自绘LISTVIEW的滚动条(Delphi实现)

因项目需要准备对LISTVIEW的滚动条进行自绘。于是在网上搜了一下，问题没解决，却搜出一篇令人不愉快的帖子。确实，那时候实力是不够的，但现在应该是没问题了，为这个目的才不断磨练自己的。
LISTVIEW控件的滚动条是系统自带的，它不创建窗口。对LISTVIEW窗口本身进行子类化后，要处理一些跟滚动条有关的消息。
首先是要骗过WM_NCPAINT消息。这个十分容易。WM_NCPAINT消息的wParam是一个区域的句柄。当它不为1时，从它里面CLIP 掉滚动条的区域，再传给原窗口过程即可。当它为1时，创建一个包含控件全客户区域的Region，再从中CLIP掉滚动条的区域，传给原窗口过程。
然后是WM_HSCROLL和WM_VSCROLL消息。在调用原窗口过程之前需要去掉窗口的WS_HSCROLL和WS_VSCROLL样式，否则窗口过程就会在消息中绘制滚动条。调用后需要恢复。同时为避免窗口在WM_STYLECHANGING和WM_STYLECHANGED消息中重绘，也需要截获这两个消息。
WM_NCCALCSIZE消息也是必须截获的。如果是在处理WM_HSCROLL和WM_VSCROLL消息的过程中响应WM_NCCALCSIZE，则必须去掉WS_HSCROLL和WS_VSCROLL样式。
然后是WM_ERASEBACKGROUND,WM_MOUSEWHELL消息。在这消息后需要重绘滚动条。
最重要的莫过于WM_NCHITTEST消息了。因为是自绘，所以滚动条的按下和拖动都必须在这里处理。
在自己写的滚动条Track函数中，最头疼的莫过于ThumbTrack了。当你计算好滚动到的绝对位置后，用SendMessage(hWnd, WM_XSCROLL, MAKEWPARAM(SB_THUMBTRACK, Pos), 0)发给窗口时，它居然没有反应。这是因为窗口过程不会从消息中取得TrackPos，而是会调用GetScrollInfo的API取得 TrackPos（因为前者只有16位）。但是使用SetScrollInfo是没办法设置TrackPos的。虽然你可以用SIF_POS标志让它同时设置Pos和TrackPos，但当Pos等于TrackPos时，窗口过程不会做任何响应。从windows源代码中我们可以了解到，TrackPos 并不会为每个窗口保存一份，实际上，在任一时刻最多只有一个滚动条在做ThumbTrack的操作，因此系统只需要用一个全局变量来保存就可以了。
解决这个问题的办法是HookAPI。在GetScrollInfo中返回我们自己的TrackPos。要注意的是要Hook的不是本模块的 API，而是ComCtl32.dll中的GetScrollInfo。因此简单的如往@GetScrollInfo地址写几句跳转的方法是行不通的。必须遍历ComCtl32.dll的pe头。这种技术在很多文章中都有描述。
不多说了，以下是Delphi代码，要点在前面已有描述，源码中没有做特殊说明。
使用说明：
资源中是一张横条的192*16的位图，从左到右依次是：左箭头、右箭头、上箭头、下箭头、左箭头按下、右箭头按下、上箭头按下、下箭头按下、横Thumb条、纵Thumb条、横背景条、纵背景条。
初始化时，调用GetSkinSB.InitSkinSB(ListView1.Handle);即可。窗口销毁前调用GetSkinSB.UninitSkinSB(ListView1.Handle)。
虽然也可针对EDIT(TMemo)和其它使用系统滚动条的控件使用此模块，但效果各有差异，需要分别做特殊处理。
unit SkinSB;
 
interface
 
uses
  SysUtils, Classes, Windows, Messages, Graphics;
 
const
  SKINSB_PROP = '{8BC6661E-5880-4353-878D-C3B3784CFC5F}';
 
type
 
  TBarPosCode = ( bpcNone,
                  bpcHArrowL, bpcHArrowR, bpcHPageL, bpcHPageR, bpcHThumb,
                  bpcVArrowU, bpcVArrowD, bpcVPageU, bpcVPageD, bpcVThumb,
                  bpcCross );
 
  TWindowProc = function (hWnd: HWND; uMsg: UINT; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
 
  PSkinSBInfo = ^TSkinSBInfo;
  TSkinSBInfo = packed record
    OldWndProc: TWindowProc;
    Prevent: Boolean; // prevent style change message
    Scrolling: Boolean;
    Style: Cardinal; // real style
    ThumbTrack: Boolean;
    ThumbPos: Integer;
    Tracking: Boolean; // tracking: click arrow or track thumb
  end;
 
  TSkinSB = class
  protected
    FBitmap: TBitmap;
    constructor CreateInstance;
  public
    constructor Create;
    destructor Destroy; override;
    procedure InitSkinSB(H: HWND);
    procedure UnInitSkinSB(H: HWND);
    procedure DrawElem(H: HWND; Code: TBarPosCode; R: TRect; Down: Boolean);
  end;
 
function GetSkinSB: TSkinSB;
 
function SkinSBWndProc(hWnd: HWND; uMsg: UINT; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
function GetSkinSBInfo(hWnd: HWND): PSkinSBInfo;
 
implementation
 
uses
  CommCtrl;
 
{$R *.res}
 
var
  l_SkinSB: TSkinSB;
  l_SkinSB_Prop: TATOM;
 
type
  PImageImportDescriptor = ^TImageImportDescriptor;
  TImageImportDescriptor = packed record
    OriginalFirstThunk: DWORD;  // or Characteristics: DWORD
    TimeDateStamp: DWORD;
    ForwarderChain: DWORD;
    Name: DWORD;
    FirstThunk: DWORD;
  end;
  PImageChunkData = ^TImageChunkData;
  TImageChunkData = packed record
    case Integer of
      0: ( ForwarderString: DWORD );
      1: ( Func: DWORD );
      2: ( Ordinal: DWORD );
      3: ( AddressOfData: DWORD );
  end;
  PImageImportByName = ^TImageImportByName;
  TImageImportByName = packed record
    Hint: Word;
    Name: array[0..0] of Byte;
  end;
 
type
  PHookRec = ^THookRec;
  THookRec = packed record
    OldFunc: Pointer;
    NewFunc: Pointer;
  end;
 
var
  _HookGetScrollInfo: THookRec;
 
procedure HookApiInMod(ImageBase: Cardinal; ApiName: PChar; PHook: PHookRec);
var
  pidh: PImageDosHeader;
  pinh: PImageNtHeaders;
  pSymbolTable: PIMAGEDATADIRECTORY;
  piid: PIMAGEIMPORTDESCRIPTOR;
  pitd_org, pitd_1st: PImageChunkData;
  piibn: PImageImportByName;
  pAPIFunction: Pointer;
  written, oldAccess: DWORD;
begin
  if ImageBase = 0 then Exit;
  pidh := PImageDosHeader(ImageBase);
  pinh := PImageNtHeaders(DWORD(ImageBase) + Cardinal(pidh^._lfanew));
  pSymbolTable := @pinh^.OptionalHeader.DataDirectory[1];
  piid := PImageImportDescriptor(DWORD(ImageBase) + pSymbolTable^.VirtualAddress);
  repeat
    pitd_org := PImageChunkData(DWORD(ImageBase) + piid^.OriginalFirstThunk);
    pitd_1st := PImageChunkData(DWORD(ImageBase) + piid^.FirstThunk);
    repeat
      piibn := PImageImportByName(DWORD(ImageBase) + LPDWORD(pitd_org)^);
      pAPIFunction := Pointer(pitd_1st^.Func);
      if StrComp(ApiName, @piibn^.Name) = 0 then
      begin
        PHook^.OldFunc := pAPIFunction;
        VirtualProtect(@(pitd_1st^.Func), SizeOf(DWORD), PAGE_WRITECOPY, oldAccess);
        WriteProcessMemory(GetCurrentProcess(), @(pitd_1st^.Func), @PHook^.NewFunc, SizeOf(DWORD), written);
        VirtualProtect(@(pitd_1st^.Func), SizeOf(DWORD), oldAccess, oldAccess);
      end;
      Inc(pitd_org);
      Inc(pitd_1st);
    until pitd_1st^.Func = 0;
    Inc(piid);
  until piid^.FirstThunk + piid^.OriginalFirstThunk + piid^.ForwarderChain + piid^.Name = 0;
end;
 
function GetSkinSBInfo(hWnd: HWND): PSkinSBInfo;
begin
  Result := PSkinSBInfo( GetProp(hWnd, MAKEINTATOM(l_SkinSB_Prop)) );
end;
 
function GetSkinSB: TSkinSB;
begin
  if l_SkinSB = nil then l_SkinSB := TSkinSB.CreateInstance;
  Result := l_SkinSB;
end;
 
function CalcScrollBarRect(H: HWND; nBarCode: Cardinal): TRect;
var
  Style, ExStyle: Cardinal;
begin
  SetRect(Result, 0, 0, 0, 0);
  Style := GetWindowLong(H, GWL_STYLE);
  ExStyle := GetWindowLong(H, GWL_EXSTYLE);
  if (nBarCode = SB_HORZ) and ((Style and WS_HSCROLL) = 0) then Exit;
  if (nBarCode = SB_VERT) and ((Style and WS_VSCROLL) = 0) then Exit;
  GetWindowRect(H, Result);
  OffsetRect(Result, -Result.Left, -Result.Top);
  if ((ExStyle and WS_EX_DLGMODALFRAME) <> 0)
    or ((ExStyle and WS_EX_CLIENTEDGE) <> 0) then
  begin
    InflateRect(Result, -GetSystemMetrics(SM_CXEDGE), -GetSystemMetrics(SM_CYEDGE));
  end;
  // special: returns the cross
  if nBarCode = SB_BOTH then
  begin
    if ((Style and WS_HSCROLL) = 0) or ((Style and WS_VSCROLL) = 0) then
    begin
      SetRect(Result, 0, 0, 0, 0);
      Exit;
    end;
    Result.Top := Result.Bottom - GetSystemMetrics(SM_CYVSCROLL);
    if (ExStyle and WS_EX_LEFTSCROLLBAR) <> 0 then Result.Right := Result.Left + GetSystemMetrics(SM_CXHSCROLL)
    else Result.Left := Result.Right - GetSystemMetrics(SM_CXHSCROLL);
    Exit;
  end;
  if nBarCode = SB_HORZ then
  begin
  //    if (ExStyle and WS_EX_TOPSCROLLBAR) <> 0 then Result.Bottom := Result.Top + GetSystemMetrics(SM_CYVSCROLL)
    Result.Top := Result.Bottom - GetSystemMetrics(SM_CYVSCROLL);
    if ((Style and WS_VSCROLL) <> 0) then Dec(Result.Right, GetSystemMetrics(SM_CYVSCROLL));
  end;
  if nBarCode = SB_VERT then
  begin
    if (ExStyle and WS_EX_LEFTSCROLLBAR) <> 0 then Result.Right := Result.Left + GetSystemMetrics(SM_CXHSCROLL)
    else Result.Left := Result.Right - GetSystemMetrics(SM_CXHSCROLL);
    if ((Style and WS_HSCROLL) <> 0) then Dec(Result.Bottom, GetSystemMetrics(SM_CXHSCROLL));
  end;
end;
 
type
  TBarElem = (beArrow1, beBG, beThumb, beArrow2);
  TBarElemRects = array[TBarElem] of TRect;
 
function CalcBarElemRects(hWnd: HWND; nBarCode: Integer): TBarElemRects;
var
  R: TRect;
  SI: TScrollInfo;
  ThumbSize: Integer;
  X, L, H, BlockH, BlockV: Integer;
begin
  R := CalcScrollBarRect(hWnd, nBarCode);
  SI.cbSize := SizeOf(SI);
  SI.fMask := SIF_ALL;
  GetScrollInfo(hWnd, nBarCode, SI);
  Result[beArrow1] := R;
  Result[beArrow2] := R;
  Result[beBG] := R;
  Result[beThumb] := R;
  if nBarCode = SB_VERT then
  begin
    BlockV := GetSystemMetrics(SM_CYVSCROLL);
    L := Result[beArrow1].Top + BlockV;
    H := Result[beArrow2].Bottom - BlockV;
    Result[beArrow1].Bottom := L;
    Result[beArrow2].Top := H;
//    Inc(L);
//    Dec(H);
    Result[beBG].Top := L;
    Result[beBG].Bottom := H;
  end
  else
  begin
    BlockH := GetSystemMetrics(SM_CXHSCROLL);
    L := Result[beArrow1].Left + BlockH;
    H := Result[beArrow2].Right - BlockH;
    Result[beArrow1].Right := L;
    Result[beArrow2].Left := H;
//    Inc(L);
//    Dec(H);
    Result[beBG].Left := L;
    Result[beBG].Right := H;
  end;
  if SI.nMax - SI.nMin - Integer(SI.nPage) + 1 <= 0 then
  begin
    // max thumb, no thumb
    if nBarCode = SB_VERT then
    begin
      Result[beThumb].Top := L;
      Result[beThumb].Bottom := H;
    end
    else
    begin
      Result[beThumb].Left := L;
      Result[beThumb].Right := H;
    end;
    Exit;
  end;
  ThumbSize := MulDiv(H - L, SI.nPage, SI.nMax - SI.nMin + 1);
  X := L + MulDiv(SI.nTrackPos, H - ThumbSize - L, SI.nMax - Integer(SI.nPage) - SI.nMin + 1);
  if nBarCode = SB_VERT then
  begin
    Result[beThumb].Top := X;
    Result[beThumb].Bottom := X + ThumbSize;
  end
  else
  begin
    Result[beThumb].Left := X;
    Result[beThumb].Right := X + ThumbSize;
  end;
end;
 
function GetPtBarPos(H: HWND; Pt: TPoint): TBarPosCode;
var
  R: TRect;
  BR: TBarElemRects;
begin
  Result := bpcNone;
  R := CalcScrollBarRect(H, SB_HORZ);
  InflateRect(R, GetSystemMetrics(SM_CXEDGE), GetSystemMetrics(SM_CYEDGE));
  if PtInRect(R, Pt) then
  begin
    BR := CalcBarElemRects(H, SB_HORZ);
    if PtInRect(BR[beArrow1], Pt) then Result := bpcHArrowL
    else if PtInRect(BR[beThumb], Pt) then Result := bpcHThumb
    else if PtInRect(BR[beArrow2], Pt) then Result := bpcHArrowR
    else if Pt.X < BR[beThumb].Left then Result := bpcHPageL
    else Result := bpcHPageR;
    Exit;
  end;
  R := CalcScrollBarRect(H, SB_VERT);
  InflateRect(R, GetSystemMetrics(SM_CXEDGE), GetSystemMetrics(SM_CYEDGE));
  if PtInRect(R, Pt) then
  begin
    BR := CalcBarElemRects(H, SB_VERT);
    if PtInRect(BR[beArrow1], Pt) then Result := bpcVArrowU
    else if PtInRect(BR[beThumb], Pt) then Result := bpcVThumb
    else if PtInRect(BR[beArrow2], Pt) then Result := bpcVArrowD
    else if Pt.Y < BR[beThumb].Top then Result := bpcVPageU
    else Result := bpcVPageD;
    Exit;
  end;
end;
 
type
  TGetScrollInfoFunc = function (H: HWND; Code: Integer; var SI: TScrollInfo): Boolean; stdcall;
 
function _SkinSB_GetScrollInfo(H: HWND; Code: Integer; var SI: TScrollInfo): Boolean; stdcall;
var
  P: PSkinSBInfo;
begin
  Result := TGetScrollInfoFunc(_HookGetScrollInfo.OldFunc)(H, Code, SI);
  P := GetSkinSBInfo(H);
  if (P <> nil) and P^.ThumbTrack and ((SI.fMask and SIF_TRACKPOS) <> 0) then
  begin
    SI.nTrackPos := P^.ThumbPos;
  end;
end;
 
{ TSkinSB }
 
constructor TSkinSB.Create;
begin
  raise Exception.Create('use GetSkinSB.');
end;
 
constructor TSkinSB.CreateInstance;
begin
  inherited;
  _HookGetScrollInfo.OldFunc := nil;
  _HookGetScrollInfo.NewFunc := @_SkinSB_GetScrollInfo;
  HookApiInMod( GetModuleHandle('comctl32.dll'), 'GetScrollInfo', @_HookGetScrollInfo );
  FBitmap := TBitmap.Create;
  FBitmap.LoadFromResourceName(hInstance, 'scrollbar');
end;
 
destructor TSkinSB.Destroy;
begin
  FreeAndNil(FBitmap);
  inherited;
end;
 
procedure TSkinSB.DrawElem(H: HWND; Code: TBarPosCode; R: TRect;
  Down: Boolean);
var
  Canvas: TCanvas;
begin
  Canvas := TCanvas.Create;
  try
    Canvas.Handle := GetWindowDC(H);
    try
      case Code of
        bpcHArrowL:
        begin
          if Down then BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 64, 0, SRCCOPY)
          else BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 0, 0, SRCCOPY);
          Exit;
        end;
        bpcHArrowR:
        begin
          if Down then BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 80, 0, SRCCOPY)
          else BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 16, 0, SRCCOPY);
          Exit;
        end;
        bpcHThumb:
        begin
          BitBlt(Canvas.Handle, R.Left, R.Top, 2, 16, FBitmap.Canvas.Handle, 128, 0, SRCCOPY);
          BitBlt(Canvas.Handle, R.Right - 2, R.Top, 2, 16, FBitmap.Canvas.Handle, 142, 0, SRCCOPY);
          StretchBlt(Canvas.Handle, R.Left + 2, R.Top, R.Right - R.Left - 4, 16, FBitmap.Canvas.Handle,
            130, 0, 12, 16, SRCCOPY);
          Exit;
        end;
        bpcHPageL, bpcHPageR:
        begin
          if R.Right - R.Left < 4 then
          begin
            StretchBlt(Canvas.Handle, R.Left, R.Top, R.Right - R.Left, 16, FBitmap.Canvas.Handle,
              160, 0, 16, 16, SRCCOPY);
          end
          else
          begin
            BitBlt(Canvas.Handle, R.Left, R.Top, 2, 16, FBitmap.Canvas.Handle, 160, 0, SRCCOPY);
            BitBlt(Canvas.Handle, R.Right - 2, R.Top, 2, 16, FBitmap.Canvas.Handle, 174, 0, SRCCOPY);
            StretchBlt(Canvas.Handle, R.Left + 2, R.Top, R.Right - R.Left - 4, 16, FBitmap.Canvas.Handle,
              162, 0, 12, 16, SRCCOPY);
          end;
          Exit;
        end;
        bpcVArrowU:
        begin
          if Down then BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 96, 0, SRCCOPY)
          else BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 32, 0, SRCCOPY);
          Exit;
        end;
        bpcVArrowD:
        begin
          if Down then BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 112, 0, SRCCOPY)
          else BitBlt(Canvas.Handle, R.Left, R.Top, 16, 16, FBitmap.Canvas.Handle, 48, 0, SRCCOPY);
          Exit;
        end;
        bpcVThumb:
        begin
          BitBlt(Canvas.Handle, R.Left, R.Top, 16, 2, FBitmap.Canvas.Handle, 144, 0, SRCCOPY);
          BitBlt(Canvas.Handle, R.Left, R.Bottom - 2, 16, 2, FBitmap.Canvas.Handle, 144, 14, SRCCOPY);
          StretchBlt(Canvas.Handle, R.Left, R.Top + 2, 16, R.Bottom - R.Top - 4, FBitmap.Canvas.Handle,
            144, 2, 16, 12, SRCCOPY);
          Exit;
        end;
        bpcVPageU, bpcVPageD:
        begin
          if R.Bottom - R.Top < 4 then
          begin
            StretchBlt(Canvas.Handle, R.Left, R.Top, 16, R.Bottom - R.Top, FBitmap.Canvas.Handle,
              176, 0, 16, 16, SRCCOPY);
          end
          else
          begin
            BitBlt(Canvas.Handle, R.Left, R.Top, 16, 2, FBitmap.Canvas.Handle, 176, 0, SRCCOPY);
            BitBlt(Canvas.Handle, R.Left, R.Bottom - 2, 16, 2, FBitmap.Canvas.Handle, 176, 14, SRCCOPY);
            StretchBlt(Canvas.Handle, R.Left, R.Top + 2, 16, R.Bottom - R.Top - 4, FBitmap.Canvas.Handle,
              176, 2, 16, 12, SRCCOPY);
          end;
          Exit;
        end;
      end;
      Canvas.Pen.Color := clBlack;
      Canvas.Brush.Color := clWhite;
      Canvas.Rectangle(R);
    finally
      ReleaseDC(H, Canvas.Handle);
    end;
  finally
    Canvas.Handle := 0;
    FreeAndNil(Canvas);
  end;
end;
 
procedure TSkinSB.InitSkinSB(H: HWND);
var
  PInfo: PSkinSBInfo;
begin
  PInfo := GetSkinSBInfo(H);
  if PInfo <> nil then Exit; // already inited
  New(PInfo);
  PInfo^.OldWndProc := TWindowProc(GetWindowLong(H, GWL_WNDPROC));
  PInfo^.Style := GetWindowLong(H, GWL_STYLE);
  PInfo^.Prevent := False;
  PInfo^.Scrolling := False;
  PInfo^.ThumbTrack := False;
  SetWindowLong(H, GWL_WNDPROC, Cardinal(@SkinSBWndProc));
  SetProp(H, MAKEINTATOM(l_SkinSB_Prop), Cardinal(PInfo));
end;
 
procedure TSkinSB.UnInitSkinSB(H: HWND);
var
  PInfo: PSkinSBInfo;
begin
  PInfo := GetSkinSBInfo(H);
  if PInfo = nil then Exit; // not inited
  RemoveProp(H, MAKEINTATOM(l_SkinSB_Prop));
  SetWindowLong(H, GWL_WNDPROC, Cardinal(@PInfo^.OldWndProc));
  Dispose(PInfo);
end;
 
const
  WM_REPEAT_CLICK = WM_USER + $6478;
 
procedure OnRepeatClickTimer(hWnd: HWND; uMsg: UINT; idEvent: UINT; dwTime: DWORD); stdcall;
begin
  KillTimer(0, idEvent);
  PostThreadMessage(MainThreadID, WM_REPEAT_CLICK, 0, 0);
end;
 
procedure RedrawScrollBars(hWnd: HWND);
var
  RHBar, RVBar, RCross: TRect;
  BR: TBarElemRects;
begin
  RHBar := CalcScrollBarRect(hWnd, SB_HORZ);
  if not IsRectEmpty(RHBar) then
  begin
    BR := CalcBarElemRects(hWnd, SB_HORZ);
    GetSkinSB.DrawElem(hWnd, bpcHPageL, Rect(BR[beBG].Left, BR[beBG].Top, BR[beThumb].Left, BR[beBG].Bottom), False);
    GetSkinSB.DrawElem(hWnd, bpcHPageR, Rect(BR[beThumb].Right, BR[beBG].Top, BR[beBG].Right, BR[beBG].Bottom), False);
    GetSkinSB.DrawElem(hWnd, bpcHThumb, BR[beThumb], False);
    GetSkinSB.DrawElem(hWnd, bpcHArrowL, BR[beArrow1], False);
    GetSkinSB.DrawElem(hWnd, bpcHArrowR, BR[beArrow2], False);
  end;
  RVBar := CalcScrollBarRect(hWnd, SB_VERT);
  if not IsRectEmpty(RVBar) then
  begin
    BR := CalcBarElemRects(hWnd, SB_VERT);
    GetSkinSB.DrawElem(hWnd, bpcVPageU, Rect(BR[beBG].Left, BR[beBG].Top, BR[beBG].Right, BR[beThumb].Top), False);
    GetSkinSB.DrawElem(hWnd, bpcVPageD, Rect(BR[beBG].Left, BR[beThumb].Bottom, BR[beBG].Right, BR[beBG].Bottom), False);
    GetSkinSB.DrawElem(hWnd, bpcVThumb, BR[beThumb], False);
    GetSkinSB.DrawElem(hWnd, bpcVArrowU, BR[beArrow1], False);
    GetSkinSB.DrawElem(hWnd, bpcVArrowD, BR[beArrow2], False);
  end;
  RCross := CalcScrollBarRect(hWnd, SB_BOTH);
  if not IsRectEmpty(RCross) then
  begin
    GetSkinSB.DrawElem(hWnd, bpcCross, RCross, False);
  end;
end;
 
procedure TrackBar(hWnd: HWND; nBarCode: Integer; PosCode: TBarPosCode; BarElem: TBarElem; MsgCode: Integer);
var
  BR: TBarElemRects;
  Msg: tagMSG;
  Pt: TPoint;
  R: TRect;
  ScrollMsg: Cardinal;
  RepeatClick: Boolean;
  idEvent: UINT;
  SI: TScrollInfo;
 
  procedure RefreshRect;
  begin
    BR := CalcBarElemRects(hWnd, nBarCode);
    R := BR[BarElem];
  end;
 
begin
  RepeatClick := False;
  BR := CalcBarElemRects(hWnd, nBarCode);
  R := BR[BarElem];
  GetScrollInfo(hWnd, nBarCode, SI);
  if nBarCode = SB_HORZ then ScrollMsg := WM_HSCROLL
  else ScrollMsg := WM_VSCROLL;
  if BarElem = beBG then
  begin
    if PosCode = bpcHPageL then R.Right := BR[beThumb].Left
    else if PosCode = bpcHPageR then R.Left := BR[beThumb].Right
    else if PosCode = bpcVPageU then R.Bottom := BR[beThumb].Top
    else if PosCode = bpcVPageD then R.Top := BR[beThumb].Bottom;
  end;
  GetSkinSB.DrawElem(hWnd, PosCode, R, True);
  GetSkinSBInfo(hWnd)^.Tracking := True;
  idEvent := 0;
  try
    SetCapture(hWnd);
    idEvent := SetTimer(0, 0, 1000, @OnRepeatClickTimer);
    while GetCapture = hWnd do
    begin
      if not GetMessage(Msg, 0, 0, 0) then Break;
      if (Msg.hwnd = 0) and (Msg.message = WM_REPEAT_CLICK) then
      begin
        GetCursorPos(Pt);
        ScreenToClient(hWnd, Pt);
        if PtInRect(R, Pt) then
        begin
          RepeatClick := True;
          SendMessage(hWnd, ScrollMsg, MsgCode, 0);
          SendMessage(hWnd, ScrollMsg, SB_ENDSCROLL, 0);
          RefreshRect;
          GetSkinSB.DrawElem(hWnd, PosCode, R, True);
//          if MsgCode = SB_LINEDOWN then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) + 1, False);
          if MsgCode = SB_PAGEDOWN then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) + Integer(SI.nPage), False);
//          if MsgCode = SB_LINEUP then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) - 1, False);
          if MsgCode = SB_PAGEUP then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) - Integer(SI.nPage), False);
          RedrawScrollBars(hWnd);
          SetTimer(0, 0, 80, @OnRepeatClickTimer);
        end;
      end
      else if Msg.hwnd = hWnd then
      begin
        case Msg.message of
          WM_LBUTTONUP:
          begin
            if RepeatClick then Break;
            GetCursorPos(Pt);
            ScreenToClient(hWnd, Pt);
            if PtInRect(R, Pt) then
            begin
              SendMessage(hWnd, ScrollMsg, MsgCode, 0);
              SendMessage(hWnd, ScrollMsg, SB_ENDSCROLL, 0);
              RefreshRect;
//              if MsgCode = SB_LINEDOWN then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) + 1, False);
              if MsgCode = SB_PAGEDOWN then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) + Integer(SI.nPage), False);
//              if MsgCode = SB_LINEUP then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) - 1, False);
              if MsgCode = SB_PAGEUP then SetScrollPos(hWnd, nBarCode, GetScrollPos(hWnd, nBarCode) - Integer(SI.nPage), False);
            end;
            Break;
          end;
        end;
      end;
      DispatchMessage(Msg);
    end;
  finally
    if idEvent <> 0 then KillTimer(0, idEvent);
    if IsWindow(hWnd) then
    begin
      if GetCapture = hWnd then ReleaseCapture;
      GetSkinSB.DrawElem(hWnd, PosCode, R, False);
      GetSkinSBInfo(hWnd)^.Tracking := False;
    end;
  end;
end;
 
procedure TrackThumb(hWnd: HWND; nBarCode: Integer; PosCode: TBarPosCode; BarElem: TBarElem);
var
  BR: TBarElemRects;
  Msg: tagMSG;
  Pt: TPoint;
  DragX: Integer;
  R: TRect;
  ScrollMsg: Cardinal;
  SI, SI2: TScrollInfo;
  Pos: Integer;
  H, L, ThumbSize, X: Integer;
  Pushed: Boolean;
 
  function ValidDragArea(ARect: TRect; APt: TPoint): Boolean;
  begin
    if nBarCode = SB_HORZ then Result := Abs((ARect.Bottom + ARect.Top) div 2 - APt.Y) < 150
    else Result := Abs((ARect.Left + ARect.Right) div 2 - APt.X) < 150;
  end;
 
  function CalcPos(ARect: TRect; APt: TPoint; ADragX: Integer): Integer;
  var
    NewX: Integer;
  begin
    if nBarCode = SB_HORZ then NewX := APt.X - ADragX
    else NewX := APt.Y - ADragX;
    Result := SI.nMin + MulDiv(NewX - L, SI.nMax - Integer(SI.nPage) - SI.nMin + 1, H - L - ThumbSize);
    if Result < SI.nMin then Result := SI.nMin;
    if Result > SI.nMax - Integer(SI.nPage) + 1 then
      Result := SI.nMax - Integer(SI.nPage) + 1;
  end;
 
  procedure UpdateDragBar(ADown: Boolean; APos: Integer = -10000);
  var
    W: Integer;
  begin
    BR := CalcBarElemRects(hWnd, nBarCode);
    R := BR[BarElem];
    if nBarCode = SB_HORZ then
    begin
      if APos <> -10000 then
      begin
        W := R.Right - R.Left;
        if APos < BR[beArrow1].Right then APos := BR[beArrow1].Right;
        if APos + W > BR[beArrow2].Left then APos := BR[beArrow2].Left - W;
        R.Left := APos;
        R.Right := APos + W;
      end;
      GetSkinSB.DrawElem(hWnd, bpcHPageL, Rect(BR[beBG].Left, BR[beBG].Top, R.Left, BR[beBG].Bottom), False);
      GetSkinSB.DrawElem(hWnd, bpcHPageR, Rect(R.Right, BR[beBG].Top, BR[beBG].Right, BR[beBG].Bottom), False);
    end
    else
    begin
      if APos <> -10000 then
      begin
        W := R.Bottom - R.Top;
        if APos < BR[beArrow1].Bottom then APos := BR[beArrow1].Bottom;
        if APos + W >= BR[beArrow2].Top then APos := BR[beArrow2].Top - W - 1;
        R.Top := APos;
        R.Bottom := APos + W;
      end;
      GetSkinSB.DrawElem(hWnd, bpcVPageU, Rect(BR[beBG].Left, BR[beBG].Top, BR[beBG].Right, R.Top), False);
      GetSkinSB.DrawElem(hWnd, bpcVPageD, Rect(BR[beBG].Left, R.Bottom, BR[beBG].Right, BR[beBG].Bottom), False);
    end;
    GetSkinSB.DrawElem(hWnd, PosCode, R, ADown);
    OutputDebugString(PChar(Format('R=(%d,%d,%d,%d)', [R.Left, R.Top, R.Right, R.Bottom])));
  end;
 
begin
  BR := CalcBarElemRects(hWnd, nBarCode);
  R := BR[BarElem];
  if nBarCode = SB_HORZ then ScrollMsg := WM_HSCROLL
  else ScrollMsg := WM_VSCROLL;
  SI.cbSize := SizeOf(SI);
  SI.fMask := SIF_ALL;
  GetScrollInfo(hWnd, nBarCode, SI);
  GetCursorPos(Pt);
  ScreenToClient(hWnd, Pt);
  if nBarCode = SB_HORZ then
  begin
    DragX := Pt.X - BR[beThumb].Left;
    ThumbSize := BR[beThumb].Right - BR[beThumb].Left;
    L := BR[beArrow1].Right;
    H := BR[beArrow2].Left;
  end
  else
  begin
    DragX := Pt.Y - BR[beThumb].Top;
    ThumbSize := BR[beThumb].Bottom - BR[beThumb].Top;
    L := BR[beArrow1].Bottom;
    H := BR[beArrow2].Top;
  end;
{  if nBarCode = SB_HORZ then SendMessage(hWnd, WM_SYSCOMMAND, SC_HSCROLL, MAKELPARAM(Pt.X, Pt.Y))
  else SendMessage(hWnd, WM_SYSCOMMAND, SC_VSCROLL, MAKELPARAM(Pt.X, Pt.Y)); }
  GetSkinSBInfo(hWnd)^.Tracking := True;
  UpdateDragBar(True);
  try
    SetCapture(hWnd);
    while GetCapture = hWnd do
    begin
      if not GetMessage(Msg, 0, 0, 0) then Break;
      if Msg.hwnd = hWnd then
      begin
        case Msg.message of
          WM_MOUSEMOVE:
          begin
            Pushed := ValidDragArea(R, Pt);
            GetCursorPos(Pt);
            ScreenToClient(hWnd, Pt);
            if ValidDragArea(R, Pt) then
            begin
              Pos := CalcPos(R, Pt, DragX);
              if nBarCode = SB_HORZ then X := Pt.X - DragX
              else X := Pt.Y - DragX;
            end
            else
            begin
              Pos := SI.nPos;
              X := DragX;
            end;
            GetSkinSBInfo(hWnd)^.ThumbPos := Pos;
            GetSkinSBInfo(hWnd)^.ThumbTrack := True;
            SendMessage(hWnd, ScrollMsg, MAKEWPARAM(SB_THUMBTRACK, Pos), 0);
            GetSkinSBInfo(hWnd)^.ThumbTrack := False;
            UpdateDragBar(Pushed, X);
          end;
          WM_LBUTTONUP:
          begin
            GetCursorPos(Pt);
            ScreenToClient(hWnd, Pt);
            if ValidDragArea(R, Pt) then
            begin
              Pos := CalcPos(R, Pt, DragX);
              SI2.cbSize := SizeOf(SI2);
              SI2.fMask := SIF_ALL;
              GetScrollInfo(hWnd, nBarCode, SI2);
              SI2.nPos := Pos;
              SI2.nTrackPos := Pos;
              SetScrollInfo(hWnd, nBarCode, SI2, False);
              SI2.nTrackPos := 0;
              SI2.nPos := 0;
              GetScrollInfo(hWnd, nBarCode, SI2);
              SendMessage(hWnd, ScrollMsg, MAKEWPARAM(SB_THUMBPOSITION, Pos), 0);
              SendMessage(hWnd, ScrollMsg, SB_ENDSCROLL, 0);
            end;
            Break;
          end;
        end;
      end;
      DispatchMessage(Msg);
    end;
  finally
    if IsWindow(hWnd) then
    begin
      if GetCapture = hWnd then ReleaseCapture;
      GetSkinSBInfo(hWnd)^.Tracking := False;
    end;
    UpdateDragBar(False);
  end;
end;
 
function SkinSBWndProc(hWnd: HWND; uMsg: UINT; wParam: WPARAM; lParam: LPARAM): LRESULT;
var
  PInfo: PSkinSBInfo;
  Style, ExStyle: Cardinal;
  R, RHBar, RVBar, RCross: TRect;
  Pt: TPoint;
  Rgn, Rgn2: HRGN;
  PR: PRect;
  BR: TBarElemRects;
  XBar, YBar: Integer;
begin
  PInfo := GetSkinSBInfo(hWnd);
  if PInfo = nil then Result := DefWindowProc(hWnd, uMsg, wParam, lParam) //// error!!!
  else
  begin
    case uMsg of
      WM_NCHITTEST:
      begin
        GetCursorPos(Pt);
        ScreenToClient(hWnd, Pt);
        case GetPtBarPos(hWnd, Pt) of
          bpcHArrowL:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
                TrackBar(hWnd, SB_HORZ, bpcHArrowL, beArrow1, SB_LINELEFT);
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcHArrowR:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
                TrackBar(hWnd, SB_HORZ, bpcHArrowR, beArrow2, SB_LINERIGHT);
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcHPageL:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
              begin
                TrackBar(hWnd, SB_HORZ, bpcHPageL, beBG, SB_PAGELEFT);
                RedrawScrollBars(hWnd);
              end;
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcHPageR:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
              begin
                TrackBar(hWnd, SB_HORZ, bpcHPageR, beBG, SB_PAGERIGHT);
                RedrawScrollBars(hWnd);
              end;
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcHThumb:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
                TrackThumb(hWnd, SB_HORZ, bpcHThumb, beThumb);
            end;
            Result := HTNOWHERE;
            Exit;
          end;
 
          bpcVArrowU:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
                TrackBar(hWnd, SB_VERT, bpcVArrowU, beArrow1, SB_LINELEFT);
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcVArrowD:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
                TrackBar(hWnd, SB_VERT, bpcVArrowD, beArrow2, SB_LINERIGHT);
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcVPageU:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
              begin
                TrackBar(hWnd, SB_VERT, bpcVPageU, beBG, SB_PAGELEFT);
                RedrawScrollBars(hWnd);
              end;
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcVPageD:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
              begin
                TrackBar(hWnd, SB_VERT, bpcVPageD, beBG, SB_PAGERIGHT);
                RedrawScrollBars(hWnd);
              end;
            end;
            Result := HTNOWHERE;
            Exit;
          end;
          bpcVThumb:
          begin
            if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
            begin
              if GetCapture <> hWnd then
                TrackThumb(hWnd, SB_VERT, bpcVThumb, beThumb);
            end;
            Result := HTNOWHERE;
            Exit;
          end;
        end;
      end;
      WM_HSCROLL:
      begin
        PInfo^.Scrolling := True;
        Style := GetWindowLong(hWnd, GWL_STYLE);
        PInfo^.Style := Style;
        PInfo^.Prevent := True;
        try
          SetWindowLong(hWnd, GWL_STYLE, Style and (not (WS_VSCROLL or WS_HSCROLL)));
        finally
          PInfo^.Prevent := False;
        end;
        Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, wParam, lParam);
        RedrawScrollBars(hWnd);
        PInfo^.Prevent := True;
        try
          SetWindowLong(hWnd, GWL_STYLE, Style);
        finally
          PInfo^.Prevent := False;
        end;
        PInfo^.Scrolling := False;
        Exit;
      end;
 
      WM_VSCROLL:
      begin
        PInfo^.Scrolling := True;
        Style := GetWindowLong(hWnd, GWL_STYLE);
        PInfo^.Style := Style;
        PInfo^.Prevent := True;
        try
          SetWindowLong(hWnd, GWL_STYLE, Style and (not (WS_VSCROLL or WS_HSCROLL)));
        finally
          PInfo^.Prevent := False;
        end;
        Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, wParam, lParam);
        PInfo^.Prevent := True;
        try
          SetWindowLong(hWnd, GWL_STYLE, Style);
        finally
          PInfo^.Prevent := False;
        end;
        PInfo^.Scrolling := False;
        Exit;
      end;
      WM_STYLECHANGED:
      begin
        if wParam = GWL_STYLE then
        begin
          if PInfo^.Prevent then
          begin
            Result := 0;
            Exit;
          end
          else
          begin
            PInfo^.Style := GetWindowLong(hWnd, GWL_STYLE);
          end;
        end;
      end;
      WM_NCCALCSIZE:
      begin
        Style := GetWindowLong(hWnd, GWL_STYLE);
        ExStyle := GetWindowLong(hWnd, GWL_EXSTYLE);
        XBar := GetSystemMetrics(SM_CXVSCROLL);
        YBar := GetSystemMetrics(SM_CYHSCROLL);
        if PInfo^.Scrolling then
        begin
          PInfo^.Prevent := True;
          try
            SetWindowLong(hWnd, GWL_STYLE, Style and (not (WS_HSCROLL or WS_VSCROLL)));  // real style
          finally
            PInfo^.Prevent := False;
          end;
        end;
        Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, wParam, lParam);
        if PInfo^.Scrolling then
        begin
          PR := PRect(lParam);
          if (PInfo^.Style and WS_VSCROLL) <> 0 then
          begin
            if (ExStyle and WS_EX_LEFTSCROLLBAR) <> 0 then Inc(PR^.Left, XBar)
            else Dec(PR^.Right, XBar);
          end;
          if (PInfo^.Style and WS_HSCROLL) <> 0 then
          begin
            Dec(PR^.Bottom, YBar);
          end;
        end;
        if PInfo^.Scrolling then
        begin
          PInfo^.Prevent := True;
          try
            SetWindowLong(hWnd, GWL_STYLE, Style);  // old style
          finally
            PInfo^.Prevent := False;
          end;
        end;
        Exit;
      end;
      WM_NCPAINT:
      begin
        GetWindowRect(hWnd, R);
        Pt := R.TopLeft;
        if wParam = 1 then
        begin
          Rgn := CreateRectRgn(Pt.X, Pt.Y, Pt.X + R.Right, Pt.Y + R.Bottom);
        end else Rgn := wParam;
        RHBar := CalcScrollBarRect(hWnd, SB_HORZ);
        OffsetRect(RHBar, Pt.X, PT.Y);
        if not IsRectEmpty(RHBar) then
        begin
          BR := CalcBarElemRects(hWnd, SB_HORZ);
          GetSkinSB.DrawElem(hWnd, bpcHPageL, Rect(BR[beBG].Left, BR[beBG].Top, BR[beThumb].Left, BR[beBG].Bottom), False);
          GetSkinSB.DrawElem(hWnd, bpcHPageR, Rect(BR[beThumb].Right, BR[beBG].Top, BR[beBG].Right, BR[beBG].Bottom), False);
          GetSkinSB.DrawElem(hWnd, bpcHThumb, BR[beThumb], False);
          GetSkinSB.DrawElem(hWnd, bpcHArrowL, BR[beArrow1], False);
          GetSkinSB.DrawElem(hWnd, bpcHArrowR, BR[beArrow2], False);
        end;
        Rgn2 := CreateRectRgn(RHBar.Left, RHBar.Top, RHBar.Right, RHBar.Bottom);
        CombineRgn(Rgn, Rgn, Rgn2, RGN_DIFF);
        DeleteObject(Rgn2);
        RVBar := CalcScrollBarRect(hWnd, SB_VERT);
        if not IsRectEmpty(RVBar) then
        begin
          BR := CalcBarElemRects(hWnd, SB_VERT);
          GetSkinSB.DrawElem(hWnd, bpcVPageU, Rect(BR[beBG].Left, BR[beBG].Top, BR[beBG].Right, BR[beThumb].Top), False);
          GetSkinSB.DrawElem(hWnd, bpcVPageD, Rect(BR[beBG].Left, BR[beThumb].Bottom, BR[beBG].Right, BR[beBG].Bottom), False);
          GetSkinSB.DrawElem(hWnd, bpcVThumb, BR[beThumb], False);
          GetSkinSB.DrawElem(hWnd, bpcVArrowU, BR[beArrow1], False);
          GetSkinSB.DrawElem(hWnd, bpcVArrowD, BR[beArrow2], False);
        end;
        OffsetRect(RVBar, Pt.X, PT.Y);
        Rgn2 := CreateRectRgn(RVBar.Left, RVBar.Top, RVBar.Right, RVBar.Bottom);
        CombineRgn(Rgn, Rgn, Rgn2, RGN_DIFF);
        DeleteObject(Rgn2);
        RCross := CalcScrollBarRect(hWnd, SB_BOTH);
        if not IsRectEmpty(RCross) then
        begin
          GetSkinSB.DrawElem(hWnd, bpcCross, RCross, False);
        end;
        OffsetRect(RCross, Pt.X, PT.Y);
        Rgn2 := CreateRectRgn(RCross.Left, RCross.Top, RCross.Right, RCross.Bottom);
        CombineRgn(Rgn, Rgn, Rgn2, RGN_DIFF);
        DeleteObject(Rgn2);
        Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, Rgn, lParam);
        if wParam = 1 then DeleteObject(Rgn);
        Exit;
      end;
      WM_ERASEBKGND:
      begin
        Style := GetWindowLong(hWnd, GWL_STYLE);
        PInfo^.Prevent := True;
        try
          SetWindowLong(hWnd, GWL_STYLE, Style and (not (WS_VSCROLL or WS_HSCROLL)));
        finally
          PInfo^.Prevent := False;
        end;
 
        Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, wParam, lParam);
        PInfo^.Prevent := True;
        try
          SetWindowLong(hWnd, GWL_STYLE, Style);  // old style
        finally
          PInfo^.Prevent := False;
        end;
        Exit;
      end;
      WM_MOUSEWHEEL, WM_MOUSEMOVE:
      begin
        Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, wParam, lParam);
        if PInfo^.Tracking then Exit;
        if (uMsg = WM_MOUSEMOVE) and ((wParam and MK_LBUTTON) = 0) then Exit;
        RedrawScrollBars(hWnd);
        Exit;
      end;
    end;
    Result := CallWindowProc(@PInfo^.OldWndProc, hWnd, uMsg, wParam, lParam);
  end;
end;
 
initialization
 
  l_SkinSB := nil;
  l_SkinSB_Prop := GlobalAddAtom(SKINSB_PROP);
 
finalization
 
  if Assigned(l_SkinSB) then FreeAndNil(l_SkinSB);
 
end.
补充：使用此方法后，在调用SetScrollInfo后也必须调用RedrawScrollBars重绘滚动条。Hook本模块的SetScrollInfo API是个好方法。在这里就不给出代码了。
学习中的点点滴滴予以记载，以便以后的学习复习。本篇博客转自Lucky2011的博客(http://www.cnblogs.com/Lucky2011/)
http://www.cnblogs.com/Lucky2011/archive/2011/04/01/2002131.html
关于ListView 设置OwnerData 为 True时 Items删除节点不起作用

当ListView 设置OwnerData := True 时，再调用ListView.Items.delete(I)，是不起作用的。
在使用很多方法和查询资料的方法的也没有解决这个问题。
但是在我仔细研究listView源码后发现可以利用消息的方法删除某个节点，SendMessage(hWnd, LVM_DELETEITEM, i, 0);
在CommCtrl单元里面封装好了对listView的所有消息的的接口；
本例用到的接口如下：
function ListView_DeleteItem(hWnd: HWND; i: Integer): Bool;
学习中的点点滴滴予以记载，以便以后的学习复习。本篇博客转自Lucky2011的博客(http://www.cnblogs.com/Lucky2011/)
http://www.cnblogs.com/Lucky2011/archive/2011/04/06/2006554.html