[移动开发]过度下拉ScrollView

直接上代码

/**
 * 开发人员：ZHT
 * 开发时间：2022/1/10
 * 文档说明：自定义回弹ScrollView
 */
public class ReboundScrollView extends NestedScrollView {
    private Rect mNormal = new Rect();//用于记录临界状态的左、上、右、下
    private boolean mIsFinishAnimation = true;//是否动画结束
    private float mLastY;//上一次y轴方向操作的坐标位置
    private int mDownY;
    private View mChildView;
    private boolean mChildCanClick = true;

    public ReboundScrollView(@NonNull Context context) {
        super(context);
    }

    public ReboundScrollView(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public ReboundScrollView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    /**
     * @param childCanClick 是否拦截子View的Touch事件
     */
    public void setChildCanClick(boolean childCanClick) {
        mChildCanClick = childCanClick;
    }

    //获取子视图
    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        if (getChildCount() > 0) {
            mChildView = getChildAt(0);
        }
    }

    //拦截:实现父视图对子视图的拦截
    //是否拦截成功，取决于方法的返回值。返回值true:拦截成功。反之，拦截失败
    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        if (!mChildCanClick) return true;
        boolean isIntercept = false;
        int eventY = (int) ev.getY();
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mLastY = mDownY = eventY;
                break;
            case MotionEvent.ACTION_MOVE:
                //获取垂直方向的移动距离
                int absY = Math.abs(eventY - mDownY);
                if (absY >= 10) {
                    isIntercept = true;//执行拦截
                }
                mLastY = eventY;
                break;
        }
        return isIntercept;
    }

    @SuppressLint("ClickableViewAccessibility")
    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (mChildView == null || !mIsFinishAnimation) {
            return super.onTouchEvent(ev);
        }
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mLastY = ev.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                int dy = (int) (ev.getY() - mLastY);//微小的移动量
                if (isNeedMove(dy)) {
                    if (mNormal.isEmpty()) {
                        //记录了mChildView的临界状态的左、上、右、下
                        mNormal.set(mChildView.getLeft(), mChildView.getTop(), mChildView.getRight(), mChildView.getBottom());
                    }
                    //重新布局
                    mChildView.layout(mChildView.getLeft(), mChildView.getTop() + dy / 2, mChildView.getRight(), mChildView.getBottom() + dy / 2);
                }
                mLastY = ev.getY();//重新赋值
                break;
            case MotionEvent.ACTION_UP:
                if (isNeedAnimation()) {
                    //使用平移动画
                    int translateY = mChildView.getBottom() - mNormal.bottom;
                    TranslateAnimation translateAnimation = new TranslateAnimation(0, 0, 0, -translateY);
                    translateAnimation.setDuration(200);
                    translateAnimation.setAnimationListener(new Animation.AnimationListener() {
                        @Override
                        public void onAnimationStart(Animation animation) {
                            mIsFinishAnimation = false;
                        }

                        @Override
                        public void onAnimationEnd(Animation animation) {
                            mIsFinishAnimation = true;
                            mChildView.clearAnimation();//清除动画
                            //重新布局
                            mChildView.layout(mNormal.left, mNormal.top, mNormal.right, mNormal.bottom);
                            //清除normal的数据
                            mNormal.setEmpty();
                        }

                        @Override
                        public void onAnimationRepeat(Animation animation) {
                        }
                    });
                    //启动动画
                    mChildView.startAnimation(translateAnimation);
                }
                break;
        }
        return super.onTouchEvent(ev);
    }

    //判断是否需要执行平移动画
    private boolean isNeedAnimation() {
        return !mNormal.isEmpty();
    }

    //用户在y轴方向上的偏移量 (上 + 下 -)
    private boolean isNeedMove(float scaleY) {
        int childMeasuredHeight = mChildView.getMeasuredHeight();//获取子视图的高度
        int scrollViewMeasuredHeight = this.getMeasuredHeight();//获取布局的高度
        int dy = childMeasuredHeight - scrollViewMeasuredHeight;//dy >= 0
        //按照我们自定义的ScrollView的方式处理,其他处在临界范围内的，返回false。即表示，仍按照ScrollView的方式处理
        return scaleY <= 0 || scaleY >= dy;
    }
}

整体父布局NestedScrollView

红色Banner

蓝色ReboundScrollView?

问题如下：

ReboundScrollView?和Banner重叠部分是RecyclerView，此区域点击不会触发拦截，从而不会下拉回弹

setChildCanClick为true。拦截后一切正常

?

?