content: /*
   * Copyright (C) 2014 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.transition;
  
  import android.view.ViewGroup;
  
  /**
   * Extend <code>TransitionPropagation</code> to customize start delays for Animators created
   * in {@link android.transition.Transition#createAnimator(ViewGroup,
   * TransitionValues, TransitionValues)}. A Transition such as {@link android.transition.Explode}
   * defaults to using {@link android.transition.CircularPropagation} and Views closer to the
   * epicenter will move out of the scene later and into the scene sooner than Views farther
   * from the epicenter, giving the appearance of inertia. With no TransitionPropagation, all
   * Views will react simultaneously to the start of the transition.
   *
   * @see Transition#setPropagation(TransitionPropagation)
   * @see Transition#getEpicenter()
   */
  public abstract class TransitionPropagation {
      /**
       * Called by Transition to alter the Animator start delay. All start delays will be adjusted
       * such that the minimum becomes zero.
       * @param sceneRoot The root of the View hierarchy running the transition.
       * @param transition The transition that created the Animator
       * @param startValues The values for a specific target in the start scene.
       * @param endValues The values for the target in the end scene.
       * @return A start delay to use with the Animator created by <code>transition</code>. The
       * delay will be offset by the minimum delay of all <code>TransitionPropagation</code>s
       * used in the Transition so that the smallest delay will be 0. Returned values may be
       * negative.
       */
      public abstract long getStartDelay(ViewGroup sceneRoot, Transition transition,
              TransitionValues startValues, TransitionValues endValues);
  
      /**
       * Captures the values in the start or end scene for the properties that this
       * transition propagation monitors. These values are then passed as the startValues
       * or endValues structure in a later call to
       * {@link #getStartDelay(ViewGroup, Transition, TransitionValues, TransitionValues)}.
       * The main concern for an implementation is what the
       * properties are that the transition cares about and what the values are
       * for all of those properties. The start and end values will be compared
       * later during the
       * {@link #getStartDelay(ViewGroup, Transition, TransitionValues, TransitionValues)}.
       * method to determine the start delay.
       *
       * <p>Subclasses must implement this method. The method should only be called by the
       * transition system; it is not intended to be called from external classes.</p>
       *
       * @param transitionValues The holder for any values that the Transition
       * wishes to store. Values are stored in the <code>values</code> field
       * of this TransitionValues object and are keyed from
       * a String value. For example, to store a view's rotation value,
       * a transition might call
       * <code>transitionValues.values.put("appname:transitionname:rotation",
       * view.getRotation())</code>. The target view will already be stored in
       * the transitionValues structure when this method is called.
       */
      public abstract void captureValues(TransitionValues transitionValues);
  
      /**
       * Returns the set of property names stored in the {@link TransitionValues}
       * object passed into {@link #captureValues(TransitionValues)} that
       * this transition propagation cares about for the purposes of preventing
       * duplicate capturing of property values.
  
       * <p>A <code>TransitionPropagation</code> must override this method to prevent
       * duplicate capturing of values and must contain at least one </p>
       *
       * @return An array of property names as described in the class documentation for
       * {@link TransitionValues}.
       */
      public abstract String[] getPropagationProperties() ;
  }
  