导航抽屉在配置更改时关闭

Question

在我的片段中，我以编程方式将片段添加到导航抽屉中，然后从右侧打开抽屉。请注意，我无法直接访问 DrawerLayout 的 xml 文件，因此需要一个编程解决方案。抽屉从右侧打开并正确关闭，我保留抽屉的 open/close 状态，并在配置基于该状态更改后打开它。

问题是，在配置更改时，抽屉关闭（我可以看到抽屉动画到关闭状态），即使我根据 savedInstanceState 布尔值恢复其 open/close 状态。我在 DrawerLayout.class 中的所有 closeDrawer 方法中放置了一个调试器，但它们没有被命中。

更新：我想我知道问题出在哪里，但我不确定如何在不扩展 DrawerLayout 本身的情况下解决这个问题。在 DrawerLayout#onRestoreInstanceState 中调用的 DrawerLayout#findDrawerWithGravity 在我的例子中返回 null。

@Override
public void onSaveInstanceState(Bundle outState)
{
    super.onSaveInstanceState(outState);
    outState.putBoolean(STATE_DRAWER_OPEN,
        getDrawerLayout() == null ? false : getDrawerLayout().isDrawerOpen(Gravity.RIGHT));
}

@Override
public void onActivityCreated(Bundle savedInstanceState)
{
    super.onActivityCreated(savedInstanceState);
    if (savedInstanceState != null)
        isDrawerOpen = savedInstanceState.getBoolean(STATE_DRAWER_OPEN);
}

private void setDrawer() //this is called in onCreate
{
    DrawerLayout drawer = getActivity().findViewById(R.id.drawer_layout);
    if (drawer == null)
        drawer = getDrawerLayout();

    View existing = drawer.findViewById(R.id.m_drawer_container);
    if (existing != null)
        drawer.removeView(existing);

    drawer.setFocusableInTouchMode(false);
    drawer.addDrawerListener(this);

    FrameLayout fragmentContainer = new FrameLayout(getActivity());
    fragmentContainer.setId(R.id.m_drawer_container);
    final DrawerLayout.LayoutParams layoutParams = new DrawerLayout.LayoutParams(
        getResources().getDimensionPixelSize(R.dimen.m_drawer_max_width),
        ViewGroup.LayoutParams.MATCH_PARENT, Gravity.RIGHT);
    drawer.addView(fragmentContainer, layoutParams);

    FragmentManager fragmentManager = getFragmentManager();
    MyDrawerFragment mDrawerFragment = null;
    Fragment frag = fragmentManager.findFragmentByTag(TAG_DRAWER_FRAGMENT);
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    if (frag != null && frag.isAdded())
        fragmentTransaction.remove(frag);
    mDrawerFragment = MyDrawerFragment.newInstance(myArgs);
    fragmentTransaction.add(R.id.m_drawer_container, drawerFragment, TAG_DRAWER_FRAGMENT);
    fragmentTransaction.commitAllowingStateLoss();

    if (isDrawerOpen)
        drawer.openDrawer(Gravity.RIGHT);
}

Answer 1

事实证明，答案是调用 drawer.openDrawer(Gravity.RIGHT, false); 以在从配置更改恢复时禁用动画。原因是调用 drawer.openDrawer(Gravity.RIGHT) 时默认将动画设置为 true，深入研究该方法最终会导致 DrawerLayout.java 中的这段代码，从而导致宽度计算不正确，从而导致抽屉 "hidden":

DrawerLayout.java

else if (animate) {
    lp.openState |= LayoutParams.FLAG_IS_OPENING;

    if (checkDrawerViewAbsoluteGravity(drawerView, Gravity.LEFT)) {
        mLeftDragger.smoothSlideViewTo(drawerView, 0, drawerView.getTop());
    } else {
        mRightDragger.smoothSlideViewTo(drawerView, getWidth() - drawerView.getWidth(),
                drawerView.getTop());
    }

解决方案是在从配置更改恢复时将 animate 设置为 false。

if (isDrawerOpen && isRestoreFromConfigChange)
    drawer.openDrawer(Gravity.RIGHT, false);

导航抽屉在配置更改时关闭

Navigation drawer closes on configuration change

android

navigation-drawer

drawerlayout