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Created
March 30, 2018 10:25
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class NavigationView @JvmOverloads constructor(context: Context, | |
attrs: AttributeSet? = null) : FrameLayout(context, attrs) { | |
private enum class Operation { | |
FORWARD, BACKWARD, ROOT | |
} | |
lateinit var rootFragment: Fragment | |
var fragmentManager: FragmentManager? = null | |
private var activeFragment: Fragment? = null | |
private val fragments = mutableListOf<Fragment>() | |
val hasFragmentsVisible: Boolean | |
get() = fragments.isNotEmpty() | |
val canPop: Boolean | |
get() = fragments.size > 1 | |
fun push(fragment: Fragment) { | |
fragments.add(fragment) | |
updateUi(Operation.FORWARD) | |
} | |
fun pop() { | |
if (!canPop) return | |
fragments.removeAt(fragments.size - 1) | |
updateUi(Operation.BACKWARD) | |
} | |
fun popToRoot() { | |
updateUi(Operation.ROOT) | |
} | |
private fun updateUi(op: Operation) { | |
if (fragmentManager == null) throw IllegalStateException("Fragment manager has not be set") | |
val transaction = fragmentManager!!.beginTransaction() | |
if (activeFragment != null) { | |
transaction.detach(activeFragment) | |
} | |
when (op) { | |
Operation.FORWARD -> { | |
activeFragment = fragments.last() | |
transaction.add(id, activeFragment) | |
} | |
Operation.BACKWARD -> { | |
transaction.remove(activeFragment) | |
activeFragment = fragments.last() | |
transaction.attach(activeFragment) | |
} | |
Operation.ROOT -> { | |
fragments.forEach { | |
transaction.remove(it) | |
} | |
fragments.clear() | |
activeFragment = rootFragment | |
fragments.add(activeFragment!!) | |
transaction.add(id, activeFragment) | |
} | |
} | |
transaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out, android.R.anim.fade_in, android.R.anim.fade_out) | |
transaction.disallowAddToBackStack() | |
transaction.commit() | |
} | |
} |
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