Minimize EditText Spans 6/9: letterSpacing (facebook#36548)

Summary:
Pull Request resolved: facebook#36548

This is part of a series of changes to minimize the number of spans committed to EditText, as a mitigation for platform issues on Samsung devices. See this [GitHub thread]( facebook#35936 (comment)) for greater context on the platform behavior.

This change lets us set `letterSpacing` on the EditText instead of using our custom span.

Changelog:
[Android][Fixed] - Minimize EditText Spans 6/N: letterSpacing

Reviewed By: rshest

Differential Revision: D44240777

fbshipit-source-id: 9bd10c3261257037d8cacf37971011aaa94d1a77

ReactAndroid/src/main/java/com/facebook/react/views/text/CustomLetterSpacingSpan.java

@@ -37,6 +37,10 @@ public void updateMeasureState(TextPaint paint) {
     apply(paint);
   }
 
+  public float getSpacing() {
+    return mLetterSpacing;
+  }
+
   private void apply(TextPaint paint) {
     if (!Float.isNaN(mLetterSpacing)) {
       paint.setLetterSpacing(mLetterSpacing);

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactEditText.java

@@ -726,6 +726,18 @@ public boolean test(ReactUnderlineSpan span) {
             return (getPaintFlags() & Paint.UNDERLINE_TEXT_FLAG) != 0;
           }
         });
+
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+      stripSpansOfKind(
+          sb,
+          CustomLetterSpacingSpan.class,
+          new SpanPredicate<CustomLetterSpacingSpan>() {
+            @Override
+            public boolean test(CustomLetterSpacingSpan span) {
+              return span.getSpacing() == mTextAttributes.getEffectiveLetterSpacing();
+            }
+          });
+    }
   }
 
   private <T> void stripSpansOfKind(
@@ -767,6 +779,13 @@ private void restoreStyleEquivalentSpans(SpannableStringBuilder workingText) {
       spans.add(new ReactUnderlineSpan());
     }
 
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+      float effectiveLetterSpacing = mTextAttributes.getEffectiveLetterSpacing();
+      if (!Float.isNaN(effectiveLetterSpacing)) {
+        spans.add(new CustomLetterSpacingSpan(effectiveLetterSpacing));
+      }
+    }
+
     for (Object span : spans) {
       workingText.setSpan(span, 0, workingText.length(), spanFlags);
     }
@@ -1119,7 +1138,9 @@ protected void applyTextAttributes() {
 
     float effectiveLetterSpacing = mTextAttributes.getEffectiveLetterSpacing();
     if (!Float.isNaN(effectiveLetterSpacing)) {
-      setLetterSpacing(effectiveLetterSpacing);
+      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+        setLetterSpacing(effectiveLetterSpacing);
+      }
     }
   }