From a5d91ca5cb14a70796366d077313b644b94f7153 Mon Sep 17 00:00:00 2001
From: UnknownShadow200 <unknownshadow200@gmail.com>
Date: Tue, 22 Dec 2015 19:10:54 +1100
Subject: [PATCH] Fix using scroll wheel on last column past last valid item
 crashing the client. (Thanks nyxzimus)

---
 .../2D/Screens/BlockSelectScreen.Scrolling.cs | 25 ++++++++++---------
 .../2D/Screens/BlockSelectScreen.cs           |  2 +-
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/ClassicalSharp/2D/Screens/BlockSelectScreen.Scrolling.cs b/ClassicalSharp/2D/Screens/BlockSelectScreen.Scrolling.cs
index 7af6a823a..61d2f8e33 100644
--- a/ClassicalSharp/2D/Screens/BlockSelectScreen.Scrolling.cs
+++ b/ClassicalSharp/2D/Screens/BlockSelectScreen.Scrolling.cs
@@ -8,7 +8,7 @@ namespace ClassicalSharp {
 		static FastColour scrollCol = new FastColour( 10, 10, 10, 220 );
 		static FastColour scrollUsedCol = new FastColour( 100, 100, 100, 220 );
 		void DrawScrollbar() {
-			graphicsApi.Draw2DQuad( TableX, TableY, scrollbarWidth, 
+			graphicsApi.Draw2DQuad( TableX, TableY, scrollbarWidth,
 			                       TableHeight, scrollCol );
 			float scale = TableHeight / (float)rows;
 			int yOffset = (int)Math.Ceiling(scrollY * scale);
@@ -16,26 +16,27 @@ namespace ClassicalSharp {
 			
 			if( yOffset + height > TableHeight )
 				height = TableHeight - yOffset;
-			graphicsApi.Draw2DQuad( TableX, TableY + yOffset, scrollbarWidth, 
+			graphicsApi.Draw2DQuad( TableX, TableY + yOffset, scrollbarWidth,
 			                       height, scrollUsedCol );
 		}
 		
 		public override bool HandlesMouseScroll( int delta ) {
 			bool bounds = Contains( TableX, TableY, TableWidth, TableHeight,
 			                       game.Mouse.X, game.Mouse.Y );
-			if( !bounds ) return false;
+			if( !bounds || selIndex == -1 ) return false;
+			delta = -delta;
 			int startScrollY = scrollY;
-			scrollY -= delta;
-			ClampScrollY();
+			selIndex += delta * blocksPerRow;
 			
-			int diffY = scrollY - startScrollY;
-			if( selIndex >= 0 ) {
-				selIndex += diffY * blocksPerRow;
-				RecreateBlockInfoTexture();
-			}
+			if( selIndex >= blocksTable.Length || selIndex < 0 ) 
+				selIndex -= delta * blocksPerRow;
+			Utils.Clamp( ref selIndex, 0, blocksTable.Length - 1 );
+			int endScrollY = selIndex / blocksPerRow;
+			
+			UpdateSelectedState();
 			return true;
 		}
-		int scrollY;		
+		int scrollY;
 		
 		void UpdateScrollY() {
 			scrollY = selIndex / blocksPerRow;
@@ -51,7 +52,7 @@ namespace ClassicalSharp {
 		
 		void ScrollbarClick( int mouseY ) {
 			mouseY -= TableY;
-			float scale = TableHeight / (float)rows;	
+			float scale = TableHeight / (float)rows;
 			scrollY = (int)(mouseY / scale);
 			ClampScrollY();
 		}
diff --git a/ClassicalSharp/2D/Screens/BlockSelectScreen.cs b/ClassicalSharp/2D/Screens/BlockSelectScreen.cs
index cb06624dd..5ae27ae16 100644
--- a/ClassicalSharp/2D/Screens/BlockSelectScreen.cs
+++ b/ClassicalSharp/2D/Screens/BlockSelectScreen.cs
@@ -174,7 +174,7 @@ namespace ClassicalSharp {
 			lastCreatedIndex = selIndex;
 			
 			graphicsApi.DeleteTexture( ref blockInfoTexture );
-			if( selIndex == -1 || selIndex >= blocksTable.Length ) return;
+			if( selIndex == -1 ) return;
 			
 			Block block = blocksTable[selIndex];
 			UpdateBlockInfoString( block );