Do not notify text watchers when replace is a no-op

Bug 6344997

The early exit we used to do when both replaced and replacement
strings were empty has been added back.

Only this time it correctly also makes sure no spans from the
replacement string would get added with a 0-length.

Change-Id: Ifc38a7e3619c57aa7647c0a8e63d7627d86f1036

1 files changed, 20 insertions, 0 deletions

diff --git a/core/java/android/text/SpannableStringBuilder.java b/core/java/android/text/SpannableStringBuilder.java
index ea9f650..c5e2c42 100644
--- a/core/java/android/text/SpannableStringBuilder.java
+++ b/core/java/android/text/SpannableStringBuilder.java
@@ -428,6 +428,12 @@ public class SpannableStringBuilder implements CharSequence, GetChars, Spannable
         final int origLen = end - start;
         final int newLen = tbend - tbstart;
 
+        if (origLen == 0 && newLen == 0 && !hasNonExclusiveExclusiveSpanAt(tb, tbstart)) {
+            // This is a no-op iif there are no spans in tb that would be added (with a 0-length)
+            // Early exit so that the text watchers do not get notified
+            return this;
+        }
+
         TextWatcher[] textWatchers = getSpans(start, start + origLen, TextWatcher.class);
         sendBeforeTextChanged(textWatchers, start, origLen, newLen);
 
@@ -470,6 +476,20 @@ public class SpannableStringBuilder implements CharSequence, GetChars, Spannable
         return this; 
     }
 
+    private static boolean hasNonExclusiveExclusiveSpanAt(CharSequence text, int offset) {
+        if (text instanceof Spanned) {
+            Spanned spanned = (Spanned) text;
+            Object[] spans = spanned.getSpans(offset, offset, Object.class);
+            final int length = spans.length;
+            for (int i = 0; i < length; i++) {
+                Object span = spans[i];
+                int flags = spanned.getSpanFlags(span);
+                if (flags != Spanned.SPAN_EXCLUSIVE_EXCLUSIVE) return true;
+            }
+        }
+        return false;
+    }
+
     private void sendToSpanWatchers(int replaceStart, int replaceEnd, int nbNewChars) {
         for (int i = 0; i < mSpanCountBeforeAdd; i++) {
             int spanStart = mSpanStarts[i];