Fix raw text update clearing Text (#11000)

* Fix raw text update clearing Text

In #10811, a bug was introduced where a raw text update to a
non-optimized Text component would call ClearValue on the
TextBlock::TextProperty. This behavior was introduced to ensure that we
cleared out the TextProperty before transitioning from optimized to
non-optimized text.

To fix this bug, we check that the text is actually optimized before
clearing the TextProperty, and for the case of transitioning text from
optimized to non-optimized, added an optional flag that must be set to
true before attempting to clear the text.

Please note, we never transition from non-optimized to optimized text,
so we don't need to worry about that case.

* Change files

change/react-native-windows-dc9c358f-08b5-4a90-aca1-37f042a31a3f.json

@@ -0,0 +1,7 @@
+{
+  "type": "prerelease",
+  "comment": "Fix raw text update clearing Text",
+  "packageName": "react-native-windows",
+  "email": "erozell@outlook.com",
+  "dependentChangeType": "patch"
+}

vnext/Microsoft.ReactNative/Views/TextViewManager.cpp

@@ -69,7 +69,7 @@ class TextShadowNode final : public ShadowNodeBase {
       UpdateOptimizedText();
     } else if (wasOptimized) {
       // Remove optimized text and re-construct as Inline tree
-      UpdateOptimizedText();
+      UpdateOptimizedText(true);
       if (const auto uiManager = GetNativeUIManager(GetViewManager()->GetReactContext()).lock()) {
         for (size_t i = 0; i < m_children.size(); ++i) {
           if (const auto childNode =
@@ -88,8 +88,7 @@ class TextShadowNode final : public ShadowNodeBase {
 
   void removeAllChildren() override {
     if (m_isTextOptimized) {
-      auto textBlock = this->GetView().as<xaml::Controls::TextBlock>();
-      textBlock.ClearValue(xaml::Controls::TextBlock::TextProperty());
+      UpdateOptimizedText();
     } else {
       Super::removeAllChildren();
     }
@@ -107,7 +106,7 @@ class TextShadowNode final : public ShadowNodeBase {
     GetViewManager()->MarkDirty(m_tag);
   }
 
-  void UpdateOptimizedText() {
+  void UpdateOptimizedText(bool clearOptimizedText = false) {
     if (m_children.size() > 0 && m_isTextOptimized) {
       if (const auto uiManager = GetNativeUIManager(GetViewManager()->GetReactContext()).lock()) {
         winrt::hstring text = L"";
@@ -120,7 +119,7 @@ class TextShadowNode final : public ShadowNodeBase {
         auto textBlock = this->GetView().as<xaml::Controls::TextBlock>();
         textBlock.Text(text);
       }
-    } else {
+    } else if (m_isTextOptimized || clearOptimizedText) {
       auto textBlock = this->GetView().as<xaml::Controls::TextBlock>();
       textBlock.ClearValue(xaml::Controls::TextBlock::TextProperty());
     }