Merge pull request gui-cs#3571 from tig/v2_3570-TextView-ENTER

Fixes gui-cs#3570 & gui-cs#3561. Fixes a bunch of `EventArgs` sins

Terminal.Gui/Application/Application.cs

@@ -308,7 +308,7 @@ internal static void InternalInit (
         SupportedCultures = GetSupportedCultures ();
         _mainThreadId = Thread.CurrentThread.ManagedThreadId;
         _initialized = true;
-        InitializedChanged?.Invoke (null, new (false, _initialized));
+        InitializedChanged?.Invoke (null, new (in _initialized));
     }
 
     private static void Driver_SizeChanged (object sender, SizeChangedEventArgs e) { OnSizeChanging (e); }
@@ -349,16 +349,18 @@ public static void Shutdown ()
         // TODO: Throw an exception if Init hasn't been called.
         ResetState ();
         PrintJsonErrors ();
-        InitializedChanged?.Invoke (null, new (true, _initialized));
+        InitializedChanged?.Invoke (null, new (in _initialized));
     }
 
+#nullable enable
     /// <summary>
-    ///     This event is fired after the <see cref="Init"/> and <see cref="Shutdown"/> methods have been called.
+    ///     This event is raised after the <see cref="Init"/> and <see cref="Shutdown"/> methods have been called.
     /// </summary>
     /// <remarks>
     ///     Intended to support unit tests that need to know when the application has been initialized.
     /// </remarks>
-    public static event EventHandler<StateEventArgs<bool>> InitializedChanged;
+    public static event EventHandler<EventArgs<bool>>? InitializedChanged;
+#nullable restore
 
     #endregion Initialization (Init/Shutdown)
 

Terminal.Gui/Drawing/Glyphs.cs

@@ -32,13 +32,13 @@ public class GlyphDefinitions
     #region ----------------- Single Glyphs -----------------
 
     /// <summary>Checked indicator (e.g. for <see cref="ListView"/> and <see cref="CheckBox"/>).</summary>
-    public Rune Checked { get; set; } = (Rune)'☑';
+    public Rune CheckStateChecked { get; set; } = (Rune)'☑';
 
     /// <summary>Not Checked indicator (e.g. for <see cref="ListView"/> and <see cref="CheckBox"/>).</summary>
-    public Rune UnChecked { get; set; } = (Rune)'☐';
+    public Rune CheckStateUnChecked { get; set; } = (Rune)'☐';
 
     /// <summary>Null Checked indicator (e.g. for <see cref="ListView"/> and <see cref="CheckBox"/>).</summary>
-    public Rune NullChecked { get; set; } = (Rune)'☒';
+    public Rune CheckStateNone { get; set; } = (Rune)'☒';
 
     /// <summary>Selected indicator  (e.g. for <see cref="ListView"/> and <see cref="RadioGroup"/>).</summary>
     public Rune Selected { get; set; } = (Rune)'◉';

Terminal.Gui/View/Adornment/Adornment.cs

@@ -1,4 +1,6 @@
-namespace Terminal.Gui;
+#nullable enable
+using Terminal.Gui;
+using Attribute = Terminal.Gui.Attribute;
 
 /// <summary>
 ///     Adornments are a special form of <see cref="View"/> that appear outside the <see cref="View.Viewport"/>:
@@ -33,7 +35,7 @@ public Adornment (View parent)
     ///     Adornments are distinguished from typical View classes in that they are not sub-views, but have a parent/child
     ///     relationship with their containing View.
     /// </remarks>
-    public View Parent { get; set; }
+    public View? Parent { get; set; }
 
     #region Thickness
 
@@ -45,10 +47,10 @@ public Thickness Thickness
         get => _thickness;
         set
         {
-            Thickness prev = _thickness;
+            Thickness current = _thickness;
             _thickness = value;
 
-            if (prev != _thickness)
+            if (current != _thickness)
             {
                 if (Parent?.IsInitialized == false)
                 {
@@ -61,21 +63,19 @@ public Thickness Thickness
                     Parent?.LayoutSubviews ();
                 }
 
-                OnThicknessChanged (prev);
+                OnThicknessChanged ();
             }
         }
     }
 
     /// <summary>Fired whenever the <see cref="Thickness"/> property changes.</summary>
-    public event EventHandler<ThicknessEventArgs> ThicknessChanged;
+    [CanBeNull]
+    public event EventHandler? ThicknessChanged;
 
     /// <summary>Called whenever the <see cref="Thickness"/> property changes.</summary>
-    public void OnThicknessChanged (Thickness previousThickness)
+    public void OnThicknessChanged ()
     {
-        ThicknessChanged?.Invoke (
-                                  this,
-                                  new () { Thickness = Thickness, PreviousThickness = previousThickness }
-                                 );
+        ThicknessChanged?.Invoke (this, EventArgs.Empty);
     }
 
     #endregion Thickness
@@ -88,7 +88,7 @@ public void OnThicknessChanged (Thickness previousThickness)
     /// </summary>
     public override View SuperView
     {
-        get => null;
+        get => null!;
         set => throw new InvalidOperationException (@"Adornments can not be Subviews or have SuperViews. Use Parent instead.");
     }
 
@@ -137,7 +137,7 @@ public override Rectangle FrameToScreen ()
     /// <inheritdoc/>
     public override Point ScreenToFrame (in Point location)
     {
-        return Parent.ScreenToFrame (new (location.X - Frame.X, location.Y - Frame.Y));
+        return Parent!.ScreenToFrame (new (location.X - Frame.X, location.Y - Frame.Y));
     }
 
     /// <summary>Does nothing for Adornment</summary>

Terminal.Gui/View/Adornment/Border.cs

@@ -220,15 +220,15 @@ public bool ShowTitle
 
     private Color? _savedForeColor;
 
-    private void Border_Highlight (object sender, HighlightEventArgs e)
+    private void Border_Highlight (object sender, CancelEventArgs<HighlightStyle> e)
     {
         if (!Parent.Arrangement.HasFlag (ViewArrangement.Movable))
         {
             e.Cancel = true;
             return;
         }
 
-        if (e.HighlightStyle.HasFlag (HighlightStyle.Pressed))
+        if (e.NewValue.HasFlag (HighlightStyle.Pressed))
         {
             if (!_savedForeColor.HasValue)
             {
@@ -252,7 +252,7 @@ private void Border_Highlight (object sender, HighlightEventArgs e)
         }
 #endif
 
-        if (e.HighlightStyle == HighlightStyle.None && _savedForeColor.HasValue)
+        if (e.NewValue == HighlightStyle.None && _savedForeColor.HasValue)
         {
             ColorScheme cs = new ColorScheme (ColorScheme)
             {
@@ -299,6 +299,7 @@ protected internal override bool OnMouseEvent (MouseEvent mouseEvent)
                 _startGrabPoint = new (mouseEvent.Position.X + Frame.X, mouseEvent.Position.Y + Frame.Y);
                 _dragPosition = mouseEvent.Position;
                 Application.GrabMouse (this);
+
                 SetHighlight (HighlightStyle);
             }
 

Terminal.Gui/View/Adornment/Margin.cs

@@ -39,11 +39,11 @@ private void Margin_LayoutStarted (object? sender, LayoutEventArgs e)
     }
 
     private bool _pressed;
-    private void Margin_Highlight (object? sender, HighlightEventArgs e)
+    private void Margin_Highlight (object? sender, CancelEventArgs<HighlightStyle> e)
     {
         if (ShadowStyle != Gui.ShadowStyle.None)
         {
-            if (_pressed && e.HighlightStyle == HighlightStyle.None)
+            if (_pressed && e.CurrentValue == HighlightStyle.None)
             {
                 Thickness = new (Thickness.Left - 1, Thickness.Top, Thickness.Right + 1, Thickness.Bottom);
 
@@ -61,7 +61,7 @@ private void Margin_Highlight (object? sender, HighlightEventArgs e)
                 return;
             }
 
-            if (!_pressed && (e.HighlightStyle.HasFlag (HighlightStyle.Pressed) /*|| e.HighlightStyle.HasFlag (HighlightStyle.PressedOutside)*/))
+            if (!_pressed && (e.CurrentValue.HasFlag (HighlightStyle.Pressed) /*|| e.HighlightStyle.HasFlag (HighlightStyle.PressedOutside)*/))
             {
                 Thickness = new (Thickness.Left + 1, Thickness.Top, Thickness.Right - 1, Thickness.Bottom);
                 _pressed = true;

Terminal.Gui/View/CancelEventArgs.cs

@@ -0,0 +1,35 @@
+#nullable enable
+using System.ComponentModel;
+
+namespace Terminal.Gui;
+
+#pragma warning disable CS1711
+
+/// <summary>
+///     <see cref="EventArgs"/> for events that convey changes to a property of type <typeparamref name="T"/>.
+/// </summary>
+/// <typeparam name="T">The type of the value that was part of the change being canceled.</typeparam>
+/// <remarks>
+///     Events that use this class can be cancellable. Where applicable, the <see cref="CancelEventArgs.Cancel"/> property
+///     should be set to
+///     <see langword="true"/> to prevent the state change from occurring.
+/// </remarks>
+public class CancelEventArgs<T> : CancelEventArgs where T : notnull
+{
+    /// <summary>Initializes a new instance of the <see cref="CancelEventArgs{T}"/> class.</summary>
+    /// <param name="currentValue">The current (old) value of the property.</param>
+    /// <param name="newValue">The value the property will be set to if the event is not cancelled.</param>
+    /// <param name="cancel">Whether the event should be canceled or not.</param>
+    /// <typeparam name="T">The type of the value for the change being canceled.</typeparam>
+    public CancelEventArgs (ref readonly T currentValue, ref T newValue, bool cancel = false) : base (cancel)
+    {
+        CurrentValue = currentValue;
+        NewValue = newValue;
+    }
+
+    /// <summary>The current value of the property.</summary>
+    public T CurrentValue { get; }
+
+    /// <summary>The value the property will be set to if the event is not cancelled.</summary>
+    public T NewValue { get; set; }
+}

Terminal.Gui/View/EventArgs.cs

@@ -0,0 +1,18 @@
+#nullable enable
+namespace Terminal.Gui;
+
+#pragma warning disable CS1711
+/// <summary>
+///     <see cref="EventArgs"/> for events that convey changes to a property of type <typeparamref name="T"/>.
+/// </summary>
+/// <typeparam name="T">The type of the value that was part of the change being canceled.</typeparam>
+public class EventArgs<T> : EventArgs where T : notnull
+{
+    /// <summary>Initializes a new instance of the <see cref="EventArgs{T}"/> class.</summary>
+    /// <param name="currentValue">The current value of the property.</param>
+    /// <typeparam name="T">The type of the value.</typeparam>
+    public EventArgs (ref readonly T currentValue) { CurrentValue = currentValue; }
+
+    /// <summary>The current value of the property.</summary>
+    public T CurrentValue { get; }
+}

Terminal.Gui/View/HighlightStyle.cs

@@ -0,0 +1,30 @@
+namespace Terminal.Gui;
+
+/// <summary>
+/// Describes the highlight style of a view.
+/// </summary>
+[Flags]
+public enum HighlightStyle
+{
+    /// <summary>
+    /// No highlight.
+    /// </summary>
+    None = 0,
+
+#if HOVER
+    /// <summary>
+    /// The mouse is hovering over the view.
+    /// </summary>
+    Hover = 1,
+#endif
+
+    /// <summary>
+    /// The mouse is pressed within the <see cref="View.Viewport"/>.
+    /// </summary>
+    Pressed = 2,
+
+    /// <summary>
+    /// The mouse is pressed but moved outside the <see cref="View.Viewport"/>.
+    /// </summary>
+    PressedOutside = 4
+}