From 9d95687d3cbb3b8e01203fbb201afc3469cce7a3 Mon Sep 17 00:00:00 2001
From: InsanusMokrassar <ovsyannikov.alexey95@gmail.com>
Date: Mon, 26 Sep 2022 01:02:12 +0600
Subject: [PATCH] FlowOnHierarchyChangeListener

---
 CHANGELOG.md                                  |  5 ++
 .../kotlin/FlowOnHierarchyChangeListener.kt   | 50 +++++++++++++++++++
 .../kotlin/RecursiveHierarchySubscriber.kt    | 17 +++++++
 3 files changed, 72 insertions(+)
 create mode 100644 coroutines/src/main/kotlin/FlowOnHierarchyChangeListener.kt
 create mode 100644 coroutines/src/main/kotlin/RecursiveHierarchySubscriber.kt

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9664e270945..9aae3ae9c7b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 ## 0.12.16
 
+* `Coroutines`:
+  * `Android`:
+    * Add class `FlowOnHierarchyChangeListener`
+    * Add `ViewGroup#setOnHierarchyChangeListenerRecursively(OnHierarchyChangeListener)`
+
 ## 0.12.15
 
 * `Common`:
diff --git a/coroutines/src/main/kotlin/FlowOnHierarchyChangeListener.kt b/coroutines/src/main/kotlin/FlowOnHierarchyChangeListener.kt
new file mode 100644
index 00000000000..f05056bcd9a
--- /dev/null
+++ b/coroutines/src/main/kotlin/FlowOnHierarchyChangeListener.kt
@@ -0,0 +1,50 @@
+package dev.inmo.micro_utils.coroutines
+
+import android.view.View
+import android.view.ViewGroup
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.asSharedFlow
+
+/**
+ * [kotlinx.coroutines.flow.Flow]-based [android.view.ViewGroup.OnHierarchyChangeListener]
+ *
+ * @param recursive If set, any call of [onChildViewAdded] will check if child [View] is [ViewGroup] and subscribe to this
+ * [ViewGroup] too
+ * @param [_onChildViewAdded] Internal [MutableSharedFlow] which will be used to pass data to [onChildViewAdded] flow
+ * @param [_onChildViewRemoved] Internal [MutableSharedFlow] which will be used to pass data to [onChildViewRemoved] flow
+ */
+class FlowOnHierarchyChangeListener(
+    private val recursive: Boolean = false,
+    private val _onChildViewAdded: MutableSharedFlow<Pair<View, View>> = MutableSharedFlow(extraBufferCapacity = Int.MAX_VALUE),
+    private val _onChildViewRemoved: MutableSharedFlow<Pair<View, View>> = MutableSharedFlow(extraBufferCapacity = Int.MAX_VALUE)
+) : ViewGroup.OnHierarchyChangeListener {
+    val onChildViewAdded = _onChildViewAdded.asSharedFlow()
+    val onChildViewRemoved = _onChildViewRemoved.asSharedFlow()
+
+    /**
+     * Will emit data into [onChildViewAdded] flow. If [recursive] is true and [child] is [ViewGroup] will also
+     * subscribe to [child] hierarchy changes.
+     *
+     * Due to the fact that this method is not suspendable, [FlowOnHierarchyChangeListener] will use
+     * [MutableSharedFlow.tryEmit] to send data into [_onChildViewAdded]. That is why its default extraBufferCapacity is
+     * [Int.MAX_VALUE]
+     */
+    override fun onChildViewAdded(parent: View, child: View) {
+        _onChildViewAdded.tryEmit(parent to child)
+
+        if (recursive && child is ViewGroup) {
+            child.setOnHierarchyChangeListener(this)
+        }
+    }
+
+    /**
+     * Just emit data into [onChildViewRemoved]
+     *
+     * Due to the fact that this method is not suspendable, [FlowOnHierarchyChangeListener] will use
+     * [MutableSharedFlow.tryEmit] to send data into [_onChildViewRemoved]. That is why its default extraBufferCapacity is
+     * [Int.MAX_VALUE]
+     */
+    override fun onChildViewRemoved(parent: View, child: View) {
+        _onChildViewRemoved.tryEmit(parent to child)
+    }
+}
diff --git a/coroutines/src/main/kotlin/RecursiveHierarchySubscriber.kt b/coroutines/src/main/kotlin/RecursiveHierarchySubscriber.kt
new file mode 100644
index 00000000000..c991f8d50c8
--- /dev/null
+++ b/coroutines/src/main/kotlin/RecursiveHierarchySubscriber.kt
@@ -0,0 +1,17 @@
+package dev.inmo.micro_utils.coroutines
+
+import android.view.ViewGroup
+import android.view.ViewGroup.OnHierarchyChangeListener
+
+/**
+ * Use [ViewGroup.setOnHierarchyChangeListener] recursively for all available [ViewGroup]s starting with [this].
+ * This extension DO NOT guarantee that recursive subscription will happen after this method call
+ */
+fun ViewGroup.setOnHierarchyChangeListenerRecursively(
+    listener: OnHierarchyChangeListener
+) {
+    setOnHierarchyChangeListener(listener)
+    (0 until childCount).forEach {
+        (getChildAt(it) as? ViewGroup) ?.setOnHierarchyChangeListener(listener)
+    }
+}