launchSingleTop属性跳转页面问题

hele-jeremy commented 3 years ago

launchSingleTop属性跳转页面在不同的手机上有不同的表现,某些手机会闪一下,某些机型会直接显示上一级的页面

原因为hide隐藏的其实就是DFragment，而add添加的fragment其实也是Dfragment因此在同一个FragmentTransation中隐藏和添加同一个Fragment会有问题的,if (mBackStack.size() > 0 && mFragmentManager.getFragments().size() > 0) { Log.d("Nav"," --Hide --Add"); ft.hide(mFragmentManager.getFragments().get(mBackStack.size() - 1)); ft.add(mContainerId, frag); } 我修改了FragmentNavigator的navigate方法相当是launchsingletop的情况下,不将新创建的fragmet入栈: public NavDestination navigate(@NonNull Destination destination, @Nullable Bundle args, @Nullable NavOptions navOptions, @Nullable Navigator.Extras navigatorExtras) { if (mFragmentManager.isStateSaved()) { Log.i(TAG, "Ignoring navigate() call: FragmentManager has already"

" saved its state"); return null; } String className = destination.getClassName(); if (className.charAt(0) == '.') { className = mContext.getPackageName() + className; } final Fragment frag = instantiateFragment(mContext, mFragmentManager, className, args); frag.setArguments(args); final FragmentTransaction ft = mFragmentManager.beginTransaction();

int enterAnim = navOptions != null ? navOptions.getEnterAnim() : -1;
int exitAnim = navOptions != null ? navOptions.getExitAnim() : -1;
int popEnterAnim = navOptions != null ? navOptions.getPopEnterAnim() : -1;
int popExitAnim = navOptions != null ? navOptions.getPopExitAnim() : -1;
if (enterAnim != -1 || exitAnim != -1 || popEnterAnim != -1 || popExitAnim != -1) {
    enterAnim = enterAnim != -1 ? enterAnim : 0;
    exitAnim = exitAnim != -1 ? exitAnim : 0;
    popEnterAnim = popEnterAnim != -1 ? popEnterAnim : 0;
    popExitAnim = popExitAnim != -1 ? popExitAnim : 0;
    ft.setCustomAnimations(enterAnim, exitAnim, popEnterAnim, popExitAnim);
}

final @IdRes int destId = destination.getId();
final boolean initialNavigation = mBackStack.isEmpty();
// TODO Build first class singleTop behavior for fragments
final boolean isSingleTopReplacement = navOptions != null && !initialNavigation
        && navOptions.shouldLaunchSingleTop()
        && mBackStack.peekLast() == destId;

Log.d("testnav", " --isSingleTopReplacement --- " + isSingleTopReplacement);

//TODO Tip 1: Solve the unexpected display of popUpToInclusive under the add hide solution
//TODO Tip 2: Increase fault tolerance to deal with incorrectly-timed jumps in the case of nested sub-fragments
Log.d("testnav", " --mBackStack.size:" + mBackStack.size()
        + " getFragments().size():" + mFragmentManager.getFragments().size());
if (mBackStack.size() > 0 && mFragmentManager.getFragments().size() > 0) {
    Log.d("testnav", " --Add --- " + frag);
    Fragment hideFrag = mFragmentManager.getFragments().get(mBackStack.size() - 1);
    Log.d("testnav", " --Hide --- " + hideFrag);

    if (isSingleTopReplacement) {
        hideFrag.setArguments(args);
        ft.setMaxLifecycle(hideFrag, Lifecycle.State.RESUMED);
    } else {
        ft.hide(hideFrag);
        ft.add(mContainerId, frag);
        ft.setPrimaryNavigationFragment(frag);
    }

} else {
    Log.d("testnav", " --Replace --- " + frag);
    ft.replace(mContainerId, frag);
    ft.setPrimaryNavigationFragment(frag);
}

// ft.setPrimaryNavigationFragment(frag);

    boolean isAdded;
    if (initialNavigation) {
        isAdded = true;
    } else if (isSingleTopReplacement) {
        // Single Top means we only want one instance on the back stack

// if (mBackStack.size() > 1) { // // If the Fragment to be replaced is on the FragmentManager's // // back stack, a simple replace() isn't enough so we // // remove it from the back stack and put our replacement // // on the back stack in its place // mFragmentManager.popBackStack( // generateBackStackName(mBackStack.size(), mBackStack.peekLast()), // FragmentManager.POP_BACK_STACK_INCLUSIVE); // ft.addToBackStack(generateBackStackName(mBackStack.size(), destId)); // } isAdded = false; } else { ft.addToBackStack(generateBackStackName(mBackStack.size() + 1, destId)); isAdded = true; } if (navigatorExtras instanceof Extras && !isSingleTopReplacement) { Extras extras = (Extras) navigatorExtras; for (Map.Entry<View, String> sharedElement : extras.getSharedElements().entrySet()) { ft.addSharedElement(sharedElement.getKey(), sharedElement.getValue()); } } ft.setReorderingAllowed(true); ft.commit(); // The commit succeeded, update our view of the world if (isAdded) { mBackStack.add(destId); return destination; } else { return null; } }

hele-jeremy commented 3 years ago

原生的navigation跳转页面时replace替换Fragment的因此launchSingleTop只能工作在自己跳转自己页面的情况,因此在原生的情况下,机制是launchSingleTop每次都会新建一个新的页面fragment实例,并将上一个自己页面的fragment实例给popupbackstatck 出栈并且将新创建的fragment页面实例给入栈,而改为了hide的机制后, launchSingleTop不应该将老的上一个页面给出栈,而是应该继续保持老的fragment页面实例在栈中

KunMinX commented 3 years ago

@hele-jeremy 感谢你的分享，经测试，上述代码可实现预期效果，且在目前已知场景下皆未产生副作用，为此可以邀请你 pull request 上述设计吗？这可以让你的这次分享出现在贡献名单中。开源不是一个人的战斗，我们希望每位贡献者都能出现在贡献者名单。

hele-jeremy commented 3 years ago

已提交pr

KunMinX / Smooth-Navigation

launchSingleTop属性跳转页面问题 #11