Merge "Suppress linebreaks in emoji ZWJ sequences" into nyc-dev

am: e87aac42d0

* commit 'e87aac42d0f7c80a0836d4cde29ed36e4e848003':
  Suppress linebreaks in emoji ZWJ sequences

engine/src/flutter/libs/minikin/WordBreaker.cpp

@@ -25,6 +25,7 @@
 namespace android {
 
 const uint32_t CHAR_SOFT_HYPHEN = 0x00AD;
+const uint16_t CHAR_ZWJ = 0x200D;
 
 void WordBreaker::setLocale(const icu::Locale& locale) {
     UErrorCode status = U_ZERO_ERROR;
@@ -62,6 +63,32 @@ enum ScanState {
     SAW_COLON_SLASH_SLASH,
 };
 
+/**
+ * Determine whether a line break at position i within the buffer buf is valid. This
+ * represents customization beyond the ICU behavior, because plain ICU provides some
+ * line break opportunities that we don't want.
+ **/
+static bool isBreakValid(uint16_t codeUnit, const uint16_t* buf, size_t bufEnd, size_t i) {
+    if (codeUnit == CHAR_SOFT_HYPHEN) {
+        return false;
+    }
+    if (codeUnit == CHAR_ZWJ) {
+        // Possible emoji ZWJ sequence
+        uint32_t next_codepoint;
+        U16_NEXT(buf, i, bufEnd, next_codepoint);
+        if (next_codepoint == 0x2764 ||       // HEAVY BLACK HEART
+                next_codepoint == 0x1F466 ||  // BOY
+                next_codepoint == 0x1F467 ||  // GIRL
+                next_codepoint == 0x1F468 ||  // MAN
+                next_codepoint == 0x1F469 ||  // WOMAN
+                next_codepoint == 0x1F48B ||  // KISS MARK
+                next_codepoint == 0x1F5E8) {  // LEFT SPEECH BUBBLE
+            return false;
+        }
+    }
+    return true;
+}
+
 // Chicago Manual of Style recommends breaking after these characters in URLs and email addresses
 static bool breakAfter(uint16_t c) {
     return c == ':' || c == '=' || c == '&';
@@ -149,7 +176,7 @@ ssize_t WordBreaker::next() {
             result = mBreakIterator->next();
         }
     } while (result != icu::BreakIterator::DONE && (size_t)result != mTextSize
-             && mText[result - 1] == CHAR_SOFT_HYPHEN);
+            && !isBreakValid(mText[result - 1], mText, mTextSize, result));
     mCurrent = (ssize_t)result;
     return mCurrent;
 }

engine/src/flutter/tests/WordBreakerTests.cpp

@@ -67,6 +67,30 @@ TEST_F(WordBreakerTest, softHyphen) {
     EXPECT_EQ(0, breaker.breakBadness());
 }
 
+TEST_F(WordBreakerTest, zwjEmojiSequences) {
+    uint16_t buf[] = {
+        // man + zwj + heart + zwj + man
+        0xD83D, 0xDC68, 0x200D, 0x2764, 0x200D, 0xD83D, 0xDC68,
+        // woman + zwj + heart + zwj + woman
+        0xD83D, 0xDC69, 0x200D, 0x2764, 0x200D, 0xD83D, 0xDC8B, 0x200D, 0xD83D, 0xDC69,
+        // eye + zwj + left speech bubble
+        0xD83D, 0xDC41, 0x200D, 0xD83D, 0xDDE8,
+    };
+    WordBreaker breaker;
+    breaker.setLocale(icu::Locale::getEnglish());
+    breaker.setText(buf, NELEM(buf));
+    EXPECT_EQ(0, breaker.current());
+    EXPECT_EQ(7, breaker.next());  // after man + zwj + heart + zwj + man
+    EXPECT_EQ(0, breaker.wordStart());
+    EXPECT_EQ(7, breaker.wordEnd());
+    EXPECT_EQ(17, breaker.next());  // after woman + zwj + heart + zwj + woman
+    EXPECT_EQ(7, breaker.wordStart());
+    EXPECT_EQ(17, breaker.wordEnd());
+    EXPECT_EQ((ssize_t)NELEM(buf), breaker.next());  // end
+    EXPECT_EQ(17, breaker.wordStart());
+    EXPECT_EQ(22, breaker.wordEnd());
+}
+
 TEST_F(WordBreakerTest, punct) {
     uint16_t buf[] = {0x00A1, 0x00A1, 'h', 'e', 'l', 'l' ,'o', ',', ' ', 'w', 'o', 'r', 'l', 'd',
         '!', '!'};