#nullable enable

Author: tig

Terminal.Gui/Drawing/Thickness.cs

@@ -1,4 +1,5 @@
-using System.Numerics;
+#nullable enable
+using System.Numerics;
 using System.Text.Json.Serialization;
 
 namespace Terminal.Gui;
@@ -15,10 +16,7 @@ namespace Terminal.Gui;
 ///         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>
-///         Thickness uses <see langword="float"/> intenrally. As a result, there is a potential precision loss for very
+///         Thickness uses <see langword="float"/> internally. 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>
@@ -91,7 +89,7 @@ public bool Contains (in Rectangle outside, in Point location)
     /// <param name="diagnosticFlags"></param>
     /// <param name="label">The diagnostics label to draw on the bottom of the <see cref="Bottom"/>.</param>
     /// <returns>The inner rectangle remaining to be drawn.</returns>
-    public Rectangle Draw (Rectangle rect, ViewDiagnosticFlags diagnosticFlags = ViewDiagnosticFlags.Off, string label = null)
+    public Rectangle Draw (Rectangle rect, ViewDiagnosticFlags diagnosticFlags = ViewDiagnosticFlags.Off, string? label = null)
     {
         if (rect.Size.Width < 1 || rect.Size.Height < 1)
         {
@@ -134,26 +132,26 @@ public Rectangle Draw (Rectangle rect, ViewDiagnosticFlags diagnosticFlags = Vie
         if (Right > 0)
         {
             Application.Driver?.FillRect (
-                                         rect with
-                                         {
-                                             X = Math.Max (0, rect.X + rect.Width - Right),
-                                             Width = Math.Min (rect.Width, Right)
-                                         },
-                                         rightChar
-                                        );
+                                          rect with
+                                          {
+                                              X = Math.Max (0, rect.X + rect.Width - Right),
+                                              Width = Math.Min (rect.Width, Right)
+                                          },
+                                          rightChar
+                                         );
         }
 
         // Draw the Bottom side
         if (Bottom > 0)
         {
             Application.Driver?.FillRect (
-                                         rect with
-                                         {
-                                             Y = rect.Y + Math.Max (0, rect.Height - Bottom),
-                                             Height = Bottom
-                                         },
-                                         bottomChar
-                                        );
+                                          rect with
+                                          {
+                                              Y = rect.Y + Math.Max (0, rect.Height - Bottom),
+                                              Height = Bottom
+                                          },
+                                          bottomChar
+                                         );
         }
 
         if (diagnosticFlags.HasFlag (ViewDiagnosticFlags.Ruler))
@@ -192,6 +190,7 @@ rect with
         {
             // Draw the diagnostics label on the bottom
             string text = label is null ? string.Empty : $"{label} {this}";
+
             var tf = new TextFormatter
             {
                 Text = text,

Terminal.Gui/View/Adornment/Border.cs

@@ -483,8 +483,8 @@ protected override bool OnMouseEvent (MouseEventArgs mouseEvent)
                 Point parentLoc = Parent.SuperView?.ScreenToViewport (new (mouseEvent.ScreenPosition.X, mouseEvent.ScreenPosition.Y))
                                   ?? mouseEvent.ScreenPosition;
 
-                int minHeight = Thickness.Vertical + Parent!.Margin.Thickness.Bottom;
-                int minWidth = Thickness.Horizontal + Parent!.Margin.Thickness.Right;
+                int minHeight = Thickness.Vertical + Parent!.Margin!.Thickness.Bottom;
+                int minWidth = Thickness.Horizontal + Parent!.Margin!.Thickness.Right;
 
                 // TODO: This code can be refactored to be more readable and maintainable.
                 switch (_arranging)
@@ -1072,7 +1072,7 @@ private static void GetAppealingGradientColors (out List<Color> stops, out List<
                 NoPadding = true,
                 ShadowStyle = ShadowStyle.None,
                 Text = $"{Glyphs.SizeVertical}",
-                X = Pos.Center () + Parent!.Margin.Thickness.Horizontal,
+                X = Pos.Center () + Parent!.Margin!.Thickness.Horizontal,
                 Y = 0,
                 Visible = false,
                 Data = ViewArrangement.TopResizable
@@ -1095,7 +1095,7 @@ private static void GetAppealingGradientColors (out List<Color> stops, out List<
                 ShadowStyle = ShadowStyle.None,
                 Text = $"{Glyphs.SizeHorizontal}",
                 X = Pos.AnchorEnd (),
-                Y = Pos.Center () + Parent!.Margin.Thickness.Vertical / 2,
+                Y = Pos.Center () + Parent!.Margin!.Thickness.Vertical / 2,
                 Visible = false,
                 Data = ViewArrangement.RightResizable
             };
@@ -1117,7 +1117,7 @@ private static void GetAppealingGradientColors (out List<Color> stops, out List<
                 ShadowStyle = ShadowStyle.None,
                 Text = $"{Glyphs.SizeHorizontal}",
                 X = 0,
-                Y = Pos.Center () + Parent!.Margin.Thickness.Vertical / 2,
+                Y = Pos.Center () + Parent!.Margin!.Thickness.Vertical / 2,
                 Visible = false,
                 Data = ViewArrangement.LeftResizable
             };
@@ -1138,7 +1138,7 @@ private static void GetAppealingGradientColors (out List<Color> stops, out List<
                 NoPadding = true,
                 ShadowStyle = ShadowStyle.None,
                 Text = $"{Glyphs.SizeVertical}",
-                X = Pos.Center () + Parent!.Margin.Thickness.Horizontal / 2,
+                X = Pos.Center () + Parent!.Margin!.Thickness.Horizontal / 2,
                 Y = Pos.AnchorEnd (),
                 Visible = false,
                 Data = ViewArrangement.BottomResizable

Terminal.Gui/View/Adornment/Margin.cs

@@ -275,13 +275,13 @@ private void Margin_LayoutStarted (object? sender, LayoutEventArgs e)
             {
                 case ShadowStyle.Transparent:
                     // BUGBUG: This doesn't work right for all Border.Top sizes - Need an API on Border that gives top-right location of line corner.
-                    _rightShadow.Y = Parent!.Border.Thickness.Top > 0 ? ScreenToViewport (Parent.Border.GetBorderRectangle ().Location).Y + 1 : 0;
+                    _rightShadow.Y = Parent!.Border!.Thickness.Top > 0 ? ScreenToViewport (Parent.Border.GetBorderRectangle ().Location).Y + 1 : 0;
 
                     break;
 
                 case ShadowStyle.Opaque:
                     // BUGBUG: This doesn't work right for all Border.Top sizes - Need an API on Border that gives top-right location of line corner.
-                    _rightShadow.Y = Parent!.Border.Thickness.Top > 0 ? ScreenToViewport (Parent.Border.GetBorderRectangle ().Location).Y + 1 : 0;
+                    _rightShadow.Y = Parent!.Border!.Thickness.Top > 0 ? ScreenToViewport (Parent.Border.GetBorderRectangle ().Location).Y + 1 : 0;
                     _bottomShadow.X = Parent.Border.Thickness.Left > 0 ? ScreenToViewport (Parent.Border.GetBorderRectangle ().Location).X + 1 : 0;
 
                     break;

Terminal.Gui/View/DrawEventArgs.cs

@@ -20,9 +20,6 @@ public DrawEventArgs (Rectangle newViewport, Rectangle oldViewport)
         OldViewport = oldViewport;
     }
 
-    /// <summary>If set to true, the draw operation will be canceled, if applicable.</summary>
-    public bool Cancel { get; set; }
-
     /// <summary>Gets the Content-relative rectangle describing the old visible viewport into the <see cref="View"/>.</summary>
     public Rectangle OldViewport { get; }
 

Terminal.Gui/View/View.Adornments.cs

@@ -1,4 +1,5 @@
-namespace Terminal.Gui;
+#nullable enable
+namespace Terminal.Gui;
 
 public partial class View // Adornments
 {
@@ -7,9 +8,10 @@ public partial class View // Adornments
     /// </summary>
     private void SetupAdornments ()
     {
-        //// TODO: Move this to Adornment as a static factory method
+        // TODO: Move this to Adornment as a static factory method
         if (this is not Adornment)
         {
+            // TODO: Make the Adornments Lazy and only create them when needed
             Margin = new (this);
             Border = new (this);
             Padding = new (this);
@@ -61,7 +63,7 @@ private void DisposeAdornments ()
     ///         <see cref="SuperView"/> and its <see cref="Subviews"/>.
     ///     </para>
     /// </remarks>
-    public Margin Margin { get; private set; }
+    public Margin? Margin { get; private set; }
 
     private ShadowStyle _shadowStyle;
 
@@ -117,7 +119,7 @@ public virtual ShadowStyle ShadowStyle
     ///         <see cref="SuperView"/> and its <see cref="Subviews"/>.
     ///     </para>
     /// </remarks>
-    public Border Border { get; private set; }
+    public Border? Border { get; private set; }
 
     /// <summary>Gets or sets whether the view has a one row/col thick border.</summary>
     /// <remarks>
@@ -130,6 +132,10 @@ public virtual ShadowStyle ShadowStyle
     ///         Setting this property to <see cref="LineStyle.None"/> is equivalent to setting <see cref="Border"/>'s
     ///         <see cref="Adornment.Thickness"/> to `0` and <see cref="BorderStyle"/> to <see cref="LineStyle.None"/>.
     ///     </para>
+    ///     <para>
+    ///         Calls <see cref="OnBorderStyleChanging"/> and raises <see cref="BorderStyleChanging"/>, which allows change
+    ///         to be cancelled.
+    ///     </para>
     ///     <para>For more advanced customization of the view's border, manipulate see <see cref="Border"/> directly.</para>
     /// </remarks>
     public LineStyle BorderStyle
@@ -150,32 +156,32 @@ public LineStyle BorderStyle
                 return;
             }
 
+            BorderStyleChanging?.Invoke (this, e);
+
+            if (e.Cancel)
+            {
+                return;
+            }
+
             SetBorderStyle (e.NewValue);
             SetAdornmentFrames ();
             SetNeedsLayout ();
-
         }
     }
 
     /// <summary>
-    ///     Called when the <see cref="BorderStyle"/> is changing. Invokes <see cref="BorderStyleChanging"/>, which allows the
-    ///     event to be cancelled.
+    ///     Called when the <see cref="BorderStyle"/> is changing.
     /// </summary>
     /// <remarks>
-    ///     Override <see cref="SetBorderStyle"/> to prevent the <see cref="BorderStyle"/> from changing.
+    ///     Set e.Cancel to true to prevent the <see cref="BorderStyle"/> from changing.
     /// </remarks>
     /// <param name="e"></param>
-    protected virtual bool OnBorderStyleChanging (CancelEventArgs<LineStyle> e)
-    {
-        if (Border is null)
-        {
-            return false;
-        }
-
-        BorderStyleChanging?.Invoke (this, e);
+    protected virtual bool OnBorderStyleChanging (CancelEventArgs<LineStyle> e) { return false; }
 
-        return e.Cancel;
-    }
+    /// <summary>
+    ///     Fired when the <see cref="BorderStyle"/> is changing. Allows the event to be cancelled.
+    /// </summary>
+    public event EventHandler<CancelEventArgs<LineStyle>>? BorderStyleChanging;
 
     /// <summary>
     ///     Sets the <see cref="BorderStyle"/> of the view to the specified value.
@@ -198,25 +204,19 @@ public virtual void SetBorderStyle (LineStyle value)
     {
         if (value != LineStyle.None)
         {
-            if (Border.Thickness == Thickness.Empty)
+            if (Border!.Thickness == Thickness.Empty)
             {
                 Border.Thickness = new (1);
             }
         }
         else
         {
-            Border.Thickness = new (0);
+            Border!.Thickness = new (0);
         }
 
         Border.LineStyle = value;
     }
 
-    /// <summary>
-    ///     Fired when the <see cref="BorderStyle"/> is changing. Allows the event to be cancelled.
-    /// </summary>
-    [CanBeNull]
-    public event EventHandler<CancelEventArgs<LineStyle>> BorderStyleChanging;
-
     /// <summary>
     ///     The <see cref="Adornment"/> inside of the view that offsets the <see cref="Viewport"/>
     ///     from the <see cref="Border"/>.
@@ -232,7 +232,7 @@ public virtual void SetBorderStyle (LineStyle value)
     ///         <see cref="SuperView"/> and its <see cref="Subviews"/>.
     ///     </para>
     /// </remarks>
-    public Padding Padding { get; private set; }
+    public Padding? Padding { get; private set; }
 
     /// <summary>
     ///     <para>Gets the thickness describing the sum of the Adornments' thicknesses.</para>
@@ -245,12 +245,24 @@ public virtual void SetBorderStyle (LineStyle value)
     /// <returns>A thickness that describes the sum of the Adornments' thicknesses.</returns>
     public Thickness GetAdornmentsThickness ()
     {
-        if (Margin is null)
+        Thickness result = Thickness.Empty;
+
+        if (Margin is { })
+        {
+            result += Margin.Thickness;
+        }
+
+        if (Border is { })
         {
-            return Thickness.Empty;
+            result += Border.Thickness;
         }
 
-        return Margin.Thickness + Border.Thickness + Padding.Thickness;
+        if (Padding is { })
+        {
+            result += Padding.Thickness;
+        }
+
+        return result;
     }
 
     /// <summary>Sets the Frame's of the Margin, Border, and Padding.</summary>
@@ -262,13 +274,19 @@ internal void SetAdornmentFrames ()
             return;
         }
 
-        if (Margin is null)
+        if (Margin is { })
+        {
+            Margin!.Frame = Rectangle.Empty with { Size = Frame.Size };
+        }
+
+        if (Border is { } && Margin is { })
         {
-            return; // CreateAdornments () has not been called yet
+            Border!.Frame = Margin!.Thickness.GetInside (Margin!.Frame);
         }
 
-        Margin.Frame = Rectangle.Empty with { Size = Frame.Size };
-        Border.Frame = Margin.Thickness.GetInside (Margin.Frame);
-        Padding.Frame = Border.Thickness.GetInside (Border.Frame);
+        if (Padding is { } && Border is { })
+        {
+            Padding!.Frame = Border!.Thickness.GetInside (Border!.Frame);
+        }
     }
 }

Terminal.Gui/View/View.Arrangement.cs

@@ -1,4 +1,5 @@
-namespace Terminal.Gui;
+#nullable enable
+namespace Terminal.Gui;
 
 public partial class View
 {