滚动位置位于顶部时,SwipeRefreshLayout + WebView

Question

我正在尝试将SwipeRefreshLayout与WebView一起使用.

我正面临着问题,在页面中间,当用户向下滚动时,不必要的刷新开始.

如何在webview的滚动位置位于顶部时才进行刷新事件.(即,他正在查看页面的顶部)？

Answer 1

我设法解决它而不必扩展任何东西.看看这个片段(片段特定):

private ViewTreeObserver.OnScrollChangedListener mOnScrollChangedListener;

@Override
public void onStart() {
    super.onStart();

    swipeLayout.getViewTreeObserver().addOnScrollChangedListener(mOnScrollChangedListener =
            new ViewTreeObserver.OnScrollChangedListener() {
                @Override
                public void onScrollChanged() {
                    if (mWebView.getScrollY() == 0)
                        swipeLayout.setEnabled(true);
                    else
                        swipeLayout.setEnabled(false);

                }
            });
}

@Override
public void onStop() {
    swipeLayout.getViewTreeObserver().removeOnScrollChangedListener(mOnScrollChangedListener);
    super.onStop();
}

有关更广泛的背景,请查看我对Android的回答- 使用空textview的SwipeRefreshLayout.

Answer 2

我认为推荐的方法是扩展SwipeRefreshLayout和覆盖canChildScrollUp()- https://developer.android.com/reference/android/support/v4/widget/SwipeRefreshLayout.html#canChildScrollUp()

这就是在Google IO 2014计划应用中完成的操作 - https://github.com/google/iosched/blob/master/android/src/main/java/com/google/samples/apps/iosched/ui/widget /MultiSwipeRefreshLayout.java#L76

的CustomSwipeRefreshLayout可能会是这样的:

public class CustomSwipeRefreshLayout extends SwipeRefreshLayout {

    private CanChildScrollUpCallback mCanChildScrollUpCallback;

    public interface CanChildScrollUpCallback {
        boolean canSwipeRefreshChildScrollUp();
    }

    public void setCanChildScrollUpCallback(CanChildScrollUpCallback canChildScrollUpCallback) {
        mCanChildScrollUpCallback = canChildScrollUpCallback;
    }

    @Override
    public boolean canChildScrollUp() {
        if (mCanChildScrollUpCallback != null) {
            return mCanChildScrollUpCallback.canSwipeRefreshChildScrollUp();
        }
        return super.canChildScrollUp();
    }
}

在你的Activity那个有WebView,

public class FooActivity
        implements CustomSwipeRefreshLayout.CanChildScrollUpCallback {

    private CustomSwipeRefreshLayout mRefreshLayout;
    private WebView mWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // after initialization
        mRefreshLayout.setCanChildScrollUpCallback(this);
    }

    @Override
    public boolean canSwipeRefreshChildScrollUp() {
        return mWebview.getScrollY() > 0;
    }
}

Answer 3

只要实现你的Fragment或Activity有 ViewTreeObserver.OnScrollChangedListener再设置监听像webview.getViewTreeObserver().addOnScrollChangedListener(this);

在onScrollChanged()方法中这样做

    @Override
    public void onScrollChanged() {
        if (webview.getScrollY() == 0) {
            swipeLayout.setEnabled(true);
        } else {
            swipeLayout.setEnabled(false);
        }
    }

Answer 4

支持库的最新版本具有SwipeRefreshLayout#setOnChildScrollUpCallback允许您避免子类化的方法SwipeRefreshLayout。

mBinding.swipeRefreshLayout.setOnChildScrollUpCallback((parent, child) -> 
            mBinding.webView.getScrollY() > 10);

Answer 5

您可以通过使用接受 WebView 并使用 WebView 检查滚动位置的自定义 SwipeRefreshLayout 扩展 SwipeRefreshLayout 来解决此问题。

注意：这适用于滚动整个页面，但可能不适用于嵌套滚动。另外，如果您有水平滚动，您可能还想添加此答案中找到的逻辑： https: //stackoverflow.com/a/24453194

public class CustomSwipeToRefresh extends SwipeRefreshLayout {

    private final int yScrollBuffer = 5;
    private WebView mWebView;

    public CustomSwipeToRefresh(Context context, WebView webView) {
        super(context);

        mWebView = webView;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        if (mWebView.getScrollY() > yScrollBuffer)
            return false;

        return super.onInterceptTouchEvent(event);
    }
}