From a46d1d3f3c518b647849377feebdff0a053679d4 Mon Sep 17 00:00:00 2001
From: wp_xxyyzz <wp_xxyyzz@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Sat, 23 Sep 2023 20:59:57 +0000
Subject: [PATCH] NiceGrid: Improved mousewheel behaviour.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@8926 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 components/nicegrid/source/nicegrid.pas | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/components/nicegrid/source/nicegrid.pas b/components/nicegrid/source/nicegrid.pas
index c34b46884..7ac27e833 100644
--- a/components/nicegrid/source/nicegrid.pas
+++ b/components/nicegrid/source/nicegrid.pas
@@ -284,7 +284,7 @@ type
     procedure WMUnknown(var Msg: TLMessage); message LM_USER + $B902;
     procedure WMVScroll(var Msg: TLMVScroll); message LM_VSCROLL;
     procedure WMHScroll(var Msg: TLMHScroll); message LM_HSCROLL;
-    procedure WMMouseWheel(var Msg: TLMessage{TWMMouseWheel}); message LM_MOUSEWHEEL;
+//    procedure WMMouseWheel(var Msg: TLMessage{TWMMouseWheel}); message LM_MOUSEWHEEL;
     procedure WMEraseBkgnd(var Msg: TLMEraseBkGnd); message LM_ERASEBKGND;
 //    procedure WMSetFocus(var Msg: TLMSetFocus); message LM_SETFOCUS;
 //    procedure WMKillFocus(var Msg: TLMKillFocus); message LM_KILLFOCUS;
@@ -410,6 +410,7 @@ type
     procedure DoAutoAdjustLayout(const AMode: TLayoutAdjustmentPolicy; const AXProportion, AYProportion: Double); override;
     procedure DoEnter; override;
     procedure DoExit; override;
+    function DoMouseWheel(Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint): Boolean; override;
     procedure DoOnResize; override;
     {$ENDIF}
 
@@ -3603,12 +3604,26 @@ begin
   Msg.Result := 0;
 end;
 
-procedure TNiceGrid.WMMouseWheel(var Msg: {$IFDEF FPC}TLMessage{$ELSE}TWMMouseWheel{$ENDIF});
+{$IFDEF FPC}
+function TNiceGrid.DoMouseWheel(Shift: TShiftState; WheelDelta: Integer;
+  MousePos: TPoint): Boolean;
+{$ELSE}
+procedure TNiceGrid.WMMouseWheel(var Msg: TWMMouseWheel);
+{$ENDIF}
 var
   Old: Integer;
+  delta: Integer;
+  sgn: Integer;
 begin
+  delta := {$IFNDEF FPC}Msg.{$ENDIF}WheelDelta;
+  sgn := Sign(delta);
+  if (ssShift in Shift) then
+    delta := sgn * FLargeChange
+  else
+    delta := sgn * FSmallChange;
+
   Old := FVertOffset;
-  FVertOffset := Max(0, Min(FMaxVScroll, FVertOffset - Msg.{$IFDEF FPC}lParam{$ELSE}WheelDelta{$ENDIF}));
+  FVertOffset := Max(0, Min(FMaxVScroll, FVertOffset - delta));
   if (FVertOffset <> Old) then
   begin
     SetScrollBar(SB_VERT, 0, FVertOffset, SIF_POS);