280 lines
11 KiB
Java
280 lines
11 KiB
Java
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/*
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* Copyright (C) 2022 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.content.res;
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import android.annotation.AnyThread;
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import android.annotation.NonNull;
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import android.annotation.Nullable;
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import android.util.MathUtils;
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import android.util.SparseArray;
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import com.android.internal.annotations.VisibleForTesting;
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/**
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* Creates {@link FontScaleConverter}s at various scales.
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*
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* Generally you shouldn't need this; you can use {@link
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* android.util.TypedValue#applyDimension(int, float, DisplayMetrics)} directly and it will do the
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* scaling conversion for you. But for UI frameworks or other situations where you need to do the
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* conversion without an Android Context, you can use this class.
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*
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* @hide
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*/
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public class FontScaleConverterFactory {
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private static final float SCALE_KEY_MULTIPLIER = 100f;
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/** @hide */
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// GuardedBy("LOOKUP_TABLES_WRITE_LOCK") but only for writes!
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@VisibleForTesting
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@NonNull
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public static volatile SparseArray<FontScaleConverter> sLookupTables = new SparseArray<>();
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/**
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* This is a write lock only! We don't care about synchronization on reads; they can be a bit
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* out of date. But all writes have to be atomic, so we use this similar to a
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* CopyOnWriteArrayList.
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*/
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private static final Object LOOKUP_TABLES_WRITE_LOCK = new Object();
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private static float sMinScaleBeforeCurvesApplied = 1.05f;
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static {
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// These were generated by frameworks/base/tools/fonts/font-scaling-array-generator.js and
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// manually tweaked for optimum readability.
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synchronized (LOOKUP_TABLES_WRITE_LOCK) {
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.05f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] { 8.4f, 10.5f, 12.6f, 14.8f, 18.6f, 20.6f, 24.4f, 30f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.1f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] { 8.8f, 11f, 13.2f, 15.6f, 19.2f, 21.2f, 24.8f, 30f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.15f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] { 9.2f, 11.5f, 13.8f, 16.4f, 19.8f, 21.8f, 25.2f, 30f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.2f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] { 9.6f, 12f, 14.4f, 17.2f, 20.4f, 22.4f, 25.6f, 30f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.3f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] {10.4f, 13f, 15.6f, 18.8f, 21.6f, 23.6f, 26.4f, 30f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.5f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] { 12f, 15f, 18f, 22f, 24f, 26f, 28f, 30f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 1.8f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] {14.4f, 18f, 21.6f, 24.4f, 27.6f, 30.8f, 32.8f, 34.8f, 100})
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);
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putInto(
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sLookupTables,
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/* scaleKey= */ 2f,
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new FontScaleConverterImpl(
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/* fromSp= */
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new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100},
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/* toDp= */
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new float[] { 16f, 20f, 24f, 26f, 30f, 34f, 36f, 38f, 100})
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);
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}
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sMinScaleBeforeCurvesApplied = getScaleFromKey(sLookupTables.keyAt(0)) - 0.01f;
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if (sMinScaleBeforeCurvesApplied <= 1.0f) {
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throw new IllegalStateException(
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"You should only apply non-linear scaling to font scales > 1"
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);
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}
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}
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private FontScaleConverterFactory() {}
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/**
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* Returns true if non-linear font scaling curves would be in effect for the given scale, false
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* if the scaling would follow a linear curve or for no scaling.
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*
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* <p>Example usage:
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* <code>isNonLinearFontScalingActive(getResources().getConfiguration().fontScale)</code>
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*/
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@AnyThread
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public static boolean isNonLinearFontScalingActive(float fontScale) {
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return fontScale >= sMinScaleBeforeCurvesApplied;
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}
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/**
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* Finds a matching FontScaleConverter for the given fontScale factor.
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*
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* @param fontScale the scale factor, usually from {@link Configuration#fontScale}.
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*
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* @return a converter for the given scale, or null if non-linear scaling should not be used.
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*/
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@Nullable
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@AnyThread
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public static FontScaleConverter forScale(float fontScale) {
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if (!isNonLinearFontScalingActive(fontScale)) {
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return null;
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}
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FontScaleConverter lookupTable = get(fontScale);
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if (lookupTable != null) {
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return lookupTable;
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}
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// Didn't find an exact match: interpolate between two existing tables
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final int index = sLookupTables.indexOfKey(getKey(fontScale));
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if (index >= 0) {
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// This should never happen, should have been covered by get() above.
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return sLookupTables.valueAt(index);
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}
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// Didn't find an exact match: interpolate between two existing tables
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final int lowerIndex = -(index + 1) - 1;
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final int higherIndex = lowerIndex + 1;
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if (lowerIndex < 0 || higherIndex >= sLookupTables.size()) {
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// We have gone beyond our bounds and have nothing to interpolate between. Just give
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// them a straight linear table instead.
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// This works because when FontScaleConverter encounters a size beyond its bounds, it
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// calculates a linear fontScale factor using the ratio of the last element pair.
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FontScaleConverterImpl converter = new FontScaleConverterImpl(
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new float[]{1f},
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new float[]{fontScale}
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);
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if (Flags.fontScaleConverterPublic()) {
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// Cache for next time.
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put(fontScale, converter);
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}
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return converter;
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} else {
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float startScale = getScaleFromKey(sLookupTables.keyAt(lowerIndex));
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float endScale = getScaleFromKey(sLookupTables.keyAt(higherIndex));
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float interpolationPoint = MathUtils.constrainedMap(
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/* rangeMin= */ 0f,
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/* rangeMax= */ 1f,
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startScale,
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endScale,
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fontScale
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);
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FontScaleConverter converter = createInterpolatedTableBetween(
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sLookupTables.valueAt(lowerIndex),
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sLookupTables.valueAt(higherIndex),
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interpolationPoint
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);
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if (Flags.fontScaleConverterPublic()) {
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// Cache for next time.
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put(fontScale, converter);
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}
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return converter;
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}
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}
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@NonNull
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private static FontScaleConverter createInterpolatedTableBetween(
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FontScaleConverter start,
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FontScaleConverter end,
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float interpolationPoint
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) {
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float[] commonSpSizes = new float[] { 8f, 10f, 12f, 14f, 18f, 20f, 24f, 30f, 100f};
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float[] dpInterpolated = new float[commonSpSizes.length];
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for (int i = 0; i < commonSpSizes.length; i++) {
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float sp = commonSpSizes[i];
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float startDp = start.convertSpToDp(sp);
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float endDp = end.convertSpToDp(sp);
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dpInterpolated[i] = MathUtils.lerp(startDp, endDp, interpolationPoint);
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}
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return new FontScaleConverterImpl(commonSpSizes, dpInterpolated);
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}
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private static int getKey(float fontScale) {
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return (int) (fontScale * SCALE_KEY_MULTIPLIER);
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}
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private static float getScaleFromKey(int key) {
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return (float) key / SCALE_KEY_MULTIPLIER;
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}
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private static void put(float scaleKey, @NonNull FontScaleConverter fontScaleConverter) {
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// Dollar-store CopyOnWriteSparseArray, since this is the only write op we need.
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synchronized (LOOKUP_TABLES_WRITE_LOCK) {
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var newTable = sLookupTables.clone();
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putInto(newTable, scaleKey, fontScaleConverter);
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sLookupTables = newTable;
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}
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}
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private static void putInto(
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SparseArray<FontScaleConverter> table,
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float scaleKey,
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@NonNull FontScaleConverter fontScaleConverter
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) {
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table.put(getKey(scaleKey), fontScaleConverter);
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}
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@Nullable
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private static FontScaleConverter get(float scaleKey) {
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return sLookupTables.get(getKey(scaleKey));
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}
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}
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