From 611c971eaf823c743286e27faf856ec00a264a16 Mon Sep 17 00:00:00 2001
From: dmitry <dmitry@lazarus-ide.org>
Date: Fri, 5 Jan 2018 05:17:04 +0000
Subject: [PATCH] cocoa: improved implementation of TCocoaScrollBar - keeping
 track of the actual ranges and position of as scroll bar (that's critical for
 all custom controls using scrollbars heavily: TreeView #32931, SynEdit
 #32929, Grids #32932, #32767 ). Simplified ScrollWindowEx to just a complete
 invalidation of control content.

git-svn-id: trunk@56961 -
---
 lcl/interfaces/cocoa/cocoaint.pas    | 27 +++++++++++++++++++--------
 lcl/interfaces/cocoa/cocoaprivate.pp | 28 ++++++++++++++++++++++++++--
 lcl/interfaces/cocoa/cocoawinapi.inc | 21 +++++++++++++--------
 3 files changed, 58 insertions(+), 18 deletions(-)

diff --git a/lcl/interfaces/cocoa/cocoaint.pas b/lcl/interfaces/cocoa/cocoaint.pas
index 346db194ce..c33b8c4f5f 100644
--- a/lcl/interfaces/cocoa/cocoaint.pas
+++ b/lcl/interfaces/cocoa/cocoaint.pas
@@ -239,14 +239,6 @@ begin
   end;
 
   dl:=mx-mn;
-  if ScrollInfo.fMask and SIF_POS > 0 then
-  begin
-    if dl<>0 then
-      bar.setDoubleValue( ScrollInfo.nPos / dl )
-    else
-      bar.setDoubleValue( 0 )
-  end;
-
   bar.setEnabled(dl<>0);
 
   // if changed page or range, the knob changes
@@ -261,10 +253,29 @@ begin
     bar.minInt:=mn;
     bar.maxInt:=mx;
   end;
+
+  if ScrollInfo.fMask and SIF_POS > 0 then
+    bar.lclSetPos( ScrollInfo.nPos );
+
+  Result:=bar.lclPos;
 end;
 
 function CocoaScrollBarGetScrollInfo(bar: TCocoaScrollBar; var ScrollInfo: TScrollInfo): Boolean;
+var
+  l : integer;
 begin
+  Result:=Assigned(bar);
+  if not Result then Exit;
+
+  FillChar(ScrollInfo, sizeof(ScrollInfo), 0);
+  ScrollInfo.cbSize:=sizeof(ScrollInfo);
+  ScrollInfo.fMask:=SIF_ALL;
+  ScrollInfo.nMin:=bar.minInt;
+  ScrollInfo.nMax:=bar.maxInt;
+  ScrollInfo.nPage:=bar.pageInt;
+  ScrollInfo.nPos:=bar.lclPos;
+  ScrollInfo.nTrackPos:=ScrollInfo.nPos;
+  Result:=true;
 end;
 
 procedure NSScrollerGetScrollInfo(docSz, pageSz: CGFloat; rl: NSSCroller; Var ScrollInfo: TScrollInfo);
diff --git a/lcl/interfaces/cocoa/cocoaprivate.pp b/lcl/interfaces/cocoa/cocoaprivate.pp
index 6d9ea24379..4b2648b112 100644
--- a/lcl/interfaces/cocoa/cocoaprivate.pp
+++ b/lcl/interfaces/cocoa/cocoaprivate.pp
@@ -610,7 +610,7 @@ type
   TCocoaScrollBar = objcclass(NSScroller)
   public
     callback: ICommonCallback;
-    // minInt,maxInt are used to calculate POS on callback event
+    // minInt,maxInt are used to calculate position for lclPos and lclSetPos
     minInt  : Integer;
     maxInt  : Integer;
     pageInt : Integer;
@@ -623,6 +623,8 @@ type
     procedure lclClearCallback; override;
     procedure resetCursorRects; override;
     function lclIsHandle: Boolean; override;
+    function lclPos: Integer; message 'lclPos';
+    procedure lclSetPos(aPos: integer); message 'lclSetPos:';
   end;
 
   TCocoaListBox = objcclass;
@@ -1864,7 +1866,9 @@ end;
 procedure TCocoaScrollBar.actionScrolling(sender: NSObject);
 begin
   if Assigned(callback) then
-    callback.scroll( not IsHorizontal(), Round(floatValue * (maxInt-minInt)));
+  begin
+    callback.scroll( not IsHorizontal(), lclPos);
+  end;
 end;
 
 function TCocoaScrollBar.IsHorizontal: Boolean;
@@ -1877,6 +1881,26 @@ begin
   Result := True;
 end;
 
+function TCocoaScrollBar.lclPos: Integer;
+begin
+  Result:=round( floatValue * (maxint-minInt)) + minInt;
+end;
+
+procedure TCocoaScrollBar.lclSetPos(aPos: integer);
+var
+  d : integer;
+begin
+  d := maxInt - minInt;
+  if d = 0 then
+    setDoubleValue(0)
+  else
+  begin
+    if aPos < minInt then aPos:=minInt
+    else if aPos > maxInt then aPos:=maxInt;
+    setDoubleValue( (aPos - minInt) / d );
+  end;
+end;
+
 function TCocoaScrollBar.acceptsFirstResponder: Boolean;
 begin
   Result := True;
diff --git a/lcl/interfaces/cocoa/cocoawinapi.inc b/lcl/interfaces/cocoa/cocoawinapi.inc
index 0490f7194f..931aaa7264 100644
--- a/lcl/interfaces/cocoa/cocoawinapi.inc
+++ b/lcl/interfaces/cocoa/cocoawinapi.inc
@@ -1620,7 +1620,16 @@ begin
   Result := Assigned(obj);
   if not Result then Exit;
 
-  if obj.isKindOfClass(NSScrollView) then
+  if obj.isKindOfClass(TCocoaScrollBar) then
+    Result := CocoaScrollBarGetScrollInfo(TCocoaScrollBar(obj), ScrollInfo)
+  else
+  if obj.isKindOfClass(TCocoaManualScrollView) then
+  begin
+    if BarFlag = SB_Vert then
+      Result := CocoaScrollBarGetScrollInfo( TCocoaScrollBar(TCocoaManualScrollView(obj).verticalScroller), ScrollInfo)
+    else
+      Result := CocoaScrollBarGetScrollInfo( TCocoaScrollBar(TCocoaManualScrollView(obj).horizontalScroller), ScrollInfo);
+  end else if obj.isKindOfClass(NSScrollView) then
     NSScrollViewGetScrollInfo(NSScrollView(obj), BarFlag, ScrollInfo)
   else
     Result := False;
@@ -2614,7 +2623,6 @@ end;
 function TCocoaWidgetSet.ScrollWindowEx(hWnd: HWND; dx, dy: Integer; prcScroll, prcClip: PRect; hrgnUpdate: HRGN; prcUpdate: PRect; flags: UINT): Boolean;
 var
   obj: NSOBject;
-  b: NSRect;
   v : NSView;
 begin
   obj:=NSObject(HandleToNSObject(hWnd));
@@ -2622,12 +2630,9 @@ begin
   if not Result then Exit;
 
   v:=NSView(obj).lclContentView;
-
-  b:=v.bounds;
-  b.origin.x:=b.origin.x-dx;
-  b.origin.y:=b.origin.y+dy; // reversed
-  v.setBounds(b);
-  // ignore all updates
+  // todo: parse the passed parameters.
+  //       the content of the window could be already prepared
+  //       thus not entire control should be invalided
   v.setNeedsDisplay_(true);
 end;