77 lines
2.9 KiB
Java
77 lines
2.9 KiB
Java
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/*
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* Copyright (C) 2023 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.FlaggedApi;
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import android.annotation.Nullable;
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/**
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* A converter for non-linear font scaling. Converts font sizes given in "sp" dimensions to a
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* "dp" dimension according to a non-linear curve.
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*
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* <p>This is meant to improve readability at larger font scales: larger fonts will scale up more
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* slowly than smaller fonts, so we don't get ridiculously huge fonts that don't fit on the screen.
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*
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* <p>The thinking here is that large fonts are already big enough to read, but we still want to
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* scale them slightly to preserve the visual hierarchy when compared to smaller fonts.
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*/
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@FlaggedApi(Flags.FLAG_FONT_SCALE_CONVERTER_PUBLIC)
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public interface FontScaleConverter {
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/**
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* Converts a dimension in "sp" to "dp".
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*/
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float convertSpToDp(float sp);
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/**
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* Converts a dimension in "dp" back to "sp".
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*/
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float convertDpToSp(float dp);
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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: {@code
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* isNonLinearFontScalingActive(getResources().getConfiguration().fontScale)}
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*/
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@AnyThread
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static boolean isNonLinearFontScalingActive(float fontScale) {
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return FontScaleConverterFactory.isNonLinearFontScalingActive(fontScale);
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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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* 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
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* the scaling conversion for you. Dimens and resources loaded from XML will also be
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* automatically converted. 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 method.
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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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static FontScaleConverter forScale(float fontScale) {
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return FontScaleConverterFactory.forScale(fontScale);
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}
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}
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