From 1df9cbaea52314a40159c0891a17a8ce959ec7e0 Mon Sep 17 00:00:00 2001
From: lazarus <lazarus@lazarus-ide.org>
Date: Sun, 27 Oct 2002 23:24:19 +0000
Subject: [PATCH] MG: reduced messages of TScrollingWinControl

git-svn-id: trunk@3576 -
---
 lcl/forms.pp                        |  4 ---
 lcl/include/scrollingwincontrol.inc | 39 +++++++++++++++++++++--------
 2 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/lcl/forms.pp b/lcl/forms.pp
index 92f7d8956f..959ee73a66 100644
--- a/lcl/forms.pp
+++ b/lcl/forms.pp
@@ -88,13 +88,9 @@ type
     procedure ScrollHandler(var Message: TLMScroll);
   public
     constructor Create(AControl: TScrollingWinControl; AKind: TScrollBarKind);
-
     procedure Assign(Source: TPersistent); override;
-
     function IsScrollBarVisible: Boolean;
-
     function ScrollPos: Integer;
-
     property Kind: TScrollBarKind read FKind;
   published
     property Increment: TScrollBarInc read FIncrement write FIncrement default 8;
diff --git a/lcl/include/scrollingwincontrol.inc b/lcl/include/scrollingwincontrol.inc
index 6f8449a15e..06a30c64ea 100644
--- a/lcl/include/scrollingwincontrol.inc
+++ b/lcl/include/scrollingwincontrol.inc
@@ -22,7 +22,8 @@ procedure TControlScrollBar.SetPosition(Value: Integer);
     Tmp := FPosition;
     FPosition := Value;
     FControl.ScrollBy(0, Tmp - FPosition);
-    if GetScrollPos(FControl.Handle, SB_VERT) <> FPosition then
+    if FControl.HandleAllocated
+    and (GetScrollPos(FControl.Handle, SB_VERT) <> FPosition) then
       SetScrollPos(FControl.Handle, SB_VERT, FPosition, Visible);
   end;
 
@@ -33,7 +34,8 @@ procedure TControlScrollBar.SetPosition(Value: Integer);
     Tmp := FPosition;
     FPosition := Value;
     FControl.ScrollBy(Tmp - FPosition, 0);
-    if GetScrollPos(FControl.Handle, SB_HORZ) <> FPosition then
+    if FControl.HandleAllocated
+    and (GetScrollPos(FControl.Handle, SB_HORZ) <> FPosition) then
       SetScrollPos(FControl.Handle, SB_HORZ, FPosition, Visible);
   end;
 
@@ -52,6 +54,13 @@ begin
       exit;
     end;
   end;
+  
+  if Value>Range then begin
+    SetPosition(Range);
+    exit;
+  end;
+  
+  if Value=FPosition then exit;
 
   if Kind = sbVertical then
     SetVPosition
@@ -66,18 +75,21 @@ begin
     Range := 0;
     exit;
   end;
+  if FRange=Value then exit;
   FRange := Value;
   FControl.UpdateScrollBars;
 end;
 
 procedure TControlScrollBar.SetVisible(Value: Boolean);
 begin
+  if FVisible = Value then exit;
   FVisible := Value;
   FControl.UpdateScrollBars;
 end;
 
 procedure TControlScrollBar.SetSmooth(Value: Boolean);
 begin
+  if FSmooth = Value then exit;
   FSmooth := Value;
   FControl.UpdateScrollBars;
 end;
@@ -136,7 +148,7 @@ var
   procedure UpdateVScroll;
   begin
     With FControl do begin
-      Page := ClientHeight + 1;
+      Page := Min(ClientHeight + 1,High(Page));
       ScrollInfo.nPage := Page;
 
       if Visible then begin
@@ -146,20 +158,21 @@ var
       else
         ScrollInfo.nMax := 0;
 
-      If (Self.Visible and not FAutoScroll) or (FAutoScroll and (ScrollInfo.nMax > 0) and
-        (ScrollInfo.nMax > Height))
+      If (Self.Visible and not FAutoScroll)
+      or (FAutoScroll and (ScrollInfo.nMax > 0) and (ScrollInfo.nMax > Height))
       then
         Self.FVisible := True
       else
         Self.FVisible := False;
-      SetScrollInfo(Handle, SB_VERT, ScrollInfo, Self.Visible);
+      if HandleAllocated then
+        SetScrollInfo(Handle, SB_VERT, ScrollInfo, Self.Visible);
     end;
   end;
 
   procedure UpdateHScroll;
   begin
     With FControl do begin
-      Page := ClientWidth + 1;
+      Page := Min(ClientWidth + 1,High(Page));
       ScrollInfo.nPage := Page;
 
       if Visible then begin
@@ -169,13 +182,14 @@ var
       else
         ScrollInfo.nMax := 0;
 
-      If (Self.Visible and not FAutoScroll) or (FAutoScroll and (ScrollInfo.nMax > 0) and
-        (ScrollInfo.nMax > Width))
+      If (Self.Visible and not FAutoScroll)
+      or (FAutoScroll and (ScrollInfo.nMax > 0) and (ScrollInfo.nMax > Width))
       then
         Self.FVisible := True
       else
         Self.FVisible := False;
-      SetScrollInfo(Handle, SB_HORZ, ScrollInfo, Self.Visible);
+      if HandleAllocated then
+        SetScrollInfo(Handle, SB_HORZ, ScrollInfo, Self.Visible);
     end;
   end;
 
@@ -269,7 +283,10 @@ end;
 
 function TControlScrollBar.ScrollPos: Integer;
 begin
-  Result := Position*ShortInt(Visible);
+  if Visible then
+    Result:=Position
+  else
+    Result:=0;
 end;
 
 procedure TScrollingWinControl.SetAutoScroll(Value: Boolean);