Refine UI for tethering

mobile/src/main/java/be/mygod/vpnhotspot/TetheringFragment.kt

@@ -1,5 +1,7 @@
 package be.mygod.vpnhotspot
 
+import android.animation.Animator
+import android.animation.AnimatorListenerAdapter
 import android.content.Intent
 import android.content.res.Resources
 import android.databinding.BaseObservable
@@ -11,6 +13,7 @@ import android.support.v7.util.SortedList
 import android.support.v7.widget.DefaultItemAnimator
 import android.support.v7.widget.LinearLayoutManager
 import android.support.v7.widget.RecyclerView
+import android.text.Html
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -18,6 +21,7 @@ import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.NetUtils.tetheredIfaces
 import be.mygod.vpnhotspot.databinding.FragmentTetheringBinding
 import be.mygod.vpnhotspot.databinding.ListitemInterfaceBinding
+import be.mygod.vpnhotspot.widget.TextViewLinkHandler
 
 class TetheringFragment : Fragment() {
     companion object {
@@ -83,9 +87,13 @@ class TetheringFragment : Fragment() {
         private val tethered = SortedList(String::class.java, StringSorter)
 
         fun update(data: Set<String> = VpnListener.connectivityManager.tetheredIfaces.toSet()) {
+            val oldEmpty = tethered.size() == 0
             tethered.clear()
             tethered.addAll(data)
             notifyDataSetChanged()
+            if (oldEmpty != data.isEmpty())
+                if (oldEmpty) crossFade(binding.empty, binding.interfaces)
+                else crossFade(binding.interfaces, binding.empty)
         }
 
         override fun getItemCount() = tethered.size()
@@ -96,6 +104,7 @@ class TetheringFragment : Fragment() {
         }
     }
 
+    private lateinit var binding: FragmentTetheringBinding
     private val adapter = InterfaceAdapter()
     private val receiver = broadcastReceiver { _, intent ->
         when (intent.action) {
@@ -107,8 +116,12 @@ class TetheringFragment : Fragment() {
     private var receiverRegistered = false
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
-        val binding = DataBindingUtil.inflate<FragmentTetheringBinding>(inflater, R.layout.fragment_tethering,
-                container, false)
+        binding = DataBindingUtil.inflate(inflater, R.layout.fragment_tethering, container, false)
+        binding.empty.text = Html.fromHtml(getString(R.string.tethering_no_interfaces))
+        binding.empty.movementMethod = TextViewLinkHandler.create {
+            startActivity(Intent().setClassName("com.android.settings",
+                    "com.android.settings.Settings\$TetherSettingsActivity"))
+        }
         binding.interfaces.layoutManager = LinearLayoutManager(context, LinearLayoutManager.VERTICAL, false)
         val animator = DefaultItemAnimator()
         animator.supportsChangeAnimations = false   // prevent fading-in/out when rebinding
@@ -138,4 +151,16 @@ class TetheringFragment : Fragment() {
         }
         super.onStop()
     }
+
+    private fun crossFade(old: View, new: View) {
+        val shortAnimTime = resources.getInteger(android.R.integer.config_shortAnimTime).toLong()
+        old.animate().alpha(0F).setListener(object : AnimatorListenerAdapter() {
+            override fun onAnimationEnd(animation: Animator) {
+                old.visibility = View.GONE
+            }
+        }).duration = shortAnimTime
+        new.alpha = 0F
+        new.visibility = View.VISIBLE
+        new.animate().alpha(1F).setListener(null).duration = shortAnimTime
+    }
 }

mobile/src/main/java/be/mygod/vpnhotspot/widget/TextViewLinkHandler.kt

@@ -0,0 +1,32 @@
+package be.mygod.vpnhotspot.widget
+
+import android.text.Spannable
+import android.text.method.LinkMovementMethod
+import android.text.style.URLSpan
+import android.view.MotionEvent
+import android.widget.TextView
+
+/**
+ * Based on: https://stackoverflow.com/a/32443884/2245107
+ */
+abstract class TextViewLinkHandler : LinkMovementMethod() {
+    companion object {
+        fun create(handler: (String) -> Unit) = object : TextViewLinkHandler() {
+            override fun onLinkClick(url: String) = handler(url)
+        }
+    }
+
+    override fun onTouchEvent(widget: TextView, buffer: Spannable, event: MotionEvent): Boolean {
+        if (event.action != MotionEvent.ACTION_UP) return super.onTouchEvent(widget, buffer, event)
+        val x = event.x - widget.totalPaddingLeft + widget.scrollX
+        val y = event.y.toInt() - widget.totalPaddingTop + widget.scrollY
+        val layout = widget.layout
+        val line = layout.getLineForVertical(y)
+        val off = layout.getOffsetForHorizontal(line, x)
+        val link = buffer.getSpans(off, off, URLSpan::class.java)
+        if (link.isNotEmpty()) onLinkClick(link[0].url)
+        return true
+    }
+
+    abstract fun onLinkClick(url: String)
+}

mobile/src/main/res/layout/fragment_tethering.xml

@@ -16,13 +16,26 @@
             android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
             app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
             android:id="@+id/toolbar"/>
+        <FrameLayout
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            android:layout_weight="1">
+            <TextView
+                android:id="@+id/empty"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:linksClickable="true"
+                android:padding="16dp"
+                tools:text="@string/tethering_no_interfaces"/>
             <android.support.v7.widget.RecyclerView
                 android:id="@+id/interfaces"
                 android:layout_width="match_parent"
-            android:layout_height="0dp"
-            android:layout_weight="1"
+                android:layout_height="match_parent"
                 android:clipToPadding="false"
                 android:scrollbars="vertical"
-            tools:listitem="@layout/listitem_interface"/>
+                android:visibility="gone"
+                tools:listitem="@layout/listitem_interface"
+                tools:visibility="visible"/>
+        </FrameLayout>
     </LinearLayout>
 </layout>

mobile/src/main/res/layout/listitem_interface.xml

@@ -21,6 +21,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:src="@{data.icon}"
+            android:tint="?android:attr/textColorPrimary"
             tools:src="@drawable/ic_device_network_wifi"/>
 
         <Space

mobile/src/main/res/values/strings.xml

@@ -6,4 +6,6 @@
         <item quantity="other">%d connected devices</item>
     </plurals>
     <string name="exception_interface_not_found">Fatal: Downstream interface not found</string>
+    <string name="tethering_no_interfaces"><![CDATA[To use this feature, turn on any <a href=&quot;#&quot;>system
+        tethering</a> first.]]></string>
 </resources>