是否可以在导航组件中更改向上按钮图标? [英] Is it possible to change up button icon in Navigation Component?

问题描述

我想更改与导航组件一起使用的ActionBar中的向上按钮图标.我尝试了几种选择，例如:

I would like to change up button icon in ActionBar that is working with Navigation Component. I've tried several options like:

supportActionBar?.setHomeAsUpIndicator(R.drawable.ic_arrow_left_blue_24dp)

在MainAcitivty或

app:navigationIcon="@drawable/ic_arrow_left_blue_24dp"

在Toolbar .xml文件中，似乎没有任何作用.

in Toolbar .xml file and nothing seems to work.

我使用

setSupportActionBar(appToolbar.toolbar)
setupActionBarWithNavController(this, navController)

在MainActivity:onCreate方法中调用.

我希望

supportActionBar?.setHomeAsUpIndicator(R.drawable.ic_arrow_left_blue_24dp)

可以工作，因为例如通过调用以下内容来禁用ActionBar的标题:

would work, because for example disabling title for ActionBar by calling:

supportActionBar?.setDisplayShowTitleEnabled(false)

可以正常工作，并且导航时标题未设置为Fragment名称.

works as expected and title is not set to Fragment name while navigating.

此外，我进行了一些调查，在ActionBarOnDestinationChangedListener中有一个对setNavigationIcon的调用，该调用将图标设置为DrawerArrowDrawable，这有点奇怪，因为我没有在其中使用Drawer我的设置.

What's more, I investigated a little bit and in ActionBarOnDestinationChangedListener there is a call to setNavigationIcon which is setting an icon to DrawerArrowDrawable, which is a little bit weird since I'm not using Drawer in my setup.

也更改为:

setupWithNavController(toolbar, navController)

不起作用，因为ToolbarOnDestinationChangedListener也使用相同的DrawerArrowDrawable.

is not working because ToolbarOnDestinationChangedListener also using the same DrawerArrowDrawable.

推荐答案

我找到了答案.我检查了导航组件的问题跟踪器，现在看来，如果没有解决方法，就无法更改它:

I have found answer. I checked issue tracker for navigation component and it seems like for now it's impossible to change it without a workaround:

https://issuetracker.google.com/u/1/issues/121078028

很高兴仍然有可能，我们只需要实现OnDestinationChangedListener并在那里更改图标，就象在AbstractAppBarOnDestinationChangedListener中的setNavigationIcon之后调用它一样.这是代码:

Gladly it's still possible, we just need to implement OnDestinationChangedListener and change icon there as it's called after setNavigationIcon in AbstractAppBarOnDestinationChangedListener. Here is a code:

navController.addOnDestinationChangedListener { _, _, _ ->
      supportActionBar?.setHomeAsUpIndicator(R.drawable.ic_arrow_left_blue_24dp)
}

您甚至可以为不同的目的地使用不同的图标.

You can even differ icon for different destinations.

这是临时解决方案，因为此功能尚不存在.我正在使用导航组件的1.0.0-alpha09版本.

It's temporary solution as this feature is not there yet. I'm using 1.0.0-alpha09 version of the navigation component.

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