From 1f5515679f6dde6c7ee90aad4dc790be533f89c7 Mon Sep 17 00:00:00 2001
From: Miguel de Icaza <miguel@gnome.org>
Date: Mon, 29 Jan 2018 22:21:53 -0500
Subject: [PATCH] Cursor keys switch focus when unhandled, implement scrolling
 with keyboard in ScrollView

---
 Terminal.Gui/Core.cs             |  5 ++
 Terminal.Gui/Views/RadioGroup.cs |  6 ++-
 Terminal.Gui/Views/ScrollView.cs | 88 +++++++++++++++++++++++++++++++-
 demo.cs                          |  4 +-
 4 files changed, 98 insertions(+), 5 deletions(-)

diff --git a/Terminal.Gui/Core.cs b/Terminal.Gui/Core.cs
index 2edfac654..79dc308c4 100644
--- a/Terminal.Gui/Core.cs
+++ b/Terminal.Gui/Core.cs
@@ -932,6 +932,8 @@ namespace Terminal.Gui {
 				return true;
 #endif
 			case Key.Tab:
+			case Key.CursorRight:
+			case Key.CursorDown:
 				var old = Focused;
 				if (!FocusNext ())
 					FocusNext ();
@@ -940,6 +942,8 @@ namespace Terminal.Gui {
 					Focused?.SetNeedsDisplay ();
 				}
 				return true;
+			case Key.CursorLeft:
+			case Key.CursorUp:
 			case Key.BackTab:
 				old = Focused;
 				if (!FocusPrev ())
@@ -949,6 +953,7 @@ namespace Terminal.Gui {
 					Focused?.SetNeedsDisplay ();
 				}
 				return true;
+			
 			case Key.ControlL:
 				Application.Refresh ();
 				return true;
diff --git a/Terminal.Gui/Views/RadioGroup.cs b/Terminal.Gui/Views/RadioGroup.cs
index 5f07709cb..bb4a2be1d 100644
--- a/Terminal.Gui/Views/RadioGroup.cs
+++ b/Terminal.Gui/Views/RadioGroup.cs
@@ -123,14 +123,16 @@ namespace Terminal.Gui {
 				if (cursor > 0) {
 					cursor--;
 					SetNeedsDisplay ();
+					return true;
 				}
-				return true;
+				break;
 			case Key.CursorDown:
 				if (cursor + 1 < radioLabels.Length) {
 					cursor++;
 					SetNeedsDisplay ();
+					return true;
 				}
-				return true;
+				break;
 			case Key.Space:
 				Selected = cursor;
 				return true;
diff --git a/Terminal.Gui/Views/ScrollView.cs b/Terminal.Gui/Views/ScrollView.cs
index 411032bf5..dd76c083e 100644
--- a/Terminal.Gui/Views/ScrollView.cs
+++ b/Terminal.Gui/Views/ScrollView.cs
@@ -282,7 +282,7 @@ namespace Terminal.Gui {
 				return contentOffset;
 			}
 			set {
-				contentOffset = new Point (-value.X, -value.Y);
+				contentOffset = new Point (-Math.Abs (value.X), -Math.Abs(value.Y));
 				contentView.Frame = new Rect (contentOffset, contentSize);
 				vertical.Position = Math.Max (0, -contentOffset.Y);
 				horizontal.Position = Math.Max (0, -contentOffset.X);
@@ -359,5 +359,91 @@ namespace Terminal.Gui {
 			else
 				base.PositionCursor ();
 		}
+
+		/// <summary>
+		/// Scrolls the view up.
+		/// </summary>
+		/// <returns><c>true</c>, if left was scrolled, <c>false</c> otherwise.</returns>
+		/// <param name="lines">Number of lines to scroll.</param>
+		public bool ScrollUp (int lines)
+		{
+			if (contentOffset.Y < 0) {
+				ContentOffset = new Point (contentOffset.X, Math.Min (contentOffset.Y + lines, 0));
+				return true;
+			}
+			return false;
+		}
+
+		/// <summary>
+		/// Scrolls the view to the left
+		/// </summary>
+		/// <returns><c>true</c>, if left was scrolled, <c>false</c> otherwise.</returns>
+		/// <param name="cols">Number of columns to scroll by.</param>
+		public bool ScrollLeft (int cols)
+		{
+			if (contentOffset.X < 0) {
+				ContentOffset = new Point (Math.Min (contentOffset.X + cols, 0), contentOffset.Y);
+				return true;
+			}
+			return false;
+		}
+
+		/// <summary>
+		/// Scrolls the view down.
+		/// </summary>
+		/// <returns><c>true</c>, if left was scrolled, <c>false</c> otherwise.</returns>
+		/// <param name="lines">Number of lines to scroll.</param>
+		public bool ScrollDown (int lines)
+		{
+			var ny = Math.Max (-contentSize.Height, contentOffset.Y - lines);
+			if (ny == contentOffset.Y)
+				return false;
+			ContentOffset = new Point (contentOffset.X, ny);
+			return true;
+		}
+
+		/// <summary>
+		/// Scrolls the view to the right.
+		/// </summary>
+		/// <returns><c>true</c>, if right was scrolled, <c>false</c> otherwise.</returns>
+		/// <param name="cols">Number of columns to scroll by.</param>
+		public bool ScrollRight (int cols)
+		{
+			var nx = Math.Max (-contentSize.Width, contentOffset.X - cols);
+			if (nx == contentOffset.X)
+				return false;
+			
+			ContentOffset = new Point (nx, contentOffset.Y);
+			return true;
+		}
+
+		public override bool ProcessKey(KeyEvent kb)
+		{
+			if (base.ProcessKey (kb))
+				return true;
+
+			switch (kb.Key) {
+			case Key.CursorUp:
+				return ScrollUp (1);
+			case (Key) 'v' | Key.AltMask:
+			case Key.PageUp:
+				return ScrollUp (Bounds.Height);
+
+			case Key.ControlV:
+			case Key.PageDown:
+				return ScrollDown (Bounds.Height);
+
+			case Key.CursorDown:
+				return ScrollDown (1);
+
+			case Key.CursorLeft:
+				return ScrollLeft (1);
+
+			case Key.CursorRight:
+				return ScrollRight (1);
+
+			}
+			return false;
+		}
 	}
 }
diff --git a/demo.cs b/demo.cs
index 6106e72bf..13f9fae94 100644
--- a/demo.cs
+++ b/demo.cs
@@ -67,7 +67,7 @@ class Demo {
 	{
 		var scrollView = new ScrollView (new Rect (50, 10, 20, 8)) {
 			ContentSize = new Size (100, 100),
-			//ContentOffset = new Point (5, -2),
+			ContentOffset = new Point (-1, -1),
 			ShowVerticalScrollIndicator = true,
 			ShowHorizontalScrollIndicator = true
 		};
@@ -93,7 +93,7 @@ class Demo {
 				new CheckBox (1, 0, "Remember me"),
 				new RadioGroup (1, 2, new [] { "_Personal", "_Company" }),
 			},
-			//scrollView,
+			scrollView,
 			//scrollView2,
 			new Button (3, 19, "Ok"),
 			new Button (10, 19, "Cancel"),