Merge branch 'hotfix/4.24.2'

Release v4.24.2 HOTFIX

Author: delphidabbler

Diff for: CHANGELOG.md

@@ -6,7 +6,14 @@ Releases are listed in reverse version number order.
 
 > Note that _CodeSnip_ v4 was developed in parallel with v3 for a while. As a consequence some v3 releases have later release dates than early v4 releases.
 
-## Release v4.24.1 of 13 April 2005
+## Release v4.24.2 of 14 April 2025
+
+Hotfix release.
+
+* Updated bug fix implemented in v4.24.1 to avoid relying on a potentially problematic windows event [issue #70 (2nd attempt)].
+* Corrected release date error for v4.24.1 in `CHANGELOG.md`.
+
+## Release v4.24.1 of 13 April 2025
 
 * Fixed bug where CodeSnip occasionally crashes after a computer resumes from hibernation [issue #70].
 * Bumped some copyright dates for 2025.

Diff for: Src/FmMain.pas

@@ -524,9 +524,10 @@   TMainForm = class(THelpAwareForm)
 
     ///  <summary>Handles the <c>WM_POWERBROADCAST</c> messages to detect and
     ///  respond to hibernation messages.</summary>
-    ///  <remarks>This is necessary as part of the fix for an obscure bug. See
+    ///  <remarks>!! HACK necessary as part of the fix for an obscure bug. See
     ///  https://github.com/delphidabbler/codesnip/issues/70</remarks>
     procedure WMPowerBroadcast(var Msg: TMessage); message WM_POWERBROADCAST;
+
     ///  <summary>Displays view item given by TViewItemAction instance
     ///  referenced by Sender and adds to history list.</summary>
     procedure ActViewItemExecute(Sender: TObject);
@@ -1587,18 +1588,15 @@ procedure TMainForm.splitVertCanResize(Sender: TObject;
 
 procedure TMainForm.WMPowerBroadcast(var Msg: TMessage);
 begin
+  // !! HACK
   // Sometimes when the computer is resumed from hibernation the tree view in
   // the overview frame is destroyed and recreated by Windows. Unfortunately the
   // IView instances associated with the recreated tree nodes are lost.
   // Attempting to read those (now nil) IView instances was resulting in an
   // access violation.
   case Msg.WParam of
     PBT_APMSUSPEND:
-      // Get ready for isolation
-      fMainDisplayMgr.PrepareForHibernate;
-    PBT_APMPOWERSTATUSCHANGE:
-      // Restore from hibernation: ensure the IView instances are recreeated
-      fMainDisplayMgr.RestoreFromHibernation;
+      fMainDisplayMgr._HACK_PrepareForHibernate;
   end;
 end;
 

Diff for: Src/FrOverview.pas

@@ -26,6 +26,29 @@ interface
 
 type
 
+  // !! HACK
+  // Horrible hack to expose CreateWnd for overiding TTreeView.CreateWnd for the
+  // existing TTreeView component of TOverviewFrame. The hack avoids having to
+  // remove the component and replacing it with a descendant class that is
+  // manually constructed at run time.
+  // This is here to enable the tree view to be recreated with correctly
+  // instantiated TViewItemTreeNode nodes after Windows recreates the tree
+  // behind the scenes after resuming from hibernation.
+  // I am deeply ashamed of this hack.
+  TTreeView = class(ComCtrls.TTreeView)
+  strict private
+    var
+      _HACK_fOnAfterCreateNilViews: TNotifyEvent;
+  protected
+    procedure CreateWnd; override;
+  public
+    ///  <summary>!! HACK. Event triggered after the inherited CreateWnd is
+    ///  called. Only called if the tree view has nil references to IView
+    ///  objects.</summary>
+    property _HACK_OnAfterCreateNilViews: TNotifyEvent
+      read _HACK_fOnAfterCreateNilViews write _HACK_fOnAfterCreateNilViews;
+  end;
+
   {
   TOverviewFrame:
     Titled frame that displays lists of snippets grouped in various ways and
@@ -214,6 +237,10 @@       TTVDraw = class(TSnippetsTVDraw)
     procedure RestoreTreeState;
       {Restores last saved treeview expansion state from memory.
       }
+    ///  <summary>!! HACK: Sets an event handler on the tree view to work
+    ///  around a bug that can occur after resuming from hibernation.</summary>
+    ///  <remarks>Method of IOverviewDisplayMgr.</remarks>
+    procedure _HACK_SetHibernateHandler(const AHandler: TNotifyEvent);
     { IPaneInfo }
     function IsInteractive: Boolean;
       {Checks if the pane is currently interactive with user.
@@ -955,6 +982,12 @@ procedure TOverviewFrame.UpdateTreeState(const State: TTreeNodeAction);
   end;
 end;
 
+procedure TOverviewFrame._HACK_SetHibernateHandler(
+  const AHandler: TNotifyEvent);
+begin
+  tvSnippets._HACK_OnAfterCreateNilViews := AHandler;
+end;
+
 { TOverviewFrame.TTVDraw }
 
 function TOverviewFrame.TTVDraw.IsSectionHeadNode(
@@ -993,5 +1026,24 @@ function TOverviewFrame.TTVDraw.IsUserDefinedNode(
     Result := False;
 end;
 
+{ TTreeView }
+
+procedure TTreeView.CreateWnd;
+var
+  HasNilViews: Boolean;
+  Node: TTreeNode;
+begin
+  inherited;
+  HasNilViews := False;
+  for Node in Items do
+  begin
+    HasNilViews := not Assigned((Node as TViewItemTreeNode).ViewItem);
+    if HasNilViews then
+      Break;
+  end;
+  if HasNilViews and Assigned(_HACK_fOnAfterCreateNilViews) then
+    _HACK_fOnAfterCreateNilViews(Self);
+end;
+
 end.
 

Diff for: Src/IntfFrameMgrs.pas

@@ -3,7 +3,7 @@
  * v. 2.0. If a copy of the MPL was not distributed with this file, You can
  * obtain one at https://mozilla.org/MPL/2.0/
  *
- * Copyright (C) 2005-2021, Peter Johnson (gravatar.com/delphidabbler).
+ * Copyright (C) 2005-2025, Peter Johnson (gravatar.com/delphidabbler).
  *
  * Declares interfaces, constants and enumerations required to manage various
  * parts of CodeSnip's UI.
@@ -19,6 +19,7 @@ interface
 uses
   // Delphi
   SHDocVw, ActiveX,
+  Classes, // !! For HACK
   // Project
   Browser.IntfDocHostUI, DB.USnippet, Compilers.UGlobals, UCommandBars, UView;
 
@@ -145,6 +146,9 @@ interface
     ///  <summary>Restore expand / collapse state of treeview to last save
     ///  state.</summary>
     procedure RestoreTreeState;
+    ///  <summary>!! HACK: Sets an event handler on the tree view to work
+    ///  around a bug that can occur after resuming from hibernation.</summary>
+    procedure _HACK_SetHibernateHandler(const AHandler: TNotifyEvent);
   end;
 
 type

Diff for: Src/UMainDisplayMgr.pas

@@ -165,6 +165,11 @@   TMainDisplayMgr = class(TObject)
     procedure DisplayViewItem(ViewItem: IView; Mode: TDetailPageDisplayMode);
       overload;
 
+    ///  <summary>!! HACK event handle to redisplay the overview pane treeview.
+    ///  Called only if Windows has mysteriously recreated the treeview and lost
+    ///  necessary object references.</summary>
+    procedure _HACK_HibernateHandler(Sender: TObject);
+
   public
     ///  <summary>Object contructor. Sets up object to work with given frame
     ///  manager objects.</summary>
@@ -292,21 +297,12 @@   TMainDisplayMgr = class(TObject)
     /// <summary>Prepares display ready for database to be reloaded.</summary>
     procedure PrepareForDBReload;
 
-    ///  <summary>Gets the overview frame prepared for program hibernation.
-    ///  </summary>
+    ///  <summary>!!HACK: gets the overview frame prepared for program
+    ///  hibernation.</summary>
     ///  <remarks>Saves the overview tree view state ready for restoring after
-    ///  hibernation.</remarks>
-    procedure PrepareForHibernate;
-
-    ///  <summary>Restores the overview's tree view to have the correct IView
-    ///  instances after hibernation restores the previously saved state.
-    ///  </summary>
-    ///  <remarks>Sometimes, Windows quietly recreates the node of the tree view
-    ///  after resuming from hibernation, without restoring the associated IView
-    ///  instances, leading to access violations. This method should be called
-    ///  after resuming from hibernation to recreate the tree view with the
-    ///  correct IView instances.</remarks>
-    procedure RestoreFromHibernation;
+    ///  hibernation if Windows has recreated the overview pane's treeview,
+    ///  losing necessary IView object references..</remarks>
+    procedure _HACK_PrepareForHibernate;
 
   end;
 
@@ -583,12 +579,6 @@ procedure TMainDisplayMgr.PrepareForDBViewChange(View: IView);
   fPendingViewChange := True;
 end;
 
-procedure TMainDisplayMgr.PrepareForHibernate;
-begin
-  // simply save the state of the overview tree view ready for later restoration
-  (fOverviewMgr as IOverviewDisplayMgr).SaveTreeState;
-end;
-
 procedure TMainDisplayMgr.RedisplayOverview;
 begin
   (fOverviewMgr as IOverviewDisplayMgr).Display(Query.Selection, True);
@@ -616,12 +606,6 @@ procedure TMainDisplayMgr.ReStart;
   (fOverviewMgr as IOverviewDisplayMgr).Display(Query.Selection, True);
 end;
 
-procedure TMainDisplayMgr.RestoreFromHibernation;
-begin
-  (fOverviewMgr as IOverviewDisplayMgr).Display(Query.Selection, True);
-  (fOverviewMgr as IOverviewDisplayMgr).RestoreTreeState;
-end;
-
 procedure TMainDisplayMgr.SelectAll;
 begin
   // Only details pane supports text selection
@@ -720,5 +704,21 @@ procedure TMainDisplayMgr.UpdateOverviewTreeState(const State: TTreeNodeAction);
   (fOverviewMgr as IOverviewDisplayMgr).UpdateTreeState(State);
 end;
 
+procedure TMainDisplayMgr._HACK_HibernateHandler(Sender: TObject);
+begin
+  (fOverviewMgr as IOverviewDisplayMgr).Display(Query.Selection, True);
+  (fOverviewMgr as IOverviewDisplayMgr).RestoreTreeState;
+  // disable this handler until next resume from hibernation
+  (fOverviewMgr as IOverviewDisplayMgr)._HACK_SetHibernateHandler(nil);
+end;
+
+procedure TMainDisplayMgr._HACK_PrepareForHibernate;
+begin
+  (fOverviewMgr as IOverviewDisplayMgr).SaveTreeState;
+  (fOverviewMgr as IOverviewDisplayMgr)._HACK_SetHibernateHandler(
+    _HACK_HibernateHandler
+  );
+end;
+
 end.
 

Diff for: Src/VersionInfo.vi-inc

@@ -1,8 +1,8 @@
 # CodeSnip Version Information Macros for Including in .vi files
 
 # Version & build numbers
-version=4.24.1
-build=273
+version=4.24.2
+build=274
 
 # String file information
 copyright=Copyright © P.D.Johnson, 2005-<YEAR>.