Fixes #2489. New ScrollSlider and ScrollBar - Any View can have scrollbars easily

Terminal.Gui/Drawing/Glyphs.cs

@@ -79,10 +79,10 @@ public class GlyphDefinitions
     /// <summary>Continuous block meter segment (e.g. for <see cref="ProgressBar"/>).</summary>
     public Rune ContinuousMeterSegment { get; set; } = (Rune)'█';
 
-    /// <summary>Stipple pattern (e.g. for <see cref="ScrollBarView"/>). Default is Light Shade (U+2591) - ░.</summary>
+    /// <summary>Stipple pattern (e.g. for <see cref="ScrollBar"/>). Default is Light Shade (U+2591) - ░.</summary>
     public Rune Stipple { get; set; } = (Rune)'░';
 
-    /// <summary>Diamond (e.g. for <see cref="ScrollBarView"/>. Default is Lozenge (U+25CA) - ◊.</summary>
+    /// <summary>Diamond. Default is Lozenge (U+25CA) - ◊.</summary>
     public Rune Diamond { get; set; } = (Rune)'◊';
 
     /// <summary>Close. Default is Heavy Ballot X (U+2718) - ✘.</summary>

Terminal.Gui/Drawing/Thickness.cs

@@ -236,7 +236,7 @@ public Rectangle GetInside (Rectangle rect)
     }
 
     /// <summary>
-    ///     Gets the total width of the left and right sides of the rectangle. Sets the width of the left and rigth sides
+    ///     Gets the total width of the left and right sides of the rectangle. Sets the width of the left and right sides
     ///     of the rectangle to half the specified value.
     /// </summary>
     public int Horizontal

Terminal.Gui/Terminal.Gui.csproj

@@ -109,9 +109,6 @@
       <LastGenOutput>Strings.Designer.cs</LastGenOutput>
     </EmbeddedResource>
   </ItemGroup>
-  <ItemGroup>
-    <Folder Include="Views\Scroll\" />
-  </ItemGroup>
   <!-- =================================================================== -->
   <!-- Nuget  -->
   <!-- =================================================================== -->

Terminal.Gui/View/View.Content.cs

@@ -312,7 +312,7 @@ private void SetViewport (Rectangle viewport)
                 //SetSubViewNeedsDraw();
             }
 
-            OnViewportChanged (new (IsInitialized ? Viewport : Rectangle.Empty, oldViewport));
+            RaiseViewportChangedEvent (oldViewport);
 
             return;
         }
@@ -325,6 +325,10 @@ private void SetViewport (Rectangle viewport)
             Size = newSize
         };
 
+        // Note, setting the Frame will cause ViewportChanged to be raised.
+
+        return;
+
         void ApplySettings (ref Rectangle newViewport)
         {
             if (!ViewportSettings.HasFlag (ViewportSettings.AllowXGreaterThanContentWidth))
@@ -344,6 +348,14 @@ void ApplySettings (ref Rectangle newViewport)
                 }
             }
 
+            if (!ViewportSettings.HasFlag (ViewportSettings.AllowNegativeXWhenWidthGreaterThanContentWidth))
+            {
+                if (Viewport.Width > GetContentSize ().Width)
+                {
+                    newViewport.X = 0;
+                }
+            }
+
             if (!ViewportSettings.HasFlag (ViewportSettings.AllowYGreaterThanContentHeight))
             {
                 if (newViewport.Y >= GetContentSize ().Height)
@@ -352,6 +364,14 @@ void ApplySettings (ref Rectangle newViewport)
                 }
             }
 
+            if (!ViewportSettings.HasFlag (ViewportSettings.AllowNegativeYWhenHeightGreaterThanContentHeight))
+            {
+                if (Viewport.Height > GetContentSize ().Height)
+                {
+                    newViewport.Y = 0;
+                }
+            }
+
             // IMPORTANT: Check for negative location AFTER checking for location greater than content width
             if (!ViewportSettings.HasFlag (ViewportSettings.AllowNegativeY))
             {
@@ -363,6 +383,13 @@ void ApplySettings (ref Rectangle newViewport)
         }
     }
 
+    private void RaiseViewportChangedEvent (Rectangle oldViewport)
+    {
+        var args = new DrawEventArgs (IsInitialized ? Viewport : Rectangle.Empty, oldViewport);
+        OnViewportChanged (args);
+        ViewportChanged?.Invoke (this, args);
+    }
+
     /// <summary>
     ///     Fired when the <see cref="Viewport"/> changes. This event is fired after the <see cref="Viewport"/> has been
     ///     updated.
@@ -373,7 +400,7 @@ void ApplySettings (ref Rectangle newViewport)
     ///     Called when the <see cref="Viewport"/> changes. Invokes the <see cref="ViewportChanged"/> event.
     /// </summary>
     /// <param name="e"></param>
-    protected virtual void OnViewportChanged (DrawEventArgs e) { ViewportChanged?.Invoke (this, e); }
+    protected virtual void OnViewportChanged (DrawEventArgs e) { }
 
     /// <summary>
     ///     Converts a <see cref="Viewport"/>-relative location and size to a screen-relative location and size.

Terminal.Gui/View/View.Drawing.Clipping.cs

@@ -104,7 +104,7 @@ public static void SetClip (Region? region)
         if (this is Adornment adornment && adornment.Thickness != Thickness.Empty)
         {
             // Ensure adornments can't draw outside their thickness
-            frameRegion.Exclude (adornment.Thickness.GetInside (Frame));
+            frameRegion.Exclude (adornment.Thickness.GetInside (FrameToScreen()));
         }
 
         SetClip (frameRegion);

Terminal.Gui/View/View.Drawing.Primitives.cs

@@ -7,9 +7,6 @@ public partial class View
     /// <summary>Moves the drawing cursor to the specified <see cref="Viewport"/>-relative location in the view.</summary>
     /// <remarks>
     ///     <para>
-    ///         If the provided coordinates are outside the visible content area, this method does nothing.
-    ///     </para>
-    ///     <para>
     ///         The top-left corner of the visible content area is <c>ViewPort.Location</c>.
     ///     </para>
     /// </remarks>
@@ -22,11 +19,6 @@ public bool Move (int col, int row)
             return false;
         }
 
-        if (col < 0 || row < 0 || col >= Viewport.Width || row >= Viewport.Height)
-        {
-            return false;
-        }
-
         Point screen = ViewportToScreen (new Point (col, row));
         Driver?.Move (screen.X, screen.Y);
 

Terminal.Gui/View/View.Hierarchy.cs

@@ -145,7 +145,7 @@ public virtual void OnRemoved (SuperViewChangedEventArgs e)
     ///     <para>
     ///         Normally Subviews will be disposed when this View is disposed. Removing a Subview causes ownership of the
     ///         Subview's
-    ///         lifecycle to be transferred to the caller; the caller muse call <see cref="Dispose"/>.
+    ///         lifecycle to be transferred to the caller; the caller must call <see cref="Dispose()"/>.
     ///     </para>
     /// </remarks>
     /// <returns>
@@ -214,7 +214,7 @@ public virtual void OnRemoved (SuperViewChangedEventArgs e)
     ///     <para>
     ///         Normally Subviews will be disposed when this View is disposed. Removing a Subview causes ownership of the
     ///         Subview's
-    ///         lifecycle to be transferred to the caller; the caller must call <see cref="Dispose"/> on any Views that were
+    ///         lifecycle to be transferred to the caller; the caller must call <see cref="Dispose()"/> on any Views that were
     ///         added.
     ///     </para>
     /// </remarks>

Terminal.Gui/View/View.Layout.cs

@@ -96,11 +96,28 @@ private bool SetFrame (in Rectangle frame)
         SetNeedsLayout ();
 
         // BUGBUG: When SetFrame is called from Frame_set, this event gets raised BEFORE OnResizeNeeded. Is that OK?
-        OnViewportChanged (new (IsInitialized ? Viewport : Rectangle.Empty, oldViewport));
+        OnFrameChanged (in frame);
+        FrameChanged?.Invoke (this, new (in frame));
 
+        if (oldViewport != Viewport)
+        {
+            RaiseViewportChangedEvent (oldViewport);
+        }
         return true;
     }
 
+    /// <summary>
+    ///     Called when <see cref="Frame"/> changes.
+    /// </summary>
+    /// <param name="frame">The new Frame.</param>
+    protected virtual void OnFrameChanged (in Rectangle frame) { }
+
+    /// <summary>
+    ///     Raised when the <see cref="Frame"/> changes. This event is raised after the <see cref="Frame"/> has been
+    ///     updated.
+    /// </summary>
+    public event EventHandler<EventArgs<Rectangle>>? FrameChanged;
+
     /// <summary>Gets the <see cref="Frame"/> with a screen-relative location.</summary>
     /// <returns>The location and size of the view in screen-relative coordinates.</returns>
     public virtual Rectangle FrameToScreen ()