Priority.java

/*
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

package com.facebook.imagepipeline.common;

import javax.annotation.Nullable;

/**
 * Priority levels recognized by the image pipeline.
 */
public enum Priority {
  /**
   * NOTE: DO NOT CHANGE ORDERING OF THOSE CONSTANTS UNDER ANY CIRCUMSTANCES.
   * Doing so will make ordering incorrect.
   */

  /**
   * Lowest priority level. Used for prefetches of non-visible images.
   */
  LOW,

  /**
   * Medium priority level. Used for warming of images that might soon get visible.
   */
  MEDIUM,

  /**
   * Highest priority level. Used for images that are currently visible on screen.
   */
  HIGH;

  /**
   * Gets the higher priority among the two.
   * @param priority1
   * @param priority2
   * @return higher priority
   */
  public static Priority getHigherPriority(
      @Nullable Priority priority1,
      @Nullable Priority priority2) {
    if (priority1 == null) {
      return priority2;
    }
    if (priority2 == null) {
      return priority1;
    }
    if (priority1.ordinal() > priority2.ordinal()) {
      return priority1;
    } else {
      return priority2;
    }
  }

}