Minimize EditText Spans 5/N: Strikethrough and Underline

Summary:
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 makes us apply strikethrough and underline as paint flags to the underlying EditText, instead of just the spans. We then opt ReactUnderlineSpan and ReactStrikethroughSpan into being strippable.

This does actually create visual behavior changes, where child text will inherit any underline or strikethrough of the root EditText (including if the child specifies `textDecorationLine: "none"`. The new behavior is consistent with both iOS and web though, so it seems like more of a bugfix than a regression.

Changelog:
[Android][Fixed] - Minimize Spans 5/N: Strikethrough and Underline

Differential Revision: https://www.internalfb.com/diff/D44240778?entry_point=27

fbshipit-source-id: c024ad12bdc0bfc45ed24ebca3ca46aa6d7a5c4b

Author: NickGerleman

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

@@ -12,6 +12,7 @@
 
 import android.content.Context;
 import android.graphics.Color;
+import android.graphics.Paint;
 import android.graphics.Rect;
 import android.graphics.Typeface;
 import android.graphics.drawable.Drawable;
@@ -54,8 +55,10 @@
 import com.facebook.react.views.text.ReactBackgroundColorSpan;
 import com.facebook.react.views.text.ReactForegroundColorSpan;
 import com.facebook.react.views.text.ReactSpan;
+import com.facebook.react.views.text.ReactStrikethroughSpan;
 import com.facebook.react.views.text.ReactTextUpdate;
 import com.facebook.react.views.text.ReactTypefaceUtils;
+import com.facebook.react.views.text.ReactUnderlineSpan;
 import com.facebook.react.views.text.TextAttributes;
 import com.facebook.react.views.text.TextInlineImageSpan;
 import com.facebook.react.views.text.TextLayoutManager;
@@ -703,6 +706,26 @@ public boolean test(ReactForegroundColorSpan span) {
             return span.getForegroundColor() == getCurrentTextColor();
           }
         });
+
+    stripSpansOfKind(
+        sb,
+        ReactStrikethroughSpan.class,
+        new SpanPredicate<ReactStrikethroughSpan>() {
+          @Override
+          public boolean test(ReactStrikethroughSpan span) {
+            return (getPaintFlags() & Paint.STRIKE_THRU_TEXT_FLAG) != 0;
+          }
+        });
+
+    stripSpansOfKind(
+        sb,
+        ReactUnderlineSpan.class,
+        new SpanPredicate<ReactUnderlineSpan>() {
+          @Override
+          public boolean test(ReactUnderlineSpan span) {
+            return (getPaintFlags() & Paint.UNDERLINE_TEXT_FLAG) != 0;
+          }
+        });
   }
 
   private <T> void stripSpansOfKind(
@@ -749,6 +772,14 @@ private void restoreStyleEquivalentSpans(SpannableStringBuilder workingText) {
       spans.add(new ReactBackgroundColorSpan(backgroundColor));
     }
 
+    if ((getPaintFlags() & Paint.STRIKE_THRU_TEXT_FLAG) != 0) {
+      spans.add(new ReactStrikethroughSpan());
+    }
+
+    if ((getPaintFlags() & Paint.UNDERLINE_TEXT_FLAG) != 0) {
+      spans.add(new ReactUnderlineSpan());
+    }
+
     for (Object span : spans) {
       workingText.setSpan(span, 0, workingText.length(), spanFlags);
     }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java

@@ -13,6 +13,7 @@
 import android.content.res.ColorStateList;
 import android.graphics.BlendMode;
 import android.graphics.BlendModeColorFilter;
+import android.graphics.Paint;
 import android.graphics.PorterDuff;
 import android.graphics.drawable.Drawable;
 import android.os.Build;
@@ -935,6 +936,20 @@ public void setAutoFocus(ReactEditText view, boolean autoFocus) {
     view.setAutoFocus(autoFocus);
   }
 
+  @ReactProp(name = ViewProps.TEXT_DECORATION_LINE)
+  public void setTextDecorationLine(ReactEditText view, @Nullable String textDecorationLineString) {
+    view.setPaintFlags(
+        view.getPaintFlags() & ~(Paint.STRIKE_THRU_TEXT_FLAG | Paint.UNDERLINE_TEXT_FLAG));
+
+    for (String token : textDecorationLineString.split(" ")) {
+      if (token.equals("underline")) {
+        view.setPaintFlags(view.getPaintFlags() | Paint.UNDERLINE_TEXT_FLAG);
+      } else if (token.equals("line-through")) {
+        view.setPaintFlags(view.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
+      }
+    }
+  }
+
   @ReactPropGroup(
       names = {
         ViewProps.BORDER_WIDTH,