Question

情况： 我在TableRow的两个HorizontalScrollView中分别有两个ScrollView
的目标： 当我触摸拖动其中一个ScrollView时，另一个ScrollView必须滚动尽可能多。例如，如果我在左侧ScrollView上有一个名称列表，并且右侧ScrollView中有相应的电话号码，则滚动一个ScrollView不应该破坏名称和电话号码之间的原始界限。

可以通过onTouchEvent实现吗？如果是这样，我应该如何实现它（在两个或一个ScrollView上）？

请帮我解决Android Gurus！

Answer 1

我有一个适合我的简单解决方案：

将两个ScrollView子类化，并在滚动更改时覆盖其onScrollChanged事件以更新ScrollManager：

public interface ScrollNotifier {   
    public void setScrollListener(ScrollListener scrollListener);

    public ScrollListener getScrollListener();
}

public class SyncedScrollView extends ScrollView implements ScrollNotifier {

    //...

    private ScrollListener scrollListener = null;

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        if (scrollListener != null)
            scrollListener.onScrollChanged(this, l, t, oldl, oldt);
    }
    @Override
    public void setScrollListener(ScrollListener scrollListener) {
        this.scrollListener = scrollListener;
    }
    @Override
    public ScrollListener getScrollListener() {
        return scrollListener;
    }
}

创建一个ScrollManager类，用于协调多个参与者的滚动

public interface ScrollListener {
    void onScrollChanged(View syncedScrollView, int l, int t, int oldl,
        int oldt);
}

public class ScrollManager implements ScrollListener {
    private static final int SCROLL_HORIZONTAL = 1;
    private static final int SCROLL_VERTICAL = 2;

    private ArrayList<ScrollNotifier> clients = new ArrayList<ScrollNotifier>(4);

    private volatile boolean isSyncing = false;
    private int scrollType = SCROLL_HORIZONTAL;

    public void addScrollClient(ScrollNotifier client) {
        clients.add(client);
        client.setScrollListener(this);
    }

    // TODO fix dependency on all views being of equal horizontal/ vertical
    // dimensions
    @Override
    public void onScrollChanged(View sender, int l, int t, int oldl, int oldt) {
        // avoid notifications while scroll bars are being synchronized
        if (isSyncing) {
            return;
        }

        isSyncing = true;

        // remember scroll type
        if (l != oldl) {
            scrollType = SCROLL_HORIZONTAL;
        } else if (t != oldt) {
            scrollType = SCROLL_VERTICAL;
        } else {
            // not sure why this should happen
            isSyncing = false;
            return;
        }

        // update clients
        for (ScrollNotifier client : clients) {
            View view = (View) client;
            // don't update sender
            if (view == sender) {
                continue;
            }

            // scroll relevant views only
            // TODO Add support for horizontal ListViews - currently weird things happen when ListView is being scrolled horizontally
            if ((scrollType == SCROLL_HORIZONTAL && view instanceof HorizontalScrollView)
                    || (scrollType == SCROLL_VERTICAL && view instanceof ScrollView)
                    || (scrollType == SCROLL_VERTICAL && view instanceof ListView)) {
                view.scrollTo(l, t);
            }
        }

        isSyncing = false;
    }
}

创建自定义ScrollView并在{/ 1>上设置ScrollManager通知

private void setupScrolling() {
    ScrollNotifier view;
    ScrollManager scrollManager = new ScrollManager();

    // timeline horizontal scroller
    view = (ScrollNotifier) findViewById(R.id.epgtimeline_container);
    scrollManager.addScrollClient(view);

    // services vertical scroller
    view = (ScrollNotifier) findViewById(R.id.epgservices_container);
    scrollManager.addScrollClient(view);

    // content area scrollers
    view = (ScrollNotifier) findViewById(R.id.epgevents_container_inner);
    scrollManager.addScrollClient(view);
    view = (ScrollNotifier) findViewById(R.id.epgevents_container_outer);
    scrollManager.addScrollClient(view);
}

Answer 2

感谢andig这么棒的synching scrollview solution。

但是在投掷时两个滚动视图之间存在一点延迟。

所以我在这里写扩展解决方案，以消除两个scrollview之间的延迟。

我刚刚使用过OverScroller类并在SyncedScrollView中手动处理了fling事件。

您必须使用以下代码替换SyncedScrollView。使用andig's solution

中的其他类

import android.content.Context;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.OverScroller;
import android.widget.ScrollView;

/**
 * Created by mitul.varmora on 11/7/2016.
 * SyncedScrollView
 * https://stackoverflow.com/questions/3527119/sync-two-scrollview
 */
public class SyncedScrollView extends ScrollView implements ScrollNotifier {

    private ScrollListener scrollListener = null;

    private OverScroller scroller;
    private Runnable scrollerTaskRunnable;

    public SyncedScrollView(Context context) {
        super(context);
        init();
    }

    public SyncedScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public SyncedScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {

        scroller = new OverScroller(getContext());
        scrollerTaskRunnable = new Runnable() {
            @Override
            public void run() {
                scroller.computeScrollOffset();

                smoothScrollTo(0, scroller.getCurrY());

                if (!scroller.isFinished()) {
                    SyncedScrollView.this.post(this);
                } else {
                    //deceleration ends here, do your code
                    ViewCompat.postInvalidateOnAnimation(SyncedScrollView.this);
                }
            }
        };
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        if (scrollListener != null)
            scrollListener.onScrollChanged(this, l, t, oldl, oldt);
    }

    @Override
    public ScrollListener getScrollListener() {
        return scrollListener;
    }

    @Override
    public void setScrollListener(ScrollListener scrollListener) {
        this.scrollListener = scrollListener;
    }

    @Override
    public void fling(int velocityY) {

        scroller.forceFinished(true);
        scroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0, getChildAt(0).getHeight());
        post(scrollerTaskRunnable);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
//        return super.onTouchEvent(ev);
        boolean eventConsumed = super.onTouchEvent(ev);
        if (eventConsumed && ev.getAction() == MotionEvent.ACTION_UP) {
            if (scroller.isFinished()) {
                //do your code
            }
        }
        return eventConsumed;
    }
}

同步两个ScrollView

2 个答案: