package com.hdl.photovoltaic.widget.refreshlayout;
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import android.content.Context;
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import android.util.AttributeSet;
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import android.util.Log;
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import android.view.View;
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import android.view.ViewGroup;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import androidx.core.widget.NestedScrollView;
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import androidx.recyclerview.widget.RecyclerView;
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import io.dcloud.weex.FlingHelper;
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public class NestedScrollLayout extends NestedScrollView {
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private View topView;
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private ViewGroup contentView;
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private static final String TAG = "NestedScrollLayout";
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public NestedScrollLayout(Context context) {
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this(context, null);
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init();
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}
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public NestedScrollLayout(Context context, @Nullable AttributeSet attrs) {
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this(context, attrs, 0);
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init();
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}
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public NestedScrollLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
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this(context, attrs, defStyleAttr, 0);
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init();
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}
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public NestedScrollLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
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super(context, attrs, defStyleAttr);
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init();
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}
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private FlingHelper mFlingHelper;
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int totalDy = 0;
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/**
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* 用于判断RecyclerView是否在fling
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*/
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boolean isStartFling = false;
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/**
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* 记录当前滑动的y轴加速度
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*/
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private int velocityY = 0;
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private void init() {
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mFlingHelper = new FlingHelper(getContext());
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setOnScrollChangeListener(new View.OnScrollChangeListener() {
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@Override
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public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
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if (isStartFling) {
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totalDy = 0;
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isStartFling = false;
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}
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if (scrollY == 0) {
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Log.e(TAG, "TOP SCROLL");
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// refreshLayout.setEnabled(true);
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}
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if (scrollY == (getChildAt(0).getMeasuredHeight() - v.getMeasuredHeight())) {
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Log.e(TAG, "BOTTOM SCROLL");
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dispatchChildFling();
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}
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//在RecyclerView fling情况下，记录当前RecyclerView在y轴的偏移
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totalDy += scrollY - oldScrollY;
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}
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});
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}
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private void dispatchChildFling() {
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if (velocityY != 0) {
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Double splineFlingDistance = mFlingHelper.getSplineFlingDistance(velocityY);
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if (splineFlingDistance > totalDy) {
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childFling(mFlingHelper.getVelocityByDistance(splineFlingDistance - Double.valueOf(totalDy)));
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}
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}
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totalDy = 0;
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velocityY = 0;
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}
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private void childFling(int velY) {
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RecyclerView childRecyclerView = getChildRecyclerView(contentView);
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if (childRecyclerView != null) {
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childRecyclerView.fling(0, velY);
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}
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}
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@Override
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public void fling(int velocityY) {
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super.fling(velocityY);
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if (velocityY <= 0) {
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this.velocityY = 0;
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} else {
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isStartFling = true;
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this.velocityY = velocityY;
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}
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}
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@Override
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protected void onFinishInflate() {
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super.onFinishInflate();
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topView = ((ViewGroup) getChildAt(0)).getChildAt(0);
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contentView = (ViewGroup) ((ViewGroup) getChildAt(0)).getChildAt(1);
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}
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@Override
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protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
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// 调整contentView的高度为父容器高度，使之填充布局，避免父容器滚动后出现空白
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super.onMeasure(widthMeasureSpec, heightMeasureSpec);
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ViewGroup.LayoutParams lp = contentView.getLayoutParams();
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lp.height = getMeasuredHeight();
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contentView.setLayoutParams(lp);
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}
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/**
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* 解决滑动冲突：RecyclerView在滑动之前会问下父布局是否需要拦截，父布局使用此方法
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*/
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@Override
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public void onNestedPreScroll(@NonNull View target, int dx, int dy, @NonNull int[] consumed, int type) {
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// Log.e("NestedScrollLayout", getScrollY() + "::onNestedPreScroll::" + topView.getMeasuredHeight() + "::dy::" + dy);
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// 向上滑动。若当前topview可见，需要将topview滑动至不可见
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boolean hideTop = dy > 0 && getScrollY() < topView.getMeasuredHeight();
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if (hideTop) {
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scrollBy(0, dy);
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// 这个是被消费的距离，如果没有会被重复消费，现象是父布局与子布局同时滑动
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consumed[1] = dy;
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}
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}
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private RecyclerView getChildRecyclerView(ViewGroup viewGroup) {
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for (int i = 0; i < viewGroup.getChildCount(); i++) {
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View view = viewGroup.getChildAt(i);
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if (view instanceof RecyclerView) {
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return (RecyclerView) viewGroup.getChildAt(i);
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} else if (viewGroup.getChildAt(i) instanceof ViewGroup) {
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ViewGroup childRecyclerView = getChildRecyclerView((ViewGroup) viewGroup.getChildAt(i));
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if (childRecyclerView instanceof RecyclerView) {
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return (RecyclerView) childRecyclerView;
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}
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}
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continue;
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}
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return null;
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}
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}
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