gfx/thebes/gfxScriptItemizer.cpp

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /*
   7  * This file is based on usc_impl.c from ICU 4.2.0.1, slightly adapted
   8  * for use within Mozilla Gecko, separate from a standard ICU build.
   9  *
  10  * The original ICU license of the code follows:
  11  *
  12  * ICU License - ICU 1.8.1 and later
  13  *
  14  * COPYRIGHT AND PERMISSION NOTICE
  15  *
  16  * Copyright (c) 1995-2009 International Business Machines Corporation and
  17  * others
  18  *
  19  * All rights reserved.
  20  *
  21  * Permission is hereby granted, free of charge, to any person obtaining a
  22  * copy of this software and associated documentation files (the "Software"),
  23  * to deal in the Software without restriction, including without limitation
  24  * the rights to use, copy, modify, merge, publish, distribute, and/or sell
  25  * copies of the Software, and to permit persons to whom the Software is
  26  * furnished to do so, provided that the above copyright notice(s) and this
  27  * permission notice appear in all copies of the Software and that both the
  28  * above copyright notice(s) and this permission notice appear in supporting
  29  * documentation.
  30  *
  31  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  32  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  33  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
  34  * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE
  35  * BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES,
  36  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  37  * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  38  * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  39  * SOFTWARE.
  40  *
  41  * Except as contained in this notice, the name of a copyright holder shall
  42  * not be used in advertising or otherwise to promote the sale, use or other
  43  * dealings in this Software without prior written authorization of the
  44  * copyright holder.
  45  *
  46  * All trademarks and registered trademarks mentioned herein are the property
  47  * of their respective owners.
  48  */
  49
  50 #include "gfxScriptItemizer.h"
  51 #include "mozilla/intl/UnicodeProperties.h"
  52 #include "nsCharTraits.h"
  53 #include "nsUnicodeProperties.h"
  54 #include "harfbuzz/hb.h"
  55
  56 using namespace mozilla::intl;
  57 using namespace mozilla::unicode;
  58
  59 #define MOD(sp) ((sp) % PAREN_STACK_DEPTH)
  60 #define LIMIT_INC(sp) \
  61   (((sp) < PAREN_STACK_DEPTH) ? (sp) + 1 : PAREN_STACK_DEPTH)
  62 #define INC(sp, count) (MOD((sp) + (count)))
  63 #define INC1(sp) (INC(sp, 1))
  64 #define DEC(sp, count) (MOD((sp) + PAREN_STACK_DEPTH - (count)))
  65 #define DEC1(sp) (DEC(sp, 1))
  66 #define STACK_IS_EMPTY() (pushCount <= 0)
  67 #define STACK_IS_NOT_EMPTY() (!STACK_IS_EMPTY())
  68 #define TOP() (parenStack[parenSP])
  69 #define SYNC_FIXUP() (fixupCount = 0)
  70
  71 void gfxScriptItemizer::push(uint32_t endPairChar, Script newScriptCode) {
  72   pushCount = LIMIT_INC(pushCount);
  73   fixupCount = LIMIT_INC(fixupCount);
  74
  75   parenSP = INC1(parenSP);
  76   parenStack[parenSP].endPairChar = endPairChar;
  77   parenStack[parenSP].scriptCode = newScriptCode;
  78 }
  79
  80 void gfxScriptItemizer::pop() {
  81   if (STACK_IS_EMPTY()) {
  82     return;
  83   }
  84
  85   if (fixupCount > 0) {
  86     fixupCount -= 1;
  87   }
  88
  89   pushCount -= 1;
  90   parenSP = DEC1(parenSP);
  91
  92   /* If the stack is now empty, reset the stack
  93      pointers to their initial values.
  94    */
  95   if (STACK_IS_EMPTY()) {
  96     parenSP = -1;
  97   }
  98 }
  99
 100 void gfxScriptItemizer::fixup(Script newScriptCode) {
 101   int32_t fixupSP = DEC(parenSP, fixupCount);
 102
 103   while (fixupCount-- > 0) {
 104     fixupSP = INC1(fixupSP);
 105     parenStack[fixupSP].scriptCode = newScriptCode;
 106   }
 107 }
 108
 109 static inline bool CanMergeWithContext(Script aScript) {
 110   return aScript <= Script::INHERITED || aScript == Script::UNKNOWN;
 111 }
 112
 113 // We regard the current char as having the same script as the in-progress run
 114 // if either script is Common/Inherited/Unknown, or if the run script appears
 115 // in the character's ScriptExtensions, or if the char is a cluster extender.
 116 static inline bool SameScript(Script runScript, Script currCharScript,
 117                               uint32_t aCurrCh) {
 118   return CanMergeWithContext(runScript) ||
 119          CanMergeWithContext(currCharScript) || currCharScript == runScript ||
 120          IsClusterExtender(aCurrCh) ||
 121          UnicodeProperties::HasScript(aCurrCh, runScript);
 122 }
 123
 124 gfxScriptItemizer::Run gfxScriptItemizer::Next() {
 125   MOZ_ASSERT(textLength == 0 || (textIs8bit && textPtr._1b) ||
 126              (!textIs8bit && textPtr._2b));
 127
 128   /* if we've fallen off the end of the text, we're done */
 129   if (scriptLimit >= textLength) {
 130     return Run{};
 131   }
 132
 133   SYNC_FIXUP();
 134   scriptCode = Script::COMMON;
 135   Script fallbackScript = Script::UNKNOWN;
 136
 137   for (scriptStart = scriptLimit; scriptLimit < textLength; scriptLimit += 1) {
 138     uint32_t ch;
 139     Script sc;
 140     uint32_t startOfChar = scriptLimit;
 141
 142     ch = textIs8bit ? textPtr._1b[scriptLimit] : textPtr._2b[scriptLimit];
 143
 144     /* decode UTF-16 (may be surrogate pair) */
 145     if (NS_IS_HIGH_SURROGATE(ch) && scriptLimit < textLength - 1) {
 146       uint32_t low = textPtr._2b[scriptLimit + 1];
 147       if (NS_IS_LOW_SURROGATE(low)) {
 148         ch = SURROGATE_TO_UCS4(ch, low);
 149         scriptLimit += 1;
 150       }
 151     }
 152
 153     // Initialize gc to UNASSIGNED; we'll only set it to the true GC
 154     // if the character has script=COMMON, otherwise we don't care.
 155     uint8_t gc = HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED;
 156
 157     sc = UnicodeProperties::GetScriptCode(ch);
 158     if (sc == Script::COMMON) {
 159       /*
 160        * Paired character handling:
 161        *
 162        * if it's an open character, push it onto the stack.
 163        * if it's a close character, find the matching open on the
 164        * stack, and use that script code. Any non-matching open
 165        * characters above it on the stack will be popped.
 166        *
 167        * We only do this if the script is COMMON; for chars with
 168        * specific script assignments, we just use them as-is.
 169        */
 170       gc = GetGeneralCategory(ch);
 171       if (gc == HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION) {
 172         uint32_t endPairChar = UnicodeProperties::CharMirror(ch);
 173         if (endPairChar != ch) {
 174           push(endPairChar, scriptCode);
 175         }
 176       } else if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&
 177                  UnicodeProperties::IsMirrored(ch)) {
 178         while (STACK_IS_NOT_EMPTY() && TOP().endPairChar != ch) {
 179           pop();
 180         }
 181
 182         if (STACK_IS_NOT_EMPTY()) {
 183           sc = TOP().scriptCode;
 184         }
 185       }
 186     }
 187
 188     // Both Hiragana and Katakana are shaped as OpenType 'kana'. Merge them
 189     // here to avoid script-run breaks and allow kerning to apply between the
 190     // two alphabets.
 191     if (sc == Script::HIRAGANA) {
 192       sc = Script::KATAKANA;
 193     }
 194
 195     if (SameScript(scriptCode, sc, ch)) {
 196       if (scriptCode == Script::COMMON) {
 197         // If we have not yet resolved a specific scriptCode for the run,
 198         // check whether this character provides it.
 199         if (!CanMergeWithContext(sc)) {
 200           // Use this character's script.
 201           scriptCode = sc;
 202           fixup(scriptCode);
 203         } else if (fallbackScript == Script::UNKNOWN) {
 204           // See if the character has a ScriptExtensions property we can
 205           // store for use in the event the run remains unresolved.
 206           UnicodeProperties::ScriptExtensionVector extensions;
 207           auto extResult = UnicodeProperties::GetExtensions(ch, extensions);
 208           if (extResult.isOk()) {
 209             Script ext = Script(extensions[0]);
 210             if (!CanMergeWithContext(ext)) {
 211               fallbackScript = ext;
 212             }
 213           }
 214         }
 215       }
 216
 217       /*
 218        * if this character is a close paired character,
 219        * pop the matching open character from the stack
 220        */
 221       if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&
 222           UnicodeProperties::IsMirrored(ch)) {
 223         pop();
 224       }
 225     } else {
 226       /*
 227        * reset scriptLimit in case it was advanced during reading a
 228        * multiple-code-unit character
 229        */
 230       scriptLimit = startOfChar;
 231
 232       break;
 233     }
 234   }
 235
 236   return Run{scriptStart, scriptLimit - scriptStart,
 237              (scriptCode == Script::COMMON && fallbackScript != Script::UNKNOWN)
 238                  ? fallbackScript
 239                  : scriptCode};
 240 }