Update documentation of pointer types

src/Avalonia.Input/IPointer.cs

@@ -1,15 +1,53 @@
 namespace Avalonia.Input
 {
+    /// <summary>
+    /// Identifies specific pointer generated by input device.
+    /// </summary>
+    /// <remarks>
+    /// Some devices, for instance, touchscreen might generate a pointer on each physical contact.
+    /// </remarks>
     public interface IPointer
     {
+        /// <summary>
+        /// Gets a unique identifier for the input pointer.
+        /// </summary>
         int Id { get; }
+
+        /// <summary>
+        /// Captures pointer input to the specified control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <remarks>
+        /// When an element captures the pointer, it receives pointer input whether the cursor is 
+        /// within the control's bounds or not. The current pointer capture control is exposed
+        /// by the <see cref="Captured"/> property.
+        /// </remarks>
         void Capture(IInputElement? control);
+
+        /// <summary>
+        /// Gets the control that is currently capturing by the pointer, if any.
+        /// </summary>
+        /// <remarks>
+        /// When an element captures the pointer, it receives pointer input whether the cursor is 
+        /// within the control's bounds or not. To set the pointer capture, call the 
+        /// <see cref="Capture"/> method.
+        /// </remarks>
         IInputElement? Captured { get; }
+
+        /// <summary>
+        /// Gets the pointer device type.
+        /// </summary>
         PointerType Type { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the input is from the primary pointer when multiple pointers are registered.
+        /// </summary>
         bool IsPrimary { get; }
-        
     }
 
+    /// <summary>
+    /// Enumerates pointer device types.
+    /// </summary>
     public enum PointerType
     {
         Mouse,

src/Avalonia.Input/PointerEventArgs.cs

@@ -67,7 +67,14 @@ namespace Avalonia.Input
             public IPointer? TryGetPointer(RawPointerEventArgs ev) => _ev.Pointer;
         }
 
+        /// <summary>
+        /// Gets specific pointer generated by input device.
+        /// </summary>
         public IPointer Pointer { get; }
+
+        /// <summary>
+        /// Gets the time when the input occurred.
+        /// </summary>
         public ulong Timestamp { get; }
 
         private IPointerDevice? _device;
@@ -91,7 +98,10 @@ namespace Avalonia.Input
                 return mods;
             }
         }
-        
+
+        /// <summary>
+        /// Gets a value that indicates which key modifiers were active at the time that the pointer event was initiated.
+        /// </summary>
         public KeyModifiers KeyModifiers { get; }
 
         private Point GetPosition(Point pt, IVisual? relativeTo)
@@ -102,7 +112,12 @@ namespace Avalonia.Input
                 return pt;
             return pt * _rootVisual.TransformToVisual(relativeTo) ?? default;
         }
-        
+
+        /// <summary>
+        /// Gets the pointer position relative to a control.
+        /// </summary>
+        /// <param name="relativeTo">The control.</param>
+        /// <returns>The pointer position in the control's coordinates.</returns>
         public Point GetPosition(IVisual? relativeTo) => GetPosition(_rootVisualPosition, relativeTo);
 
         [Obsolete("Use GetCurrentPoint")]

src/Avalonia.Input/PointerPoint.cs

@@ -2,6 +2,9 @@ using Avalonia.Input.Raw;
 
 namespace Avalonia.Input
 {
+    /// <summary>
+    /// Provides basic properties for the input pointer associated with a single mouse, pen/stylus, or touch contact.
+    /// </summary>
     public sealed class PointerPoint
     {
         public PointerPoint(IPointer pointer, Point position, PointerPointProperties properties)
@@ -10,34 +13,109 @@ namespace Avalonia.Input
             Position = position;
             Properties = properties;
         }
+
+        /// <summary>
+        /// Gets specific pointer generated by input device.
+        /// </summary>
         public IPointer Pointer { get; }
+
+        /// <summary>
+        /// Gets extended information about the input pointer.
+        /// </summary>
         public PointerPointProperties Properties { get; }
+
+        /// <summary>
+        /// Gets the location of the pointer input in client coordinates.
+        /// </summary>
         public Point Position { get; }
     }
 
+    /// <summary>
+    /// Provides extended properties for a PointerPoint object.
+    /// </summary>
     public sealed class PointerPointProperties
     {
+        /// <summary>
+        /// Gets a value that indicates whether the pointer input was triggered by the primary action mode of an input device.
+        /// </summary>
         public bool IsLeftButtonPressed { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the pointer input was triggered by the tertiary action mode of an input device.
+        /// </summary>
         public bool IsMiddleButtonPressed { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the pointer input was triggered by the secondary action mode (if supported) of an input device.
+        /// </summary>
         public bool IsRightButtonPressed { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the pointer input was triggered by the first extended mouse button (XButton1).
+        /// </summary>
         public bool IsXButton1Pressed { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the pointer input was triggered by the second extended mouse button (XButton2).
+        /// </summary>
         public bool IsXButton2Pressed { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the barrel button of the pen/stylus device is pressed.
+        /// </summary>
         public bool IsBarrelButtonPressed { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the input is from a pen eraser.
+        /// </summary>
         public bool IsEraser { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether the digitizer pen is inverted.
+        /// </summary>
         public bool IsInverted { get; }
 
+        /// <summary>
+        /// Gets the clockwise rotation in degrees of a pen device around its own major axis (such as when the user spins the pen in their fingers).
+        /// </summary>
+        /// <returns>
+        /// A value between 0.0 and 359.0 in degrees of rotation. The default value is 0.0.
+        /// </returns>
         public float Twist { get; }
-        public float Pressure { get; }
+
+        /// <summary>
+        /// Gets a value that indicates the force that the pointer device (typically a pen/stylus) exerts on the surface of the digitizer.
+        /// </summary>
+        /// <returns>
+        /// A value from 0 to 1.0. The default value is 0.5.
+        /// </returns>
+        public float Pressure { get; } = 0.5f;
+
+        /// <summary>
+        /// Gets the plane angle between the Y-Z plane and the plane that contains the Y axis and the axis of the input device (typically a pen/stylus).
+        /// </summary>
+        /// <returns>
+        /// The value is 0.0 when the finger or pen is perpendicular to the digitizer surface, between 0.0 and 90.0 when tilted to the right of perpendicular, and between 0.0 and -90.0 when tilted to the left of perpendicular. The default value is 0.0.
+        /// </returns>
         public float XTilt { get; }
-        public float YTilt { get; }
 
+        /// <summary>
+        /// Gets the plane angle between the X-Z plane and the plane that contains the X axis and the axis of the input device (typically a pen/stylus).
+        /// </summary>
+        /// <returns>
+        /// The value is 0.0 when the finger or pen is perpendicular to the digitizer surface, between 0.0 and 90.0 when tilted towards the user, and between 0.0 and -90.0 when tilted away from the user. The default value is 0.0.
+        /// </returns>
+        public float YTilt { get; }
 
+        /// <summary>
+        /// Gets the kind of pointer state change.
+        /// </summary>
         public PointerUpdateKind PointerUpdateKind { get; }
 
         private PointerPointProperties()
-        {            
+        {
         }
-        
+
         public PointerPointProperties(RawInputModifiers modifiers, PointerUpdateKind kind)
         {
             PointerUpdateKind = kind;