Android TextInput: Improve application of styles for value prop (#2…

…2461)

Summary:
Prior to this change, when you passed text to `TextInput` via the `value` or `defaultValue` props, React Native didn't apply any of the styles in `buildSpannedFromShadowNode` to the text. This is because `spannedFromShadowNode` appends `value` after calling `buildSpannedFromShadowNode`. Many styles worked because their logic is included in both `buildSpannedFromShadowNode` and `ReactTextInputManager`. However, some only appear in `buildSpannedFromShadowNode` such as `textDecorationLine` (it would be good to understand why we need to duplicate styling logic in `buildSpannedFromShadowNode` & `ReactTextInputManager` and to know whether `ReactTextInputManager` should be handling `textDecorationLine`).

Also, this commit improves consistency between iOS and Android if you specify both `value` and children on a `TextInput`. Prior to this, iOS concatenated the strings such that the `value` prop came before the children whereas Android put the children before the `value` prop. Now Android matches iOS's behavior and puts the `value` prop before the children.

These appear to be regressions. The `value` prop used to be appended before calling `buildSpannedFromShadowNode` (this behavior appears to have been changed by accident in 80027ce#diff-4f5947f2fe0381c4a6373a30e596b8c3).

The fix is to append the `value` prop before calling `buildSpannedFromShadowNode`. Additionally, we have to expose a new `start` parameter on `buildSpannedFromShadowNode` so that we can tell it to include the text from the `value` prop in the range that it styles. Without this, the start of the styled text would be immediately after `value` because `value` is appended before calling `buildSpannedFromShadowNode`
Pull Request resolved: #22461

Reviewed By: mdvacca

Differential Revision: D13282065

Pulled By: shergin

fbshipit-source-id: 4c99094741441cf54cdec0075bfd08ff7d889e66

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

@@ -85,17 +85,16 @@ public void execute(SpannableStringBuilder sb, int priority) {
   private static void buildSpannedFromShadowNode(
       ReactBaseTextShadowNode textShadowNode,
       SpannableStringBuilder sb,
-      List<SetSpanOperation> ops) {
-
-    int start = sb.length();
+      List<SetSpanOperation> ops,
+      int start) {
 
     for (int i = 0, length = textShadowNode.getChildCount(); i < length; i++) {
       ReactShadowNode child = textShadowNode.getChildAt(i);
 
       if (child instanceof ReactRawTextShadowNode) {
         sb.append(((ReactRawTextShadowNode) child).getText());
       } else if (child instanceof ReactBaseTextShadowNode) {
-        buildSpannedFromShadowNode((ReactBaseTextShadowNode) child, sb, ops);
+        buildSpannedFromShadowNode((ReactBaseTextShadowNode) child, sb, ops, sb.length());
       } else if (child instanceof ReactTextInlineImageShadowNode) {
         // We make the image take up 1 character in the span and put a corresponding character into
         // the text so that the image doesn't run over any following text.
@@ -201,12 +200,14 @@ protected static Spannable spannedFromShadowNode(
     // a new spannable will be wiped out
     List<SetSpanOperation> ops = new ArrayList<>();
 
-    buildSpannedFromShadowNode(textShadowNode, sb, ops);
-
     if (text != null) {
+      // Handle text that is provided via a prop (e.g. the `value` and `defaultValue` props on
+      // TextInput).
       sb.append(text);
     }
 
+    buildSpannedFromShadowNode(textShadowNode, sb, ops, 0);
+
     if (textShadowNode.mFontSize == UNSET) {
       int defaultFontSize = textShadowNode.getDefaultFontSize();