禁用动作列表的滚动效果

Question

我有一个 GuidedStepSupportFragment 这样的片段。

public class SampleStepFragment extends GuidedStepSupportFragment {

    @NonNull
    @Override
    public GuidanceStylist.Guidance onCreateGuidance(Bundle savedInstanceState) {
        String title = "Title";
        String breadcrumb = "Breadcrumb";
        String description = "Description";
        Drawable icon = getActivity().getDrawable(R.drawable.ic_videocam_black_24dp);

        return new GuidanceStylist.Guidance(title, description, breadcrumb, icon);
    }

    @Override
    public void onCreateActions(@NonNull List<GuidedAction> actions, Bundle savedInstanceState) {

        addAction(actions, ACTION_CONTINUE, "Action1");
        addAction(actions, ACTION_BACK, "Action2");

    }
}

问题：当我滚动动作列表时，它显示如下；

但我想要这样的东西；

如何在我的动作列表中禁用此效果？

谢谢

Answer 1

我做到了，但并不容易弄明白。

没有 支持的 方法，因为实际上使这成为可能的 API 是私有包或隐藏包 public 故意使用. （你可以自己做，但你最终只是从 leanback 库中复制类。）

解决方法：

@Override
public void onCreateActions(@NonNull List<GuidedAction> actions, Bundle savedInstanceState) {

    addAction(actions, GuidedAction.ACTION_ID_CONTINUE, "Action1");
    addAction(actions, GuidedAction.ACTION_ID_CANCEL, "Action2");

    // Run code delayed on mainThread (any other/better method can/should be used)
    // It's delayed because if focus scroll is disabled, the list will stick to the top of the layout
    new Handler(Looper.getMainLooper()).postDelayed(this::disableFocusScroll, 500);
}

private void disableFocusScroll() {
    RecyclerView.LayoutManager layoutManager = SampleStepFragment.this.getGuidedActionsStylist().getActionsGridView().getLayoutManager();
    try {
        Method method = layoutManager.getClass().getMethod("setFocusScrollStrategy", int.class);
        method.invoke(layoutManager, 1 /* FOCUS_SCROLL_ITEM */);
    } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
        Log.e(TAG, "disableFocusScroll: ", e);
    }
}

Full example

解释：

A GuidedStepSupportFragment 请求 GuidedActionsStylist 负责在右侧呈现列表项。 ^source

GuidedActionsStylist 设计师扩充了包含 VerticalGridView ^source

的布局 lb_guidedactions.xml

VerticalGridView 扩展了 BaseGridView 并创建了一个 GridLayoutManager 作为它的布局管理器。遗憾的是，这个 GridLayoutManager 是私有包和最终包...（android 为什么...？）。它有方法 setFocusScrollStrategy 用于确定滚动行为。^source

查看不同的焦点滚动策略：

/**
 * Always keep focused item at a aligned position.  Developer can use
 * WINDOW_ALIGN_XXX and ITEM_ALIGN_XXX to define how focused item is aligned.
 * In this mode, the last focused position will be remembered and restored when focus
 * is back to the view.
 * @hide
 */
@RestrictTo(LIBRARY_GROUP)
public final static int FOCUS_SCROLL_ALIGNED = 0;

/**
 * Scroll to make the focused item inside client area.
 * @hide
 */
@RestrictTo(LIBRARY_GROUP)
public final static int FOCUS_SCROLL_ITEM = 1;

/**
 * Scroll a page of items when focusing to item outside the client area.
 * The page size matches the client area size of RecyclerView.
 * @hide
 */
@RestrictTo(LIBRARY_GROUP)
public final static int FOCUS_SCROLL_PAGE = 2;

所以既然API是隐藏的，我们就用反射把setFocusScrollStrategy方法暴露出来，设置为FOCUS_SCROLL_ITEM.

不过我们不能立即执行此操作，因为如果没有默认的滚动设置，列表项将弹出到布局的顶部并且不会保持居中。所以我添加了 500 毫秒的延迟，这太可怕了......如果你设法找出什么时候最好触发它，请告诉我。

Answer 2

事实证明，有一个更优雅、更简单的解决方案。在继承guideStepSupportFragment windowAlignment 选项的class中的onViewCreated的body中添加即可（还有其他对齐选项）：

override fun onViewCreated(view: View, savedInstanceState: Bundle?) { 
    // ... 
    val gridView = guidedActionsStylist.actionsGridView 
    gridView.windowAlignment = VerticalGridView.WINDOW_ALIGN_BOTH_EDGE 
    // ... 
    super.onViewCreated(view, savedInstanceState) 
}

Answer 3

这是禁用 VerticalGridView 滚动的简单方法

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    VerticalGridView gridView = getGuidedActionsStylist().getActionsGridView();
    gridView.setScrollEnabled(false);
    super.onViewCreated(view, savedInstanceState);
}

禁用动作列表的滚动效果

disable the scroll effect of the action list

android

android-tv

leanback

解决方法：

解释：