Add new API useful for determining text height for empty text field

Bug: 303326708
Test: atest Paint_FontMetricsForLocaleTest
Change-Id: I4395c778a8de459ffdddba0c0d4dc2ba050e50ac
diff --git a/core/api/current.txt b/core/api/current.txt
index d037c31..d53e6d47 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -16086,10 +16086,12 @@
     method public String getFontFeatureSettings();
     method public float getFontMetrics(android.graphics.Paint.FontMetrics);
     method public android.graphics.Paint.FontMetrics getFontMetrics();
+    method @FlaggedApi("com.android.text.flags.fix_line_height_for_locale") public void getFontMetricsForLocale(@NonNull android.graphics.Paint.FontMetrics);
     method public void getFontMetricsInt(@NonNull CharSequence, @IntRange(from=0) int, @IntRange(from=0) int, @IntRange(from=0) int, @IntRange(from=0) int, boolean, @NonNull android.graphics.Paint.FontMetricsInt);
     method public void getFontMetricsInt(@NonNull char[], @IntRange(from=0) int, @IntRange(from=0) int, @IntRange(from=0) int, @IntRange(from=0) int, boolean, @NonNull android.graphics.Paint.FontMetricsInt);
     method public int getFontMetricsInt(android.graphics.Paint.FontMetricsInt);
     method public android.graphics.Paint.FontMetricsInt getFontMetricsInt();
+    method @FlaggedApi("com.android.text.flags.fix_line_height_for_locale") public void getFontMetricsIntForLocale(@NonNull android.graphics.Paint.FontMetricsInt);
     method public float getFontSpacing();
     method public String getFontVariationSettings();
     method public int getHinting();
diff --git a/core/java/android/text/flags/fix_line_height_for_locale.aconfig b/core/java/android/text/flags/fix_line_height_for_locale.aconfig
new file mode 100644
index 0000000..8696bfa
--- /dev/null
+++ b/core/java/android/text/flags/fix_line_height_for_locale.aconfig
@@ -0,0 +1,8 @@
+package: "com.android.text.flags"
+
+flag {
+  name: "fix_line_height_for_locale"
+  namespace: "text"
+  description: "Feature flag that preserve the line height of the TextView and EditText even if the the locale is different from Latin"
+  bug: "303326708"
+}
diff --git a/graphics/java/android/graphics/Paint.java b/graphics/java/android/graphics/Paint.java
index 9d32272..db1cc44 100644
--- a/graphics/java/android/graphics/Paint.java
+++ b/graphics/java/android/graphics/Paint.java
@@ -16,8 +16,11 @@
 
 package android.graphics;
 
+import static com.android.text.flags.Flags.FLAG_FIX_LINE_HEIGHT_FOR_LOCALE;
+
 import android.annotation.ColorInt;
 import android.annotation.ColorLong;
+import android.annotation.FlaggedApi;
 import android.annotation.IntDef;
 import android.annotation.IntRange;
 import android.annotation.NonNull;
@@ -2125,7 +2128,7 @@
      * @return the font's recommended interline spacing.
      */
     public float getFontMetrics(FontMetrics metrics) {
-        return nGetFontMetrics(mNativePaint, metrics);
+        return nGetFontMetrics(mNativePaint, metrics, false);
     }
 
     /**
@@ -2139,6 +2142,32 @@
     }
 
     /**
+     * Get the font metrics used for the locale
+     *
+     * Obtain the metrics of the font that is used for the specified locale by
+     * {@link #setTextLocales(LocaleList)}. If multiple locales are specified, the minimum ascent
+     * and maximum descent will be set.
+     *
+     * This API is useful for determining the default line height of the empty text field, e.g.
+     * {@link android.widget.EditText}.
+     *
+     * Note, if the {@link android.graphics.Typeface} is created from the custom font files, its
+     * metrics are reserved, i.e. the ascent will be the custom font's ascent or smaller, the
+     * descent will be the custom font's descent or larger.
+     *
+     * Note, if the {@link android.graphics.Typeface} is a system fallback, e.g.
+     * {@link android.graphics.Typeface#SERIF}, the default font's metrics are reserved, i.e. the
+     * ascent will be the serif font's ascent or smaller, the descent will be the serif font's
+     * descent or larger.
+     *
+     * @param metrics an output parameter. All members will be set by calling this function.
+     */
+    @FlaggedApi(FLAG_FIX_LINE_HEIGHT_FOR_LOCALE)
+    public void getFontMetricsForLocale(@NonNull FontMetrics metrics) {
+        nGetFontMetrics(mNativePaint, metrics, true);
+    }
+
+    /**
      * Returns the font metrics value for the given text.
      *
      * If the text is rendered with multiple font files, this function returns the large ascent and
@@ -2318,7 +2347,7 @@
      * @return the font's interline spacing.
      */
     public int getFontMetricsInt(FontMetricsInt fmi) {
-        return nGetFontMetricsInt(mNativePaint, fmi);
+        return nGetFontMetricsInt(mNativePaint, fmi, false);
     }
 
     public FontMetricsInt getFontMetricsInt() {
@@ -2328,6 +2357,32 @@
     }
 
     /**
+     * Get the font metrics used for the locale
+     *
+     * Obtain the metrics of the font that is used for the specified locale by
+     * {@link #setTextLocales(LocaleList)}. If multiple locales are specified, the minimum ascent
+     * and maximum descent will be set.
+     *
+     * This API is useful for determining the default line height of the empty text field, e.g.
+     * {@link android.widget.EditText}.
+     *
+     * Note, if the {@link android.graphics.Typeface} is created from the custom font files, its
+     * metrics are reserved, i.e. the ascent will be the custom font's ascent or smaller, the
+     * descent will be the custom font's descent or larger.
+     *
+     * Note, if the {@link android.graphics.Typeface} is a system fallback, e.g.
+     * {@link android.graphics.Typeface#SERIF}, the default font's metrics are reserved, i.e. the
+     * ascent will be the serif font's ascent or smaller, the descent will be the serif font's
+     * descent or larger.
+     *
+     * @param metrics an output parameter. All members will be set by calling this function.
+     */
+    @FlaggedApi(FLAG_FIX_LINE_HEIGHT_FOR_LOCALE)
+    public void getFontMetricsIntForLocale(@NonNull FontMetricsInt metrics) {
+        nGetFontMetricsInt(mNativePaint, metrics, true);
+    }
+
+    /**
      * Return the recommend line spacing based on the current typeface and
      * text size.
      *
@@ -3446,9 +3501,11 @@
     @FastNative
     private static native void nSetFontFeatureSettings(long paintPtr, String settings);
     @FastNative
-    private static native float nGetFontMetrics(long paintPtr, FontMetrics metrics);
+    private static native float nGetFontMetrics(long paintPtr, FontMetrics metrics,
+            boolean useLocale);
     @FastNative
-    private static native int nGetFontMetricsInt(long paintPtr, FontMetricsInt fmi);
+    private static native int nGetFontMetricsInt(long paintPtr, FontMetricsInt fmi,
+            boolean useLocale);
 
     // ---------------- @CriticalNative ------------------------
 
diff --git a/libs/hwui/jni/Paint.cpp b/libs/hwui/jni/Paint.cpp
index 7aef7a5..1463945 100644
--- a/libs/hwui/jni/Paint.cpp
+++ b/libs/hwui/jni/Paint.cpp
@@ -593,7 +593,7 @@
         return result;
     }
 
-    static SkScalar getMetricsInternal(jlong paintHandle, SkFontMetrics *metrics) {
+    static SkScalar getMetricsInternal(jlong paintHandle, SkFontMetrics* metrics, bool useLocale) {
         const int kElegantTop = 2500;
         const int kElegantBottom = -1000;
         const int kElegantAscent = 1900;
@@ -622,6 +622,17 @@
             metrics->fLeading = size * kElegantLeading / 2048;
             spacing = metrics->fDescent - metrics->fAscent + metrics->fLeading;
         }
+
+        if (useLocale) {
+            minikin::MinikinPaint minikinPaint = MinikinUtils::prepareMinikinPaint(paint, typeface);
+            minikin::MinikinExtent extent =
+                    typeface->fFontCollection->getReferenceExtentForLocale(minikinPaint);
+            metrics->fAscent = std::min(extent.ascent, metrics->fAscent);
+            metrics->fDescent = std::max(extent.descent, metrics->fDescent);
+            metrics->fTop = std::min(metrics->fAscent, metrics->fTop);
+            metrics->fBottom = std::max(metrics->fDescent, metrics->fBottom);
+        }
+
         return spacing;
     }
 
@@ -634,7 +645,7 @@
                 MinikinUtils::getFontExtent(paint, bidiFlags, typeface, buf, start, count, bufSize);
 
         SkFontMetrics metrics;
-        getMetricsInternal(paintHandle, &metrics);
+        getMetricsInternal(paintHandle, &metrics, false /* useLocale */);
 
         metrics.fAscent = extent.ascent;
         metrics.fDescent = extent.descent;
@@ -686,20 +697,21 @@
         }
     }
 
-    static jfloat getFontMetrics(JNIEnv* env, jobject, jlong paintHandle, jobject metricsObj) {
+    static jfloat getFontMetrics(JNIEnv* env, jobject, jlong paintHandle, jobject metricsObj,
+                                 jboolean useLocale) {
         SkFontMetrics metrics;
-        SkScalar spacing = getMetricsInternal(paintHandle, &metrics);
+        SkScalar spacing = getMetricsInternal(paintHandle, &metrics, useLocale);
         GraphicsJNI::set_metrics(env, metricsObj, metrics);
         return SkScalarToFloat(spacing);
     }
 
-    static jint getFontMetricsInt(JNIEnv* env, jobject, jlong paintHandle, jobject metricsObj) {
+    static jint getFontMetricsInt(JNIEnv* env, jobject, jlong paintHandle, jobject metricsObj,
+                                  jboolean useLocale) {
         SkFontMetrics metrics;
-        getMetricsInternal(paintHandle, &metrics);
+        getMetricsInternal(paintHandle, &metrics, useLocale);
         return GraphicsJNI::set_metrics_int(env, metricsObj, metrics);
     }
 
-
     // ------------------ @CriticalNative ---------------------------
 
     static void reset(CRITICAL_JNI_PARAMS_COMMA jlong objHandle) {
@@ -1002,19 +1014,19 @@
 
     static jfloat ascent(CRITICAL_JNI_PARAMS_COMMA jlong paintHandle) {
         SkFontMetrics metrics;
-        getMetricsInternal(paintHandle, &metrics);
+        getMetricsInternal(paintHandle, &metrics, false /* useLocale */);
         return SkScalarToFloat(metrics.fAscent);
     }
 
     static jfloat descent(CRITICAL_JNI_PARAMS_COMMA jlong paintHandle) {
         SkFontMetrics metrics;
-        getMetricsInternal(paintHandle, &metrics);
+        getMetricsInternal(paintHandle, &metrics, false /* useLocale */);
         return SkScalarToFloat(metrics.fDescent);
     }
 
     static jfloat getUnderlinePosition(CRITICAL_JNI_PARAMS_COMMA jlong paintHandle) {
         SkFontMetrics metrics;
-        getMetricsInternal(paintHandle, &metrics);
+        getMetricsInternal(paintHandle, &metrics, false /* useLocale */);
         SkScalar position;
         if (metrics.hasUnderlinePosition(&position)) {
             return SkScalarToFloat(position);
@@ -1026,7 +1038,7 @@
 
     static jfloat getUnderlineThickness(CRITICAL_JNI_PARAMS_COMMA jlong paintHandle) {
         SkFontMetrics metrics;
-        getMetricsInternal(paintHandle, &metrics);
+        getMetricsInternal(paintHandle, &metrics, false /* useLocale */);
         SkScalar thickness;
         if (metrics.hasUnderlineThickness(&thickness)) {
             return SkScalarToFloat(thickness);
@@ -1121,9 +1133,9 @@
         {"nSetTextLocales", "(JLjava/lang/String;)I", (void*)PaintGlue::setTextLocales},
         {"nSetFontFeatureSettings", "(JLjava/lang/String;)V",
          (void*)PaintGlue::setFontFeatureSettings},
-        {"nGetFontMetrics", "(JLandroid/graphics/Paint$FontMetrics;)F",
+        {"nGetFontMetrics", "(JLandroid/graphics/Paint$FontMetrics;Z)F",
          (void*)PaintGlue::getFontMetrics},
-        {"nGetFontMetricsInt", "(JLandroid/graphics/Paint$FontMetricsInt;)I",
+        {"nGetFontMetricsInt", "(JLandroid/graphics/Paint$FontMetricsInt;Z)I",
          (void*)PaintGlue::getFontMetricsInt},
 
         // --------------- @CriticalNative ------------------