[Reland] Cache the variation instance of Typeface

This is a reland of the 4cefdc6df295534f7f94b26371dbacdba75db32f

The previous attempt breaks robolectric tests of settings but it
needs to be fix-forward. Context: b/358347869

Performance numbers on Pixel 8 Pro.

Non-Cached: 366,835 ns
    Cached:   2,427 ns

Bug: 355462362
Test: PaintTest
Flag: com.android.text.flags.typeface_cache_for_var_settings
Change-Id: I0f1e253eae5e2774ef4f10dcf5d0c8e8fbe6e367

5 files changed, 236 insertions, 5 deletions

diff --git a/apct-tests/perftests/core/src/android/text/VariableFontPerfTest.java b/apct-tests/perftests/core/src/android/text/VariableFontPerfTest.java
index fbe67a477f5d..c34936f930f9 100644
--- a/apct-tests/perftests/core/src/android/text/VariableFontPerfTest.java
+++ b/apct-tests/perftests/core/src/android/text/VariableFontPerfTest.java
@@ -19,6 +19,7 @@ package android.text;
 import android.graphics.Paint;
 import android.graphics.RecordingCanvas;
 import android.graphics.RenderNode;
+import android.graphics.Typeface;
 import android.perftests.utils.BenchmarkState;
 import android.perftests.utils.PerfStatusReporter;
 
@@ -120,13 +121,34 @@ public class VariableFontPerfTest {
     public void testSetFontVariationSettings() {
         final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
         final Paint paint = new Paint(PAINT);
-        final Random random = new Random(0);
         while (state.keepRunning()) {
             state.pauseTiming();
-            int weight = random.nextInt(1000);
+            paint.setTypeface(null);
+            paint.setFontVariationSettings(null);
+            Typeface.clearTypefaceCachesForTestingPurpose();
             state.resumeTiming();
 
-            paint.setFontVariationSettings("'wght' " + weight);
+            paint.setFontVariationSettings("'wght' 450");
+        }
+        Typeface.clearTypefaceCachesForTestingPurpose();
+    }
+
+    @Test
+    public void testSetFontVariationSettings_Cached() {
+        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+        final Paint paint = new Paint(PAINT);
+        Typeface.clearTypefaceCachesForTestingPurpose();
+
+        while (state.keepRunning()) {
+            state.pauseTiming();
+            paint.setTypeface(null);
+            paint.setFontVariationSettings(null);
+            state.resumeTiming();
+
+            paint.setFontVariationSettings("'wght' 450");
         }
+
+        Typeface.clearTypefaceCachesForTestingPurpose();
     }
+
 }
diff --git a/core/java/android/text/flags/flags.aconfig b/core/java/android/text/flags/flags.aconfig
index 3d190fe43626..5c5a2f687d3b 100644
--- a/core/java/android/text/flags/flags.aconfig
+++ b/core/java/android/text/flags/flags.aconfig
@@ -267,3 +267,13 @@ flag {
     purpose: PURPOSE_BUGFIX
   }
 }
+
+flag {
+  name: "typeface_cache_for_var_settings"
+  namespace: "text"
+  description: "Cache Typeface instance for font variation settings."
+  bug: "355462362"
+  metadata {
+    purpose: PURPOSE_BUGFIX
+  }
+}
\ No newline at end of file
diff --git a/core/tests/coretests/src/android/graphics/PaintFontVariationTest.java b/core/tests/coretests/src/android/graphics/PaintFontVariationTest.java
new file mode 100644
index 000000000000..8a54e5b998e7
--- /dev/null
+++ b/core/tests/coretests/src/android/graphics/PaintFontVariationTest.java
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.graphics;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.platform.test.annotations.RequiresFlagsEnabled;
+import android.platform.test.flag.junit.CheckFlagsRule;
+import android.platform.test.flag.junit.DeviceFlagsValueProvider;
+import android.test.InstrumentationTestCase;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.text.flags.Flags;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/**
+ * PaintTest tests {@link Paint}.
+ */
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class PaintFontVariationTest extends InstrumentationTestCase {
+    @Rule
+    public final CheckFlagsRule mCheckFlagsRule = DeviceFlagsValueProvider.createCheckFlagsRule();
+
+    @RequiresFlagsEnabled(Flags.FLAG_TYPEFACE_CACHE_FOR_VAR_SETTINGS)
+    @Test
+    public void testDerivedFromSameTypeface() {
+        final Paint p = new Paint();
+
+        p.setTypeface(Typeface.SANS_SERIF);
+        assertThat(p.setFontVariationSettings("'wght' 450")).isTrue();
+        Typeface first = p.getTypeface();
+
+        p.setTypeface(Typeface.SANS_SERIF);
+        assertThat(p.setFontVariationSettings("'wght' 480")).isTrue();
+        Typeface second = p.getTypeface();
+
+        assertThat(first.getDerivedFrom()).isSameInstanceAs(second.getDerivedFrom());
+    }
+
+    @RequiresFlagsEnabled(Flags.FLAG_TYPEFACE_CACHE_FOR_VAR_SETTINGS)
+    @Test
+    public void testDerivedFromChained() {
+        final Paint p = new Paint();
+
+        p.setTypeface(Typeface.SANS_SERIF);
+        assertThat(p.setFontVariationSettings("'wght' 450")).isTrue();
+        Typeface first = p.getTypeface();
+
+        assertThat(p.setFontVariationSettings("'wght' 480")).isTrue();
+        Typeface second = p.getTypeface();
+
+        assertThat(first.getDerivedFrom()).isSameInstanceAs(second.getDerivedFrom());
+    }
+}
diff --git a/core/tests/coretests/src/android/graphics/PaintTest.java b/core/tests/coretests/src/android/graphics/PaintTest.java
index 0dec756d7611..878ba703c8fe 100644
--- a/core/tests/coretests/src/android/graphics/PaintTest.java
+++ b/core/tests/coretests/src/android/graphics/PaintTest.java
@@ -16,13 +16,22 @@
 
 package android.graphics;
 
+import static com.google.common.truth.Truth.assertThat;
+
 import static org.junit.Assert.assertNotEquals;
 
+import android.platform.test.annotations.RequiresFlagsEnabled;
+import android.platform.test.flag.junit.CheckFlagsRule;
+import android.platform.test.flag.junit.DeviceFlagsValueProvider;
 import android.test.InstrumentationTestCase;
 import android.text.TextUtils;
 
 import androidx.test.filters.SmallTest;
 
+import com.android.text.flags.Flags;
+
+import org.junit.Rule;
+
 import java.util.Arrays;
 import java.util.HashSet;
 
@@ -30,6 +39,9 @@ import java.util.HashSet;
  * PaintTest tests {@link Paint}.
  */
 public class PaintTest extends InstrumentationTestCase {
+    @Rule
+    public final CheckFlagsRule mCheckFlagsRule = DeviceFlagsValueProvider.createCheckFlagsRule();
+
     private static final String FONT_PATH = "fonts/HintedAdvanceWidthTest-Regular.ttf";
 
     static void assertEquals(String message, float[] expected, float[] actual) {
@@ -403,4 +415,33 @@ public class PaintTest extends InstrumentationTestCase {
         assertEquals(6, getClusterCount(p, rtlStr + ltrStr));
         assertEquals(9, getClusterCount(p, ltrStr + rtlStr + ltrStr));
     }
+
+    @RequiresFlagsEnabled(Flags.FLAG_TYPEFACE_CACHE_FOR_VAR_SETTINGS)
+    public void testDerivedFromSameTypeface() {
+        final Paint p = new Paint();
+
+        p.setTypeface(Typeface.SANS_SERIF);
+        assertThat(p.setFontVariationSettings("'wght' 450")).isTrue();
+        Typeface first = p.getTypeface();
+
+        p.setTypeface(Typeface.SANS_SERIF);
+        assertThat(p.setFontVariationSettings("'wght' 480")).isTrue();
+        Typeface second = p.getTypeface();
+
+        assertThat(first.getDerivedFrom()).isSameInstanceAs(second.getDerivedFrom());
+    }
+
+    @RequiresFlagsEnabled(Flags.FLAG_TYPEFACE_CACHE_FOR_VAR_SETTINGS)
+    public void testDerivedFromChained() {
+        final Paint p = new Paint();
+
+        p.setTypeface(Typeface.SANS_SERIF);
+        assertThat(p.setFontVariationSettings("'wght' 450")).isTrue();
+        Typeface first = p.getTypeface();
+
+        assertThat(p.setFontVariationSettings("'wght' 480")).isTrue();
+        Typeface second = p.getTypeface();
+
+        assertThat(first.getDerivedFrom()).isSameInstanceAs(second.getDerivedFrom());
+    }
 }
diff --git a/graphics/java/android/graphics/Typeface.java b/graphics/java/android/graphics/Typeface.java
index fd788167a0d8..889a778556b7 100644
--- a/graphics/java/android/graphics/Typeface.java
+++ b/graphics/java/android/graphics/Typeface.java
@@ -56,6 +56,7 @@ import android.util.SparseArray;
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.Preconditions;
+import com.android.text.flags.Flags;
 
 import dalvik.annotation.optimization.CriticalNative;
 import dalvik.annotation.optimization.FastNative;
@@ -74,6 +75,7 @@ import java.nio.ByteOrder;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -143,6 +145,23 @@ public class Typeface {
     private static final LruCache<String, Typeface> sDynamicTypefaceCache = new LruCache<>(16);
     private static final Object sDynamicCacheLock = new Object();
 
+    private static final LruCache<Long, LruCache<String, Typeface>> sVariableCache =
+            new LruCache<>(16);
+    private static final Object sVariableCacheLock = new Object();
+
+    /** @hide */
+    @VisibleForTesting
+    public static void clearTypefaceCachesForTestingPurpose() {
+        synchronized (sWeightCacheLock) {
+            sWeightTypefaceCache.clear();
+        }
+        synchronized (sDynamicCacheLock) {
+            sDynamicTypefaceCache.evictAll();
+        }
+        synchronized (sVariableCacheLock) {
+            sVariableCache.evictAll();
+        }
+    }
 
     @GuardedBy("SYSTEM_FONT_MAP_LOCK")
     static Typeface sDefaultTypeface;
@@ -195,6 +214,8 @@ public class Typeface {
     @UnsupportedAppUsage
     public final long native_instance;
 
+    private final Typeface mDerivedFrom;
+
     private final String mSystemFontFamilyName;
 
     private final Runnable mCleaner;
@@ -274,6 +295,18 @@ public class Typeface {
     }
 
     /**
+     * Returns the Typeface used for creating this Typeface.
+     *
+     * Maybe null if this is not derived from other Typeface.
+     * TODO(b/357707916): Make this public API.
+     * @hide
+     */
+    @VisibleForTesting
+    public final @Nullable Typeface getDerivedFrom() {
+        return mDerivedFrom;
+    }
+
+    /**
      * Returns the system font family name if the typeface was created from a system font family,
      * otherwise returns null.
      */
@@ -1021,9 +1054,51 @@ public class Typeface {
         return typeface;
     }
 
-    /** @hide */
+    private static String axesToVarKey(@NonNull List<FontVariationAxis> axes) {
+        // The given list can be mutated because it is allocated in Paint#setFontVariationSettings.
+        // Currently, Paint#setFontVariationSettings is the only code path reaches this method.
+        axes.sort(Comparator.comparingInt(FontVariationAxis::getOpenTypeTagValue));
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < axes.size(); ++i) {
+            final FontVariationAxis fva = axes.get(i);
+            sb.append(fva.getTag());
+            sb.append(fva.getStyleValue());
+        }
+        return sb.toString();
+    }
+
+    /**
+     * TODO(b/357707916): Make this public API.
+     * @hide
+     */
     public static Typeface createFromTypefaceWithVariation(@Nullable Typeface family,
             @NonNull List<FontVariationAxis> axes) {
+        if (Flags.typefaceCacheForVarSettings()) {
+            final Typeface target = (family == null) ? Typeface.DEFAULT : family;
+            final Typeface base = (target.mDerivedFrom == null) ? target : target.mDerivedFrom;
+
+            final String key = axesToVarKey(axes);
+
+            synchronized (sVariableCacheLock) {
+                LruCache<String, Typeface> innerCache = sVariableCache.get(base.native_instance);
+                if (innerCache == null) {
+                    // Cache up to 16 var instance per root Typeface
+                    innerCache = new LruCache<>(16);
+                    sVariableCache.put(base.native_instance, innerCache);
+                } else {
+                    Typeface cached = innerCache.get(key);
+                    if (cached != null) {
+                        return cached;
+                    }
+                }
+                Typeface typeface = new Typeface(
+                        nativeCreateFromTypefaceWithVariation(base.native_instance, axes),
+                        base.getSystemFontFamilyName(), base);
+                innerCache.put(key, typeface);
+                return typeface;
+            }
+        }
+
         final Typeface base = family == null ? Typeface.DEFAULT : family;
         Typeface typeface = new Typeface(
                 nativeCreateFromTypefaceWithVariation(base.native_instance, axes),
@@ -1184,11 +1259,19 @@ public class Typeface {
     // don't allow clients to call this directly
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
     private Typeface(long ni) {
-        this(ni, null);
+        this(ni, null, null);
     }
 
+
     // don't allow clients to call this directly
+    // This is kept for robolectric.
     private Typeface(long ni, @Nullable String systemFontFamilyName) {
+        this(ni, systemFontFamilyName, null);
+    }
+
+    // don't allow clients to call this directly
+    private Typeface(long ni, @Nullable String systemFontFamilyName,
+            @Nullable Typeface derivedFrom) {
         if (ni == 0) {
             throw new RuntimeException("native typeface cannot be made");
         }
@@ -1198,6 +1281,7 @@ public class Typeface {
         mStyle = nativeGetStyle(ni);
         mWeight = nativeGetWeight(ni);
         mSystemFontFamilyName = systemFontFamilyName;
+        mDerivedFrom = derivedFrom;
     }
 
     /**