Merge pull request #3585 from tig/v2_3303-Thickness-Record-Struct

Fixes #3303. Makes `Thickness` a `record struct`

Terminal.Gui/Drawing/Thickness.cs

@@ -1,4 +1,5 @@
-using System.Text.Json.Serialization;
+using System.Numerics;
+using System.Text.Json.Serialization;
 
 namespace Terminal.Gui;
 
@@ -13,28 +14,18 @@ namespace Terminal.Gui;
 ///         frame,
 ///         with the thickness widths subtracted.
 ///     </para>
-///     <para>Use the helper API (<see cref="Draw(Rectangle, string)"/> to draw the frame with the specified thickness.</para>
+///     <para>
+///         Use the helper API (<see cref="Draw(Rectangle, string)"/> to draw the frame with the specified thickness.
+///     </para>
+///     <para>
+///         Thickness uses <see langword="float"/> intenrally. As a result, there is a potential precision loss for very
+///         large numbers. This is typically not an issue for UI dimensions but could be relevant in other contexts.
+///     </para>
 /// </remarks>
-public class Thickness : IEquatable<Thickness>
+public record struct Thickness
 {
-    /// <summary>Gets or sets the width of the lower side of the rectangle.</summary>
-    [JsonInclude]
-    public int Bottom;
-
-    /// <summary>Gets or sets the width of the left side of the rectangle.</summary>
-    [JsonInclude]
-    public int Left;
-
-    /// <summary>Gets or sets the width of the right side of the rectangle.</summary>
-    [JsonInclude]
-    public int Right;
-
-    /// <summary>Gets or sets the width of the upper side of the rectangle.</summary>
-    [JsonInclude]
-    public int Top;
-
     /// <summary>Initializes a new instance of the <see cref="Thickness"/> class with all widths set to 0.</summary>
-    public Thickness () { }
+    public Thickness () { _sides = Vector4.Zero; }
 
     /// <summary>Initializes a new instance of the <see cref="Thickness"/> class with a uniform width to each side.</summary>
     /// <param name="width"></param>
@@ -56,36 +47,24 @@ public Thickness (int left, int top, int right, int bottom)
         Bottom = bottom;
     }
 
-    // TODO: add operator overloads
-    /// <summary>Gets an empty thickness.</summary>
-    public static Thickness Empty => new (0);
+    private Vector4 _sides;
 
     /// <summary>
-    ///     Gets the total width of the left and right sides of the rectangle. Sets the width of the left and rigth sides
-    ///     of the rectangle to half the specified value.
+    ///     Adds the thickness widths of another <see cref="Thickness"/> to the current <see cref="Thickness"/>, returning a
+    ///     new <see cref="Thickness"/>.
     /// </summary>
-    public int Horizontal
-    {
-        get => Left + Right;
-        set => Left = Right = value / 2;
-    }
+    /// <param name="other"></param>
+    /// <returns></returns>
+    public readonly Thickness Add (Thickness other) { return new (Left + other.Left, Top + other.Top, Right + other.Right, Bottom + other.Bottom); }
 
-    /// <summary>
-    ///     Gets the total height of the top and bottom sides of the rectangle. Sets the height of the top and bottom
-    ///     sides of the rectangle to half the specified value.
-    /// </summary>
-    public int Vertical
+    /// <summary>Gets or sets the width of the lower side of the rectangle.</summary>
+    [JsonInclude]
+    public int Bottom
     {
-        get => Top + Bottom;
-        set => Top = Bottom = value / 2;
+        get => (int)_sides.W;
+        set => _sides.W = value;
     }
 
-    // IEquitable
-    /// <summary>Indicates whether the current object is equal to another object of the same type.</summary>
-    /// <param name="other"></param>
-    /// <returns>true if the current object is equal to the other parameter; otherwise, false.</returns>
-    public bool Equals (Thickness other) { return other is { } && Left == other.Left && Right == other.Right && Top == other.Top && Bottom == other.Bottom; }
-
     /// <summary>
     ///     Gets whether the specified coordinates lie within the thickness (inside the bounding rectangle but outside
     ///     the rectangle described by <see cref="GetInside(Rectangle)"/>.
@@ -100,22 +79,6 @@ public bool Contains (in Rectangle outside, in Point location)
         return outside.Contains (location) && !inside.Contains (location);
     }
 
-    /// <summary>
-    ///     Adds the thickness widths of another <see cref="Thickness"/> to the current <see cref="Thickness"/>, returning a
-    ///     new <see cref="Thickness"/>.
-    /// </summary>
-    /// <param name="other"></param>
-    /// <returns></returns>
-    public Thickness Add (Thickness other) { return new (Left + other.Left, Top + other.Top, Right + other.Right, Bottom + other.Bottom); }
-
-    /// <summary>
-    ///     Adds the thickness widths of another <see cref="Thickness"/> to another <see cref="Thickness"/>.
-    /// </summary>
-    /// <param name="a"></param>
-    /// <param name="b"></param>
-    /// <returns></returns>
-    public static Thickness operator + (Thickness a, Thickness b) { return a.Add (b); }
-
     /// <summary>Draws the <see cref="Thickness"/> rectangle with an optional diagnostics label.</summary>
     /// <remarks>
     ///     If <see cref="ViewDiagnosticFlags"/> is set to
@@ -240,31 +203,8 @@ rect with
         return GetInside (rect);
     }
 
-    /// <summary>Determines whether the specified object is equal to the current object.</summary>
-    /// <param name="obj">The object to compare with the current object.</param>
-    /// <returns><c>true</c> if the specified object is equal to the current object; otherwise, <c>false</c>.</returns>
-    public override bool Equals (object obj)
-    {
-        //Check for null and compare run-time types.
-        if (obj is null || !GetType ().Equals (obj.GetType ()))
-        {
-            return false;
-        }
-
-        return Equals ((Thickness)obj);
-    }
-
-    /// <inheritdoc/>
-    public override int GetHashCode ()
-    {
-        var hashCode = 1380952125;
-        hashCode = hashCode * -1521134295 + Left.GetHashCode ();
-        hashCode = hashCode * -1521134295 + Right.GetHashCode ();
-        hashCode = hashCode * -1521134295 + Top.GetHashCode ();
-        hashCode = hashCode * -1521134295 + Bottom.GetHashCode ();
-
-        return hashCode;
-    }
+    /// <summary>Gets an empty thickness.</summary>
+    public static Thickness Empty => new (0);
 
     /// <summary>
     ///     Returns a rectangle describing the location and size of the inside area of <paramref name="rect"/> with the
@@ -289,23 +229,59 @@ public Rectangle GetInside (Rectangle rect)
         return new (x, y, width, height);
     }
 
-    /// <inheritdoc/>
-    public static bool operator == (Thickness left, Thickness right) { return EqualityComparer<Thickness>.Default.Equals (left, right); }
+    /// <summary>
+    ///     Gets the total width of the left and right sides of the rectangle. Sets the width of the left and rigth sides
+    ///     of the rectangle to half the specified value.
+    /// </summary>
+    public int Horizontal
+    {
+        get => Left + Right;
+        set => Left = Right = value / 2;
+    }
 
-    /// <inheritdoc/>
-    public static bool operator != (Thickness left, Thickness right) { return !(left == right); }
+    /// <summary>Gets or sets the width of the left side of the rectangle.</summary>
+    [JsonInclude]
+    public int Left
+    {
+        get => (int)_sides.X;
+        set => _sides.X = value;
+    }
+
+    /// <summary>
+    ///     Adds the thickness widths of another <see cref="Thickness"/> to another <see cref="Thickness"/>.
+    /// </summary>
+    /// <param name="a"></param>
+    /// <param name="b"></param>
+    /// <returns></returns>
+    public static Thickness operator + (Thickness a, Thickness b) { return a.Add (b); }
+
+    /// <summary>Gets or sets the width of the right side of the rectangle.</summary>
+    [JsonInclude]
+    public int Right
+    {
+        get => (int)_sides.Z;
+        set => _sides.Z = value;
+    }
+
+    /// <summary>Gets or sets the width of the upper side of the rectangle.</summary>
+    [JsonInclude]
+    public int Top
+    {
+        get => (int)_sides.Y;
+        set => _sides.Y = value;
+    }
 
     /// <summary>Returns the thickness widths of the Thickness formatted as a string.</summary>
     /// <returns>The thickness widths as a string.</returns>
     public override string ToString () { return $"(Left={Left},Top={Top},Right={Right},Bottom={Bottom})"; }
 
-    private int validate (int width)
+    /// <summary>
+    ///     Gets the total height of the top and bottom sides of the rectangle. Sets the height of the top and bottom
+    ///     sides of the rectangle to half the specified value.
+    /// </summary>
+    public int Vertical
     {
-        if (width < 0)
-        {
-            throw new ArgumentException ("Thickness widths cannot be negative.");
-        }
-
-        return width;
+        get => Top + Bottom;
+        set => Top = Bottom = value / 2;
     }
 }

UnitTests/View/Adornment/BorderTests.cs

@@ -18,7 +18,7 @@ public void Border_Parent_HasFocus_Title_Uses_FocusAttribute ()
         view.Border.Thickness = new (0, 1, 0, 0);
         view.Border.LineStyle = LineStyle.Single;
 
-        view.ColorScheme = new()
+        view.ColorScheme = new ()
         {
             Normal = new (Color.Red, Color.Green),
             Focus = new (Color.Green, Color.Red)
@@ -53,7 +53,7 @@ public void Border_Uses_Parent_ColorScheme ()
         view.Border.Thickness = new (0, 1, 0, 0);
         view.Border.LineStyle = LineStyle.Single;
 
-        view.ColorScheme = new()
+        view.ColorScheme = new ()
         {
             Normal = new (Color.Red, Color.Green), Focus = new (Color.Green, Color.Red)
         };
@@ -90,7 +90,7 @@ public void Border_With_Title_Border_Double_Thickness_Top_Four_Size_Width (int w
         {
             Title = "1234", Width = Dim.Fill (), Height = Dim.Fill (), BorderStyle = LineStyle.Double
         };
-        win.Border.Thickness.Top = 4;
+        win.Border.Thickness = win.Border.Thickness with { Top = 4 };
 
         RunState rs = Application.Begin (win);
         var firstIteration = false;
@@ -224,7 +224,7 @@ public void Border_With_Title_Border_Double_Thickness_Top_Three_Size_Width (int
         {
             Title = "1234", Width = Dim.Fill (), Height = Dim.Fill (), BorderStyle = LineStyle.Double
         };
-        win.Border.Thickness.Top = 3;
+        win.Border.Thickness = win.Border.Thickness with { Top = 3 };
 
         RunState rs = Application.Begin (win);
         var firstIteration = false;
@@ -358,7 +358,7 @@ public void Border_With_Title_Border_Double_Thickness_Top_Two_Size_Width (int wi
         {
             Title = "1234", Width = Dim.Fill (), Height = Dim.Fill (), BorderStyle = LineStyle.Double
         };
-        win.Border.Thickness.Top = 2;
+        win.Border.Thickness = win.Border.Thickness with { Top = 2 };
 
         RunState rs = Application.Begin (win);
         var firstIteration = false;