打造Android微信朋友圈下拉刷新控件

三好码农

发布于 2018-09-11 10:53:48

1.8K0

发布于 2018-09-11 10:53:48

微信朋友圈我们都经常用，朋友圈的下拉刷新比较有意思，我们今天将要模仿打造微信朋友圈的下拉刷新控件，当然微信的这种刷新设计可能不是最好的，实际项目中你可以用V4包里面的SwipeRefreshView或者Chris Banes的AndroidPullRerfresh，看产品经理的设计。

思路

我们初步分析下，界面上主要有二个控件，一个彩虹状的圆形LoadingView，一个是ListView，那么我大致可以有下面三个步骤：

第一步：需要自定义一个ViewGroup，把上面的2个控件add进来。第二步：利用ViewDragHelper处理控件拖动。当ListView处于顶部时，如果继续向下拖动，就拦截触摸事件，将触摸事件传递给ViewDragHelper处理，这里比较关键，主要是是否拦截触摸事件的判断条件要处理好，否则如果ListView的点击和滚动事件被我们拦截了，那就悲剧了。第三步：在ViewDragHelper的拖动回调方法里面，设置listView和彩虹LoadingView的位置，调用requestLayout。第四步：手势松开后，开始刷新，LoadingView在固定位置做旋转动画。第五步：如果设置了onRefreshListener，执行onRefresh接口。第六步：调用stopRefresh，完成刷新，这一步需要控件使用者手动去调用，控件本身不自动触发。

代码实现

篇幅关系，我还是贴出部分关键代码，项目我惯例共享到Github了，大家可以去直接下载 https://github.com/aliouswang/FriendRefreshView

public class FriendRefreshView extends ViewGroup{

//圆形指示器
private ImageView mRainbowView;
private ListView mContentView;

//控件宽，高
private int sWidth;
private int sHeight;

private ViewDragHelper mDragHelper;

//contentView的当前top属性
private int currentTop;
//listView首个item
private int firstItem;
private boolean bScrollDown = false;
private boolean bDraging = false;

//圆形加载指示器最大top
private int rainbowMaxTop = 80;
//圆形加载指示器刷新时的top
private int rainbowStickyTop = 80;
//圆形加载指示器初始top
private int rainbowStartTop = -120;
//圆形加载指示器的半径
private int rainbowRadius = 100;
private int rainbowTop = - 120;
//圆形加载指示器旋转的角度
private int rainbowRotateAngle = 0;
private boolean bViewHelperSettling = false;

//刷新接口listener
private OnRefreshListener mRefreshLisenter;

private AbsListView.OnScrollListener onScrollListener;
private com.sw.library.widget.friendrefreshview.OnDetectScrollListener onDetectScrollListener;

public enum State {
    NORMAL,
    REFRESHING,
    DRAGING
}

//控件当前状态
private State mState = State.NORMAL;

public FriendRefreshView(Context context) {
    this(context, null);
}

public FriendRefreshView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
}

public FriendRefreshView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    initHandler();
    initDragHelper();
    initListView();
    initRainbowView();
    setBackgroundColor(Color.parseColor("#000000"));
    onDetectScrollListener = this;
}
....
}

这里我们还是利用handler来处理LoadingView 执行刷新时的转动动画和stopRefresh时滚动到初始位置的位移动画。

/**
 * 初始化handler，当ViewDragHelper释放了mContentView时，
 * 我们通过循环发送消息刷新mRainbowView的位置和角度
 */
private void initHandler() {
    mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case 0:
                    if (rainbowTop > rainbowStartTop) {
                        rainbowTop -= 10;
                        requestLayout();
                        mHandler.sendEmptyMessageDelayed(0, 15);
                    }
                    break;
                case 1:
                    if (rainbowTop <= rainbowStickyTop) {
                        if (rainbowTop < rainbowStickyTop) {
                            rainbowTop += 10;
                            if (rainbowTop > rainbowStickyTop) {
                                rainbowTop = rainbowStickyTop;
                            }
                        }
                        mRainbowView.setRotation(rainbowRotateAngle -= 10);
                    }else {
                        mRainbowView.setRotation(rainbowRotateAngle += 10);
                    }

                    requestLayout();

                    mHandler.sendEmptyMessageDelayed(1, 15);
                    break;
            }
        }
    };
}

初始化ViewDragHelper，已经是我们的老朋友了，有不熟悉的朋友可以参考我上一篇分享--实现小米应用我的小米

/**
 * 初始化mDragHelper，我们处理拖动的核心类
 */
private void initDragHelper() {
    mDragHelper = ViewDragHelper.create(this, new ViewDragHelper.Callback() {
        @Override
        public boolean tryCaptureView(View view, int i) {
            return view == mContentView && !bViewHelperSettling;
        }

        @Override
        public int clampViewPositionHorizontal(View child, int left, int dx) {
            return 0;
        }

        @Override
        public int clampViewPositionVertical(View child, int top, int dy) {
            return top;
        }

        @Override
        public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
            super.onViewPositionChanged(changedView, left, top, dx, dy);
            if (changedView == mContentView) {
                int lastContentTop = currentTop;
                if (top >= 0) {
                    currentTop = top;
                }else {
                    top = 0;
                }
                int lastTop = rainbowTop;
                int rTop = top + rainbowStartTop;
                if (rTop >= rainbowMaxTop) {
                    if (!isRefreshing()) {
                        rainbowRotateAngle += (currentTop - lastContentTop) * 2;
                        rTop = rainbowMaxTop;
                        rainbowTop = rTop;
                        mRainbowView.setRotation(rainbowRotateAngle);
                    }else {
                        rTop = rainbowMaxTop;
                        rainbowTop = rTop;
                    }

                }else {
                    if (isRefreshing()) {
                        rainbowTop = rainbowStickyTop;
                    }else {
                        rainbowTop = rTop;
                        rainbowRotateAngle += (rainbowTop - lastTop) * 3;
                        mRainbowView.setRotation(rainbowRotateAngle);
                    }
                }

                requestLayout();

            }
        }

        @Override
        public void onViewReleased(View releasedChild, float xvel, float yvel) {
            super.onViewReleased(releasedChild, xvel, yvel);
            mDragHelper.settleCapturedViewAt(0, 0);
            ViewCompat.postInvalidateOnAnimation(FriendRefreshView.this);
            //如果手势释放时，拖动的距离大于rainbowStickyTop，开始刷新
            if (currentTop >= rainbowStickyTop) {
                startRefresh();
            }

        }
    });


}

@Override
public void computeScroll() {
    super.computeScroll();
    if (mDragHelper.continueSettling(true)) {
        ViewCompat.postInvalidateOnAnimation(this);
        bViewHelperSettling = true;
    }else {
        bViewHelperSettling = false;
    }
}

触摸事件的分发和拦截，核心部分。

/**
 * 我们invoke 方法shouldIntercept来判断是否需要拦截事件，
 * 拦截事件是为了将事件传递给mDragHelper来处理，我们这里只有当mContentView滑动到顶部
 * 且mContentView没有处于滑动状态时才触发拦截。
 * @param ev
 * @return
 */
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
    mDragHelper.shouldInterceptTouchEvent(ev);
    return shouldIntercept();
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    mDragHelper.processTouchEvent(event);
    final int action = event.getActionMasked();
    switch (action) {
        case MotionEvent.ACTION_DOWN:
            break;
        case MotionEvent.ACTION_UP:
            mLastMotionY = 0;
            bDraging = false;
            bScrollDown = false;
            rainbowRotateAngle = 0;
            break;
        case MotionEvent.ACTION_MOVE:
            int index = MotionEventCompat.getActionIndex(event);
            int pointerId = MotionEventCompat.getPointerId(event, index);
            if (shouldIntercept()) {
                mDragHelper.captureChildView(mContentView, pointerId);
            }
            break;
    }
    return true;
}

/**
 * 判断是否需要拦截触摸事件
 * @return
 */
private boolean shouldIntercept() {
    if (bDraging) return true;
    int childCount = mContentView.getChildCount();
    if (childCount > 0) {
        View firstChild = mContentView.getChildAt(0);
        if (firstChild.getTop() >= 0
                && firstItem == 0 && currentTop == 0
                && bScrollDown) {
            return true;
        }else return false;
    }else {
        return true;
    }
}

/**
 * 判断mContentView是否处于顶部
 * @return
 */
private boolean checkIsTop() {
    int childCount = mContentView.getChildCount();
    if (childCount > 0) {
        View firstChild = mContentView.getChildAt(0);
        if (firstChild.getTop() >= 0
                && firstItem == 0 && currentTop == 0) {
            return true;
        }else return false;
    }else {
        return false;
    }
}

measure和layout，我们的老朋友了，不多解释。

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    sWidth = MeasureSpec.getSize(widthMeasureSpec);
    sHeight = MeasureSpec.getSize(heightMeasureSpec);
    measureChildren(widthMeasureSpec, heightMeasureSpec);
    LayoutParams contentParams = (LayoutParams) mContentView.getLayoutParams();
    contentParams.left = 0;
    contentParams.top = 0;
}


@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    LayoutParams contentParams = (LayoutParams) mContentView.getLayoutParams();
    mContentView.layout(contentParams.left, currentTop,
            contentParams.left + sWidth, currentTop + sHeight);

    mRainbowView.layout(rainbowRadius, rainbowTop,
            rainbowRadius * 2 , rainbowTop + rainbowRadius);
}

自定义ListView，处理触摸事件

private float mLastMotionX;
private float mLastMotionY;

/**
 * 对ListView的触摸事件进行判断，是否处于滑动状态
 */
private class FriendRefreshListView extends ListView {



    public FriendRefreshListView(Context context) {
        this(context, null);
    }

    public FriendRefreshListView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public FriendRefreshListView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setBackgroundColor(Color.parseColor("#ffffff"));
    }

    /*当前活动的点Id,有效的点的Id*/
    protected int mActivePointerId = INVALID_POINTER;

    /*无效的点*/
    private static final int INVALID_POINTER = -1;

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        final int action = ev.getActionMasked();
        switch (action) {
            case MotionEvent.ACTION_DOWN:
                int index = MotionEventCompat.getActionIndex(ev);
                mActivePointerId = MotionEventCompat.getPointerId(ev, index);
                if (mActivePointerId == INVALID_POINTER)
                    break;
                mLastMotionX = ev.getX();
                mLastMotionY = ev.getY();
                break;

            case MotionEvent.ACTION_MOVE:
                int indexMove = MotionEventCompat.getActionIndex(ev);
                mActivePointerId = MotionEventCompat.getPointerId(ev, indexMove);

                if (mActivePointerId == INVALID_POINTER) {

                }else {
                    final float y = ev.getY();
                    float dy = y - mLastMotionY;
                    if (checkIsTop() && dy >= 1.0f) {
                        bScrollDown = true;
                        bDraging = true;
                    }else {
                        bScrollDown = false;
                        bDraging = false;
                    }
                    mLastMotionX = y;
                }
                break;

            case MotionEvent.ACTION_UP:
                mLastMotionY = 0;
                break;
        }
        return super.onTouchEvent(ev);
    }
}

public void setAdapter(BaseAdapter adapter) {
    if (mContentView != null) {
        mContentView.setAdapter(adapter);
    }
}

暴露onRefreshListener接口，和startRefresh和stopRefresh方法，供外部调用。

Handler mHandler;
public void startRefresh() {
    if (!isRefreshing()) {
        mHandler.removeMessages(0);
        mHandler.removeMessages(1);
        mHandler.sendEmptyMessage(1);
        mState = State.REFRESHING;
        invokeListner();
    }

}

private void invokeListner() {
    if (mRefreshLisenter != null) {
        mRefreshLisenter.onRefresh();
    }
}

public void stopRefresh() {
    mHandler.removeMessages(1);
    mHandler.sendEmptyMessage(0);
    mState = State.NORMAL;
}

public void setOnRefreshListener(OnRefreshListener listener) {
    this.mRefreshLisenter = listener;
}

public interface OnRefreshListener {
    public void onRefresh();
}

更多的细节，大家可以下源码参考，最后还是提供最终的运行效果图，因为附件有容量限制，我只好分成2部分上传了。