core/java/android/view/FrameStats.java

/*
 * 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];
    }
}