Introduce and switch to FragmentViewBindingDelegate (#797)

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

1 files changed, 66 insertions, 0 deletions

diff --git a/app/src/main/java/com/zeapo/pwdstore/utils/FragmentViewBindingDelegate.kt b/app/src/main/java/com/zeapo/pwdstore/utils/FragmentViewBindingDelegate.kt
new file mode 100644
index 00000000..35eb7ae3
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/utils/FragmentViewBindingDelegate.kt
@@ -0,0 +1,66 @@
+/*
+ * Copyright © 2014-2020 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package com.zeapo.pwdstore.utils
+
+
+import android.view.LayoutInflater
+import android.view.View
+import androidx.appcompat.app.AppCompatActivity
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.DefaultLifecycleObserver
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleOwner
+import androidx.lifecycle.observe
+import androidx.viewbinding.ViewBinding
+import kotlin.properties.ReadOnlyProperty
+import kotlin.reflect.KProperty
+
+/**
+ * Imported from https://medium.com/@Zhuinden/simple-one-liner-viewbinding-in-fragments-and-activities-with-kotlin-961430c6c07c
+ */
+class FragmentViewBindingDelegate<T : ViewBinding>(
+    val fragment: Fragment,
+    val viewBindingFactory: (View) -> T
+) : ReadOnlyProperty<Fragment, T> {
+
+    private var binding: T? = null
+
+    init {
+        fragment.lifecycle.addObserver(object : DefaultLifecycleObserver {
+            override fun onCreate(owner: LifecycleOwner) {
+                fragment.viewLifecycleOwnerLiveData.observe(fragment) { viewLifecycleOwner ->
+                    viewLifecycleOwner.lifecycle.addObserver(object : DefaultLifecycleObserver {
+                        override fun onDestroy(owner: LifecycleOwner) {
+                            binding = null
+                        }
+                    })
+                }
+            }
+        })
+    }
+
+    override fun getValue(thisRef: Fragment, property: KProperty<*>): T {
+        val binding = binding
+        if (binding != null) {
+            return binding
+        }
+
+        val lifecycle = fragment.viewLifecycleOwner.lifecycle
+        if (!lifecycle.currentState.isAtLeast(Lifecycle.State.INITIALIZED)) {
+            throw IllegalStateException("Should not attempt to get bindings when Fragment views are destroyed.")
+        }
+
+        return viewBindingFactory(thisRef.requireView()).also { this.binding = it }
+    }
+}
+
+fun <T : ViewBinding> Fragment.viewBinding(viewBindingFactory: (View) -> T) =
+    FragmentViewBindingDelegate(this, viewBindingFactory)
+
+inline fun <T : ViewBinding> AppCompatActivity.viewBinding(crossinline bindingInflater: (LayoutInflater) -> T) =
+    lazy(LazyThreadSafetyMode.NONE) {
+        bindingInflater.invoke(layoutInflater)
+    }