android - 同步两个 ScrollView

Question

情况: 我在 TableRow 的两个 Horizo​​ntalScrollView 中分别有两个 ScrollView。

目标: 当我触摸拖动其中一个 ScrollView 时，另一个 ScrollView 必须滚动同样多。例如，如果我在左侧 ScrollView 中有一个名称列表，在右侧 ScrollView 中有相应的电话号码，则滚动一个 ScrollView 不应破坏名称和电话号码之间的原始边界。

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

请帮帮我 Android 高手!

Answer 1

我有一个适合我的简单解决方案:

• 子类化 ScrollView 并覆盖它们的 onScrollChanged 事件以在滚动更改时更新 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 类来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 并设置 ScrollManager 以在两者上进行通知

  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);
  }