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Commit 6dbd9626 authored by Tyler Freeman's avatar Tyler Freeman
Browse files

fix(non linear font scaling): make FontScaleConverterFactory thread-safe 

We use the same technique as CopyOnWriteArrayList to protect the writes
only. Reads can be a bit out of date since they are only used for
caching.

Bug: b/239736383
Flag: android.content.res.font_scale_converter_public
Test: atest FrameworksCoreTests:android.content.res.FontScaleConverterFactoryTest
Change-Id: I2cfefcf7a5c6f56294e87d4c35afc8499c2e7c02
parent a407ee86

core/api/current.txt

+2 −2
Original line number Diff line number Diff line
@@ -13584,8 +13584,8 @@ package android.content.res { 
  }















  @FlaggedApi("android.content.res.font_scale_converter_public") public class FontScaleConverterFactory {













    method @FlaggedApi("android.content.res.font_scale_converter_public") @Nullable public static android.content.res.FontScaleConverter forScale(float);













    method @FlaggedApi("android.content.res.font_scale_converter_public") public static boolean isNonLinearFontScalingActive(float);













    method @FlaggedApi("android.content.res.font_scale_converter_public") @AnyThread @Nullable public static android.content.res.FontScaleConverter forScale(float);













    method @FlaggedApi("android.content.res.font_scale_converter_public") @AnyThread public static boolean isNonLinearFontScalingActive(float);















  }





























  public class ObbInfo implements android.os.Parcelable {

























core/java/android/content/res/FontScaleConverterFactory.java



+88
−56




























Original line number
Diff line number
Diff line








@@ -16,6 +16,7 @@





























package android.content.res;





























import android.annotation.AnyThread;















import android.annotation.FlaggedApi;















import android.annotation.NonNull;















import android.annotation.Nullable;









@@ -37,15 +38,26 @@ public class FontScaleConverterFactory {













    private static final float SCALE_KEY_MULTIPLIER = 100f;































    /** @hide */













    // GuardedBy("LOOKUP_TABLES_WRITE_LOCK") but only for writes!















    @VisibleForTesting













    public static final SparseArray<FontScaleConverter> LOOKUP_TABLES = new SparseArray<>();













    @NonNull













    public static volatile SparseArray<FontScaleConverter> sLookupTables = new SparseArray<>();



























    /**













     * This is a write lock only! We don't care about synchronization on reads; they can be a bit













     * out of date. But all writes have to be atomic, so we use this similar to a













     * CopyOnWriteArrayList.













     */













    private static final Object LOOKUP_TABLES_WRITE_LOCK = new Object();































    private static float sMinScaleBeforeCurvesApplied = 1.05f;































    static {















        // These were generated by frameworks/base/tools/fonts/font-scaling-array-generator.js and















        // manually tweaked for optimum readability.













        put(













        synchronized (LOOKUP_TABLES_WRITE_LOCK) {













            putInto(













                    sLookupTables,















                    /* scaleKey= */ 1.15f,















                    new FontScaleConverterImpl(















                            /* fromSp= */









@@ -54,7 +66,8 @@ public class FontScaleConverterFactory {













                            new float[] { 9.2f, 11.5f, 13.8f, 16.4f, 19.8f, 21.8f, 25.2f,   30f,  100})















            );





























        put(













            putInto(













                    sLookupTables,















                    /* scaleKey= */ 1.3f,















                    new FontScaleConverterImpl(















                            /* fromSp= */









@@ -63,7 +76,8 @@ public class FontScaleConverterFactory {













                            new float[] {10.4f,   13f, 15.6f, 18.8f, 21.6f, 23.6f, 26.4f,   30f,  100})















            );





























        put(













            putInto(













                    sLookupTables,















                    /* scaleKey= */ 1.5f,















                    new FontScaleConverterImpl(















                            /* fromSp= */









@@ -72,7 +86,8 @@ public class FontScaleConverterFactory {













                            new float[] {  12f,   15f,   18f,   22f,   24f,   26f,   28f,   30f,  100})















            );





























        put(













            putInto(













                    sLookupTables,















                    /* scaleKey= */ 1.8f,















                    new FontScaleConverterImpl(















                            /* fromSp= */









@@ -81,7 +96,8 @@ public class FontScaleConverterFactory {













                            new float[] {14.4f,   18f, 21.6f, 24.4f, 27.6f, 30.8f, 32.8f, 34.8f,  100})















            );





























        put(













            putInto(













                    sLookupTables,















                    /* scaleKey= */ 2f,















                    new FontScaleConverterImpl(















                            /* fromSp= */









@@ -89,8 +105,9 @@ public class FontScaleConverterFactory {













                            /* toDp=   */















                            new float[] {  16f,   20f,   24f,   26f,   30f,   34f,   36f,   38f,  100})















            );













        }





























        sMinScaleBeforeCurvesApplied = getScaleFromKey(LOOKUP_TABLES.keyAt(0)) - 0.02f;













        sMinScaleBeforeCurvesApplied = getScaleFromKey(sLookupTables.keyAt(0)) - 0.02f;















        if (sMinScaleBeforeCurvesApplied <= 1.0f) {















            throw new IllegalStateException(















                    "You should only apply non-linear scaling to font scales > 1"









@@ -108,6 +125,7 @@ public class FontScaleConverterFactory {













     * <code>isNonLinearFontScalingActive(getResources().getConfiguration().fontScale)</code>















     */















    @FlaggedApi(Flags.FLAG_FONT_SCALE_CONVERTER_PUBLIC)













    @AnyThread















    public static boolean isNonLinearFontScalingActive(float fontScale) {















        return fontScale >= sMinScaleBeforeCurvesApplied;















    }









@@ -121,6 +139,7 @@ public class FontScaleConverterFactory {













     */















    @FlaggedApi(Flags.FLAG_FONT_SCALE_CONVERTER_PUBLIC)















    @Nullable













    @AnyThread















    public static FontScaleConverter forScale(float fontScale) {















        if (!isNonLinearFontScalingActive(fontScale)) {















            return null;









@@ -132,15 +151,15 @@ public class FontScaleConverterFactory {













        }































        // Didn't find an exact match: interpolate between two existing tables













        final int index = LOOKUP_TABLES.indexOfKey(getKey(fontScale));













        final int index = sLookupTables.indexOfKey(getKey(fontScale));















        if (index >= 0) {















            // This should never happen, should have been covered by get() above.













            return LOOKUP_TABLES.valueAt(index);













            return sLookupTables.valueAt(index);















        }















        // Didn't find an exact match: interpolate between two existing tables















        final int lowerIndex = -(index + 1) - 1;















        final int higherIndex = lowerIndex + 1;













        if (lowerIndex < 0 || higherIndex >= LOOKUP_TABLES.size()) {













        if (lowerIndex < 0 || higherIndex >= sLookupTables.size()) {















            // We have gone beyond our bounds and have nothing to interpolate between. Just give















            // them a straight linear table instead.















            // This works because when FontScaleConverter encounters a size beyond its bounds, it









@@ -157,8 +176,8 @@ public class FontScaleConverterFactory {





























            return converter;















        } else {













            float startScale = getScaleFromKey(LOOKUP_TABLES.keyAt(lowerIndex));













            float endScale = getScaleFromKey(LOOKUP_TABLES.keyAt(higherIndex));













            float startScale = getScaleFromKey(sLookupTables.keyAt(lowerIndex));













            float endScale = getScaleFromKey(sLookupTables.keyAt(higherIndex));















            float interpolationPoint = MathUtils.constrainedMap(















                    /* rangeMin= */ 0f,















                    /* rangeMax= */ 1f,









@@ -167,8 +186,8 @@ public class FontScaleConverterFactory {













                    fontScale















            );















            FontScaleConverter converter = createInterpolatedTableBetween(













                    LOOKUP_TABLES.valueAt(lowerIndex),













                    LOOKUP_TABLES.valueAt(higherIndex),













                    sLookupTables.valueAt(lowerIndex),













                    sLookupTables.valueAt(higherIndex),















                    interpolationPoint















            );


























@@ -209,11 +228,24 @@ public class FontScaleConverterFactory {













    }































    private static void put(float scaleKey, @NonNull FontScaleConverter fontScaleConverter) {













        LOOKUP_TABLES.put(getKey(scaleKey), fontScaleConverter);













        // Dollar-store CopyOnWriteSparseArray, since this is the only write op we need.













        synchronized (LOOKUP_TABLES_WRITE_LOCK) {













            var newTable = sLookupTables.clone();













            putInto(newTable, scaleKey, fontScaleConverter);













            sLookupTables = newTable;













        }













    }



























    private static void putInto(













            SparseArray<FontScaleConverter> table,













            float scaleKey,













            @NonNull FontScaleConverter fontScaleConverter













    ) {













        table.put(getKey(scaleKey), fontScaleConverter);















    }































    @Nullable















    private static FontScaleConverter get(float scaleKey) {













        return LOOKUP_TABLES.get(getKey(scaleKey));













        return sLookupTables.get(getKey(scaleKey));















    }















}
























core/tests/coretests/src/android/content/res/FontScaleConverterFactoryTest.kt



+7
−7




























Original line number
Diff line number
Diff line








@@ -99,10 +99,10 @@ class FontScaleConverterFactoryTest {













    fun missingLookupTable_cachesInterpolated() {















        val table = FontScaleConverterFactory.forScale(1.6F)!!





























        assertThat(FontScaleConverterFactory.LOOKUP_TABLES.contains((1.6F * 100).toInt())).isTrue()













        assertThat(FontScaleConverterFactory.sLookupTables.contains((1.6F * 100).toInt())).isTrue()















        // Double check known existing values













        assertThat(FontScaleConverterFactory.LOOKUP_TABLES.contains((1.5F * 100).toInt())).isTrue()













        assertThat(FontScaleConverterFactory.LOOKUP_TABLES.contains((1.7F * 100).toInt())).isFalse()













        assertThat(FontScaleConverterFactory.sLookupTables.contains((1.5F * 100).toInt())).isTrue()













        assertThat(FontScaleConverterFactory.sLookupTables.contains((1.7F * 100).toInt())).isFalse()















    }































    @Test









@@ -110,10 +110,10 @@ class FontScaleConverterFactoryTest {













    fun missingLookupTablePastEnd_cachesLinear() {















        val table = FontScaleConverterFactory.forScale(3F)!!





























        assertThat(FontScaleConverterFactory.LOOKUP_TABLES.contains((3F * 100).toInt())).isTrue()













        assertThat(FontScaleConverterFactory.sLookupTables.contains((3F * 100).toInt())).isTrue()















        // Double check known existing values













        assertThat(FontScaleConverterFactory.LOOKUP_TABLES.contains((1.5F * 100).toInt())).isTrue()













        assertThat(FontScaleConverterFactory.LOOKUP_TABLES.contains((1.7F * 100).toInt())).isFalse()













        assertThat(FontScaleConverterFactory.sLookupTables.contains((1.5F * 100).toInt())).isTrue()













        assertThat(FontScaleConverterFactory.sLookupTables.contains((1.7F * 100).toInt())).isFalse()















    }































    @SmallTest









@@ -134,7 +134,7 @@ class FontScaleConverterFactoryTest {













    @SmallTest















    @Test















    fun tablesMatchAndAreMonotonicallyIncreasing() {













        FontScaleConverterFactory.LOOKUP_TABLES.forEach { _, lookupTable ->













        FontScaleConverterFactory.sLookupTables.forEach { _, lookupTable ->















            if (lookupTable !is FontScaleConverterImpl) {















                throw IllegalStateException("Didn't return a FontScaleConverterImpl")















            }