From 484b0817bd4a5efaeffa7d8d11c13dcbc0fa1966 Mon Sep 17 00:00:00 2001
From: biwa <6475593+biwa@users.noreply.github.com>
Date: Thu, 3 Feb 2022 19:35:10 +0100
Subject: [PATCH] Snap selection to grid: fixed a problem that could cause a
 crash if geometry got removed by snapping it to the grid

---
 Source/Core/Editing/EditMode.cs                      |  4 ++++
 Source/Core/General/MapManager.cs                    |  3 +++
 .../BuilderModes/ClassicModes/LinedefsMode.cs        | 10 ++++++++++
 .../Plugins/BuilderModes/ClassicModes/SectorsMode.cs | 10 ++++++++++
 .../BuilderModes/ClassicModes/VerticesMode.cs        | 12 +++++++++++-
 5 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/Source/Core/Editing/EditMode.cs b/Source/Core/Editing/EditMode.cs
index 6c8c3590..a2c4aa56 100755
--- a/Source/Core/Editing/EditMode.cs
+++ b/Source/Core/Editing/EditMode.cs
@@ -260,6 +260,10 @@ namespace CodeImp.DoomBuilder.Editing
 		// Script events
 		public virtual bool OnScriptRunBegin() { return true; }
 		public virtual void OnScriptRunEnd() { }
+
+		// This should be called by global actions (i.e. that are not part of an editing mode) when they changed map elements,
+		// so that the mode can react to it (for example by rebuilding a blockmap)
+		public virtual void OnMapElementsChanged() { }
 		
 		#endregion
 	}
diff --git a/Source/Core/General/MapManager.cs b/Source/Core/General/MapManager.cs
index ace48966..20b06028 100755
--- a/Source/Core/General/MapManager.cs
+++ b/Source/Core/General/MapManager.cs
@@ -2643,6 +2643,9 @@ namespace CodeImp.DoomBuilder
 				undoredo.WithdrawUndo();
 			}
 
+			// Let the current editing mode know that we changed something
+			General.Editing.Mode.OnMapElementsChanged();
+
 			// Done
 			General.Interface.RedrawDisplay();
 			Cursor.Current = Cursors.Default;
diff --git a/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs b/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs
index c7e2ee8b..cbd3261f 100755
--- a/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs
@@ -1217,6 +1217,16 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			return base.OnCopyBegin();
 		}
 
+		/// <summary>
+		/// If map elements have changed the blockmap needs to be recreated.
+		/// </summary>
+		public override void OnMapElementsChanged()
+		{
+			base.OnMapElementsChanged();
+
+			CreateBlockmap();
+		}
+
 		//mxd
 		private void RenderComment(Linedef l)
 		{
diff --git a/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs b/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs
index 7a3a6bcb..9bf15d9b 100755
--- a/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs
@@ -1596,6 +1596,16 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			General.Interface.RedrawDisplay();
 		}
 
+		/// <summary>
+		/// If map elements have changed the blockmap needs to be recreated.
+		/// </summary>
+		public override void OnMapElementsChanged()
+		{
+			base.OnMapElementsChanged();
+
+			CreateBlockmap();
+		}
+
 		//mxd
 		public override void OnViewSelectionNumbersChanged(bool enabled)
 		{
diff --git a/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs b/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs
index ab07bd24..ae68e7be 100755
--- a/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs
@@ -759,7 +759,17 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			
 			return base.OnCopyBegin();
 		}
-		
+
+		/// <summary>
+		/// If map elements have changed the blockmap needs to be recreated.
+		/// </summary>
+		public override void OnMapElementsChanged()
+		{
+			base.OnMapElementsChanged();
+
+			CreateBlockmap();
+		}
+
 		#endregion
 
 		#region ================== Actions