Added basic Pen support for X11 (#19910)

* Added surface dispose to DrawingSurfaceDemoBase

* Added pen support for x11

* Fixed intermediate points defaulting properties

* Detect the current device being an eraser

* Formatting fixes

* Removed spaces

---------

Co-authored-by: flabbet <flabbet@fedora>
Co-authored-by: Nikita Tsukanov <keks9n@gmail.com>

src/Avalonia.X11/X11Window.cs

@@ -44,6 +44,7 @@ namespace Avalonia.X11
         private bool _triggeredExpose;
         private IInputRoot? _inputRoot;
         private readonly MouseDevice _mouse;
+        private readonly PenDevice _pen;
         private readonly TouchDevice _touch;
         private readonly IKeyboardDevice _keyboard;
         private readonly ITopLevelNativeMenuExporter? _nativeMenuExporter;
@@ -97,6 +98,7 @@ namespace Avalonia.X11
             _overrideRedirect = _popup || overrideRedirect;
             _x11 = platform.Info;
             _mouse = Avalonia.Input.MouseDevice.Primary;
+            _pen = new PenDevice();
             _touch = new TouchDevice();
             _keyboard = platform.KeyboardDevice;
 
@@ -1072,6 +1074,7 @@ namespace Avalonia.X11
                 _platform.XI2?.OnWindowDestroyed(_handle);
                 var handle = _handle;
                 _handle = IntPtr.Zero;
+                _pen.Dispose();
                 _touch.Dispose();
                 if (!fromDestroyNotification) 
                     XDestroyWindow(_x11.Display, handle);
@@ -1238,6 +1241,7 @@ namespace Avalonia.X11
         }
 
         public IMouseDevice MouseDevice => _mouse;
+        public IPenDevice PenDevice => _pen;
         public TouchDevice TouchDevice => _touch;
 
         public IPopupImpl? CreatePopup() 

src/Avalonia.X11/XI2Manager.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.InteropServices;
 using Avalonia.Input;
 using Avalonia.Input.Raw;
 using static Avalonia.X11.XLib;
@@ -16,7 +17,6 @@ namespace Avalonia.X11
             XiEventType.XI_ButtonRelease,
             XiEventType.XI_Leave,
             XiEventType.XI_Enter,
-            
         };
 
         private static readonly XiEventType[] MultiTouchEventTypes = new XiEventType[]
@@ -35,13 +35,14 @@ namespace Avalonia.X11
             public int Id { get; }
             public XIValuatorClassInfo[] Valuators { get; private set; } = [];
             public XIScrollClassInfo[] Scrollers { get; private set; } = [];
+
             public DeviceInfo(XIDeviceInfo info)
             {
                 Id = info.Deviceid;
                 UpdateCore(info.Classes, info.NumClasses);
             }
 
-            public virtual void Update(XIAnyClassInfo** classes, int num)
+            public virtual void Update(XIAnyClassInfo** classes, int num, int? slaveId)
             {
                 UpdateCore(classes, num);
             }
@@ -74,6 +75,9 @@ namespace Avalonia.X11
 
         private class PointerDeviceInfo : DeviceInfo
         {
+            private string? _currentSlaveName = null;
+            private bool _currentSlaveIsEraser = false;
+            
             public PointerDeviceInfo(XIDeviceInfo info, X11Info x11Info) : base(info)
             {
                 _x11 = x11Info;
@@ -91,6 +95,9 @@ namespace Avalonia.X11
                 var touchMinorAtom = XInternAtom(_x11.Display, "Abs MT Touch Minor", false);
 
                 var pressureAtom = XInternAtom(_x11.Display, "Abs MT Pressure", false);
+                var pressureAtomPen = XInternAtom(_x11.Display, "Abs Pressure", false);
+                var absTiltXAtom = XInternAtom(_x11.Display, "Abs Tilt X", false);
+                var absTiltYAtom = XInternAtom(_x11.Display, "Abs Tilt Y", false);
 
                 PressureXIValuatorClassInfo = null;
                 TouchMajorXIValuatorClassInfo = null;
@@ -98,7 +105,8 @@ namespace Avalonia.X11
 
                 foreach (var xiValuatorClassInfo in Valuators)
                 {
-                    if (xiValuatorClassInfo.Label == pressureAtom)
+                    if (xiValuatorClassInfo.Label == pressureAtom ||
+                        xiValuatorClassInfo.Label == pressureAtomPen)
                     {
                         PressureXIValuatorClassInfo = xiValuatorClassInfo;
                     }
@@ -110,15 +118,52 @@ namespace Avalonia.X11
                     {
                         TouchMinorXIValuatorClassInfo = xiValuatorClassInfo;
                     }
+                    else if (xiValuatorClassInfo.Label == absTiltXAtom)
+                    {
+                        TiltXXIValuatorClassInfo = xiValuatorClassInfo;
+                    }
+                    else if (xiValuatorClassInfo.Label == absTiltYAtom)
+                    {
+                        TiltYXIValuatorClassInfo = xiValuatorClassInfo;
+                    }
                 }
             }
 
-            public override void Update(XIAnyClassInfo** classes, int num)
+            public override void Update(XIAnyClassInfo** classes, int num, int? slaveId)
             {
-                base.Update(classes, num);
+                base.Update(classes, num, slaveId);
+
+                if (slaveId != null)
+                {
+                    _currentSlaveName = null;
+                    _currentSlaveIsEraser = false;
+                    var devices = (XIDeviceInfo*)XIQueryDevice(_x11.Display,
+                        (int)XiPredefinedDeviceId.XIAllDevices, out int deviceNum);
+
+                    for (var c = 0; c < deviceNum; c++)
+                    {
+                        if (devices[c].Deviceid == slaveId)
+                        {
+                            _currentSlaveName = Marshal.PtrToStringAnsi(devices[c].Name);
+                            _currentSlaveIsEraser =
+                                _currentSlaveName?.IndexOf("eraser", StringComparison.OrdinalIgnoreCase) >= 0;
+                            break;
+                        }
+                    }
+                    XIFreeDeviceInfo(devices);
+                }
+                
                 UpdateKnownValuator();
             }
 
+            public bool HasPressureValuator()
+            {
+                return PressureXIValuatorClassInfo is not null;
+            }
+
+            public bool IsEraser => _currentSlaveIsEraser;
+            public string? Name => _currentSlaveName;
+
             public bool HasScroll(ParsedDeviceEvent ev)
             {
                 foreach (var val in ev.Valuators)
@@ -140,6 +185,8 @@ namespace Avalonia.X11
             public XIValuatorClassInfo? PressureXIValuatorClassInfo { get; private set; }
             public XIValuatorClassInfo? TouchMajorXIValuatorClassInfo { get; private set; }
             public XIValuatorClassInfo? TouchMinorXIValuatorClassInfo { get; private set; }
+            public XIValuatorClassInfo? TiltXXIValuatorClassInfo { get; private set; }
+            public XIValuatorClassInfo? TiltYXIValuatorClassInfo { get; private set; }
         }
 
         private readonly PointerDeviceInfo _pointerDevice;
@@ -225,10 +272,9 @@ namespace Avalonia.X11
             if (xev->evtype == XiEventType.XI_DeviceChanged)
             {
                 var changed = (XIDeviceChangedEvent*)xev;
-                _pointerDevice.Update(changed->Classes, changed->NumClasses);
+                _pointerDevice.Update(changed->Classes, changed->NumClasses, changed->Reason == XiDeviceChangeReason.XISlaveSwitch ? changed->Sourceid : null);
             }
 
-
             if ((xev->evtype >= XiEventType.XI_ButtonPress && xev->evtype <= XiEventType.XI_Motion)
                 || (xev->evtype >= XiEventType.XI_TouchBegin && xev->evtype <= XiEventType.XI_TouchEnd))
             {
@@ -280,17 +326,15 @@ namespace Avalonia.X11
                         RawPointerEventType.TouchUpdate :
                         RawPointerEventType.TouchEnd);
 
-                var rawPointerPoint = new RawPointerPoint()
-                {
-                    Position = ev.Position
-                };
+                var rawPointerPoint = new RawPointerPoint() { Position = ev.Position };
 
                 if (_pointerDevice.PressureXIValuatorClassInfo is { } valuatorClassInfo)
                 {
                     if (ev.Valuators.TryGetValue(valuatorClassInfo.Number, out var pressureValue))
                     {
                         // In our API we use range from 0.0 to 1.0.
-                        var pressure = (pressureValue - valuatorClassInfo.Min) / (valuatorClassInfo.Max - valuatorClassInfo.Min);
+                        var pressure = (pressureValue - valuatorClassInfo.Min) /
+                                       (valuatorClassInfo.Max - valuatorClassInfo.Min);
                         rawPointerPoint.Pressure = (float)pressure;
                     }
                 }
@@ -310,7 +354,8 @@ namespace Avalonia.X11
 
                             // As https://www.kernel.org/doc/html/latest/input/multi-touch-protocol.html says, using `screenBounds.Width` is not accurate enough.
                             touchMajor = (touchMajorValue - touchMajorXIValuatorClassInfo.Min) /
-                                (touchMajorXIValuatorClassInfo.Max - touchMajorXIValuatorClassInfo.Min) * screenBounds.Width;
+                                         (touchMajorXIValuatorClassInfo.Max - touchMajorXIValuatorClassInfo.Min) *
+                                         screenBounds.Width;
                         }
                     }
 
@@ -321,7 +366,8 @@ namespace Avalonia.X11
                             if (ev.Valuators.TryGetValue(touchMinorXIValuatorClassInfo.Number, out var touchMinorValue))
                             {
                                 touchMinor = (touchMinorValue - touchMinorXIValuatorClassInfo.Min) /
-                                             (touchMinorXIValuatorClassInfo.Max - touchMinorXIValuatorClassInfo.Min) * screenBounds.Height;
+                                             (touchMinorXIValuatorClassInfo.Max - touchMinorXIValuatorClassInfo.Min) *
+                                             screenBounds.Height;
                             }
                         }
 
@@ -352,9 +398,16 @@ namespace Avalonia.X11
             if (!client.IsEnabled || (_multitouch && ev.Emulated))
                 return;
 
+            var eventModifiers = ev.Modifiers;
+            if (_pointerDevice.IsEraser)
+                eventModifiers |= RawInputModifiers.PenEraser;
+            
             if (ev.Type == XiEventType.XI_Motion)
             {
                 Vector scrollDelta = default;
+                var rawPointerPoint = new RawPointerPoint() { Position = ev.Position };
+                IInputDevice device = _pointerDevice.HasPressureValuator() ? client.PenDevice : client.MouseDevice;
+
                 foreach (var v in ev.Valuators)
                 {
                     foreach (var scroller in _pointerDevice.Scrollers)
@@ -374,15 +427,15 @@ namespace Avalonia.X11
                         }
                     }
 
-
+                    SetPenSpecificValues(v, ref rawPointerPoint);
                 }
 
                 if (scrollDelta != default)
-                    client.ScheduleXI2Input(new RawMouseWheelEventArgs(client.MouseDevice, ev.Timestamp,
-                        client.InputRoot, ev.Position, scrollDelta, ev.Modifiers));
+                    client.ScheduleXI2Input(new RawMouseWheelEventArgs(device, ev.Timestamp,
+                        client.InputRoot, ev.Position, scrollDelta, eventModifiers));
                 if (_pointerDevice.HasMotion(ev))
-                    client.ScheduleXI2Input(new RawPointerEventArgs(client.MouseDevice, ev.Timestamp, client.InputRoot,
-                        RawPointerEventType.Move, ev.Position, ev.Modifiers));
+                    client.ScheduleXI2Input(new RawPointerEventArgs(device, ev.Timestamp, client.InputRoot,
+                        RawPointerEventType.Move, rawPointerPoint, eventModifiers));
             }
 
             if (ev.Type == XiEventType.XI_ButtonPress && ev.Button >= 4 && ev.Button <= 7 && !ev.Emulated)
@@ -398,7 +451,7 @@ namespace Avalonia.X11
                 
                 if (scrollDelta.HasValue)
                     client.ScheduleXI2Input(new RawMouseWheelEventArgs(client.MouseDevice, ev.Timestamp,
-                        client.InputRoot, ev.Position, scrollDelta.Value, ev.Modifiers));
+                        client.InputRoot, ev.Position, scrollDelta.Value, eventModifiers));
             }
 
             if (ev.Type == XiEventType.XI_ButtonPress || ev.Type == XiEventType.XI_ButtonRelease)
@@ -413,13 +466,57 @@ namespace Avalonia.X11
                     9 => down ? RawPointerEventType.XButton2Down : RawPointerEventType.XButton2Up,
                     _ => (RawPointerEventType?)null
                 };
+
                 if (type.HasValue)
-                    client.ScheduleXI2Input(new RawPointerEventArgs(client.MouseDevice, ev.Timestamp, client.InputRoot,
-                        type.Value, ev.Position, ev.Modifiers));
+                {
+                    IInputDevice device = _pointerDevice.HasPressureValuator() ? client.PenDevice : client.MouseDevice;
+                    var pointerPoint = new RawPointerPoint() { Position = ev.Position };
+
+                    SetPenSpecificValues(ev, ref pointerPoint);
+
+                    client.ScheduleXI2Input(new RawPointerEventArgs(device, ev.Timestamp, client.InputRoot,
+                        type.Value, pointerPoint, eventModifiers));
+                }
             }
 
             _pointerDevice.UpdateValuators(ev.Valuators);
         }
+        
+        private void SetPenSpecificValues(ParsedDeviceEvent ev, ref RawPointerPoint pointerPoint)
+        {
+            foreach (var evValuator in ev.Valuators)
+            {
+                SetPenSpecificValues(evValuator, ref pointerPoint);
+            }
+        }
+
+        private void SetPenSpecificValues(KeyValuePair<int, double> item, ref RawPointerPoint rawPointerPoint)
+        {
+            if (_pointerDevice.PressureXIValuatorClassInfo is { } valuatorClassInfo)
+            {
+                if (item.Key == valuatorClassInfo.Number)
+                {
+                    var pressure = (item.Value - valuatorClassInfo.Min) /
+                                   (valuatorClassInfo.Max - valuatorClassInfo.Min);
+                    rawPointerPoint.Pressure = (float)pressure;
+                }
+            }
+
+            if (_pointerDevice.TiltXXIValuatorClassInfo is { } tiltXValuatorClassInfo)
+            {
+                if (item.Key == tiltXValuatorClassInfo.Number)
+                {
+                    rawPointerPoint.XTilt = (float)item.Value;
+                }
+            }
+
+            if (_pointerDevice.TiltYXIValuatorClassInfo is { } tiltYValuatorClassInfo)
+            {
+                if (item.Key == tiltYValuatorClassInfo.Number)
+                {
+                    rawPointerPoint.YTilt = (float)item.Value;
+                }
+            }
         }
 
         internal unsafe class ParsedDeviceEvent
@@ -453,6 +550,7 @@ namespace Avalonia.X11
                             rv |= RawInputModifiers.XButton2MouseButton;
                     }
                 }
+
                 return rv;
             }
 
@@ -487,6 +585,7 @@ namespace Avalonia.X11
                 Emulated = ev->flags.HasAllFlags(XiDeviceEventFlags.XIPointerEmulated);
             }
         }
+    }
 
     internal interface IXI2Client
     {
@@ -494,6 +593,7 @@ namespace Avalonia.X11
             IInputRoot InputRoot { get; }
             void ScheduleXI2Input(RawInputEventArgs args);
             IMouseDevice MouseDevice { get; }
+            IPenDevice PenDevice { get; }
             TouchDevice TouchDevice { get; }
     }
 }

src/Avalonia.X11/XIStructs.cs

@@ -205,7 +205,7 @@ namespace Avalonia.X11
         public IntPtr Time;
         public int Deviceid; /* id of the device that changed */
         public int Sourceid; /* Source for the new classes. */
-        public int Reason; /* Reason for the change */
+        public XiDeviceChangeReason Reason; /* Reason for the change */
         public int NumClasses;
         public XIAnyClassInfo** Classes; /* same as in XIDeviceInfo */
     }
@@ -272,6 +272,12 @@ namespace Avalonia.X11
         XIPointerEmulated = (1 << 16)
     }
 
+    internal enum XiDeviceChangeReason : int
+    {
+        XISlaveSwitch = 1,
+        XIDeviceChange = 2
+    }
+
     [StructLayout(LayoutKind.Sequential)]
     internal unsafe struct XIEvent
     {

src/Shared/RawEventGrouping.cs

@@ -180,7 +180,7 @@ internal class RawEventGrouper : IDisposable
     {
         
         last.IntermediatePoints ??= new Lazy<IReadOnlyList<RawPointerPoint>?>(s_getPooledListDelegate);
-        ((PooledList<RawPointerPoint>)last.IntermediatePoints.Value!).Add(new RawPointerPoint { Position = last.Position });
+        ((PooledList<RawPointerPoint>)last.IntermediatePoints.Value!).Add(new RawPointerPoint { Position = last.Position, Pressure = last.Point.Pressure, ContactRect = last.Point.ContactRect, Twist = last.Point.Twist, XTilt = last.Point.XTilt, YTilt = last.Point.YTilt });
         last.Position = current.Position;
         last.Timestamp = current.Timestamp;
         last.InputModifiers = current.InputModifiers;