Exclude trailing whitespace on measuring text width (#37590)

Summary:
Multiline text in Android shows some extra space. It's easily noticeable when you set the text `alignSelf` to `flex-start`. This is because we are using `layout.getLineWidth` which will include trailing whitespace.
<img width="300" alt="image" src="https://github.com/facebook/react-native/assets/50919443/8939092b-caef-4ad8-9b34-2ccef5d20968">

Based on Android doc, `getLineMax` exclude trailing whitespace.
<img width="625" alt="image" src="https://github.com/facebook/react-native/assets/50919443/0b32e842-5fab-4fc7-8fd9-299877b9c553">

## Changelog:

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[ANDROID] [FIXED] - Exclude trailing whitespace from newline character on measuring text line width

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[ANDROID] [FIXED] - Exclude trailing whitespace from newline character on measuring text line width

Pull Request resolved: https://github.com/facebook/react-native/pull/37590

Test Plan:
After applying the changes:
<img width="300" alt="image" src="https://github.com/facebook/react-native/assets/50919443/bfbf52b0-7e7d-4c89-8958-6af38d8bc1c7">

Code snippet:
```
<Text style={{backgroundColor: 'red', alignSelf: 'flex-start', color: 'white'}}>
    1{'\n'}
</Text>
```

Reviewed By: rshest

Differential Revision: D46501420

Pulled By: NickGerleman

fbshipit-source-id: fba4acd38747f09791ce8af4439ee88ab12ac827

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

@@ -42,12 +42,14 @@ public class FontMetricsUtil {
         X_HEIGHT_MEASUREMENT_TEXT, 0, X_HEIGHT_MEASUREMENT_TEXT.length(), xHeightBounds);
     double xHeight = xHeightBounds.height() / AMPLIFICATION_FACTOR / dm.density;
     for (int i = 0; i < layout.getLineCount(); i++) {
+      boolean endsWithNewLine = text.charAt(layout.getLineEnd(i) - 1) == '\n';
+      float lineWidth = endsWithNewLine ? layout.getLineMax(i) : layout.getLineWidth(i);
       Rect bounds = new Rect();
       layout.getLineBounds(i, bounds);
       WritableMap line = Arguments.createMap();
       line.putDouble("x", layout.getLineLeft(i) / dm.density);
       line.putDouble("y", bounds.top / dm.density);
-      line.putDouble("width", layout.getLineWidth(i) / dm.density);
+      line.putDouble("width", lineWidth / dm.density);
       line.putDouble("height", bounds.height() / dm.density);
       line.putDouble("descender", layout.getLineDescent(i) / dm.density);
       line.putDouble("ascender", -layout.getLineAscent(i) / dm.density);

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

@@ -135,7 +135,9 @@ public class ReactTextShadowNode extends ReactBaseTextShadowNode {
             layoutWidth = width;
           } else {
             for (int lineIndex = 0; lineIndex < lineCount; lineIndex++) {
-              float lineWidth = layout.getLineWidth(lineIndex);
+              boolean endsWithNewLine = text.charAt(layout.getLineEnd(lineIndex) - 1) == '\n';
+              float lineWidth =
+                  endsWithNewLine ? layout.getLineMax(lineIndex) : layout.getLineWidth(lineIndex);
               if (lineWidth > layoutWidth) {
                 layoutWidth = lineWidth;
               }

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

@@ -267,11 +267,13 @@ public class ReactTextView extends AppCompatTextView implements ReactCompoundVie
         // the last offset in the layout will result in an endless loop. Work around
         // this bug by avoiding getPrimaryHorizontal in that case.
         if (start == text.length() - 1) {
+          boolean endsWithNewLine = text.charAt(layout.getLineEnd(line) - 1) == '\n';
+          float lineWidth = endsWithNewLine ? layout.getLineMax(line) : layout.getLineWidth(line);
           placeholderHorizontalPosition =
               isRtlParagraph
                   // Equivalent to `layout.getLineLeft(line)` but `getLineLeft` returns incorrect
                   // values when the paragraph is RTL and `setSingleLine(true)`.
-                  ? textViewWidth - (int) layout.getLineWidth(line)
+                  ? textViewWidth - (int) lineWidth
                   : (int) layout.getLineRight(line) - width;
         } else {
           // The direction of the paragraph may not be exactly the direction the string is heading

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

@@ -407,7 +407,9 @@ public class TextLayoutManager {
       calculatedWidth = width;
     } else {
       for (int lineIndex = 0; lineIndex < calculatedLineCount; lineIndex++) {
-        float lineWidth = layout.getLineWidth(lineIndex);
+        boolean endsWithNewLine = text.charAt(layout.getLineEnd(lineIndex) - 1) == '\n';
+        float lineWidth =
+            endsWithNewLine ? layout.getLineMax(lineIndex) : layout.getLineWidth(lineIndex);
         if (lineWidth > calculatedWidth) {
           calculatedWidth = lineWidth;
         }
@@ -462,11 +464,13 @@ public class TextLayoutManager {
           // the last offset in the layout will result in an endless loop. Work around
           // this bug by avoiding getPrimaryHorizontal in that case.
           if (start == text.length() - 1) {
+            boolean endsWithNewLine = text.charAt(layout.getLineEnd(line) - 1) == '\n';
+            float lineWidth = endsWithNewLine ? layout.getLineMax(line) : layout.getLineWidth(line);
             placeholderLeftPosition =
                 isRtlParagraph
                     // Equivalent to `layout.getLineLeft(line)` but `getLineLeft` returns incorrect
                     // values when the paragraph is RTL and `setSingleLine(true)`.
-                    ? calculatedWidth - layout.getLineWidth(line)
+                    ? calculatedWidth - lineWidth
                     : layout.getLineRight(line) - placeholderWidth;
           } else {
             // The direction of the paragraph may not be exactly the direction the string is heading

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

@@ -429,7 +429,9 @@ public class TextLayoutManagerMapBuffer {
       calculatedWidth = width;
     } else {
       for (int lineIndex = 0; lineIndex < calculatedLineCount; lineIndex++) {
-        float lineWidth = layout.getLineWidth(lineIndex);
+        boolean endsWithNewLine = text.charAt(layout.getLineEnd(lineIndex) - 1) == '\n';
+        float lineWidth =
+            endsWithNewLine ? layout.getLineMax(lineIndex) : layout.getLineWidth(lineIndex);
         if (lineWidth > calculatedWidth) {
           calculatedWidth = lineWidth;
         }
@@ -484,12 +486,14 @@ public class TextLayoutManagerMapBuffer {
           // the last offset in the layout will result in an endless loop. Work around
           // this bug by avoiding getPrimaryHorizontal in that case.
           if (start == text.length() - 1) {
+            boolean endsWithNewLine = text.charAt(layout.getLineEnd(line) - 1) == '\n';
+            float lineWidth = endsWithNewLine ? layout.getLineMax(line) : layout.getLineWidth(line);
             placeholderLeftPosition =
                 isRtlParagraph
                     // Equivalent to `layout.getLineLeft(line)` but `getLineLeft` returns
                     // incorrect
                     // values when the paragraph is RTL and `setSingleLine(true)`.
-                    ? calculatedWidth - layout.getLineWidth(line)
+                    ? calculatedWidth - lineWidth
                     : layout.getLineRight(line) - placeholderWidth;
           } else {
             // The direction of the paragraph may not be exactly the direction the string is