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.view;
  
  /**
   * This is the base class for frame statistics.
   */
  public abstract class FrameStats {
      /**
       * Undefined time.
       */
      public static final long UNDEFINED_TIME_NANO = -1;
  
      /** @hide */
      protected long mRefreshPeriodNano;
  
      /** @hide */
      protected long[] mFramesPresentedTimeNano;
  
      /**
       * Gets the refresh period of the display hosting the window(s) for
       * which these statistics apply.
       *
       * @return The refresh period in nanoseconds.
       */
      public final long getRefreshPeriodNano() {
          return mRefreshPeriodNano;
      }
  
      /**
       * Gets the number of frames for which there is data.
       *
       * @return The number of frames.
       */
      public final int getFrameCount() {
          return mFramesPresentedTimeNano != null
                  ? mFramesPresentedTimeNano.length : 0;
      }
  
      /**
       * Gets the start time of the interval for which these statistics
       * apply. The start interval is the time when the first frame was
       * presented.
       *
       * @return The start time in nanoseconds or {@link #UNDEFINED_TIME_NANO}
       *         if there is no frame data.
       */
      public final long getStartTimeNano() {
          if (getFrameCount() <= 0) {
              return UNDEFINED_TIME_NANO;
          }
          return mFramesPresentedTimeNano[0];
      }
  
      /**
       * Gets the end time of the interval for which these statistics
       * apply. The end interval is the time when the last frame was
       * presented.
       *
       * @return The end time in nanoseconds or {@link #UNDEFINED_TIME_NANO}
       *         if there is no frame data.
       */
      public final long getEndTimeNano() {
          if (getFrameCount() <= 0) {
              return UNDEFINED_TIME_NANO;
          }
          return mFramesPresentedTimeNano[mFramesPresentedTimeNano.length - 1];
      }
  
      /**
       * Get the time a frame at a given index was presented.
       *
       * @param index The frame index.
       * @return The presented time in nanoseconds or {@link #UNDEFINED_TIME_NANO}
       *         if the frame is not presented yet.
       */
      public final long getFramePresentedTimeNano(int index) {
          if (mFramesPresentedTimeNano == null) {
              throw new IndexOutOfBoundsException();
          }
          return mFramesPresentedTimeNano[index];
      }
  }
  