LCL/ListView: Fix multi-selection in virtual mode. Issue #39693.

lcl/comctrls.pp

@@ -29,7 +29,7 @@ unit ComCtrls;
 interface
 
 uses
-  SysUtils, Types, Classes, Math, Laz_AVL_Tree,
+  SysUtils, Types, Classes, Math, Laz_AVL_Tree, IntegerList,
   // LCL
   LCLStrConsts, LResources, LCLIntf, LCLType, LCLProc, LMessages, WSLCLClasses,
   WSReferences, Graphics, ImgList, ActnList, Themes, Menus,
@@ -1545,6 +1545,14 @@ type
     function DoOwnerDataHint(AStartIndex, AEndIndex: Integer): Boolean; virtual;
     function DoOwnerDataStateChange(AStartIndex, AEndIndex: Integer; AOldState,
       ANewState: TListItemStates): Boolean; virtual;
+
+  protected
+    // Multiselection
+    FMultiSelList: TIntegerList;
+    function GetFirstSelected: TListItem;
+    procedure InitMultiSelList(AEnable: Boolean);
+    procedure UpdateMultiSelList(AItem: TListItem; Add: Boolean);
+
   protected
     procedure DblClick; override;
     procedure KeyDown(var Key: Word; Shift: TShiftState); override;

lcl/include/customlistview.inc

@@ -347,6 +347,9 @@ begin
           if (((nm^.uOldState and LVIS_SELECTED) <> (nm^.uNewState and LVIS_SELECTED)))
           or (not (lffSelectedValid in FFlags) and (nm^.uNewState and LVIS_SELECTED <> 0)) then
           begin
+            if MultiSelect and OwnerData then
+              UpdateMultiSelList(Item, nm^.uNewState and LVIS_SELECTED <> 0);
+
             // select state changed
             if (nm^.uNewState and LVIS_SELECTED) = 0 then
             begin
@@ -1443,20 +1446,27 @@ begin
       not the last selected one see issue #16773 }
     if not (lffSelectedValid in FFlags) or MultiSelect then
     begin
-      FSelected := nil;
-      if (not FOwnerData) or (FSelectedIdx >= 0) then
+      if MultiSelect and OwnerData then
       begin
-        if MultiSelect and FOwnerData and (FSelectedIdx >= 0) then
-          FSelected := Items[FSelectedIdx]
-        else
-          for i := 0 to Items.Count - 1 do
-          begin
-            if Items[i].Selected then
+        FSelected := GetFirstSelected;
+        if FSelected <> nil then FSelectedIdx := FSelected.Index else FSelectedIdx := -1;
+      end else
+      begin
+        FSelected := nil;
+        if (not FOwnerData) or (FSelectedIdx >= 0) then
+        begin
+          if MultiSelect and FOwnerData and (FSelectedIdx >= 0) then
+            FSelected := Items[FSelectedIdx]
+          else
+            for i := 0 to Items.Count - 1 do
             begin
-              FSelected := Items[i];
-              break;
+              if Items[i].Selected then
+              begin
+                FSelected := Items[i];
+                break;
+              end;
             end;
-          end;
+        end;
       end;
       Include(FFlags, lffSelectedValid);
     end;
@@ -1826,3 +1836,19 @@ begin
   if not HandleAllocated then exit;
 end;
 
+// Multi-selection
+procedure TCustomListView.InitMultiSelList(AEnable: Boolean);
+begin
+  TWSCustomListViewClass(WidgetSetClass).InitMultiSelList(Self, AEnable);
+end;
+
+procedure TCustomListView.UpdateMultiSelList(AItem: TListItem; Add: Boolean);
+begin
+  TWSCustomListViewClass(WidgetSetClass).UpdateMultiSelList(Self, AItem, Add);
+end;
+
+function TCustomListView.GetFirstSelected: TListItem;
+begin
+  Result := TWSCustomListViewClass(WidgetSetClass).GetFirstSelected(Self);
+end;
+

lcl/interfaces/win32/win32wscomctrls.pp

@@ -195,6 +195,11 @@ type
       const ASortDirection: TSortDirection); override;
     class procedure SetViewOrigin(const ALV: TCustomListView; const AValue: TPoint); override;
     class procedure SetViewStyle(const ALV: TCustomListView; const Avalue: TViewStyle); override;
+
+    // Multi-selection
+    class function GetFirstSelected(const ALV: TCustomListView): TListItem; override;
+    class procedure InitMultiSelList(const ALV: TCustomListView; AEnable: Boolean); override;
+    class procedure UpdateMultiSelList(const ALV: TCustomListView; AItem: TListItem; Add: Boolean); override;
   end;
 
   { TWin32WSListView }

lcl/interfaces/win32/win32wscustomlistview.inc

@@ -1484,3 +1484,27 @@ begin
   Index := ListView_GetNextItem(ALV.Handle, Index, Flags);
   if Index <> -1 then Result := ALV.Items[Index];
 end;
+
+
+// Multi-selection in virtual mode
+// Is handled by Windows. We don't need the MultiSelList.
+
+class function TWin32WSCustomListView.GetFirstSelected(const ALV: TCustomListView): TListItem; 
+var
+  idx: Integer;
+begin
+  idx := ListView_GetNextItem(ALV.Handle, -1, LVNI_ALL + LVNI_SELECTED);
+  if idx > -1 then
+    Result := ALV.Items[idx]
+  else
+    Result := nil;
+end;
+
+class procedure TWin32WSCustomListView.InitMultiSelList(const ALV: TCustomListView; AEnable: Boolean); 
+begin
+end;
+
+class procedure TWin32WSCustomListView.UpdateMultiSelList(const ALV: TCustomListView; AItem: TListItem; Add: Boolean); 
+begin
+end;
+

lcl/widgetset/wscomctrls.pp

@@ -39,7 +39,7 @@ uses
 // To get as little as posible circles,
 // uncomment only when needed for registration
 ////////////////////////////////////////////////////
-  Graphics, ImgList, Controls, StdCtrls, ComCtrls,
+  Graphics, ImgList, Controls, StdCtrls, ComCtrls, IntegerList,
 ////////////////////////////////////////////////////
   WSLCLClasses, WSControls, WSExtCtrls, WSToolwin, WSFactory;
 
@@ -178,6 +178,11 @@ type
     // for every item previously checked. Only widgetsets that don't support native sort
     // AND/OR that don't support native checkboxes should have this method return true
     class function RestoreItemCheckedAfterSort(const ALV: TCustomListView): Boolean; virtual;
+
+    // Multi-selection
+    class function GetFirstSelected(const ALV: TCustomListView): TListItem; virtual;
+    class procedure InitMultiSelList(const ALV: TCustomListView; AEnable: Boolean); virtual;
+    class procedure UpdateMultiSelList(const ALV: TCustomListView; AItem: TListItem; Add: Boolean); virtual;
   end;
 
   TWSCustomListViewClass = class of TWSCustomListView;
@@ -484,6 +489,9 @@ end;
     
 { TWSCustomListView }
 
+type
+  TCustomListViewAccess = class(TCustomListView);
+
 class procedure TWSCustomListView.ColumnDelete(const ALV: TCustomListView;
   const AIndex: Integer);
 begin
@@ -845,6 +853,56 @@ begin
   end;
 end;
 
+class function TWSCustomListView.GetFirstSelected(const ALV: TCustomListView): TListItem;
+var
+  idx: Integer;
+begin
+  Result := nil;
+  with TCustomListViewAccess(ALV) do
+  begin
+    if (FMultiSelList <> nil) and (FMultiSelList.Count > 0) then
+    begin
+      idx := FMultiSelList[0];
+      Result := Items[idx];
+    end;
+  end;
+end;
+
+class procedure TWSCustomListView.InitMultiSelList(const ALV: TCustomListView; AEnable: Boolean);
+begin
+  with TCustomListViewAccess(ALV) do
+  begin
+    FMultiSelList.Free;
+    FMultiSelList := nil;
+    if AEnable then FMultiSelList := TIntegerList.Create;
+  end;
+end;
+
+class procedure TWSCustomListView.UpdateMultiSelList(const ALV: TCustomListView;
+  AItem: TListItem; Add: Boolean);
+var
+  idx: Integer;
+begin
+  with TCustomListViewAccess(ALV) do
+  begin
+    if FMultiSelList = nil then
+      FMultiSelList := TIntegerList.Create;
+    idx := FMultiSelList.IndexOf(AItem.Index);
+    if Add then
+    begin
+      if idx = -1 then 
+      begin
+        FMultiSelList.Add(AItem.Index);
+        FMultiSelList.Sort;
+      end;
+    end else
+    begin
+      if idx > -1 then FMultiSelList.Delete(idx);
+    end;
+  end;
+end;
+
+
 { TWSProgressBar }
 
 class procedure TWSProgressBar.ApplyChanges(const AProgressBar: TCustomProgressBar);