layout/generic/nsTextFrameUtils.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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  15  * The Original Code is Novell code.
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  18  * Portions created by the Initial Developer are Copyright (C) 2006
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  21  * Contributor(s):
  22  *   robert@ocallahan.org
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  37
  38 #include "nsTextFrameUtils.h"
  39
  40 #include "nsContentUtils.h"
  41 #include "nsIWordBreaker.h"
  42 #include "gfxFont.h"
  43 #include "nsUnicharUtils.h"
  44 #include "nsBidiUtils.h"
  45
  46 // XXX TODO implement transform of backslash to yen that nsTextTransform does
  47 // when requested by PresContext->LanguageSpecificTransformType(). Do it with
  48 // a new factory type that just munges the input stream. But first, check
  49 // that we really still need this, it's only enabled via a hidden pref
  50 // which defaults false...
  51
  52 #define UNICODE_ZWSP 0x200B
  53
  54 static PRBool IsDiscardable(PRUnichar ch, PRUint32* aFlags)
  55 {
  56   // Unlike IS_DISCARDABLE, we don't discard \r. \r will be ignored by gfxTextRun
  57   // and discarding it would force us to copy text in many cases of preformatted
  58   // text containing \r\n.
  59   if (ch == CH_SHY) {
  60     *aFlags |= nsTextFrameUtils::TEXT_HAS_SHY;
  61     return PR_TRUE;
  62   }
  63   if ((ch & 0xFF00) != 0x2000) {
  64     // Not a Bidi control character
  65     return PR_FALSE;
  66   }
  67   return IS_BIDI_CONTROL_CHAR(ch);
  68 }
  69
  70 static PRBool IsDiscardable(PRUint8 ch, PRUint32* aFlags)
  71 {
  72   if (ch == CH_SHY) {
  73     *aFlags |= nsTextFrameUtils::TEXT_HAS_SHY;
  74     return PR_TRUE;
  75   }
  76   return PR_FALSE;
  77 }
  78
  79 PRUnichar*
  80 nsTextFrameUtils::TransformText(const PRUnichar* aText, PRUint32 aLength,
  81                                 PRUnichar* aOutput,
  82                                 CompressionMode aCompression,
  83                                 PRPackedBool* aIncomingWhitespace,
  84                                 gfxSkipCharsBuilder* aSkipChars,
  85                                 PRUint32* aAnalysisFlags)
  86 {
  87   PRUint32 flags = 0;
  88   PRUnichar* outputStart = aOutput;
  89
  90   if (aCompression == COMPRESS_NONE) {
  91     // Skip discardables.
  92     PRUint32 i;
  93     for (i = 0; i < aLength; ++i) {
  94       PRUnichar ch = *aText++;
  95       if (IsDiscardable(ch, &flags)) {
  96         aSkipChars->SkipChar();
  97       } else {
  98         aSkipChars->KeepChar();
  99         if (ch == '\t') {
 100           flags |= TEXT_HAS_TAB;
 101         }
 102         *aOutput++ = ch;
 103       }
 104     }
 105     *aIncomingWhitespace = PR_FALSE;
 106   } else {
 107     PRBool inWhitespace = *aIncomingWhitespace;
 108     PRUint32 i;
 109     for (i = 0; i < aLength; ++i) {
 110       PRUnichar ch = *aText++;
 111       PRBool nowInWhitespace;
 112       if (ch == ' ' &&
 113           (i + 1 >= aLength ||
 114            !IsSpaceCombiningSequenceTail(aText, aLength - (i + 1)))) {
 115         nowInWhitespace = PR_TRUE;
 116       } else if (ch == '\n' && aCompression == COMPRESS_WHITESPACE_NEWLINE) {
 117         if (i > 0 && IS_CJ_CHAR(aText[-1]) &&
 118             i + 1 < aLength && IS_CJ_CHAR(aText[1])) {
 119           // Discard newlines between CJK chars.
 120           // XXX this really requires more context to get right!
 121           aSkipChars->SkipChar();
 122           continue;
 123         }
 124         nowInWhitespace = PR_TRUE;
 125       } else {
 126         nowInWhitespace = ch == '\t';
 127       }
 128
 129       if (!nowInWhitespace) {
 130         if (IsDiscardable(ch, &flags)) {
 131           aSkipChars->SkipChar();
 132           nowInWhitespace = inWhitespace;
 133         } else {
 134           *aOutput++ = ch;
 135           aSkipChars->KeepChar();
 136         }
 137       } else {
 138         if (inWhitespace) {
 139           aSkipChars->SkipChar();
 140         } else {
 141           if (ch != ' ') {
 142             flags |= TEXT_WAS_TRANSFORMED;
 143           }
 144           *aOutput++ = ' ';
 145           aSkipChars->KeepChar();
 146         }
 147       }
 148       inWhitespace = nowInWhitespace;
 149     }
 150     *aIncomingWhitespace = inWhitespace;
 151   }
 152
 153   if (outputStart + aLength != aOutput) {
 154     flags |= TEXT_WAS_TRANSFORMED;
 155   }
 156   *aAnalysisFlags = flags;
 157   return aOutput;
 158 }
 159
 160 PRUint8*
 161 nsTextFrameUtils::TransformText(const PRUint8* aText, PRUint32 aLength,
 162                                 PRUint8* aOutput,
 163                                 CompressionMode aCompression,
 164                                 PRPackedBool* aIncomingWhitespace,
 165                                 gfxSkipCharsBuilder* aSkipChars,
 166                                 PRUint32* aAnalysisFlags)
 167 {
 168   PRUint32 flags = 0;
 169   PRUint8* outputStart = aOutput;
 170
 171   if (aCompression == COMPRESS_NONE) {
 172     // Skip discardables.
 173     PRUint32 i;
 174     for (i = 0; i < aLength; ++i) {
 175       PRUint8 ch = *aText++;
 176       if (IsDiscardable(ch, &flags)) {
 177         aSkipChars->SkipChar();
 178       } else {
 179         aSkipChars->KeepChar();
 180         if (ch == '\t') {
 181           flags |= TEXT_HAS_TAB;
 182         }
 183         *aOutput++ = ch;
 184       }
 185     }
 186     *aIncomingWhitespace = PR_FALSE;
 187   } else {
 188     PRBool inWhitespace = *aIncomingWhitespace;
 189     PRUint32 i;
 190     for (i = 0; i < aLength; ++i) {
 191       PRUint8 ch = *aText++;
 192       PRBool nowInWhitespace = ch == ' ' || ch == '\t' ||
 193         (ch == '\n' && aCompression == COMPRESS_WHITESPACE_NEWLINE);
 194       if (!nowInWhitespace) {
 195         if (IsDiscardable(ch, &flags)) {
 196           aSkipChars->SkipChar();
 197           nowInWhitespace = inWhitespace;
 198         } else {
 199           *aOutput++ = ch;
 200           aSkipChars->KeepChar();
 201         }
 202       } else {
 203         if (inWhitespace) {
 204           aSkipChars->SkipChar();
 205         } else {
 206           if (ch != ' ') {
 207             flags |= TEXT_WAS_TRANSFORMED;
 208           }
 209           *aOutput++ = ' ';
 210           aSkipChars->KeepChar();
 211         }
 212       }
 213       inWhitespace = nowInWhitespace;
 214     }
 215     *aIncomingWhitespace = inWhitespace;
 216   }
 217
 218   if (outputStart + aLength != aOutput) {
 219     flags |= TEXT_WAS_TRANSFORMED;
 220   }
 221   *aAnalysisFlags = flags;
 222   return aOutput;
 223 }
 224
 225 PRBool nsSkipCharsRunIterator::NextRun() {
 226   do {
 227     if (mRunLength) {
 228       mIterator.AdvanceOriginal(mRunLength);
 229       NS_ASSERTION(mRunLength > 0, "No characters in run (initial length too large?)");
 230       if (!mSkipped || mLengthIncludesSkipped) {
 231         mRemainingLength -= mRunLength;
 232       }
 233     }
 234     if (!mRemainingLength)
 235       return PR_FALSE;
 236     PRInt32 length;
 237     mSkipped = mIterator.IsOriginalCharSkipped(&length);
 238     mRunLength = PR_MIN(length, mRemainingLength);
 239   } while (!mVisitSkipped && mSkipped);
 240
 241   return PR_TRUE;
 242 }