Align logic in BaseTextInputShadowNode to calculate placeholder string with AndroidTextInputShadowNode (facebook#48584)

Summary:
Pull Request resolved: facebook#48584

[Changelog] [Internal] - Align logic in BaseTextInputShadowNode to calculate placeholder string with AndroidTextInputShadowNode

As a preparation for facebook#48165 this aligns the implementation of those 2 methods

Reviewed By: NickGerleman

Differential Revision: D68004218

fbshipit-source-id: 722a33bb2665c59347ef1b0cd8ed7b35a05b2113

Author: christophpurrer

packages/react-native/ReactCommon/react/renderer/components/textinput/BaseTextInputShadowNode.h

@@ -97,13 +97,7 @@ class BaseTextInputShadowNode : public ConcreteViewShadowNode<
     auto attributedString = getAttributedString(layoutContext);
 
     if (attributedString.isEmpty()) {
-      auto placeholderString = !props.placeholder.empty()
-          ? props.placeholder
-          : BaseTextShadowNode::getEmptyPlaceholder();
-      auto textAttributes =
-          props.getEffectiveTextAttributes(layoutContext.fontSizeMultiplier);
-      attributedString.appendFragment(
-          {std::move(placeholderString), textAttributes, {}});
+      attributedString = getPlaceholderAttributedString(layoutContext);
     }
 
     // Yoga expects a baseline relative to the Node's border-box edge instead of
@@ -217,21 +211,33 @@ class BaseTextInputShadowNode : public ConcreteViewShadowNode<
         : getAttributedString(layoutContext);
 
     if (attributedString.isEmpty()) {
-      const auto& props = BaseShadowNode::getConcreteProps();
-      auto placeholder = props.placeholder;
-      // Note: `zero-width space` is insufficient in some cases (e.g. when we
-      // need to measure the "hight" of the font).
-      // TODO T67606511: We will redefine the measurement of empty strings as
-      // part of T67606511
-      auto string = !placeholder.empty()
-          ? placeholder
-          : BaseTextShadowNode::getEmptyPlaceholder();
-      auto textAttributes =
-          props.getEffectiveTextAttributes(layoutContext.fontSizeMultiplier);
-      attributedString.appendFragment({string, textAttributes, {}});
+      attributedString = getPlaceholderAttributedString(layoutContext);
     }
     return AttributedStringBox{attributedString};
   }
+
+  // For measurement purposes, we want to make sure that there's at least a
+  // single character in the string so that the measured height is greater
+  // than zero. Otherwise, empty TextInputs with no placeholder don't
+  // display at all.
+  // TODO T67606511: We will redefine the measurement of empty strings as part
+  // of T67606511
+  AttributedString getPlaceholderAttributedString(
+      const LayoutContext& layoutContext) const {
+    const auto& props = BaseShadowNode::getConcreteProps();
+
+    AttributedString attributedString;
+    auto placeholderString = !props.placeholder.empty()
+        ? props.placeholder
+        : BaseTextShadowNode::getEmptyPlaceholder();
+    auto textAttributes =
+        props.getEffectiveTextAttributes(layoutContext.fontSizeMultiplier);
+    attributedString.appendFragment(
+        {.string = std::move(placeholderString),
+         .textAttributes = textAttributes,
+         .parentShadowView = {}});
+    return attributedString;
+  }
 };
 
 } // namespace facebook::react

packages/react-native/ReactCommon/react/renderer/components/textinput/platform/android/react/renderer/components/androidtextinput/AndroidTextInputShadowNode.cpp

@@ -215,25 +215,19 @@ AttributedString AndroidTextInputShadowNode::getMostRecentAttributedString()
 // of T67606511
 AttributedString AndroidTextInputShadowNode::getPlaceholderAttributedString()
     const {
-  // Return placeholder text, since text and children are empty.
-  auto textAttributedString = AttributedString{};
-  auto fragment = AttributedString::Fragment{};
-  fragment.string = getConcreteProps().placeholder;
-
-  if (fragment.string.empty()) {
-    fragment.string = BaseTextShadowNode::getEmptyPlaceholder();
-  }
+  const auto& props = BaseShadowNode::getConcreteProps();
 
+  AttributedString attributedString;
+  auto placeholderString = !props.placeholder.empty()
+      ? props.placeholder
+      : BaseTextShadowNode::getEmptyPlaceholder();
   auto textAttributes = TextAttributes::defaultTextAttributes();
-  textAttributes.apply(getConcreteProps().textAttributes);
-
-  // If there's no text, it's possible that this Fragment isn't actually
-  // appended to the AttributedString (see implementation of appendFragment)
-  fragment.textAttributes = textAttributes;
-  fragment.parentShadowView = ShadowView(*this);
-  textAttributedString.appendFragment(std::move(fragment));
-
-  return textAttributedString;
+  textAttributes.apply(props.textAttributes);
+  attributedString.appendFragment(
+      {.string = std::move(placeholderString),
+       .textAttributes = textAttributes,
+       .parentShadowView = ShadowView(*this)});
+  return attributedString;
 }
 
 } // namespace facebook::react