https://source.android.com/ 
/*
 * Copyright (C) 2017 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.hardware.display;

import android.annotation.Nullable;
import android.annotation.SystemApi;
import android.annotation.TestApi;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.Pair;

import com.android.internal.util.Preconditions;

import java.util.Arrays;
import java.util.Objects;


@hide
/** @hide */
@SystemApi
@TestApi
public final class BrightnessConfiguration implements Parcelable {
    private final float[] mLux;
    private final float[] mNits;
    private final String mDescription;

    private BrightnessConfiguration(float[] lux, float[] nits, String description) {
        mLux = lux;
        mNits = nits;
        mDescription = description;
    }

    
Gets the base brightness as curve.
The curve is returned as a pair of float arrays, the first representing all of the lux
points of the brightness curve and the second representing all of the nits values of the
brightness curve.

Returns:the control points for the brightness curve.
/**
     * Gets the base brightness as curve.
     *
     * The curve is returned as a pair of float arrays, the first representing all of the lux
     * points of the brightness curve and the second representing all of the nits values of the
     * brightness curve.
     *
     * @return the control points for the brightness curve.
     */
    public Pair<float[], float[]> getCurve() {
        return Pair.create(Arrays.copyOf(mLux, mLux.length), Arrays.copyOf(mNits, mNits.length));
    }

    
Returns description string.

@hide
/**
     * Returns description string.
     * @hide
     */
    public String getDescription() {
        return mDescription;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeFloatArray(mLux);
        dest.writeFloatArray(mNits);
        dest.writeString(mDescription);
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("BrightnessConfiguration{[");
        final int size = mLux.length;
        for (int i = 0; i < size; i++) {
            if (i != 0) {
                sb.append(", ");
            }
            sb.append("(").append(mLux[i]).append(", ").append(mNits[i]).append(")");
        }
        sb.append("], '");
        if (mDescription != null) {
            sb.append(mDescription);
        }
        sb.append("'}");
        return sb.toString();
    }

    @Override
    public int hashCode() {
        int result = 1;
        result = result * 31 + Arrays.hashCode(mLux);
        result = result * 31 + Arrays.hashCode(mNits);
        if (mDescription != null) {
            result = result * 31 + mDescription.hashCode();
        }
        return result;
    }

    @Override
    public boolean equals(Object o) {
        if (o == this) {
            return true;
        }
        if (!(o instanceof BrightnessConfiguration)) {
            return false;
        }
        final BrightnessConfiguration other = (BrightnessConfiguration) o;
        return Arrays.equals(mLux, other.mLux) && Arrays.equals(mNits, other.mNits)
                && Objects.equals(mDescription, other.mDescription);
    }

    public static final Creator<BrightnessConfiguration> CREATOR =
            new Creator<BrightnessConfiguration>() {
        public BrightnessConfiguration createFromParcel(Parcel in) {
            float[] lux = in.createFloatArray();
            float[] nits = in.createFloatArray();
            Builder builder = new Builder(lux, nits);
            builder.setDescription(in.readString());
            return builder.build();
        }

        public BrightnessConfiguration[] newArray(int size) {
            return new BrightnessConfiguration[size];
        }
    };

    
A builder class for BrightnessConfigurations. 
/**
     * A builder class for {@link BrightnessConfiguration}s.
     */
    public static class Builder {
        private float[] mCurveLux;
        private float[] mCurveNits;
        private String mDescription;

        
STOPSHIP remove when app has stopped using this.

@hide
/**
         * STOPSHIP remove when app has stopped using this.
         * @hide
         */
        public Builder() {
        }

        
Constructs the builder with the control points for the brightness curve.
Brightness curves must have strictly increasing ambient brightness values in lux and
monotonically increasing display brightness values in nits. In addition, the initial
control point must be 0 lux.

Throws:
/**
         * Constructs the builder with the control points for the brightness curve.
         *
         * Brightness curves must have strictly increasing ambient brightness values in lux and
         * monotonically increasing display brightness values in nits. In addition, the initial
         * control point must be 0 lux.
         *
         * @throws IllegalArgumentException if the initial control point is not at 0 lux.
         * @throws IllegalArgumentException if the lux levels are not strictly increasing.
         * @throws IllegalArgumentException if the nit levels are not monotonically increasing.
         */
        public Builder(float[] lux, float[] nits) {
            setCurve(lux, nits);
        }

        
Sets the control points for the brightness curve.
Brightness curves must have strictly increasing ambient brightness values in lux and
monotonically increasing display brightness values in nits. In addition, the initial
control point must be 0 lux.

Throws:
  • IllegalArgumentException – if the initial control point is not at 0 lux.
  • IllegalArgumentException – if the lux levels are not strictly increasing.
  • IllegalArgumentException – if the nit levels are not monotonically increasing.
STOPSHIP remove when app has stopped using this.
@hide
/**
         * Sets the control points for the brightness curve.
         *
         * Brightness curves must have strictly increasing ambient brightness values in lux and
         * monotonically increasing display brightness values in nits. In addition, the initial
         * control point must be 0 lux.
         *
         * @throws IllegalArgumentException if the initial control point is not at 0 lux.
         * @throws IllegalArgumentException if the lux levels are not strictly increasing.
         * @throws IllegalArgumentException if the nit levels are not monotonically increasing.
         *
         * STOPSHIP remove when app has stopped using this.
         * @hide
         */
        public Builder setCurve(float[] lux, float[] nits) {
            Preconditions.checkNotNull(lux);
            Preconditions.checkNotNull(nits);
            if (lux.length == 0 || nits.length == 0) {
                throw new IllegalArgumentException("Lux and nits arrays must not be empty");
            }
            if (lux.length != nits.length) {
                throw new IllegalArgumentException("Lux and nits arrays must be the same length");
            }
            if (lux[0] != 0) {
                throw new IllegalArgumentException("Initial control point must be for 0 lux");
            }
            Preconditions.checkArrayElementsInRange(lux, 0, Float.MAX_VALUE, "lux");
            Preconditions.checkArrayElementsInRange(nits, 0, Float.MAX_VALUE, "nits");
            checkMonotonic(lux, true/*strictly increasing*/, "lux");
            checkMonotonic(nits, false /*strictly increasing*/, "nits");
            mCurveLux = lux;
            mCurveNits = nits;
            return this;
        }

        
Set description of the brightness curve.

Params:
  • description – brief text describing the curve pushed. It maybe truncated
                   and will not be displayed in the UI
/**
         * Set description of the brightness curve.
         *
         * @param description brief text describing the curve pushed. It maybe truncated
         *                    and will not be displayed in the UI
         */
        public Builder setDescription(@Nullable String description) {
            mDescription = description;
            return this;
        }

        
Builds the BrightnessConfiguration. A brightness curve must be set before calling this.

/**
         * Builds the {@link BrightnessConfiguration}.
         *
         * A brightness curve <b>must</b> be set before calling this.
         */
        public BrightnessConfiguration build() {
            if (mCurveLux == null || mCurveNits == null) {
                throw new IllegalStateException("A curve must be set!");
            }
            return new BrightnessConfiguration(mCurveLux, mCurveNits, mDescription);
        }

        private static void checkMonotonic(float[] vals, boolean strictlyIncreasing, String name) {
            if (vals.length <= 1) {
                return;
            }
            float prev = vals[0];
            for (int i = 1; i < vals.length; i++) {
                if (prev > vals[i] || prev == vals[i] && strictlyIncreasing) {
                    String condition = strictlyIncreasing ? "strictly increasing" : "monotonic";
                    throw new IllegalArgumentException(name + " values must be " + condition);
                }
                prev = vals[i];
            }
        }
    }
}