D-pad support for mount/unmount buttons

app/src/main/AndroidManifest.xml

@@ -3,6 +3,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 
+    <uses-feature android:name="android.hardware.touchscreen" android:required="false" />
+
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

app/src/main/java/ru/nsu/bobrofon/easysshfs/mountpointlist/MountpointFragment.kt

@@ -2,6 +2,7 @@
 package ru.nsu.bobrofon.easysshfs.mountpointlist
 
 import android.os.Bundle
+import android.view.KeyEvent
 import android.view.LayoutInflater
 import android.view.Menu
 import android.view.MenuInflater
@@ -10,6 +11,7 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.AbsListView
 import android.widget.AdapterView
+import android.widget.Button
 import android.widget.ListAdapter
 import androidx.core.view.MenuHost
 import androidx.core.view.MenuProvider
@@ -28,6 +30,96 @@ class MountpointFragment : EasySSHFSFragment(), AdapterView.OnItemClickListener,
     private lateinit var listAdapter: ListAdapter
     private lateinit var mountPointsList: MountPointsList
 
+    /**
+     * buttonOnKeyListener is used when a mount button is focused, to implement custom D-pad
+     * navigation between the button and an enclosing ListView's items.
+     *
+     * The listener expects the ListView item to look like this:
+     * |----------------------|
+     * |            +--------+|
+     * | Item view  | Button ||
+     * |            +--------+|
+     * |----------------------|
+     */
+    private val buttonOnKeyListener = View.OnKeyListener { _, keycode, event ->
+        if (event.action != KeyEvent.ACTION_DOWN) {
+            return@OnKeyListener false
+        }
+
+        val dpadNavigationKeys = arrayOf(
+            KeyEvent.KEYCODE_DPAD_RIGHT,
+            KeyEvent.KEYCODE_DPAD_LEFT,
+            KeyEvent.KEYCODE_DPAD_UP,
+            KeyEvent.KEYCODE_DPAD_DOWN
+        )
+        if (!dpadNavigationKeys.contains(keycode)) {
+            return@OnKeyListener false
+        }
+
+        // We are leaving the button, so we need to pass the focus back.
+        listView.descendantFocusability = ViewGroup.FOCUS_BLOCK_DESCENDANTS
+        listView.requestFocus()
+
+        // The button is on the right side of the ListView item.
+        // Moving left means "go back to the item containing this button".
+        if (keycode == KeyEvent.KEYCODE_DPAD_LEFT) {
+            // Focus is already passed to the original ListView item.
+            true
+        } else {
+            // Allow ListView to select the next item. Otherwise, the currently selected item will
+            // remain selected after moving out of the button.
+            listView.onKeyDown(keycode, event)
+        }
+    }
+
+    /**
+     * buttonOnFocusChangeListener implements custom focus logic for buttons inside a ListView.
+     */
+    private val buttonOnFocusChangeListener = View.OnFocusChangeListener { buttonView, hasFocus ->
+        if (hasFocus) {
+            return@OnFocusChangeListener
+        }
+
+        // We should keep ButtonView unfocusable to allow ListView/GridView to handle onItemClick
+        // properly.
+        buttonView.isFocusable = false
+
+        // Restore the original state in case the button lost the focus not via buttonOnKeyListener.
+        listView.descendantFocusability = ViewGroup.FOCUS_BLOCK_DESCENDANTS
+    }
+
+    /**
+     * listViewOnKeyListener is used when a mount button is not focused, to implement custom D-pad
+     * navigation between the selected ListView item and the button inside it.
+     *
+     * The listener expects the ListView item to look like this:
+     * |----------------------|
+     * |            +--------+|
+     * | Item view  | Button ||
+     * |            +--------+|
+     * |----------------------|
+     */
+    private val listViewOnKeyListener = View.OnKeyListener { _, keycode, event ->
+        val selectedItemView = listView.selectedView ?: return@OnKeyListener false
+
+        if (event.action != KeyEvent.ACTION_DOWN) {
+            return@OnKeyListener false
+        }
+        if (keycode != KeyEvent.KEYCODE_DPAD_RIGHT) {
+            return@OnKeyListener false
+        }
+        // The button is on the right side of the item view.
+        // Moving right means "moving to the button".
+
+        listView.descendantFocusability = ViewGroup.FOCUS_AFTER_DESCENDANTS
+
+        val button = selectedItemView.findViewById<Button>(R.id.mountButton)
+        button.isFocusable = true
+        button.requestFocus()
+
+        true
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
     ): View? {
@@ -37,11 +129,18 @@ class MountpointFragment : EasySSHFSFragment(), AdapterView.OnItemClickListener,
         val view = inflater.inflate(R.layout.fragment_mountpoint, container, false)
 
         mountPointsList = MountPointsList.instance(context)
-        listAdapter = MountPointsArrayAdapter(context, mountPointsList.mountPoints, shell)
+        listAdapter = MountPointsArrayAdapter(
+            context,
+            mountPointsList.mountPoints,
+            shell,
+            buttonOnFocusChangeListener,
+            buttonOnKeyListener
+        )
 
         listView = view.findViewById(android.R.id.list)
         listView.adapter = listAdapter
         listView.onItemClickListener = this
+        listView.setOnKeyListener(listViewOnKeyListener)
 
         mountPointsList.registerMountObserver(this)
         // mountPointsList.autoMount();

app/src/main/java/ru/nsu/bobrofon/easysshfs/mountpointlist/mountpoint/MountPointsArrayAdapter.kt

@@ -17,7 +17,9 @@ import ru.nsu.bobrofon.easysshfs.databinding.RowLayoutBinding
 class MountPointsArrayAdapter(
     context: Context,
     private val values: List<MountPoint>,
-    private val shell: Shell
+    private val shell: Shell,
+    private val buttonOnFocusChangeListener: View.OnFocusChangeListener,
+    private val buttonOnKeyListener: View.OnKeyListener
 ) : ArrayAdapter<MountPoint>(context, R.layout.row_layout, values) {
 
     override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
@@ -39,6 +41,8 @@ class MountPointsArrayAdapter(
             mountButton.text = context.getString(R.string.mount)
             mountButton.setOnClickListener { self.mount(shell, context) }
         }
+        mountButton.onFocusChangeListener = buttonOnFocusChangeListener
+        mountButton.setOnKeyListener(buttonOnKeyListener)
 
         return rowView
     }