lcl, win32: move TCustomCheckListBox WS specific settings to WS implementataion

Other widgetsets use widgets with builtin check support, no need to have
ownerdraw details in the LCL class
+ publish OnMeasureItem, it can now be used like TCustomListBox

lcl/checklst.pas

@@ -55,7 +55,6 @@ type
     class procedure WSRegisterClass; override;
     procedure AssignItemDataToCache(const AIndex: Integer; const AData: Pointer); override;
     procedure AssignCacheToItemData(const AIndex: Integer; const AData: Pointer); override;
-    procedure CreateParams(var Params: TCreateParams); override;
     procedure DrawItem(AIndex: Integer; ARect: TRect; State: TOwnerDrawState); override;
     function  GetCachedDataSize: Integer; override;
     function  GetCheckWidth: Integer;
@@ -68,7 +67,7 @@ type
     procedure FontChanged(Sender: TObject); override;
   public
     constructor Create(AOwner: TComponent); override;
-    procedure MeasureItem(Index: Integer; var TheHeight: Integer); override;
+    function CalculateStandardItemHeight: Integer; override;
     procedure Toggle(AIndex: Integer);
     procedure CheckAll(AState: TCheckBoxState; aAllowGrayed: Boolean = True; aAllowDisabled: Boolean = True);
     procedure Exchange(AIndex1, AIndex2: Integer);
@@ -121,6 +120,7 @@ type
     property OnKeyPress;
     property OnKeyDown;
     property OnKeyUp;
+    property OnMeasureItem;
     property OnMouseDown;
     property OnMouseEnter;
     property OnMouseLeave;
@@ -183,12 +183,6 @@ begin
   SendItemHeader(AIndex, PCachedItemData(AData + FItemDataOffset)^.Header);
 end;
 
-procedure TCustomCheckListBox.CreateParams(var Params: TCreateParams);
-begin
-  inherited CreateParams(Params);
-  Params.Style := (Params.Style and not LBS_OWNERDRAWVARIABLE) or LBS_OWNERDRAWFIXED;
-end;
-
 procedure TCustomCheckListBox.DrawItem(AIndex: Integer; ARect: TRect; State: TOwnerDrawState);
 begin
   if not Header[AIndex] then begin
@@ -216,12 +210,12 @@ begin
   FItemDataOffset := inherited GetCachedDataSize;
 end;
 
-procedure TCustomCheckListBox.MeasureItem(Index: Integer; var TheHeight: Integer);
+function TCustomCheckListBox.CalculateStandardItemHeight: Integer;
 begin
-  if (Style = lbStandard) then
-    TheHeight := Max(CalculateStandardItemHeight, GetSystemMetrics(SM_CYMENUCHECK) + 2)
-  else
-    inherited MeasureItem(Index, TheHeight);
+  Result:=inherited CalculateStandardItemHeight;
+  // for Win32WS, ensure item height for internally owner-drawn checkmarks
+  if Style <> lbOwnerDrawVariable then
+    Result:= Max(Result, GetSystemMetrics(SM_CYMENUCHECK) + 2);
 end;
 
 procedure TCustomCheckListBox.Toggle(AIndex: Integer);

lcl/include/customlistbox.inc

@@ -342,10 +342,8 @@ begin
     // don't call GetItemHeight: causes errors on Windows due to recursion on control creation
     if FItemHeight <> 0 then
       AHeight := FItemHeight
-    else begin
-      Canvas.Font := Font;
-      AHeight := Canvas.TextHeight('Hg');
-    end;
+    else
+      AHeight:= CalculateStandardItemHeight;
     if FStyle = lbOwnerDrawVariable then
       MeasureItem(Integer(ItemId), AHeight);
     if AHeight > 0 then

lcl/interfaces/win32/win32wschecklst.pp

@@ -159,6 +159,9 @@ begin
     pClassName := ListBoxClsName;
     pSubClassName := LCLCheckListboxClsName;
     SubClassWndProc := @CheckListBoxWndProc;
+    // require always owner-drawn, add flags if not already set due to Style
+    if (Flags and (LBS_OWNERDRAWFIXED or LBS_OWNERDRAWVARIABLE)) = 0 then
+      Flags:= Flags or LBS_OWNERDRAWFIXED;
   end;
   // create window
   FinishCreateWindow(AWinControl, Params, False, True);
@@ -262,6 +265,10 @@ begin
   case TLMessage(AMessage).Msg of
     LM_DRAWITEM:
     begin
+      { If the user set one of the OwnerDraw Styles, the widgetset will have translated the draw messages to LM_DRAWLISTITEM
+        instead (in TWindowProcHelper.DoMsgDrawItem). This means we don't get to draw the checkmark and the CLB looks like a
+        regular list.
+      }
       with TLMDrawItems(AMessage) do
       begin
         // ItemID not UINT(-1)
@@ -270,15 +277,10 @@ begin
       end;
     end;
 
-    LM_MEASUREITEM:
-    begin
-      with TLMMeasureItem(AMessage).MeasureItemStruct^ do
-      begin
-        itemHeight := TCustomListBox(AWinControl).ItemHeight;
-        if TCustomListBox(AWinControl).Style = lbOwnerDrawVariable then
-          TCustomListBox(AWinControl).MeasureItem(Integer(itemID), integer(itemHeight));
-      end;
-    end;
+    { LM_MEASUREITEM:
+      TCustomListBox has a message handler, so DefaultWndHandler is never called.
+      We handle CLB specialcasing via a CalculateStandardItemHeight override
+    }
   end;
 
   inherited DefaultWndHandler(AWinControl, AMessage);

lcl/stdctrls.pp

@@ -581,7 +581,7 @@ type
     procedure AssignCacheToItemData(const AIndex: Integer; const AData: Pointer); virtual; // called to restore the itemdata after a handle is created
     procedure BeforeDragStart; override;
     procedure BeginAutoDrag; override;
-    function CalculateStandardItemHeight: Integer;
+    function CalculateStandardItemHeight: Integer; virtual;
     procedure CreateParams(var Params: TCreateParams); override;
     procedure InitializeWnd; override;
     procedure DestroyWnd; override;