Migrate com.facebook.react.views.text.FontMetricsUtil to Kotlin

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -7200,9 +7200,9 @@ public final class com/facebook/react/views/text/DefaultStyleValuesUtil {
 	public static final fun getDefaultTextColorHint (Landroid/content/Context;)Landroid/content/res/ColorStateList;
 }
 
-public class com/facebook/react/views/text/FontMetricsUtil {
-	public fun <init> ()V
-	public static fun getFontMetrics (Ljava/lang/CharSequence;Landroid/text/Layout;Landroid/text/TextPaint;Landroid/content/Context;)Lcom/facebook/react/bridge/WritableArray;
+public final class com/facebook/react/views/text/FontMetricsUtil {
+	public static final field INSTANCE Lcom/facebook/react/views/text/FontMetricsUtil;
+	public static final fun getFontMetrics (Ljava/lang/CharSequence;Landroid/text/Layout;Landroid/text/TextPaint;Landroid/content/Context;)Lcom/facebook/react/bridge/WritableArray;
 }
 
 public abstract class com/facebook/react/views/text/ReactBaseTextShadowNode : com/facebook/react/uimanager/LayoutShadowNode {

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

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.views.text
+
+import android.content.Context
+import android.graphics.Rect
+import android.text.Layout
+import android.text.TextPaint
+import com.facebook.react.bridge.Arguments
+import com.facebook.react.bridge.WritableArray
+
+public object FontMetricsUtil {
+
+  private const val CAP_HEIGHT_MEASUREMENT_TEXT = "T"
+  private const val X_HEIGHT_MEASUREMENT_TEXT = "x"
+  private const val AMPLIFICATION_FACTOR = 100f
+
+  @JvmStatic
+  public fun getFontMetrics(
+      text: CharSequence,
+      layout: Layout,
+      paint: TextPaint,
+      context: Context
+  ): WritableArray {
+    val dm = context.resources.displayMetrics
+    val lines = Arguments.createArray()
+
+    // To calculate xHeight and capHeight we have to render an "x" and "T" and manually measure
+    // their height. In order to get more precision than Android offers, we blow up the text size by
+    // 100 and
+    // measure it. Luckily, text size affects rendering linearly, so we can do this trick.
+    val paintCopy = TextPaint(paint).apply { textSize *= AMPLIFICATION_FACTOR }
+
+    val capHeightBounds = Rect()
+    paintCopy.getTextBounds(
+        CAP_HEIGHT_MEASUREMENT_TEXT, 0, CAP_HEIGHT_MEASUREMENT_TEXT.length, capHeightBounds)
+    val capHeight = capHeightBounds.height() / AMPLIFICATION_FACTOR / dm.density
+
+    val xHeightBounds = Rect()
+    paintCopy.getTextBounds(
+        X_HEIGHT_MEASUREMENT_TEXT, 0, X_HEIGHT_MEASUREMENT_TEXT.length, xHeightBounds)
+    val xHeight = xHeightBounds.height() / AMPLIFICATION_FACTOR / dm.density
+
+    for (i in 0 until layout.lineCount) {
+      val endsWithNewLine = text.isNotEmpty() && text[layout.getLineEnd(i) - 1] == '\n'
+      val lineWidth = if (endsWithNewLine) layout.getLineMax(i) else layout.getLineWidth(i)
+      val bounds = Rect()
+      layout.getLineBounds(i, bounds)
+      val line =
+          Arguments.createMap().apply {
+            putDouble("x", (layout.getLineLeft(i) / dm.density).toDouble())
+            putDouble("y", (bounds.top / dm.density).toDouble())
+            putDouble("width", (lineWidth / dm.density).toDouble())
+            putDouble("height", (bounds.height() / dm.density).toDouble())
+            putDouble("descender", (layout.getLineDescent(i) / dm.density).toDouble())
+            putDouble("ascender", (-layout.getLineAscent(i) / dm.density).toDouble())
+            putDouble("baseline", (layout.getLineBaseline(i) / dm.density).toDouble())
+            putDouble("capHeight", capHeight.toDouble())
+            putDouble("xHeight", xHeight.toDouble())
+            putString(
+                "text", text.subSequence(layout.getLineStart(i), layout.getLineEnd(i)).toString())
+          }
+      lines.pushMap(line)
+    }
+    return lines
+  }
+}