layout/generic/nsTextFrameUtils.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
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  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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  14  *
  15  * The Original Code is Novell code.
  16  *
  17  * The Initial Developer of the Original Code is Novell Corporation.
  18  * Portions created by the Initial Developer are Copyright (C) 2006
  19  * the Initial Developer. All Rights Reserved.
  20  *
  21  * Contributor(s):
  22  *   robert@ocallahan.org
  23  *   Ehsan Akhgari <ehsan.akhgari@gmail.com>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either the GNU General Public License Version 2 or later (the "GPL"), or
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  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #include "nsTextFrameUtils.h"
  40
  41 #include "nsContentUtils.h"
  42 #include "nsIWordBreaker.h"
  43 #include "gfxFont.h"
  44 #include "nsUnicharUtils.h"
  45 #include "nsBidiUtils.h"
  46
  47 // XXX TODO implement transform of backslash to yen that nsTextTransform does
  48 // when requested by PresContext->LanguageSpecificTransformType(). Do it with
  49 // a new factory type that just munges the input stream. But first, check
  50 // that we really still need this, it's only enabled via a hidden pref
  51 // which defaults false...
  52
  53 #define UNICODE_ZWSP 0x200B
  54
  55 static PRBool IsDiscardable(PRUnichar ch, PRUint32* aFlags)
  56 {
  57   // Unlike IS_DISCARDABLE, we don't discard \r. \r will be ignored by gfxTextRun
  58   // and discarding it would force us to copy text in many cases of preformatted
  59   // text containing \r\n.
  60   if (ch == CH_SHY) {
  61     *aFlags |= nsTextFrameUtils::TEXT_HAS_SHY;
  62     return PR_TRUE;
  63   }
  64   if ((ch & 0xFF00) != 0x2000) {
  65     // Not a Bidi control character
  66     return PR_FALSE;
  67   }
  68   return IS_BIDI_CONTROL_CHAR(ch);
  69 }
  70
  71 static PRBool IsDiscardable(PRUint8 ch, PRUint32* aFlags)
  72 {
  73   if (ch == CH_SHY) {
  74     *aFlags |= nsTextFrameUtils::TEXT_HAS_SHY;
  75     return PR_TRUE;
  76   }
  77   return PR_FALSE;
  78 }
  79
  80 PRUnichar*
  81 nsTextFrameUtils::TransformText(const PRUnichar* aText, PRUint32 aLength,
  82                                 PRUnichar* aOutput,
  83                                 CompressionMode aCompression,
  84                                 PRUint8* aIncomingFlags,
  85                                 gfxSkipCharsBuilder* aSkipChars,
  86                                 PRUint32* aAnalysisFlags)
  87 {
  88   PRUint32 flags = 0;
  89   PRUnichar* outputStart = aOutput;
  90
  91   PRBool lastCharArabic = PR_FALSE;
  92
  93   if (aCompression == COMPRESS_NONE) {
  94     // Skip discardables.
  95     PRUint32 i;
  96     for (i = 0; i < aLength; ++i) {
  97       PRUnichar ch = *aText++;
  98       if (IsDiscardable(ch, &flags)) {
  99         aSkipChars->SkipChar();
 100       } else {
 101         aSkipChars->KeepChar();
 102         if (ch == '\t') {
 103           flags |= TEXT_HAS_TAB;
 104         } else if (ch != ' ' && ch != '\n') {
 105           // we already know it's not a tab from the previous check
 106           lastCharArabic = IS_ARABIC_CHAR(ch);
 107         }
 108         *aOutput++ = ch;
 109       }
 110     }
 111     if (lastCharArabic) {
 112       *aIncomingFlags |= INCOMING_ARABICCHAR;
 113     } else {
 114       *aIncomingFlags &= ~INCOMING_ARABICCHAR;
 115     }
 116     *aIncomingFlags &= ~INCOMING_WHITESPACE;
 117   } else {
 118     PRBool inWhitespace = (*aIncomingFlags & INCOMING_WHITESPACE) != 0;
 119     PRUint32 i;
 120     for (i = 0; i < aLength; ++i) {
 121       PRUnichar ch = *aText++;
 122       PRBool nowInWhitespace;
 123       if (ch == ' ' &&
 124           (i + 1 >= aLength ||
 125            !IsSpaceCombiningSequenceTail(aText, aLength - (i + 1)))) {
 126         nowInWhitespace = PR_TRUE;
 127       } else if (ch == '\n' && aCompression == COMPRESS_WHITESPACE_NEWLINE) {
 128         if (i > 0 && IS_CJ_CHAR(aText[-1]) &&
 129             i + 1 < aLength && IS_CJ_CHAR(aText[1])) {
 130           // Discard newlines between CJK chars.
 131           // XXX this really requires more context to get right!
 132           aSkipChars->SkipChar();
 133           continue;
 134         }
 135         nowInWhitespace = PR_TRUE;
 136       } else {
 137         nowInWhitespace = ch == '\t';
 138       }
 139
 140       if (!nowInWhitespace) {
 141         if (IsDiscardable(ch, &flags)) {
 142           aSkipChars->SkipChar();
 143           nowInWhitespace = inWhitespace;
 144         } else {
 145           *aOutput++ = ch;
 146           aSkipChars->KeepChar();
 147           lastCharArabic = IS_ARABIC_CHAR(ch);
 148         }
 149       } else {
 150         if (inWhitespace) {
 151           aSkipChars->SkipChar();
 152         } else {
 153           if (ch != ' ') {
 154             flags |= TEXT_WAS_TRANSFORMED;
 155           }
 156           *aOutput++ = ' ';
 157           aSkipChars->KeepChar();
 158         }
 159       }
 160       inWhitespace = nowInWhitespace;
 161     }
 162     if (lastCharArabic) {
 163       *aIncomingFlags |= INCOMING_ARABICCHAR;
 164     } else {
 165       *aIncomingFlags &= ~INCOMING_ARABICCHAR;
 166     }
 167     if (inWhitespace) {
 168       *aIncomingFlags |= INCOMING_WHITESPACE;
 169     } else {
 170       *aIncomingFlags &= ~INCOMING_WHITESPACE;
 171     }
 172   }
 173
 174   if (outputStart + aLength != aOutput) {
 175     flags |= TEXT_WAS_TRANSFORMED;
 176   }
 177   *aAnalysisFlags = flags;
 178   return aOutput;
 179 }
 180
 181 PRUint8*
 182 nsTextFrameUtils::TransformText(const PRUint8* aText, PRUint32 aLength,
 183                                 PRUint8* aOutput,
 184                                 CompressionMode aCompression,
 185                                 PRUint8* aIncomingFlags,
 186                                 gfxSkipCharsBuilder* aSkipChars,
 187                                 PRUint32* aAnalysisFlags)
 188 {
 189   PRUint32 flags = 0;
 190   PRUint8* outputStart = aOutput;
 191
 192   if (aCompression == COMPRESS_NONE) {
 193     // Skip discardables.
 194     PRUint32 i;
 195     for (i = 0; i < aLength; ++i) {
 196       PRUint8 ch = *aText++;
 197       if (IsDiscardable(ch, &flags)) {
 198         aSkipChars->SkipChar();
 199       } else {
 200         aSkipChars->KeepChar();
 201         if (ch == '\t') {
 202           flags |= TEXT_HAS_TAB;
 203         }
 204         *aOutput++ = ch;
 205       }
 206     }
 207     *aIncomingFlags &= ~(INCOMING_ARABICCHAR | INCOMING_WHITESPACE);
 208   } else {
 209     PRBool inWhitespace = (*aIncomingFlags & INCOMING_WHITESPACE) != 0;
 210     PRUint32 i;
 211     for (i = 0; i < aLength; ++i) {
 212       PRUint8 ch = *aText++;
 213       PRBool nowInWhitespace = ch == ' ' || ch == '\t' ||
 214         (ch == '\n' && aCompression == COMPRESS_WHITESPACE_NEWLINE);
 215       if (!nowInWhitespace) {
 216         if (IsDiscardable(ch, &flags)) {
 217           aSkipChars->SkipChar();
 218           nowInWhitespace = inWhitespace;
 219         } else {
 220           *aOutput++ = ch;
 221           aSkipChars->KeepChar();
 222         }
 223       } else {
 224         if (inWhitespace) {
 225           aSkipChars->SkipChar();
 226         } else {
 227           if (ch != ' ') {
 228             flags |= TEXT_WAS_TRANSFORMED;
 229           }
 230           *aOutput++ = ' ';
 231           aSkipChars->KeepChar();
 232         }
 233       }
 234       inWhitespace = nowInWhitespace;
 235     }
 236     *aIncomingFlags &= ~INCOMING_ARABICCHAR;
 237     if (inWhitespace) {
 238       *aIncomingFlags |= INCOMING_WHITESPACE;
 239     } else {
 240       *aIncomingFlags &= ~INCOMING_WHITESPACE;
 241     }
 242   }
 243
 244   if (outputStart + aLength != aOutput) {
 245     flags |= TEXT_WAS_TRANSFORMED;
 246   }
 247   *aAnalysisFlags = flags;
 248   return aOutput;
 249 }
 250
 251 PRBool nsSkipCharsRunIterator::NextRun() {
 252   do {
 253     if (mRunLength) {
 254       mIterator.AdvanceOriginal(mRunLength);
 255       NS_ASSERTION(mRunLength > 0, "No characters in run (initial length too large?)");
 256       if (!mSkipped || mLengthIncludesSkipped) {
 257         mRemainingLength -= mRunLength;
 258       }
 259     }
 260     if (!mRemainingLength)
 261       return PR_FALSE;
 262     PRInt32 length;
 263     mSkipped = mIterator.IsOriginalCharSkipped(&length);
 264     mRunLength = NS_MIN(length, mRemainingLength);
 265   } while (!mVisitSkipped && mSkipped);
 266
 267   return PR_TRUE;
 268 }