Rebuild the TextView Layout before drawing text effects on Android

ReactTextView.onDraw paints CanvasEffectSpans (underline, strikethrough) only when
getLayout() is non-null. TextView drops its Layout in setText and rebuilds it in
onMeasure, and Fabric measures a view only when its frame changed, so a text update
that keeps the frame reaches onDraw with no Layout and the decorations are skipped.
Any animation that changes textDecorationLine or textDecorationColor hits this on
every frame, so the decoration never shows. Rebuild the Layout at the current size
before painting, the same way TextView.onDraw assumes one.

Author: MatiPl01

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactTextView.java

@@ -257,6 +257,17 @@ protected void onDraw(Canvas canvas) {
 
       if (spanned != null) {
         Layout layout = getLayout();
+        if (layout == null && getWidth() > 0 && getHeight() > 0) {
+          // TextView drops its Layout in setText and only rebuilds it in onMeasure. Fabric measures
+          // a view only when its frame changed, so a text update that keeps the frame (a color or
+          // decoration change, e.g. driven by an animation) gets here with no Layout and the
+          // CanvasEffectSpans below would be skipped for that frame. Rebuild the Layout at the
+          // current size first, the same way TextView.onDraw itself assumes one.
+          measure(
+              MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.EXACTLY),
+              MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.EXACTLY));
+          layout = getLayout();
+        }
         if (layout != null) {
           CanvasEffectSpan[] drawSpans =
               spanned.getSpans(0, spanned.length(), CanvasEffectSpan.class);