CameraFilter.java

/*
 * Copyright 2020 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 androidx.camera.core;

import androidx.annotation.NonNull;

import java.util.LinkedHashSet;

/**
 * An interface for filtering cameras.
 */
@ExperimentalCameraFilter
public interface CameraFilter {
    /**
     * Filters a set of {@link Camera}s and returns those matching the requirements.
     *
     * <p>If the output set contains cameras not in the input set, when used by a
     * {@link androidx.camera.core.CameraSelector} then it will result in an
     * IllegalArgumentException thrown when calling bindToLifecycle.
     *
     * <p>The camera that has lower index in the set has higher priority. When used by
     * {@link androidx.camera.core.CameraSelector.Builder#addCameraFilter(CameraFilter)}, the
     * available cameras will be filtered by all {@link CameraFilter}s by the order they were
     * added. The first camera in the result will be selected if there are multiple cameras left.
     *
     * @param cameras The input set of {@link Camera}s being filtered. It's not expected to be
     *                modified.
     * @return The output set of {@link Camera}s that match the requirements. Users are expected
     * to create a new set to return with.
     */
    @NonNull
    LinkedHashSet<Camera> filter(@NonNull LinkedHashSet<Camera> cameras);
}