databinding: rewrite in kotlin

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 112 insertions, 0 deletions

diff --git a/ui/src/main/java/com/wireguard/android/databinding/ItemChangeListener.kt b/ui/src/main/java/com/wireguard/android/databinding/ItemChangeListener.kt
new file mode 100644
index 00000000..131f3877
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/databinding/ItemChangeListener.kt
@@ -0,0 +1,112 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.databinding
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.databinding.ObservableList
+import androidx.databinding.ViewDataBinding
+import com.wireguard.android.BR
+import java.lang.ref.WeakReference
+
+/**
+ * Helper class for binding an ObservableList to the children of a ViewGroup.
+ */
+internal class ItemChangeListener<T>(private val container: ViewGroup, private val layoutId: Int) {
+    private val callback = OnListChangedCallback(this)
+    private val layoutInflater: LayoutInflater = LayoutInflater.from(container.context)
+    private var list: ObservableList<T>? = null
+
+    private fun getView(position: Int, convertView: View?): View {
+        var binding = if (convertView != null) DataBindingUtil.getBinding<ViewDataBinding>(convertView) else null
+        if (binding == null) {
+            binding = DataBindingUtil.inflate(layoutInflater, layoutId, container, false)
+        }
+        require(list != null) { "Trying to get a view while list is still null" }
+        binding!!.setVariable(BR.collection, list)
+        binding.setVariable(BR.item, list!![position])
+        binding.executePendingBindings()
+        return binding.root
+    }
+
+    fun setList(newList: ObservableList<T>?) {
+        list?.removeOnListChangedCallback(callback)
+        list = newList
+        if (list != null) {
+            list!!.addOnListChangedCallback(callback)
+            callback.onChanged(list!!)
+        } else {
+            container.removeAllViews()
+        }
+    }
+
+    private class OnListChangedCallback<T> constructor(listener: ItemChangeListener<T>) : ObservableList.OnListChangedCallback<ObservableList<T>>() {
+        private val weakListener: WeakReference<ItemChangeListener<T>> = WeakReference(listener)
+
+        override fun onChanged(sender: ObservableList<T>) {
+            val listener = weakListener.get()
+            if (listener != null) {
+                // TODO: recycle views
+                listener.container.removeAllViews()
+                for (i in sender.indices)
+                    listener.container.addView(listener.getView(i, null))
+            } else {
+                sender.removeOnListChangedCallback(this)
+            }
+        }
+
+        override fun onItemRangeChanged(sender: ObservableList<T>, positionStart: Int,
+                                        itemCount: Int) {
+            val listener = weakListener.get()
+            if (listener != null) {
+                for (i in positionStart until positionStart + itemCount) {
+                    val child = listener.container.getChildAt(i)
+                    listener.container.removeViewAt(i)
+                    listener.container.addView(listener.getView(i, child))
+                }
+            } else {
+                sender.removeOnListChangedCallback(this)
+            }
+        }
+
+        override fun onItemRangeInserted(sender: ObservableList<T>, positionStart: Int,
+                                         itemCount: Int) {
+            val listener = weakListener.get()
+            if (listener != null) {
+                for (i in positionStart until positionStart + itemCount)
+                    listener.container.addView(listener.getView(i, null))
+            } else {
+                sender.removeOnListChangedCallback(this)
+            }
+        }
+
+        override fun onItemRangeMoved(sender: ObservableList<T>, fromPosition: Int,
+                                      toPosition: Int, itemCount: Int) {
+            val listener = weakListener.get()
+            if (listener != null) {
+                val views = arrayOfNulls<View>(itemCount)
+                for (i in 0 until itemCount) views[i] = listener.container.getChildAt(fromPosition + i)
+                listener.container.removeViews(fromPosition, itemCount)
+                for (i in 0 until itemCount) listener.container.addView(views[i], toPosition + i)
+            } else {
+                sender.removeOnListChangedCallback(this)
+            }
+        }
+
+        override fun onItemRangeRemoved(sender: ObservableList<T>, positionStart: Int,
+                                        itemCount: Int) {
+            val listener = weakListener.get()
+            if (listener != null) {
+                listener.container.removeViews(positionStart, itemCount)
+            } else {
+                sender.removeOnListChangedCallback(this)
+            }
+        }
+
+    }
+
+}