org/show_bug.cgi?id=728866 */
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// Hebrew presentation forms with dagesh, for characters 0x05D0..0x05EA;
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// note that some letters do not have a dagesh presForm encoded
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static const hb_codepoint_t sDageshForms[0x05EA - 0x05D0 + 1] = {
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0xFB30, // ALEF
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0xFB31, // BET
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0xFB32, // GIMEL
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0xFB33, // DALET
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0xFB34, // HE
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0xFB35, // VAV
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0xFB36, // ZAYIN
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0, // HET
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0xFB38, // TET
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0xFB39, // YOD
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0xFB3A, // FINAL KAF
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0xFB3B, // KAF
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0xFB3C, // LAMED
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0, // FINAL MEM
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0xFB3E, // MEM
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0, // FINAL NUN
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0xFB40, // NUN
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0xFB41, // SAMEKH
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0, // AYIN
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0xFB43, // FINAL PE
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0xFB44, // PE
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0, // FINAL TSADI
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0xFB46, // TSADI
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0xFB47, // QOF
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0xFB48, // RESH
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0xFB49, // SHIN
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0xFB4A // TAV
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};
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hb_bool_t found = unicode->compose (a, b, ab);
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if (!found && (b & ~0x7F) == 0x0580) {
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// special-case Hebrew presentation forms that are excluded from
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// standard normalization, but wanted for old fonts
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switch (b) {
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case 0x05B4: // HIRIQ
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if (a == 0x05D9) { // YOD
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*ab = 0xFB1D;
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found = true;
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}
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break;
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case 0x05B7: // patah
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if (a == 0x05F2) { // YIDDISH YOD YOD
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*ab = 0xFB1F;
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found = true;
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} else if (a == 0x05D0) { // ALEF
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*ab = 0xFB2E;
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found = true;
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}
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break;
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case 0x05B8: // QAMATS
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if (a == 0x05D0) { // ALEF
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*ab = 0xFB2F;
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found = true;
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}
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break;
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case 0x05B9: // HOLAM
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if (a == 0x05D5) { // VAV
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*ab = 0xFB4B;
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found = true;
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}
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break;
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case 0x05BC: // DAGESH
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if (a >= 0x05D0 && a <= 0x05EA) {
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*ab = sDageshForms[a - 0x05D0];
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found = (*ab != 0);
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} else if (a == 0xFB2A) { // SHIN WITH SHIN DOT
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*ab = 0xFB2C;
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found = true;
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} else if (a == 0xFB2B) { // SHIN WITH SIN DOT
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*ab = 0xFB2D;
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found = true;
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}
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break;
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case 0x05BF: // RAFE
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switch (a) {
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case 0x05D1: // BET
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*ab = 0xFB4C;
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found = true;
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break;
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case 0x05DB: // KAF
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*ab = 0xFB4D;
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found = true;
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break;
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case 0x05E4: // PE
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*ab = 0xFB4E;
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found = true;
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break;
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}
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break;
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case 0x05C1: // SHIN DOT
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if (a == 0x05E9) { // SHIN
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*ab = 0xFB2A;
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found = true;
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} else if (a == 0xFB49) { // SHIN WITH DAGESH
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*ab = 0xFB2C;
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found = true;
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}
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break;
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case 0x05C2: // SIN DOT
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if (a == 0x05E9) { // SHIN
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*ab = 0xFB2B;
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found = true;
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} else if (a == 0xFB49) { // SHIN WITH DAGESH
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*ab = 0xFB2D;
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found = true;
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}
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break;
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}
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}
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return found;
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}
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static inline void
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set_glyph (hb_glyph_info_t &info, hb_font_t *font)
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{
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hb_font_get_glyph (font, info.codepoint, 0, &info.glyph_index());
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}
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static inline void
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output_char (hb_buffer_t *buffer, hb_codepoint_t unichar, hb_codepoint_t glyph)
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{
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buffer->cur().glyph_index() = glyph;
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buffer->output_glyph (unichar);
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_hb_glyph_info_set_unicode_props (&buffer->prev(), buffer->unicode);
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}
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static inline void
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next_char (hb_buffer_t *buffer, hb_codepoint_t glyph)
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{
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buffer->cur().glyph_index() = glyph;
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buffer->next_glyph ();
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}
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static inline void
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skip_char (hb_buffer_t *buffer)
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{
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buffer->skip_glyph ();
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}
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static bool
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decompose (hb_font_t *font, hb_buffer_t *buffer,
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bool shortest,
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hb_codepoint_t ab)
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{
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hb_codepoint_t a, b, a_glyph, b_glyph;
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if (!decompose_func (buffer->unicode, ab, &a, &b) ||
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(b && !font->get_glyph (b, 0, &b_glyph)))
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return false;
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bool has_a = font->get_glyph (a, 0, &a_glyph);
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if (shortest && has_a) {
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/* Output a and b */
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output_char (buffer, a, a_glyph);
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if (b)
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output_char (buffer, b, b_glyph);
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return true;
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}
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if (decompose (font, buffer, shortest, a)) {
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if (b)
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output_char (buffer, b, b_glyph);
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return true;
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}
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if (has_a) {
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output_char (buffer, a, a_glyph);
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if (b)
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output_char (buffer, b, b_glyph);
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return true;
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}
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return false;
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}
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static bool
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decompose_compatibility (hb_font_t *font, hb_buffer_t *buffer,
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hb_codepoint_t u)
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{
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unsigned int len, i;
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hb_codepoint_t decomposed[HB_UNICODE_MAX_DECOMPOSITION_LEN];
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hb_codepoint_t glyphs[HB_UNICODE_MAX_DECOMPOSITION_LEN];
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len = buffer->unicode->decompose_compatibility (u, decomposed);
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if (!len)
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return false;
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for (i = 0; i < len; i++)
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if (!font->get_glyph (decomposed[i], 0, &glyphs[i]))
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return false;
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for (i = 0; i < len; i++)
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output_char (buffer, decomposed[i], glyphs[i]);
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return true;
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}
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static void
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decompose_current_character (hb_font_t *font, hb_buffer_t *buffer,
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bool shortest)
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{
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hb_codepoint_t glyph;
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/* Kind of a cute waterfall here... */
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if (shortest && font->get_glyph (buffer->cur().codepoint, 0, &glyph))
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next_char (buffer, glyph);
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else if (decompose (font, buffer, shortest, buffer->cur().codepoint))
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skip_char (buffer);
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else if (!shortest && font->get_glyph (buffer->cur().codepoint, 0, &glyph))
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next_char (buffer, glyph);
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else if (decompose_compatibility (font, buffer, buffer->cur().codepoint))
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skip_char (buffer);
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else {
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/* A glyph-not-found case... */
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font->get_glyph (buffer->cur().codepoint, 0, &glyph);
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next_char (buffer, glyph);
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}
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}
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static inline void
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handle_variation_selector_cluster (hb_font_t *font, hb_buffer_t *buffer,
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unsigned int end)
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{
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for (; buffer->idx < end - 1;) {
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if (unlikely (buffer->unicode->is_variation_selector (buffer->cur(+1).codepoint))) {
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/* The next two lines are some ugly lines... But work. */
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font->get_glyph (buffer->cur().codepoint, buffer->cur(+1).codepoint, &buffer->cur().glyph_index());
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buffer->replace_glyphs (2, 1, &buffer->cur().codepoint);
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} else {
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set_glyph (buffer->cur(), font);
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buffer->next_glyph ();
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}
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}
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if (likely (buffer->idx < end)) {
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set_glyph (buffer->cur(), font);
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buffer->next_glyph ();
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}
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}
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static void
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decompose_multi_char_cluster (hb_font_t *font, hb_buffer_t *buffer,
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unsigned int end)
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{
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/* TODO Currently if there's a variation-selector we give-up, it's just too hard. */
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for (unsigned int i = buffer->idx; i < end; i++)
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if (unlikely (buffer->unicode->is_variation_selector (buffer->info[i].codepoint))) {
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handle_variation_selector_cluster (font, buffer, end);
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return;
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}
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while (buffer->idx < end)
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decompose_current_character (font, buffer, false);
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}
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static int
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compare_combining_class (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
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{
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unsigned int a = _hb_glyph_info_get_modified_combining_class (pa);
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unsigned int b = _hb_glyph_info_get_modified_combining_class (pb);
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return a < b ? -1 : a == b ? 0 : +1;
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}
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void
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_hb_ot_shape_normalize (hb_font_t *font, hb_buffer_t *buffer,
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hb_ot_shape_normalization_mode_t mode)
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{
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bool recompose = mode != HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED;
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bool has_multichar_clusters = false;
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unsigned int count;
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/* We do a fairly straightforward yet custom normalization process in three
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* separate rounds: decompose, reorder, recompose (if desired). Currently
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* this makes two buffer swaps. We can make it faster by moving the last
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* two rounds into the inner loop for the first round, but it's more readable
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* this way. */
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/* First round, decompose */
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buffer->clear_output ();
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count = buffer->len;
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for (buffer->idx = 0; buffer->idx < count;)
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{
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unsigned int end;
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for (end = buffer->idx + 1; end < count; end++)
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if (buffer->cur().cluster != buffer->info[end].cluster)
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break;
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if (buffer->idx + 1 == end)
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decompose_current_character (font, buffer, recompose);
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else {
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decompose_multi_char_cluster (font, buffer, end);
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has_multichar_clusters = true;
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}
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}
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buffer->swap_buffers ();
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if (mode != HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL && !has_multichar_clusters)
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return; /* Done! */
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/* Second round, reorder (inplace) */
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count = buffer->len;
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for (unsigned int i = 0; i < count; i++)
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{
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if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]) == 0)
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continue;
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unsigned int end;
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for (end = i + 1; end < count; end++)
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if (_hb_glyph_info_get_modified_combining_class (&buffer->info[end]) == 0)
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break;
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/* We are going to do a bubble-sort. Only do this if the
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* sequence is short. Doing it on long sequences can result
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* in an O(n^2) DoS. */
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if (end - i > 10) {
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i = end;
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continue;
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}
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hb_bubble_sort (buffer->info + i, end - i, compare_combining_class);
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i = end;
|
|
}
|
|
|
|
|
|
if (!recompose)
|
|
return;
|
|
|
|
/* Third round, recompose */
|
|
|
|
/* As noted in the comment earlier, we don't try to combine
|
|
* ccc=0 chars with their previous Starter. */
|
|
|
|
buffer->clear_output ();
|
|
count = buffer->len;
|
|
unsigned int starter = 0;
|
|
buffer->next_glyph ();
|
|
while (buffer->idx < count)
|
|
{
|
|
hb_codepoint_t composed, glyph;
|
|
if (/* If mode is NOT COMPOSED_FULL (ie. it's COMPOSED_DIACRITICS), we don't try to
|
|
* compose a CCC=0 character with it's preceding starter. */
|
|
(mode == HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL ||
|
|
_hb_glyph_info_get_modified_combining_class (&buffer->cur()) != 0) &&
|
|
/* If there's anything between the starter and this char, they should have CCC
|
|
* smaller than this character's. */
|
|
(starter == buffer->out_len - 1 ||
|
|
_hb_glyph_info_get_modified_combining_class (&buffer->prev()) < _hb_glyph_info_get_modified_combining_class (&buffer->cur())) &&
|
|
/* And compose. */
|
|
compose_func (buffer->unicode,
|
|
buffer->out_info[starter].codepoint,
|
|
buffer->cur().codepoint,
|
|
&composed) &&
|
|
/* And the font has glyph for the composite. */
|
|
font->get_glyph (composed, 0, &glyph))
|
|
{
|
|
/* Composes. */
|
|
buffer->next_glyph (); /* Copy to out-buffer. */
|
|
if (unlikely (buffer->in_error))
|
|
return;
|
|
buffer->merge_out_clusters (starter, buffer->out_len);
|
|
buffer->out_len--; /* Remove the second composable. */
|
|
buffer->out_info[starter].codepoint = composed; /* Modify starter and carry on. */
|
|
set_glyph (buffer->out_info[starter], font);
|
|
_hb_glyph_info_set_unicode_props (&buffer->out_info[starter], buffer->unicode);
|
|
|
|
continue;
|
|
}
|
|
|
|
/* Blocked, or doesn't compose. */
|
|
buffer->next_glyph ();
|
|
|
|
if (_hb_glyph_info_get_modified_combining_class (&buffer->prev()) == 0)
|
|
starter = buffer->out_len - 1;
|
|
}
|
|
buffer->swap_buffers ();
|
|
|
|
}
|