Refine hyphenation around punctuation

Implement a WordBreaker that defines our concept of valid word
boundaries, customizing the ICU behavior. Currently, we suppress line
breaks at soft hyphens (these are handled specially). Also, the
new WordBreaker class has methods that determine the start and end
of the word (punctuation stripped) for the purpose of hyphenation.

This patch, in its current form, doesn't handle email addresses and
URLs specially, but the WordBreaker class is the correct place to do
so. Also, special case handling of hyphens and dashes is still done
in LineBreaker, but all of that should be moved to WordBreaker.

Bug: 20126487
Bug: 20566159
Change-Id: I492cbad963f9b74a2915f010dad46bb91f97b2fe

1 files changed, 49 insertions, 58 deletions

diff --git a/libs/minikin/LineBreaker.cpp b/libs/minikin/LineBreaker.cpp
index a2507e0..214f195 100644
--- a/libs/minikin/LineBreaker.cpp
+++ b/libs/minikin/LineBreaker.cpp
@@ -29,7 +29,6 @@ using std::vector;
 namespace android {
 
 const int CHAR_TAB = 0x0009;
-const uint16_t CHAR_SOFT_HYPHEN = 0x00AD;
 
 // Large scores in a hierarchy; we prefer desperate breaks to an overfull line. All these
 // constants are larger than any reasonable actual width score.
@@ -55,23 +54,16 @@ const size_t LONGEST_HYPHENATED_WORD = 45;
 const size_t MAX_TEXT_BUF_RETAIN = 32678;
 
 void LineBreaker::setLocale(const icu::Locale& locale, Hyphenator* hyphenator) {
-    delete mBreakIterator;
-    UErrorCode status = U_ZERO_ERROR;
-    mBreakIterator = icu::BreakIterator::createLineInstance(locale, status);
-    // TODO: check status
+    mWordBreaker.setLocale(locale);
 
-    // TODO: load actual resource dependent on locale; letting Minikin do it is a hack
     mHyphenator = hyphenator;
 }
 
 void LineBreaker::setText() {
-    UErrorCode status = U_ZERO_ERROR;
-    utext_openUChars(&mUText, mTextBuf.data(), mTextBuf.size(), &status);
-    mBreakIterator->setText(&mUText, status);
-    mBreakIterator->first();
+    mWordBreaker.setText(mTextBuf.data(), mTextBuf.size());
 
     // handle initial break here because addStyleRun may never be called
-    mBreakIterator->next();
+    mWordBreaker.next();
     mCandidates.clear();
     Candidate cand = {0, 0, 0.0, 0.0, 0.0, 0.0, 0, 0};
     mCandidates.push_back(cand);
@@ -151,8 +143,8 @@ float LineBreaker::addStyleRun(MinikinPaint* paint, const FontCollection* typefa
         mLinePenalty = std::max(mLinePenalty, hyphenPenalty * LINE_PENALTY_MULTIPLIER);
     }
 
-    size_t current = (size_t)mBreakIterator->current();
-    size_t wordEnd = start;
+    size_t current = (size_t)mWordBreaker.current();
+    size_t afterWord = start;
     size_t lastBreak = start;
     ParaWidth lastBreakWidth = mWidth;
     ParaWidth postBreak = mWidth;
@@ -170,58 +162,56 @@ float LineBreaker::addStyleRun(MinikinPaint* paint, const FontCollection* typefa
             mWidth += mCharWidths[i];
             if (!isLineEndSpace(c)) {
                 postBreak = mWidth;
-                wordEnd = i + 1;
+                afterWord = i + 1;
             }
         }
         if (i + 1 == current) {
-            // Override ICU's treatment of soft hyphen as a break opportunity, because we want it
-            // to be a hyphen break, with penalty and drawing behavior.
-            if (c != CHAR_SOFT_HYPHEN) {
-                // TODO: Add a new type of HyphenEdit for breaks whose hyphen already exists, so
-                // we can pass the whole word down to Hyphenator like the soft hyphen case.
-                bool wordEndsInHyphen = isLineBreakingHyphen(c);
-                if (paint != nullptr && mHyphenator != nullptr &&
-                        mHyphenationFrequency != kHyphenationFrequency_None &&
-                        !wordEndsInHyphen && !temporarilySkipHyphenation &&
-                        wordEnd > lastBreak && wordEnd - lastBreak <= LONGEST_HYPHENATED_WORD) {
-                    mHyphenator->hyphenate(&mHyphBuf, &mTextBuf[lastBreak], wordEnd - lastBreak);
-    #if VERBOSE_DEBUG
-                    std::string hyphenatedString;
-                    for (size_t j = lastBreak; j < wordEnd; j++) {
-                        if (mHyphBuf[j - lastBreak]) hyphenatedString.push_back('-');
-                        // Note: only works with ASCII, should do UTF-8 conversion here
-                        hyphenatedString.push_back(buffer()[j]);
-                    }
-                    ALOGD("hyphenated string: %s", hyphenatedString.c_str());
-    #endif
-
-                    // measure hyphenated substrings
-                    for (size_t j = lastBreak; j < wordEnd; j++) {
-                        uint8_t hyph = mHyphBuf[j - lastBreak];
-                        if (hyph) {
-                            paint->hyphenEdit = hyph;
-                            layout.doLayout(mTextBuf.data(), lastBreak, j - lastBreak,
-                                    mTextBuf.size(), bidiFlags, style, *paint);
-                            ParaWidth hyphPostBreak = lastBreakWidth + layout.getAdvance();
-                            paint->hyphenEdit = 0;
-                            layout.doLayout(mTextBuf.data(), j, wordEnd - j,
-                                    mTextBuf.size(), bidiFlags, style, *paint);
-                            ParaWidth hyphPreBreak = postBreak - layout.getAdvance();
-                            addWordBreak(j, hyphPreBreak, hyphPostBreak, hyphenPenalty, hyph);
-                        }
-                    }
+            // TODO: Add a new type of HyphenEdit for breaks whose hyphen already exists, so
+            // we can pass the whole word down to Hyphenator like the soft hyphen case.
+            bool wordEndsInHyphen = isLineBreakingHyphen(c);
+            size_t wordStart = mWordBreaker.wordStart();
+            size_t wordEnd = mWordBreaker.wordEnd();
+            if (paint != nullptr && mHyphenator != nullptr &&
+                    mHyphenationFrequency != kHyphenationFrequency_None &&
+                    !wordEndsInHyphen && !temporarilySkipHyphenation &&
+                    wordEnd > wordStart && wordEnd - wordStart <= LONGEST_HYPHENATED_WORD) {
+                mHyphenator->hyphenate(&mHyphBuf, &mTextBuf[wordStart], wordEnd - wordStart);
+#if VERBOSE_DEBUG
+                std::string hyphenatedString;
+                for (size_t j = wordStart; j < wordEnd; j++) {
+                    if (mHyphBuf[j - wordStart]) hyphenatedString.push_back('-');
+                    // Note: only works with ASCII, should do UTF-8 conversion here
+                    hyphenatedString.push_back(buffer()[j]);
                 }
-                // Skip hyphenating the next word if and only if the present word ends in a hyphen
-                temporarilySkipHyphenation = wordEndsInHyphen;
+                ALOGD("hyphenated string: %s", hyphenatedString.c_str());
+#endif
 
-                // Skip break for zero-width characters inside replacement span
-                if (paint != nullptr || current == end || mCharWidths[current] > 0) {
-                    addWordBreak(current, mWidth, postBreak, 0.0, 0);
+                // measure hyphenated substrings
+                for (size_t j = wordStart; j < wordEnd; j++) {
+                    uint8_t hyph = mHyphBuf[j - wordStart];
+                    if (hyph) {
+                        paint->hyphenEdit = hyph;
+                        layout.doLayout(mTextBuf.data(), lastBreak, j - lastBreak,
+                                mTextBuf.size(), bidiFlags, style, *paint);
+                        ParaWidth hyphPostBreak = lastBreakWidth + layout.getAdvance();
+                        paint->hyphenEdit = 0;
+                        layout.doLayout(mTextBuf.data(), j, afterWord - j,
+                                mTextBuf.size(), bidiFlags, style, *paint);
+                        ParaWidth hyphPreBreak = postBreak - layout.getAdvance();
+                        addWordBreak(j, hyphPreBreak, hyphPostBreak, hyphenPenalty, hyph);
+                    }
                 }
-                lastBreak = current;
-                lastBreakWidth = mWidth;
             }
-            current = (size_t)mBreakIterator->next();
+            // Skip hyphenating the next word if and only if the present word ends in a hyphen
+            temporarilySkipHyphenation = wordEndsInHyphen;
+
+            // Skip break for zero-width characters inside replacement span
+            if (paint != nullptr || current == end || mCharWidths[current] > 0) {
+                addWordBreak(current, mWidth, postBreak, 0.0, 0);
+            }
+            lastBreak = current;
+            lastBreakWidth = mWidth;
+            current = (size_t)mWordBreaker.next();
         }
     }
 
@@ -425,6 +415,7 @@ size_t LineBreaker::computeBreaks() {
 }
 
 void LineBreaker::finish() {
+    mWordBreaker.finish();
     mWidth = 0;
     mCandidates.clear();
     mBreaks.clear();