Digitizer plugin

Add plugin that allows users to use their devices as pressure-sensitive drawing tablets.

* Schemas MR: https://invent.kde.org/network/kdeconnect-meta/-/merge_requests/16
* KDE MR: https://invent.kde.org/network/kdeconnect-kde/-/merge_requests/862

AndroidManifest.xml

@@ -403,6 +403,18 @@ SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted
                 android:value="org.kde.kdeconnect.UserInterface.PluginSettingsActivity" />
         </activity>
 
+        <activity
+            android:name="org.kde.kdeconnect.Plugins.DigitizerPlugin.DigitizerActivity"
+            android:configChanges="orientation|screenSize"
+            android:label="@string/pref_plugin_digitizer"
+            android:exported="false"
+            android:launchMode="singleTop"
+            android:parentActivityName="org.kde.kdeconnect.UserInterface.MainActivity">
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value="org.kde.kdeconnect.UserInterface.MainActivity" />
+        </activity>
+
         <activity
             android:name="org.kde.kdeconnect.UserInterface.TrustedNetworksActivity"
             android:label="@string/trusted_networks"

res/drawable/ic_draw_24dp.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M18.85,10.39l1.06,-1.06c0.78,-0.78 0.78,-2.05 0,-2.83L18.5,5.09c-0.78,-0.78 -2.05,-0.78 -2.83,0l-1.06,1.06L18.85,10.39zM13.19,7.56L4,16.76V21h4.24l9.19,-9.19L13.19,7.56zM19,17.5c0,2.19 -2.54,3.5 -5,3.5c-0.55,0 -1,-0.45 -1,-1s0.45,-1 1,-1c1.54,0 3,-0.73 3,-1.5c0,-0.47 -0.48,-0.87 -1.23,-1.2l1.48,-1.48C18.32,15.45 19,16.29 19,17.5zM4.58,13.35C3.61,12.79 3,12.06 3,11c0,-1.8 1.89,-2.63 3.56,-3.36C7.59,7.18 9,6.56 9,6c0,-0.41 -0.78,-1 -2,-1C5.74,5 5.2,5.61 5.17,5.64C4.82,6.05 4.19,6.1 3.77,5.76C3.36,5.42 3.28,4.81 3.62,4.38C3.73,4.24 4.76,3 7,3c2.24,0 4,1.32 4,3c0,1.87 -1.93,2.72 -3.64,3.47C6.42,9.88 5,10.5 5,11c0,0.31 0.43,0.6 1.07,0.86L4.58,13.35z"/>
+</vector>

res/drawable/ic_finger_24dp.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="960"
+    android:viewportHeight="960"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:pathData="M398,840q-27,0 -51.5,-11.5T305,796L46,477l26,-25q19,-19 45,-22t47,12l116,81v-403q0,-17 11.5,-28.5T320,80q17,0 28.5,11.5T360,120v557l-111,-78 118,146q6,7 14,11t17,4h282q33,0 56.5,-23.5T760,680v-280q0,-17 11.5,-28.5T800,360q17,0 28.5,11.5T840,400v280q0,66 -47,113t-113,47L398,840ZM520,600ZM440,520v-240q0,-17 11.5,-28.5T480,240q17,0 28.5,11.5T520,280v240h-80ZM600,520v-200q0,-17 11.5,-28.5T640,280q17,0 28.5,11.5T680,320v200h-80Z"
+      android:fillColor="@android:color/white"/>
+</vector>

res/drawable/ic_open_in_full_24dp.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="960"
+    android:viewportHeight="960"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M120,840v-320h80v184l504,-504L520,200v-80h320v320h-80v-184L256,760h184v80L120,840Z" />
+</vector>

res/layout/activity_digitizer.xml

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+SPDX-FileCopyrightText: 2025 Martin Sh <hemisputnik@proton.me>
+
+SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+-->
+
+<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context="org.kde.kdeconnect.Plugins.DigitizerPlugin.DigitizerActivity">
+
+    <include
+        android:id="@+id/toolbar_layout"
+        layout="@layout/toolbar" />
+
+    <FrameLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        app:layout_behavior="@string/appbar_scrolling_view_behavior">
+
+        <org.kde.kdeconnect.Plugins.DigitizerPlugin.DrawingPadView
+            android:id="@+id/drawing_pad"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:keepScreenOn="true" />
+
+        <com.google.android.material.floatingactionbutton.FloatingActionButton
+            android:id="@+id/button_draw"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:contentDescription="@string/digitizer_draw_button"
+            android:enabled="false"
+            android:longClickable="false"
+            android:src="@drawable/ic_finger_24dp"
+            tools:layout_gravity="left|bottom" />
+    </FrameLayout>
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>

res/menu/menu_digitizer.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:kdeconnect="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/menu_fullscreen"
+        android:icon="@drawable/ic_open_in_full_24dp"
+        android:title="@string/enable_fullscreen"
+        kdeconnect:iconTint="?colorOnBackground"
+        kdeconnect:showAsAction="ifRoom" />
+
+    <item
+        android:id="@+id/menu_open_settings"
+        android:title="@string/device_menu_plugins"
+        android:icon="@drawable/ic_settings_24dp"
+        kdeconnect:iconTint="?colorOnBackground"
+        kdeconnect:showAsAction="never"/>
+</menu>

res/menu/menu_mousepad.xml

@@ -9,6 +9,13 @@ SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted
 <menu xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:kdeconnect="http://schemas.android.com/apk/res-auto">
 
+    <item
+        android:id="@+id/menu_open_digitizer"
+        android:icon="@drawable/ic_draw_24dp"
+        android:title="@string/use_digitizer"
+        kdeconnect:iconTint="?colorOnBackground"
+        kdeconnect:showAsAction="ifRoom" />
+
     <item
         android:id="@+id/menu_show_keyboard"
         android:icon="@drawable/ic_action_keyboard_24dp"

res/values/strings.xml

@@ -24,6 +24,8 @@ SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted
     <string name="pref_plugin_battery_desc">Periodically report battery status</string>
     <string name="pref_plugin_connectivity_report">Connectivity report</string>
     <string name="pref_plugin_connectivity_report_desc">Report network signal strength and status</string>
+    <string name="pref_plugin_digitizer">Drawing tablet</string>
+    <string name="pref_plugin_digitizer_desc">Use your device as a pressure sensitive drawing tablet</string>
     <string name="pref_plugin_sftp">Filesystem access</string>
     <string name="pref_plugin_sftp_desc">Allows to browse this device\'s filesystem remotely</string>
     <string name="pref_plugin_clipboard">Clipboard sync</string>
@@ -321,6 +323,29 @@ SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted
     <string name="sftp_missing_permission_error">Permissions missing: filesystem access</string>
     <string name="no_players_connected">No players found</string>
     <string name="send_files">Send files</string>
+    <string name="use_digitizer">Use as drawing tablet</string>
+    <string name="digitizer_draw_button">Draw using finger</string>
+    <string name="digitizer_preference_key_hide_draw_button" translatable="false">digitizer_hide_draw_button</string>
+    <string name="digitizer_preference_title_hide_draw_button">Hide draw button</string>
+    <string name="digitizer_preference_summary_hide_draw_button">Completely hides the draw button, making finger drawing impossible. Only enable this if your device supports stylus input.</string>
+    <string name="digitizer_preference_key_draw_button_side" translatable="false">digitizer_draw_button_side</string>
+    <string name="digitizer_preference_title_draw_button_side">Side of “Draw with finger” button</string>
+    <string name="digitizer_preference_key_enable_exit_fullscreen_gesture" translatable="false">digitizer_enable_exit_fullscreen_gesture</string>
+    <string name="digitizer_preference_title_enable_exit_fullscreen_gesture">Enable fullscreen exit gesture</string>
+    <string name="digitizer_preference_summary_enable_exit_fullscreen_gesture">If enabled, tapping and holding on the drawing pad with your finger will disable fullscreen mode.</string>
+    <string-array name="digitizer_preference_values_draw_button_side" translatable="false">
+      <item>top_left</item>
+      <item>top_right</item>
+      <item>bottom_left</item>
+      <item>bottom_right</item>
+    </string-array>
+    <string-array name="digitizer_preference_entries_draw_button_side">
+      <item>Top left</item>
+      <item>Top right</item>
+      <item>Bottom left</item>
+      <item>Bottom right</item>
+    </string-array>
+    <string name="digitizer_preference_value_default_draw_button_side" translatable="false">bottom_left</string>
 
     <string name="block_notification_contents">Block notification contents</string>
     <string name="block_notification_images">Block notification images</string>
@@ -609,4 +634,6 @@ SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted
     <string name="device_host_invalid">Host is invalid. Use a valid hostname, IPv4, or IPv6</string>
     <string name="device_host_duplicate">Host already exists in the list</string>
 
+    <string name="enable_fullscreen">Enable fullscreen</string>
+
 </resources>

res/xml/digitizer_preferences.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+SPDX-FileCopyrightText: 2025 Martin Sh <hemisputnik@proton.me>
+
+SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+-->
+
+<androidx.preference.PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:keep="@xml/digitizer_preferences">
+
+    <SwitchPreference
+        android:id="@+id/digitizer_preference_key_hide_draw_button"
+        android:defaultValue="false"
+        android:key="@string/digitizer_preference_key_hide_draw_button"
+        android:title="@string/digitizer_preference_title_hide_draw_button"
+        android:summary="@string/digitizer_preference_summary_hide_draw_button"/>
+
+    <ListPreference
+        android:id="@+id/digitizer_preference_key_draw_button_side"
+        android:defaultValue="@string/digitizer_preference_value_default_draw_button_side"
+        android:entries="@array/digitizer_preference_entries_draw_button_side"
+        android:entryValues="@array/digitizer_preference_values_draw_button_side"
+        android:key="@string/digitizer_preference_key_draw_button_side"
+        android:summary="%s"
+        android:title="@string/digitizer_preference_title_draw_button_side" />
+
+</androidx.preference.PreferenceScreen>

src/org/kde/kdeconnect/Plugins/DigitizerPlugin/DigitizerActivity.kt

@@ -0,0 +1,187 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Martin Sh <hemisputnik@proton.me>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+ */
+
+package org.kde.kdeconnect.Plugins.DigitizerPlugin
+
+import android.annotation.SuppressLint
+import android.content.Intent
+import android.content.SharedPreferences
+import android.os.Bundle
+import android.view.Gravity
+import android.view.Menu
+import android.view.MenuItem
+import android.view.MotionEvent
+import android.view.View
+import android.widget.FrameLayout
+import androidx.activity.OnBackPressedCallback
+import androidx.activity.addCallback
+import androidx.core.content.edit
+import androidx.core.view.WindowCompat
+import androidx.core.view.WindowInsetsCompat
+import androidx.core.view.WindowInsetsControllerCompat
+import androidx.preference.PreferenceManager
+import org.kde.kdeconnect.KdeConnect
+import org.kde.kdeconnect.UserInterface.PluginSettingsActivity
+import org.kde.kdeconnect.base.BaseActivity
+import org.kde.kdeconnect.extensions.viewBinding
+import org.kde.kdeconnect_tp.R
+import org.kde.kdeconnect_tp.databinding.ActivityDigitizerBinding
+import kotlin.math.roundToInt
+
+class DigitizerActivity : BaseActivity<ActivityDigitizerBinding>(), DrawingPadView.EventListener {
+    override val binding: ActivityDigitizerBinding by viewBinding(ActivityDigitizerBinding::inflate)
+
+    private lateinit var prefs: SharedPreferences
+
+    private lateinit var fullscreenBackCallback: OnBackPressedCallback
+
+    private lateinit var deviceId: String
+
+    private val plugin: DigitizerPlugin?
+        get() {
+            val plugin = KdeConnect.getInstance().getDevicePlugin(deviceId, DigitizerPlugin::class.java)
+
+            if (plugin == null)
+                finish()
+
+            return plugin
+        }
+
+    private var prefHideDrawButton: Boolean
+        get() = prefs.getBoolean(getString(R.string.digitizer_preference_key_hide_draw_button), false)
+        set(value) = prefs.edit {
+            putBoolean(getString(R.string.digitizer_preference_key_hide_draw_button), value)
+        }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        deviceId = intent.getStringExtra("deviceId")!!
+
+        setSupportActionBar(binding.toolbarLayout.toolbar)
+        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
+        supportActionBar!!.setDisplayShowHomeEnabled(true)
+
+        prefs = PreferenceManager.getDefaultSharedPreferences(this)
+
+        binding.drawingPad.eventListener = this
+
+        @SuppressLint("ClickableViewAccessibility")
+        binding.buttonDraw.setOnTouchListener { _, event ->
+            when (event.action) {
+                MotionEvent.ACTION_DOWN -> {
+                    binding.drawingPad.fingerTouchEventsEnabled = true
+                    true
+                }
+                MotionEvent.ACTION_UP -> {
+                    binding.drawingPad.fingerTouchEventsEnabled = false
+                    true
+                }
+                else -> false
+            }
+        }
+
+        fullscreenBackCallback = onBackPressedDispatcher.addCallback(this) {
+            disableFullscreen()
+        }
+    }
+
+    private fun enableFullscreen() {
+        val windowInsetsController = WindowCompat.getInsetsController(window, window.decorView)
+        windowInsetsController.systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
+
+        supportActionBar!!.hide()
+        windowInsetsController.hide(WindowInsetsCompat.Type.systemBars())
+
+        fullscreenBackCallback.isEnabled = true
+    }
+
+    private fun disableFullscreen() {
+        val windowInsetsController = WindowCompat.getInsetsController(window, window.decorView)
+        windowInsetsController.systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_DEFAULT
+
+        supportActionBar!!.show()
+        windowInsetsController.show(WindowInsetsCompat.Type.systemBars())
+
+        fullscreenBackCallback.isEnabled = false
+    }
+
+    override fun onSupportNavigateUp(): Boolean {
+        onBackPressedDispatcher.onBackPressed()
+        return true
+    }
+
+    override fun onStart() {
+        super.onStart()
+        // During onStart, the views aren't laid out yet.
+        // We must wait a frame for the view to get laid out before we can query its size.
+        binding.drawingPad.post {
+            plugin?.startSession(
+                binding.drawingPad.width,
+                binding.drawingPad.height,
+                (resources.displayMetrics.xdpi * INCHES_TO_MM).roundToInt(),
+                (resources.displayMetrics.ydpi * INCHES_TO_MM).roundToInt()
+            )
+        }
+
+        if (prefHideDrawButton) {
+            binding.buttonDraw.visibility = View.GONE
+        }
+
+        binding.buttonDraw.layoutParams = (binding.buttonDraw.layoutParams as FrameLayout.LayoutParams).also {
+            @SuppressLint("RtlHardcoded")
+            when (prefs.getString(getString(R.string.digitizer_preference_key_draw_button_side), "bottom_left")) {
+                "top_left" -> it.gravity = Gravity.TOP or Gravity.LEFT
+                "top_right" -> it.gravity = Gravity.TOP or Gravity.RIGHT
+                "bottom_left" -> it.gravity = Gravity.BOTTOM or Gravity.LEFT
+                "bottom_right" -> it.gravity = Gravity.BOTTOM or Gravity.RIGHT
+            }
+        }
+    }
+
+    override fun onStop() {
+        super.onStop()
+        plugin?.endSession()
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
+        val inflater = menuInflater
+        inflater.inflate(R.menu.menu_digitizer, menu)
+        return true
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            R.id.menu_fullscreen -> {
+                enableFullscreen()
+                true
+            }
+            R.id.menu_open_settings -> {
+                startActivity(
+                    Intent(this, PluginSettingsActivity::class.java)
+                        .putExtra(PluginSettingsActivity.EXTRA_DEVICE_ID, deviceId)
+                        .putExtra(PluginSettingsActivity.EXTRA_PLUGIN_KEY, DigitizerPlugin::class.java.getSimpleName())
+                )
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    override fun onToolEvent(event: ToolEvent) {
+        plugin?.reportEvent(event)
+    }
+
+    override fun onFingerTouchEvent(touching: Boolean) {
+        binding.buttonDraw.isEnabled = touching
+    }
+
+    companion object {
+        private const val TAG = "DigitizerActivity"
+
+        private const val INCHES_TO_MM = 0.0393701
+    }
+}

src/org/kde/kdeconnect/Plugins/DigitizerPlugin/DigitizerPlugin.kt

@@ -0,0 +1,103 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Martin Sh <hemisputnik@proton.me>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+ */
+
+package org.kde.kdeconnect.Plugins.DigitizerPlugin
+
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import android.content.res.Configuration
+import android.util.Log
+import androidx.preference.PreferenceManager
+import org.kde.kdeconnect.NetworkPacket
+import org.kde.kdeconnect.Plugins.Plugin
+import org.kde.kdeconnect.Plugins.PluginFactory
+import org.kde.kdeconnect.UserInterface.PluginSettingsFragment
+import org.kde.kdeconnect_tp.R
+
+@PluginFactory.LoadablePlugin
+class DigitizerPlugin : Plugin() {
+    override val displayName: String
+        get() = context.resources.getString(R.string.pref_plugin_digitizer)
+
+    override val description: String
+        get() = context.resources.getString(R.string.pref_plugin_digitizer_desc)
+
+    override val icon: Int
+        get() = R.drawable.ic_draw_24dp
+
+    override fun onPacketReceived(np: NetworkPacket): Boolean {
+        Log.e(TAG, "The drawing tablet plugin should not be able to receive any packets!")
+        return false
+    }
+
+    override val actionName: String
+        get() = context.getString(R.string.use_digitizer)
+
+    override fun displayAsButton(context: Context): Boolean = shouldDisplayAsBigButton(context)
+
+    override fun startMainActivity(parentActivity: Activity) {
+        parentActivity.startActivity(Intent(parentActivity, DigitizerActivity::class.java).apply {
+            putExtra("deviceId", device.deviceId)
+        })
+    }
+
+    fun startSession(width: Int, height: Int, resolutionX: Int, resolutionY: Int) {
+        val np = NetworkPacket(PACKET_TYPE_DIGITIZER_SESSION).apply {
+            set("action", "start")
+            set("width", width)
+            set("height", height)
+            set("resolutionX", resolutionX)
+            set("resolutionY", resolutionY)
+        }
+        device.sendPacket(np)
+    }
+
+    fun endSession() {
+        val np = NetworkPacket(PACKET_TYPE_DIGITIZER_SESSION).apply {
+            set("action", "end")
+        }
+        device.sendPacket(np)
+    }
+
+    fun reportEvent(event: ToolEvent) {
+        Log.d(TAG, "reportEvent: $event")
+
+        val np = NetworkPacket(PACKET_TYPE_DIGITIZER).also { packet ->
+            event.active?.let { packet["active"] = it }
+            event.touching?.let { packet["touching"] = it }
+            event.tool?.let { packet["tool"] = it.name }
+            event.x?.let { packet["x"] = it }
+            event.y?.let { packet["y"] = it }
+            event.pressure?.let { packet["pressure"] = it }
+        }
+        device.sendPacket(np)
+    }
+
+    override fun hasSettings(): Boolean = true
+    override fun getSettingsFragment(activity: Activity): PluginSettingsFragment =
+        PluginSettingsFragment.newInstance(pluginKey, R.xml.digitizer_preferences)
+
+    override val supportedPacketTypes: Array<String>
+        get() = arrayOf()
+
+    override val outgoingPacketTypes: Array<String>
+        get() = arrayOf(
+            PACKET_TYPE_DIGITIZER_SESSION,
+            PACKET_TYPE_DIGITIZER,
+        )
+
+    companion object {
+        private const val PACKET_TYPE_DIGITIZER_SESSION = "kdeconnect.digitizer.session"
+        private const val PACKET_TYPE_DIGITIZER = "kdeconnect.digitizer"
+
+        private const val TAG = "DigitizerPlugin"
+
+        @JvmStatic
+        fun shouldDisplayAsBigButton(context: Context): Boolean =
+            context.resources.configuration.screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK >= Configuration.SCREENLAYOUT_SIZE_LARGE
+    }
+}

src/org/kde/kdeconnect/Plugins/DigitizerPlugin/DrawingPadView.kt

@@ -0,0 +1,163 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Martin Sh <hemisputnik@proton.me>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+ */
+
+package org.kde.kdeconnect.Plugins.DigitizerPlugin
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.util.AttributeSet
+import android.util.TypedValue
+import android.view.MotionEvent
+import android.view.View
+import com.google.android.material.R
+import com.google.android.material.color.MaterialColors
+import kotlin.math.ceil
+import kotlin.math.roundToInt
+
+class DrawingPadView(context: Context, attrs: AttributeSet?) : View(context, attrs) {
+    private fun mmToPixels(mm: Float): Float =
+        TypedValue.applyDimension(
+            TypedValue.COMPLEX_UNIT_MM,
+            mm,
+            resources.displayMetrics
+        )
+
+    val gridSpacing = mmToPixels(5.0f)
+    val gridOffset = mmToPixels(2.5f)
+
+    val backgroundPaint = Paint().apply {
+        color = MaterialColors.getColor(this@DrawingPadView, R.attr.colorSurfaceContainer, Color.WHITE)
+        style = Paint.Style.FILL
+    }
+
+    val linePaint = Paint().apply {
+        color = MaterialColors.getColor(this@DrawingPadView, R.attr.colorOutlineVariant, Color.WHITE)
+        style = Paint.Style.STROKE
+        strokeWidth = 1.0f
+    }
+
+    var eventListener: EventListener? = null
+    var fingerTouchEventsEnabled: Boolean = false
+
+    private fun convertTool(motionEventTool: Int): ToolEvent.Tool =
+        when (motionEventTool) {
+            MotionEvent.TOOL_TYPE_ERASER -> ToolEvent.Tool.Rubber
+            else -> ToolEvent.Tool.Pen
+        }
+
+    override fun onHoverEvent(event: MotionEvent): Boolean {
+        when (event.action) {
+            MotionEvent.ACTION_HOVER_ENTER -> eventListener?.onToolEvent(
+                ToolEvent(
+                    active = true,
+                    x = event.x.roundToInt(),
+                    y = event.y.roundToInt()
+                )
+            )
+
+            MotionEvent.ACTION_HOVER_EXIT -> eventListener?.onToolEvent(
+                ToolEvent(
+                    active = false,
+                )
+            )
+
+            MotionEvent.ACTION_HOVER_MOVE -> eventListener?.onToolEvent(
+                ToolEvent(
+                    tool = convertTool(event.getToolType(0)),
+                    x = event.x.roundToInt(),
+                    y = event.y.roundToInt()
+                )
+            )
+        }
+        return true
+    }
+
+    private fun findPressure(event: MotionEvent): Double =
+        if (event.getToolType(0) == MotionEvent.TOOL_TYPE_FINGER)
+            // We report constant 1.0 pressure for fingers, since most devices can't report
+            // pressure for fingers (so they report a constant 0.001).
+            if (fingerTouchEventsEnabled) 1.0
+            else 0.0
+        else
+            event.pressure.toDouble()
+
+    @SuppressLint("ClickableViewAccessibility")
+    override fun onTouchEvent(event: MotionEvent): Boolean {
+        val toolType = event.getToolType(0)
+
+        when (event.action) {
+            MotionEvent.ACTION_DOWN -> {
+                eventListener?.onToolEvent(
+                    ToolEvent(
+                        active = true,
+                        touching = toolType != MotionEvent.TOOL_TYPE_FINGER,
+                        tool = convertTool(toolType),
+                        x = event.x.roundToInt(),
+                        y = event.y.roundToInt(),
+                        pressure = findPressure(event)
+                    )
+                )
+
+                if (toolType == MotionEvent.TOOL_TYPE_FINGER)
+                    eventListener?.onFingerTouchEvent(true)
+            }
+
+            MotionEvent.ACTION_UP -> {
+                eventListener?.onToolEvent(
+                    ToolEvent(
+                        // If the finger is lifted from the screen,
+                        // we consider the device as "not tracking the tool".
+                        active = toolType != MotionEvent.TOOL_TYPE_FINGER,
+                        touching = false,
+                    )
+                )
+
+                if (toolType == MotionEvent.TOOL_TYPE_FINGER)
+                    eventListener?.onFingerTouchEvent(false)
+
+                // Set this variable to `false` if the user stopped drawing without first letting go
+                // of the "draw" button.
+                fingerTouchEventsEnabled = false
+            }
+
+            MotionEvent.ACTION_MOVE -> eventListener?.onToolEvent(
+                ToolEvent(
+                    tool = convertTool(toolType),
+                    x = event.x.roundToInt(),
+                    y = event.y.roundToInt(),
+                    pressure = findPressure(event)
+                )
+            )
+        }
+        return true
+    }
+
+    override fun onDraw(canvas: Canvas) {
+        canvas.drawPaint(backgroundPaint)
+
+        for (i in 0..<ceil(width / gridSpacing).toInt()) {
+            val x = gridOffset + i * gridSpacing
+            canvas.drawLine(x, 0f, x, height.toFloat(), linePaint)
+        }
+
+        for (i in 0..<ceil(height / gridSpacing).toInt()) {
+            val y = gridOffset + i * gridSpacing
+            canvas.drawLine(0f, y, width.toFloat(), y, linePaint)
+        }
+    }
+
+    interface EventListener {
+        fun onToolEvent(event: ToolEvent)
+        fun onFingerTouchEvent(touching: Boolean)
+    }
+
+    companion object {
+        const val TAG = "DrawingPadView"
+    }
+}

src/org/kde/kdeconnect/Plugins/DigitizerPlugin/ToolEvent.kt

@@ -0,0 +1,21 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Martin Sh <hemisputnik@proton.me>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+ */
+
+package org.kde.kdeconnect.Plugins.DigitizerPlugin
+
+data class ToolEvent(
+    val active: Boolean? = null,
+    val touching: Boolean? = null,
+    val tool: Tool? = null,
+    val x: Int? = null,
+    val y: Int? = null,
+    val pressure: Double? = null
+) {
+    enum class Tool {
+        Pen,
+        Rubber,
+    }
+}

src/org/kde/kdeconnect/Plugins/MousePadPlugin/MousePadActivity.java

@@ -28,6 +28,7 @@ import androidx.core.content.ContextCompat;
 import androidx.preference.PreferenceManager;
 
 import org.kde.kdeconnect.KdeConnect;
+import org.kde.kdeconnect.Plugins.DigitizerPlugin.DigitizerPlugin;
 import org.kde.kdeconnect.UserInterface.PluginSettingsActivity;
 import org.kde.kdeconnect.base.BaseActivity;
 import org.kde.kdeconnect_tp.R;
@@ -231,8 +232,14 @@ public class MousePadActivity
 
         boolean mouseButtonsEnabled = prefs
                 .getBoolean(getString(R.string.mousepad_mouse_buttons_enabled_pref), true);
+        boolean digitizerEnabled =
+                KdeConnect.getInstance().getDevicePlugin(deviceId, DigitizerPlugin.class) != null;
+
         menu.findItem(R.id.menu_right_click).setVisible(!mouseButtonsEnabled);
         menu.findItem(R.id.menu_middle_click).setVisible(!mouseButtonsEnabled);
+        menu.findItem(R.id.menu_open_digitizer).setVisible(
+                digitizerEnabled && !DigitizerPlugin.shouldDisplayAsBigButton(this)
+        );
 
         return true;
     }
@@ -251,6 +258,16 @@ public class MousePadActivity
                     .putExtra(PluginSettingsActivity.EXTRA_DEVICE_ID, deviceId)
                     .putExtra(PluginSettingsActivity.EXTRA_PLUGIN_KEY, MousePadPlugin.class.getSimpleName());
             startActivity(intent);
+            return true;
+        } else if (id == R.id.menu_open_digitizer) {
+            DigitizerPlugin plugin = KdeConnect.getInstance().getDevicePlugin(deviceId, DigitizerPlugin.class);
+            if (plugin == null) {
+                finish();
+                return true;
+            }
+
+            plugin.startMainActivity(this);
+
             return true;
         } else if (id == R.id.menu_show_keyboard) {
             MousePadPlugin plugin = KdeConnect.getInstance().getDevicePlugin(deviceId, MousePadPlugin.class);