com.cheng.animationstudy.customview.googleimitatecode.DiySwipeRefreshLayout.java Source code

Java tutorial

Introduction

Here is the source code for com.cheng.animationstudy.customview.googleimitatecode.DiySwipeRefreshLayout.java

Source

/*
 * Copyright (C) 2013 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 com.cheng.animationstudy.customview.googleimitatecode;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Transformation;
import android.widget.AbsListView;

/**
 * The SwipeRefreshLayout should be used whenever the user can refresh the
 * contents of a view via a vertical swipe gesture. The activity that
 * instantiates this view should add an OnRefreshListener to be notified
 * whenever the swipe to refresh gesture is completed. The SwipeRefreshLayout
 * will notify the listener each and every time the gesture is completed again;
 * the listener is responsible for correctly determining when to actually
 * initiate a refresh of its content. If the listener determines there should
 * not be a refresh, it must call setRefreshing(false) to cancel any visual
 * indication of a refresh. If an activity wishes to show just the progress
 * animation, it should call setRefreshing(true). To disable the gesture and progress
 * animation, call setEnabled(false) on the view.
 *
 * <p> This layout should be made the parent of the view that will be refreshed as a
 * result of the gesture and can only support one direct child. This view will
 * also be made the target of the gesture and will be forced to match both the
 * width and the height supplied in this layout. The SwipeRefreshLayout does not
 * provide accessibility events; instead, a menu item must be provided to allow
 * refresh of the content wherever this gesture is used.</p>
 */
public class DiySwipeRefreshLayout extends ViewGroup {
    private static final String LOG_TAG = DiySwipeRefreshLayout.class.getSimpleName();

    private static final long RETURN_TO_ORIGINAL_POSITION_TIMEOUT = 300;
    private static final float ACCELERATE_INTERPOLATION_FACTOR = 1.5f;
    private static final float DECELERATE_INTERPOLATION_FACTOR = 2f;
    private static final float PROGRESS_BAR_HEIGHT = 4;
    private static final float MAX_SWIPE_DISTANCE_FACTOR = .6f;
    private static final int REFRESH_TRIGGER_DISTANCE = 120;
    private static final int INVALID_POINTER = -1;

    private DiySwipeProgressBar mProgressBar; //the thing that shows progress is going
    private DiySwipeProgressBar mProgressBarBottom;
    private View mTarget; //the content that gets pulled down
    private int mOriginalOffsetTop;
    private OnRefreshListener mRefreshListener;
    private OnLoadListener mLoadListener;
    private int mFrom;
    private boolean mRefreshing = false;
    private boolean mLoading = false;
    private int mTouchSlop;
    private float mDistanceToTriggerSync = -1;
    private int mMediumAnimationDuration;
    private float mFromPercentage = 0;
    private float mCurrPercentage = 0;
    private int mProgressBarHeight;
    private int mCurrentTargetOffsetTop;

    private float mInitialMotionY;
    private float mLastMotionY;
    private boolean mIsBeingDragged;
    private int mActivePointerId = INVALID_POINTER;

    // Target is returning to its start offset because it was cancelled or a
    // refresh was triggered.
    private boolean mReturningToStart;
    private final DecelerateInterpolator mDecelerateInterpolator;
    private final AccelerateInterpolator mAccelerateInterpolator;
    private static final int[] LAYOUT_ATTRS = new int[] { android.R.attr.enabled };
    private Mode mMode = Mode.getDefault();
    //??????????
    //Mode.DISABLED???/?
    private Mode mLastDirection = Mode.DISABLED;
    private int mDirection = 0;
    //????
    private float mStartPoint;
    private boolean up;
    private boolean down;
    //?????
    private boolean loadNoFull = false;

    //??
    private final Animation mAnimateToStartPosition = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            int targetTop = 0;
            if (mFrom != mOriginalOffsetTop) {
                targetTop = (mFrom + (int) ((mOriginalOffsetTop - mFrom) * interpolatedTime));
            }
            int offset = targetTop - mTarget.getTop();
            //?????
            //            final int currentTop = mTarget.getTop();
            //            if (offset + currentTop < 0) {
            //                offset = 0 - currentTop;
            //            }
            setTargetOffsetTopAndBottom(offset);
        }
    };

    //??
    private Animation mShrinkTrigger = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            float percent = mFromPercentage + ((0 - mFromPercentage) * interpolatedTime);
            mProgressBar.setTriggerPercentage(percent);
        }
    };

    //??
    private Animation mShrinkTriggerBottom = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            float percent = mFromPercentage + ((0 - mFromPercentage) * interpolatedTime);
            mProgressBarBottom.setTriggerPercentage(percent);
        }
    };

    //????
    private final AnimationListener mReturnToStartPositionListener = new BaseAnimationListener() {
        @Override
        public void onAnimationEnd(Animation animation) {
            // Once the target content has returned to its start position, reset
            // the target offset to 0
            mCurrentTargetOffsetTop = 0;
            mLastDirection = Mode.DISABLED;
        }
    };

    //??
    private final AnimationListener mShrinkAnimationListener = new BaseAnimationListener() {
        @Override
        public void onAnimationEnd(Animation animation) {
            mCurrPercentage = 0;
        }
    };

    //???
    private final Runnable mReturnToStartPosition = new Runnable() {

        @Override
        public void run() {
            mReturningToStart = true;
            animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(), mReturnToStartPositionListener);
        }

    };

    // Cancel the refresh gesture and animate everything back to its original state.
    private final Runnable mCancel = new Runnable() {

        @Override
        public void run() {
            mReturningToStart = true;
            // Timeout fired since the user last moved their finger; animate the
            // trigger to 0 and put the target back at its original position
            if (mProgressBar != null || mProgressBarBottom != null) {
                mFromPercentage = mCurrPercentage;
                if (mDirection > 0 && ((mMode == Mode.PULL_FROM_START) || (mMode == Mode.BOTH))) {
                    mShrinkTrigger.setDuration(mMediumAnimationDuration);
                    mShrinkTrigger.setAnimationListener(mShrinkAnimationListener);
                    mShrinkTrigger.reset();
                    mShrinkTrigger.setInterpolator(mDecelerateInterpolator);
                    startAnimation(mShrinkTrigger);
                } else if (mDirection < 0 && ((mMode == Mode.PULL_FROM_END) || (mMode == Mode.BOTH))) {
                    mShrinkTriggerBottom.setDuration(mMediumAnimationDuration);
                    mShrinkTriggerBottom.setAnimationListener(mShrinkAnimationListener);
                    mShrinkTriggerBottom.reset();
                    mShrinkTriggerBottom.setInterpolator(mDecelerateInterpolator);
                    startAnimation(mShrinkTriggerBottom);
                }
            }
            mDirection = 0;
            animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(), mReturnToStartPositionListener);
        }

    };

    /**
     * Simple constructor to use when creating a SwipeRefreshLayout from code.
     * @param context
     */
    public DiySwipeRefreshLayout(Context context) {
        this(context, null);
    }

    /**
     * Constructor that is called when inflating SwipeRefreshLayout from XML.
     * @param context
     * @param attrs
     */
    public DiySwipeRefreshLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();

        mMediumAnimationDuration = getResources().getInteger(android.R.integer.config_mediumAnimTime);

        setWillNotDraw(false);
        mProgressBar = new DiySwipeProgressBar(this);
        mProgressBarBottom = new DiySwipeProgressBar(this);
        final DisplayMetrics metrics = getResources().getDisplayMetrics();
        mProgressBarHeight = (int) (metrics.density * PROGRESS_BAR_HEIGHT);
        mDecelerateInterpolator = new DecelerateInterpolator(DECELERATE_INTERPOLATION_FACTOR);
        mAccelerateInterpolator = new AccelerateInterpolator(ACCELERATE_INTERPOLATION_FACTOR);

        final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS);
        setEnabled(a.getBoolean(0, true));
        a.recycle();
    }

    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        removeCallbacks(mCancel);
        removeCallbacks(mReturnToStartPosition);
    }

    @Override
    public void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        removeCallbacks(mReturnToStartPosition);
        removeCallbacks(mCancel);
    }

    //?
    private void animateOffsetToStartPosition(int from, AnimationListener listener) {
        mFrom = from;
        mAnimateToStartPosition.reset();
        mAnimateToStartPosition.setDuration(mMediumAnimationDuration);
        mAnimateToStartPosition.setAnimationListener(listener);
        mAnimateToStartPosition.setInterpolator(mDecelerateInterpolator);
        mTarget.startAnimation(mAnimateToStartPosition);
    }

    /**
     * Set the listener to be notified when a refresh is triggered via the swipe
     * gesture.
     */
    public void setOnRefreshListener(OnRefreshListener listener) {
        mRefreshListener = listener;
    }

    public void setOnLoadListener(OnLoadListener listener) {
        mLoadListener = listener;
    }

    //?
    private void setTriggerPercentage(float percent) {
        if (percent == 0f) {
            // No-op. A null trigger means it's uninitialized, and setting it to zero-percent
            // means we're trying to reset state, so there's nothing to reset in this case.
            mCurrPercentage = 0;
            return;
        }
        mCurrPercentage = percent;
        if (((mMode == Mode.PULL_FROM_START) || (mMode == Mode.BOTH)) && mLastDirection != Mode.PULL_FROM_END
                && !mLoading) {
            mProgressBar.setTriggerPercentage(percent);
        } else if (((mMode == Mode.PULL_FROM_END) || (mMode == Mode.BOTH)) && mLastDirection != Mode.PULL_FROM_START
                && !mRefreshing) {
            mProgressBarBottom.setTriggerPercentage(percent);
        }
    }

    /**
     * Notify the widget that refresh state has changed. Do not call this when
     * refresh is triggered by a swipe gesture.
     *
     * @param refreshing Whether or not the view should show refresh progress.
     */
    public void setRefreshing(boolean refreshing) {
        if (mRefreshing != refreshing) {
            ensureTarget();
            mCurrPercentage = 0;
            mRefreshing = refreshing;
            if (mRefreshing) {
                mProgressBar.start();
            } else {
                mLastDirection = Mode.DISABLED;
                mProgressBar.stop();
            }
        }
    }

    public void setLoading(boolean loading) {
        if (mLoading != loading) {
            ensureTarget();
            mCurrPercentage = 0;
            mLoading = loading;
            if (mLoading) {
                mProgressBarBottom.start();
            } else {
                mLastDirection = Mode.DISABLED;
                mProgressBarBottom.stop();
            }
        }
    }

    /**
     * @deprecated Use {@link #setColorSchemeResources(int, int, int, int)}
     */
    @Deprecated
    private void setColorScheme(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
        setColorSchemeResources(colorRes1, colorRes2, colorRes3, colorRes4);
    }

    /**
     * Set the four colors used in the progress animation from color resources.
     * The first color will also be the color of the bar that grows in response
     * to a user swipe gesture.
     */
    public void setTopColor(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
        setColorSchemeResources(colorRes1, colorRes2, colorRes3, colorRes4);
    }

    public void setBottomColor(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
        setColorSchemeResourcesBottom(colorRes1, colorRes2, colorRes3, colorRes4);
    }

    public void setColor(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
        setColorSchemeResources(colorRes1, colorRes2, colorRes3, colorRes4);
        setColorSchemeResourcesBottom(colorRes1, colorRes2, colorRes3, colorRes4);
    }

    private void setColorSchemeResources(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
        final Resources res = getResources();
        setColorSchemeColors(res.getColor(colorRes1), res.getColor(colorRes2), res.getColor(colorRes3),
                res.getColor(colorRes4));
    }

    private void setColorSchemeResourcesBottom(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
        final Resources res = getResources();
        setColorSchemeColorsBottom(res.getColor(colorRes1), res.getColor(colorRes2), res.getColor(colorRes3),
                res.getColor(colorRes4));
    }

    /**
     * Set the four colors used in the progress animation. The first color will
     * also be the color of the bar that grows in response to a user swipe
     * gesture.
     */
    private void setColorSchemeColors(int color1, int color2, int color3, int color4) {
        ensureTarget();
        mProgressBar.setColorScheme(color1, color2, color3, color4);
    }

    private void setColorSchemeColorsBottom(int color1, int color2, int color3, int color4) {
        ensureTarget();
        mProgressBarBottom.setColorScheme(color1, color2, color3, color4);
    }

    /**
     * @return Whether the SwipeRefreshWidget is actively showing refresh
     *         progress.
     */
    public boolean isRefreshing() {
        return mRefreshing;
    }

    public boolean isLoading() {
        return mLoading;
    }

    private void ensureTarget() {
        // Don't bother getting the parent height if the parent hasn't been laid out yet.
        if (mTarget == null) {
            if (getChildCount() > 1 && !isInEditMode()) {
                throw new IllegalStateException("SwipeRefreshLayout can host only one direct child");
            }
            mTarget = getChildAt(0);
            mOriginalOffsetTop = mTarget.getTop() + getPaddingTop();
        }
        if (mDistanceToTriggerSync == -1) {
            if (getParent() != null && ((View) getParent()).getHeight() > 0) {
                final DisplayMetrics metrics = getResources().getDisplayMetrics();
                mDistanceToTriggerSync = (int) Math.min(
                        ((View) getParent()).getHeight() * MAX_SWIPE_DISTANCE_FACTOR,
                        REFRESH_TRIGGER_DISTANCE * metrics.density);
            }
        }
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);
        mProgressBar.draw(canvas);
        mProgressBarBottom.draw(canvas);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        final int width = getMeasuredWidth();
        final int height = getMeasuredHeight();
        mProgressBar.setBounds(0, 0, width, mProgressBarHeight);
        if (getChildCount() == 0) {
            return;
        }
        final View child = getChildAt(0);
        final int childLeft = getPaddingLeft();
        final int childTop = mCurrentTargetOffsetTop + getPaddingTop();
        final int childWidth = width - getPaddingLeft() - getPaddingRight();
        final int childHeight = height - getPaddingTop() - getPaddingBottom();
        child.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
        mProgressBarBottom.setBounds(0, height - mProgressBarHeight, width, height);
    }

    @Override
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (getChildCount() > 1 && !isInEditMode()) {
            throw new IllegalStateException("SwipeRefreshLayout can host only one direct child");
        }
        if (getChildCount() > 0) {
            getChildAt(0).measure(
                    MeasureSpec.makeMeasureSpec(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
                            MeasureSpec.EXACTLY),
                    MeasureSpec.makeMeasureSpec(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
                            MeasureSpec.EXACTLY));
        }
    }

    /**
     * @return Whether it is possible for the child view of this layout to
     *         scroll up. Override this if the child view is a custom view.
     */
    public boolean canChildScrollUp() {
        if (android.os.Build.VERSION.SDK_INT < 14) {
            if (mTarget instanceof AbsListView) {
                final AbsListView absListView = (AbsListView) mTarget;
                return absListView.getChildCount() > 0 && (absListView.getFirstVisiblePosition() > 0
                        || absListView.getChildAt(0).getTop() < absListView.getPaddingTop());
            } else {
                return mTarget.getScrollY() > 0;
            }
        } else {
            return ViewCompat.canScrollVertically(mTarget, -1);
        }
    }

    public boolean canChildScrollDown() {
        if (android.os.Build.VERSION.SDK_INT < 14) {
            if (mTarget instanceof AbsListView) {
                final AbsListView absListView = (AbsListView) mTarget;
                View lastChild = absListView.getChildAt(absListView.getChildCount() - 1);
                if (lastChild != null) {
                    return (absListView.getLastVisiblePosition() == (absListView.getCount() - 1))
                            && lastChild.getBottom() > absListView.getPaddingBottom();
                } else {
                    return false;
                }
            } else {
                return mTarget.getHeight() - mTarget.getScrollY() > 0;
            }
        } else {
            return ViewCompat.canScrollVertically(mTarget, 1);
        }
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        ensureTarget();

        final int action = MotionEventCompat.getActionMasked(ev);

        if (mReturningToStart && action == MotionEvent.ACTION_DOWN) {
            mReturningToStart = false;
        }

        if (!isEnabled() || mReturningToStart) {
            // Fail fast if we're not in a state where a swipe is possible
            return false;
        }

        switch (action) {
        case MotionEvent.ACTION_DOWN:
            mLastMotionY = mInitialMotionY = ev.getY();
            mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
            mIsBeingDragged = false;
            mCurrPercentage = 0;
            mStartPoint = mInitialMotionY;

            //up/down????????
            //????canChildScrollUp/canChildScrollDown
            //????????
            up = canChildScrollUp();
            down = canChildScrollDown();
            break;

        case MotionEvent.ACTION_MOVE:
            if (mActivePointerId == INVALID_POINTER) {
                Log.e(LOG_TAG, "Got ACTION_MOVE event but don't have an active pointer id.");
                return false;
            }

            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            if (pointerIndex < 0) {
                Log.e(LOG_TAG, "Got ACTION_MOVE event but have an invalid active pointer id.");
                return false;
            }

            final float y = MotionEventCompat.getY(ev, pointerIndex);
            //                final float yDiff = y - mInitialMotionY;
            final float yDiff = y - mStartPoint;
            //????
            if ((mLastDirection == Mode.PULL_FROM_START && yDiff < 0)
                    || (mLastDirection == Mode.PULL_FROM_END && yDiff > 0)) {
                return false;
            }
            //???
            //mStartPoint
            if ((canChildScrollUp() && yDiff > 0) || (canChildScrollDown() && yDiff < 0)) {
                mStartPoint = y;
            }

            //
            if (yDiff > mTouchSlop) {
                //???
                if (canChildScrollUp() || mLastDirection == Mode.PULL_FROM_END) {
                    mIsBeingDragged = false;
                    return false;
                }
                if ((mMode == Mode.PULL_FROM_START) || (mMode == Mode.BOTH)) {
                    mLastMotionY = y;
                    mIsBeingDragged = true;
                    mLastDirection = Mode.PULL_FROM_START;
                }
            }
            //
            else if (-yDiff > mTouchSlop) {
                //???
                if (canChildScrollDown() || mLastDirection == Mode.PULL_FROM_START) {
                    mIsBeingDragged = false;
                    return false;
                }
                //????????
                if (!up && !down && !loadNoFull) {
                    mIsBeingDragged = false;
                    return false;
                }
                if ((mMode == Mode.PULL_FROM_END) || (mMode == Mode.BOTH)) {
                    mLastMotionY = y;
                    mIsBeingDragged = true;
                    mLastDirection = Mode.PULL_FROM_END;
                }
            }
            break;

        case MotionEventCompat.ACTION_POINTER_UP:
            onSecondaryPointerUp(ev);
            break;

        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            mIsBeingDragged = false;
            mCurrPercentage = 0;
            mActivePointerId = INVALID_POINTER;
            mLastDirection = Mode.DISABLED;
            break;
        }

        return mIsBeingDragged;
    }

    @Override
    public void requestDisallowInterceptTouchEvent(boolean b) {
        // Nope.
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        final int action = MotionEventCompat.getActionMasked(ev);

        if (mReturningToStart && action == MotionEvent.ACTION_DOWN) {
            mReturningToStart = false;
        }

        if (!isEnabled() || mReturningToStart) {
            // Fail fast if we're not in a state where a swipe is possible
            return false;
        }

        switch (action) {
        case MotionEvent.ACTION_DOWN:
            mLastMotionY = mInitialMotionY = ev.getY();
            mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
            mIsBeingDragged = false;
            mCurrPercentage = 0;
            mStartPoint = mInitialMotionY;

            up = canChildScrollUp();
            down = canChildScrollDown();
            break;

        case MotionEvent.ACTION_MOVE:
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            if (pointerIndex < 0) {
                Log.e(LOG_TAG, "Got ACTION_MOVE event but have an invalid active pointer id.");
                return false;
            }

            final float y = MotionEventCompat.getY(ev, pointerIndex);
            //                final float yDiff = y - mInitialMotionY;
            final float yDiff = y - mStartPoint;

            if ((mLastDirection == Mode.PULL_FROM_START && yDiff < 0)
                    || (mLastDirection == Mode.PULL_FROM_END && yDiff > 0)) {
                return true;
            }

            if (!mIsBeingDragged && (yDiff > 0 && mLastDirection == Mode.PULL_FROM_START)
                    || (yDiff < 0 && mLastDirection == Mode.PULL_FROM_END)) {
                mIsBeingDragged = true;
            }

            if (mIsBeingDragged) {
                // User velocity passed min velocity; trigger a refresh
                if (yDiff > mDistanceToTriggerSync) {
                    // User movement passed distance; trigger a refresh
                    if (mLastDirection == Mode.PULL_FROM_END) {
                        return true;

                    }
                    if ((mMode == Mode.PULL_FROM_START) || (mMode == Mode.BOTH)) {
                        mLastDirection = Mode.PULL_FROM_START;
                        startRefresh();
                    }
                } else if (-yDiff > mDistanceToTriggerSync) {
                    if ((!up && !down && !loadNoFull) || mLastDirection == Mode.PULL_FROM_START) {
                        return true;
                    }
                    if ((mMode == Mode.PULL_FROM_END) || (mMode == Mode.BOTH)) {
                        mLastDirection = Mode.PULL_FROM_END;
                        startLoad();
                    }
                } else {
                    if (!up && !down && yDiff < 0 && !loadNoFull) {
                        return true;
                    }
                    // Just track the user's movement
                    //???
                    setTriggerPercentage(
                            mAccelerateInterpolator.getInterpolation(Math.abs(yDiff) / mDistanceToTriggerSync));
                    updateContentOffsetTop((int) yDiff);
                    if (mTarget.getTop() == getPaddingTop()) {
                        // If the user puts the view back at the top, we
                        // don't need to. This shouldn't be considered
                        // cancelling the gesture as the user can restart from the top.
                        removeCallbacks(mCancel);
                        mLastDirection = Mode.DISABLED;
                    } else {
                        mDirection = (yDiff > 0 ? 1 : -1);
                        updatePositionTimeout();
                    }
                }
                mLastMotionY = y;
            }
            break;

        case MotionEventCompat.ACTION_POINTER_DOWN: {
            final int index = MotionEventCompat.getActionIndex(ev);
            mLastMotionY = MotionEventCompat.getY(ev, index);
            mActivePointerId = MotionEventCompat.getPointerId(ev, index);
            break;
        }

        case MotionEventCompat.ACTION_POINTER_UP:
            onSecondaryPointerUp(ev);
            break;

        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            mIsBeingDragged = false;
            mCurrPercentage = 0;
            mActivePointerId = INVALID_POINTER;
            mLastDirection = Mode.DISABLED;
            return false;
        }

        return true;
    }

    private void startRefresh() {
        if (!mLoading && !mRefreshing) {
            removeCallbacks(mCancel);
            mReturnToStartPosition.run();
            setRefreshing(true);
            mRefreshListener.onRefresh();
        }
    }

    private void startLoad() {
        if (!mLoading && !mRefreshing) {
            removeCallbacks(mCancel);
            mReturnToStartPosition.run();
            setLoading(true);
            mLoadListener.onLoad();
        }
    }

    //??
    private void updateContentOffsetTop(int targetTop) {
        final int currentTop = mTarget.getTop();
        if (targetTop > mDistanceToTriggerSync) {
            targetTop = (int) mDistanceToTriggerSync;
        }
        //???
        //        else if (targetTop < 0) {
        //            targetTop = 0;
        //        }
        setTargetOffsetTopAndBottom(targetTop - currentTop);
    }

    //?????
    private void setTargetOffsetTopAndBottom(int offset) {
        mTarget.offsetTopAndBottom(offset);
        mCurrentTargetOffsetTop = mTarget.getTop();
    }

    private void updatePositionTimeout() {
        removeCallbacks(mCancel);
        postDelayed(mCancel, RETURN_TO_ORIGINAL_POSITION_TIMEOUT);
    }

    private void onSecondaryPointerUp(MotionEvent ev) {
        final int pointerIndex = MotionEventCompat.getActionIndex(ev);
        final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
        if (pointerId == mActivePointerId) {
            // This was our active pointer going up. Choose a new
            // active pointer and adjust accordingly.
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
            mLastMotionY = MotionEventCompat.getY(ev, newPointerIndex);
            mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
        }
    }

    /**
     * Classes that wish to be notified when the swipe gesture correctly
     * triggers a refresh should implement this interface.
     */
    public interface OnRefreshListener {
        public void onRefresh();
    }

    public interface OnLoadListener {
        public void onLoad();
    }

    public void setMode(Mode mode) {
        this.mMode = mode;
    }

    public void setLoadNoFull(boolean load) {
        this.loadNoFull = load;
    }

    public static enum Mode {
        /**
         * Disable all Pull-to-Refresh gesture and Refreshing handling
         */
        DISABLED(0x0),

        /**
         * Only allow the user to Pull from the start of the Refreshable View to
         * refresh. The start is either the Top or Left, depending on the
         * scrolling direction.
         */
        PULL_FROM_START(0x1),

        /**
         * Only allow the user to Pull from the end of the Refreshable View to
         * refresh. The start is either the Bottom or Right, depending on the
         * scrolling direction.
         */
        PULL_FROM_END(0x2),

        /**
         * Allow the user to both Pull from the start, from the end to refresh.
         */
        BOTH(0x3);

        static Mode getDefault() {
            return BOTH;
        }

        boolean permitsPullToRefresh() {
            return !(this == DISABLED);
        }

        boolean permitsPullFromStart() {
            return (this == Mode.BOTH || this == Mode.PULL_FROM_START);
        }

        boolean permitsPullFromEnd() {
            return (this == Mode.BOTH || this == Mode.PULL_FROM_END);
        }

        private int mIntValue;

        // The modeInt values need to match those from attrs.xml
        Mode(int modeInt) {
            mIntValue = modeInt;
        }

        int getIntValue() {
            return mIntValue;
        }

    }

    /**
     * Simple AnimationListener to avoid having to implement unneeded methods in
     * AnimationListeners.
     */
    private class BaseAnimationListener implements AnimationListener {
        @Override
        public void onAnimationStart(Animation animation) {
        }

        @Override
        public void onAnimationEnd(Animation animation) {
        }

        @Override
        public void onAnimationRepeat(Animation animation) {
        }
    }
}