From dd066edf436288be052e9c28133e75cc1cd2a357 Mon Sep 17 00:00:00 2001
From: Joachim Marder <joachim.marder@outlook.com>
Date: Sat, 1 Apr 2023 18:30:16 +0200
Subject: [PATCH] Change for #832: Turn TVirtualNode.Index into a readonly
 property.

---
 Source/VirtualTrees.BaseTree.pas | 24 ++++++++++++------------
 Source/VirtualTrees.Types.pas    | 11 ++++++++++-
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/Source/VirtualTrees.BaseTree.pas b/Source/VirtualTrees.BaseTree.pas
index 36c2f67d4..d5c6ec6d9 100644
--- a/Source/VirtualTrees.BaseTree.pas
+++ b/Source/VirtualTrees.BaseTree.pas
@@ -5045,7 +5045,7 @@ procedure TBaseVirtualTree.SetChildCount(Node: PVirtualNode; NewChildCount: Card
           while Remaining > 0 do
           begin
             Child := MakeNewNode;
-            Child.Index := Index;
+            Child.SetIndex(Index);
             Child.PrevSibling := Node.LastChild;
             if Assigned(Node.LastChild) then
               Node.LastChild.NextSibling := Child;
@@ -13776,7 +13776,7 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
           Destination.PrevSibling := Node;
           Node.NextSibling := Destination;
           Node.SetParent(Destination.Parent);
-          Node.Index := Destination.Index;
+          Node.SetIndex(Destination.Index);
           if Node.PrevSibling = nil then
             Node.Parent.FirstChild := Node
           else
@@ -13786,7 +13786,7 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
           Run := Destination;
           while Assigned(Run) do
           begin
-            System.Inc(Run.Index);
+            Run.SetIndex(Run.Index + 1);
             Run := Run.NextSibling;
           end;
         end;
@@ -13800,13 +13800,13 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
             Node.Parent.LastChild := Node
           else
             Node.NextSibling.PrevSibling := Node;
-          Node.Index := Destination.Index;
+          Node.SetIndex(Destination.Index);
 
           // reindex all following nodes
           Run := Node;
           while Assigned(Run) do
           begin
-            System.Inc(Run.Index);
+            Run.SetIndex(Run.Index + 1);
             Run := Run.NextSibling;
           end;
         end;
@@ -13828,12 +13828,12 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
           end;
           Node.PrevSibling := nil;
           Node.SetParent(Destination);
-          Node.Index := 0;
+          Node.SetIndex(0);
           // reindex all following nodes
           Run := Node.NextSibling;
           while Assigned(Run) do
           begin
-            System.Inc(Run.Index);
+            Run.SetIndex(Run.Index + 1);
             Run := Run.NextSibling;
           end;
         end;
@@ -13856,9 +13856,9 @@ procedure TBaseVirtualTree.InternalConnectNode(Node, Destination: PVirtualNode;
           Node.NextSibling := nil;
           Node.SetParent(Destination);
           if Assigned(Node.PrevSibling) then
-            Node.Index := Node.PrevSibling.Index + 1
+            Node.SetIndex(Node.PrevSibling.Index + 1)
           else
-            Node.Index := 0;
+            Node.SetIndex(0);
         end;
     else
       // amNoWhere: do nothing
@@ -13972,7 +13972,7 @@ procedure TBaseVirtualTree.InternalDisconnectNode(Node: PVirtualNode; KeepFocus:
         Index := Node.Index;
         while Assigned(Run) do
         begin
-          Run.Index := Index;
+          Run.SetIndex(Index);
           System.Inc(Index);
           Run := Run.NextSibling;
         end;
@@ -15131,7 +15131,7 @@ function TBaseVirtualTree.ReadChunk(Stream: TStream; Version: Integer; Node: PVi
 
             Run.PrevSibling := Node.LastChild;
             if Assigned(Run.PrevSibling) then
-              Run.Index := Run.PrevSibling.Index + 1;
+              Run.SetIndex(Run.PrevSibling.Index + 1);
             if Assigned(Node.LastChild) then
               Node.LastChild.NextSibling := Run
             else
@@ -22479,7 +22479,7 @@ procedure TBaseVirtualTree.Sort(Node: PVirtualNode; Column: TColumnIndex; Direct
         Run.PrevSibling := nil;
         Index := 0;
         repeat
-          Run.Index := Index;
+          Run.SetIndex(Index);
           System.Inc(Index);
           if Run.NextSibling = nil then
             Break;
diff --git a/Source/VirtualTrees.Types.pas b/Source/VirtualTrees.Types.pas
index a6212d3da..12be05a8a 100644
--- a/Source/VirtualTrees.Types.pas
+++ b/Source/VirtualTrees.Types.pas
@@ -878,7 +878,9 @@   TScrollBarOptions = class(TPersistent)
   PVirtualNode = ^TVirtualNode;
 
   TVirtualNode = packed record
-    Index,                   // index of node with regard to its parent
+  private
+    fIndex: Cardinal;         // index of node with regard to its parent
+  public
     ChildCount: Cardinal;    // number of child nodes
     NodeHeight: TDimension;  // height in pixels
     States: TVirtualNodeStates; // states describing various properties of the node (expanded, initialized etc.)
@@ -901,6 +903,8 @@   TScrollBarOptions = class(TPersistent)
     FirstChild,              // link to the node's first child...
     LastChild: PVirtualNode; // link to the node's last child...
     procedure SetParent(const pParent: PVirtualNode); inline; //internal method, do not call directly but use Parent[Node] := x on tree control.
+    procedure SetIndex(const pIndex: Cardinal); inline;       //internal method, do not call directly.
+    property Index: Cardinal read fIndex;
     property Parent: PVirtualNode read fParent;
   private
     Data: record end;        // this is a placeholder, each node gets extra data determined by NodeDataSize
@@ -1169,6 +1173,11 @@ procedure TVirtualNode.SetData<T>(pUserData: T);
   Include(Self.States, vsOnFreeNodeCallRequired);
 end;
 
+procedure TVirtualNode.SetIndex(const pIndex: Cardinal);
+begin
+  fIndex := pIndex;
+end;
+
 procedure TVirtualNode.SetParent(const pParent: PVirtualNode);
 begin
   fParent := pParent;