LCL: fixed TScrollingWinControl.AutoScroll endless loop when one scrollbars needs to be shown because of the other

git-svn-id: trunk@45082 -

lcl/forms.pp

@@ -80,12 +80,12 @@ type
 
   TControlScrollBar = class(TPersistent)
   private
-    FAutoRange: Longint; // = FRange - ClientSize, >=0
+    FAutoRange: Longint; // = Max(0, FRange - ClientSize)
     FIncrement: TScrollBarInc;
     FKind: TScrollBarKind;
     FPage: TScrollBarInc;
     FPosition: Integer;
-    FRange: Integer;
+    FRange: Integer; // if AutoScroll=true this is the needed size of the child controls
     FSmooth: Boolean;
     FTracking: Boolean;
     FVisible: Boolean;
@@ -103,7 +103,6 @@ type
     function GetSmooth: Boolean; virtual;
     function HandleAllocated: boolean; virtual;
     function IsRangeStored: boolean; virtual;
-    procedure AutoCalcRange; virtual;
     procedure ControlUpdateScrollBars; virtual;
     procedure InternalSetRange(const AValue: Integer); virtual;
     procedure ScrollHandler(var Message: TLMScroll);
@@ -158,6 +157,7 @@ type
     class procedure WSRegisterClass; override;
     procedure AlignControls(AControl: TControl; var ARect: TRect); override;
     function AutoScrollEnabled: Boolean; virtual;
+    procedure CalculateAutoRanges; virtual;
     procedure CreateWnd; override;
     function GetClientScrollOffset: TPoint; override;
     function GetLogicalClientRect: TRect; override;// logical size of client area
@@ -165,7 +165,7 @@ type
     procedure WMSize(var Message: TLMSize); message LM_Size;
     procedure WMHScroll(var Message : TLMHScroll); message LM_HScroll;
     procedure WMVScroll(var Message : TLMVScroll); message LM_VScroll;
-    function ComputeScrollbars: Boolean; virtual;
+    procedure ComputeScrollbars; virtual;
     procedure ScrollbarHandler(ScrollKind: TScrollBarKind;
                                OldPosition: Integer); virtual;
     procedure SetAutoScroll(Value: Boolean); virtual;

lcl/include/controlscrollbar.inc

@@ -41,9 +41,6 @@ begin
 
   if GetAutoScroll then
   begin
-    if FAutoRange < 0 then
-      AutoCalcRange;
-
     if Value > FAutoRange then
     begin
       {$IFDEF VerboseScrollingWinControl}
@@ -210,64 +207,6 @@ begin
   FSmooth := AValue;
 end;
 
-procedure TControlScrollBar.AutoCalcRange;
-
-  function IsNonAligned(Control: TControl): boolean;
-  begin
-    Result:=(Control.Align in [alNone,alCustom])
-      and (Control.Anchors=[akLeft,akTop])
-      and (Control.AnchorSide[akLeft].Control=nil)
-      and (Control.AnchorSide[akTop].Control=nil);
-  end;
-
-  procedure GetPreferredClientRect(out PreferredWidth, PreferredHeight: integer);
-  var
-    CurClientRect: TRect;
-  begin
-    PreferredWidth:=0;
-    PreferredHeight:=0;
-    FControl.GetPreferredSize(PreferredWidth,PreferredHeight,true,false);
-    //DebugLn(['GetPreferredClientRect ',DbgSName(FControl),' PrefSize=',PreferredWidth,'x',PreferredHeight]);
-    CurClientRect := FControl.ClientRect;
-    if PreferredWidth>0 then
-      PreferredWidth:=Max(0,PreferredWidth-(FControl.Width-CurClientRect.Right));
-    if PreferredHeight>0 then
-      PreferredHeight:=Max(0,PreferredHeight-(FControl.Height-CurClientRect.Bottom));
-    //DebugLn(['GetPreferredClientRect ',DbgSName(FControl),' PrefClient=',PreferredWidth,'x',PreferredHeight,' Client=',dbgs(CurClientRect),' Size=',dbgs(FControl.BoundsRect)]);
-  end;
-
-  procedure AutoCalcVRange;
-  var
-    PreferredWidth: Integer;
-    PreferredHeight: Integer;
-  begin
-    GetPreferredClientRect(PreferredWidth,PreferredHeight);
-    //DebugLn(['AutoCalcVRange ',DbgSName(FControl),' AutoSize=',FControl.AutoSize,' Bounds=',dbgs(FControl.BoundsRect),' Client=',dbgs(FControl.ClientRect),' ' pref=',PreferredWidth,'x',PreferredHeight]);
-    InternalSetRange(PreferredHeight);
-  end;
-
-  procedure AutoCalcHRange;
-  var
-    PreferredWidth: Integer;
-    PreferredHeight: Integer;
-  begin
-    GetPreferredClientRect(PreferredWidth,PreferredHeight);
-    //if FControl.ClassName='TEditorCodetoolsOptionsFrame' then
-      //DebugLn(['AutoCalcHRange ',DbgSName(FControl),' AutoSize=',FControl.AutoSize,' Bounds=',dbgs(FControl.BoundsRect),' Client=',dbgs(FControl.ClientRect),' pref=',PreferredWidth,'x',PreferredHeight]);
-    InternalSetRange(PreferredWidth);
-  end;
-
-begin
-  if GetAutoScroll then
-  begin
-    FVisible := True;
-    if Kind = sbVertical then
-      AutoCalcVRange
-    else
-      AutoCalcHRange;
-  end;
-end;
-
 procedure TControlScrollBar.UpdateScrollBar;
 var
   ScrollInfo: TScrollInfo;
@@ -296,8 +235,8 @@ begin
     end;
     ShowScrollBar(FControl.Handle, IntfBarKind[Kind], NewVisible);
     {$IFDEF VerboseScrollingWinControl}
-    if DebugCondition then
+    //if DebugCondition then
-      DebugLn(['TControlScrollBar.UpdateScrollBar ',DbgSName(FControl),' ',DbgSName(Self),' FVisible=',FVisible,' Range=',FRange,' FPosition=',FPosition,' FPage=',FPage,' FAutoRange=',FAutoRange,' ShouldVisible=',NewVisible]);
+      DebugLn(['TControlScrollBar.UpdateScrollBar ',DbgSName(FControl),' ',DbgSName(Self),' ',dbgs(Kind),' FVisible=',FVisible,' Range=',FRange,' FPosition=',FPosition,' FPage=',FPage,' FAutoRange=',FAutoRange,' ShouldVisible=',NewVisible]);
     {$ENDIF}
   end;
 
@@ -498,14 +437,14 @@ function TControlScrollBar.ClientSizeWithBar: integer;
 begin
   Result := ClientSize;
   if not IsScrollBarVisible then
-    dec(Result, GetSize);
+    dec(Result, GetSize+3);
 end;
 
 function TControlScrollBar.ClientSizeWithoutBar: integer;
 begin
   Result:=ClientSize;
   if IsScrollBarVisible then
-    inc(Result, GetSize);
+    inc(Result, GetSize+3);
 end;
 
 function TControlScrollBar.GetHorzScrollBar: TControlScrollBar;

lcl/include/scrollingwincontrol.inc

@@ -13,11 +13,6 @@ procedure TScrollingWinControl.SetAutoScroll(Value: Boolean);
 begin
   if FAutoScroll = Value then Exit;
   FAutoScroll := Value;
-  if Value then
-  begin
-    HorzScrollBar.AutoCalcRange;
-    VertScrollBar.AutoCalcRange;
-  end;
   UpdateScrollBars;
 end;
 
@@ -26,11 +21,6 @@ begin
   DisableAutoSizing{$IFDEF DebugDisableAutoSizing}('TScrollingWinControl.CreateWnd'){$ENDIF};
   try
     inherited CreateWnd;
-    if AutoScroll then
-    begin
-      HorzScrollBar.AutoCalcRange;
-      VertScrollBar.AutoCalcRange;
-    end;
     UpdateScrollBars;
   finally
     EnableAutoSizing{$IFDEF DebugDisableAutoSizing}('TScrollingWinControl.CreateWnd'){$ENDIF};
@@ -71,8 +61,6 @@ begin
     if (HorzScrollBar = nil) or (VertScrollBar = nil) then Exit;
     inherited AlignControls(AControl, ARect);
 
-    HorzScrollBar.AutoCalcRange;
-    VertScrollBar.AutoCalcRange;
     UpdateScrollBars;
   end
   else
@@ -84,6 +72,34 @@ begin
   Result := not (AutoSize or (DockSite and UseDockManager));
 end;
 
+procedure TScrollingWinControl.CalculateAutoRanges;
+
+  procedure GetPreferredClientRect(out PreferredWidth, PreferredHeight: integer);
+  var
+    CurClientRect: TRect;
+  begin
+    PreferredWidth:=0;
+    PreferredHeight:=0;
+    GetPreferredSize(PreferredWidth,PreferredHeight,true,false);
+    //DebugLn(['GetPreferredClientRect ',DbgSName(FControl),' PrefSize=',PreferredWidth,'x',PreferredHeight]);
+    CurClientRect := ClientRect;
+    if PreferredWidth>0 then
+      PreferredWidth:=Max(0,PreferredWidth-(Width-CurClientRect.Right));
+    if PreferredHeight>0 then
+      PreferredHeight:=Max(0,PreferredHeight-(Height-CurClientRect.Bottom));
+    //DebugLn(['GetPreferredClientRect ',DbgSName(FControl),' PrefClient=',PreferredWidth,'x',PreferredHeight,' Client=',dbgs(CurClientRect),' Size=',dbgs(FControl.BoundsRect)]);
+  end;
+
+var
+  PreferredWidth: Integer;
+  PreferredHeight: Integer;
+begin
+  GetPreferredClientRect(PreferredWidth,PreferredHeight);
+  //DebugLn(['TScrollingWinControl.CalculateAutoRanges ',DbgSName(Self),' AutoSize=',AutoSize,' Bounds=',dbgs(BoundsRect),' Client=',dbgs(ClientRect),' pref=',PreferredWidth,'x',PreferredHeight]);
+  HorzScrollBar.InternalSetRange(PreferredWidth);
+  VertScrollBar.InternalSetRange(PreferredHeight);
+end;
+
 procedure TScrollingWinControl.DoOnResize;
 begin
   inherited DoOnResize;
@@ -91,7 +107,8 @@ begin
   if AutoScroll then
   begin
     if (HorzScrollBar = nil) or (VertScrollBar = nil) then Exit;
-    if HorzScrollBar.Visible or VertScrollBar.Visible then UpdateScrollBars;
+    if HorzScrollBar.Visible or VertScrollBar.Visible then
+      UpdateScrollBars;
   end;
 end;
 
@@ -136,54 +153,47 @@ begin
   //
 end;
 
-function TScrollingWinControl.ComputeScrollbars: Boolean;
+procedure TScrollingWinControl.ComputeScrollbars;
-// true if something changed
+// true if something has changed
-// update Page, AutoRange, IsScrollBarVisible
+// update Page, AutoRange
 
-  function UpdateRange(p_Bar: TControlScrollBar): Boolean;
+  procedure UpdateBar(aBar: TControlScrollBar; aClientSize: integer);
-  var
-    SBSize: Longint;
-    OtherScrollbar: TControlScrollBar;
-    OldAutoRange: LongInt;
   begin
-    Result := False;
+    // page (must be smaller than Range but at least 1)
-    OldAutoRange := p_Bar.FAutoRange;
+    aBar.FPage := Max(1,Min(Min(aBar.Range,aClientSize), High(HorzScrollbar.FPage)));
-    p_Bar.FAutoRange := 0;
+    aBar.FAutoRange := Max(0, aBar.Range - aClientSize);
-    OtherScrollbar := p_Bar.GetOtherScrollBar;
-    SBSize := OtherScrollbar.ClientSize;
-    if (p_Bar.FRange > SBSize) and (SBSize > 0) then
-      p_Bar.FAutoRange := (p_Bar.FRange - SBSize)
-    else
-      p_Bar.FAutoRange := 0;
     {$IFDEF VerboseScrollingWinControl}
-    if p_Bar.DebugCondition then
+    debugln(['TScrollingWinControl.ComputeScrollbars ',DbgSName(Self),' ',dbgs(aBar.Kind),' Page=',aBar.Page,' Range=',aBar.Range,' ClientSize=',aClientSize]);
-      DebugLn(['UpdateRange p_Bar.fRange=',p_Bar.FRange,' SBSize=',SBSize,' ClientWidth=',ClientWidth,' FAutoRange=',p_Bar.FAutoRange]);
     {$ENDIF}
-    if OldAutoRange <> p_Bar.FAutoRange then
-      Result := True;
   end;
   
 var
-  NewPage: Integer;
+  ClientW: Integer;
+  ClientH: Integer;
 begin
-  Result := False;
+  CalculateAutoRanges;
 
-  // page (must be smaller than Range but at least 1)
+  ClientW:=VertScrollBar.ClientSizeWithoutBar;
-  NewPage := Max(1,Min(VertScrollbar.ClientSize, High(HorzScrollbar.FPage)));
+  ClientH:=HorzScrollBar.ClientSizeWithoutBar;
-  if NewPage <> HorzScrollbar.FPage then
+  if VertScrollBar.Range > ClientH then
   begin
-    HorzScrollbar.FPage := NewPage;
+    // vertical does not fit -> vertical scrollbar will be shown
-    Result := True;
+    ClientW:=VertScrollBar.ClientSizeWithBar;
   end;
-  NewPage := Max(1,Min(HorzScrollbar.ClientSize, High(VertScrollbar.FPage)));
+  if HorzScrollBar.Range > ClientW then
-  if NewPage <> VertScrollbar.FPage then
   begin
-    VertScrollbar.FPage := NewPage;
+    // horizontal does not fit -> horizontal scrollbar will be shown
-    Result := True;
+    ClientH:=HorzScrollBar.ClientSizeWithBar;
+    if VertScrollBar.Range > ClientH then
+    begin
+      // vertical does not fit, because of the other scrollbar
+      // -> vertical scrollbar will be shown too
+      ClientW:=VertScrollBar.ClientSizeWithBar;
+    end;
   end;
-  // range
+
-  if UpdateRange(HorzScrollbar) then Result:=true;
+  UpdateBar(HorzScrollBar,ClientW);
-  if UpdateRange(VertScrollbar) then Result:=true;
+  UpdateBar(VertScrollBar,ClientH);
 end;
 
 procedure TScrollingWinControl.UpdateScrollbars;