Delphi 放大api：尺寸与实际尺寸不成比例的屏幕截图

我有下面这段代码，在示例中，在没有主窗体的情况下，它可以很好地用于屏幕捕获

我的问题是，结果截图在右侧被剪切，在左侧被扩展，例如，测试此代码以捕获打开SO网站时的整个桌面：

正如您所看到的，垂直滚动条可以在两侧（左侧和右侧）看到

我怎样才能解决这个问题

以下是完整的示例：

type
  TForm1 = class(TForm)
    CAPTURE: TButton;
    SaveFileDialog1: TSaveDialog;
    procedure FormCreate(Sender: TObject);
    procedure CAPTUREClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses
  Magnification;

{$R *.dfm}

function HostWndProc(hWindow: HWND; Msg: UINT; wParam: wParam; lParam: lParam)
  : LRESULT; stdcall;
begin
  Result := DefWindowProc(hWindow, Msg, wParam, lParam);
end;

var
  MyBMP: TBitmap;
  abitmap: HBitmap;
  desktoprect: TRect;
  hWndMag: HWND;
  CallbackDone: Boolean = False;

function MagImageScalingCallback(HWND: HWND; srcdata: Pointer;
  srcheader: MAGIMAGEHEADER; destdata: Pointer; destheader: MAGIMAGEHEADER;
  unclipped: TRect; clipped: TRect; dirty: HRGN): BOOL; stdcall;
var
  lpbmi: TBitmapInfo;
  aDC: HDC;
begin

  Fillchar(lpbmi, sizeof(lpbmi), 0);
  lpbmi.bmiHeader.biSize := sizeof(lpbmi.bmiHeader);
                              // (-) Otherwise the image is upside down.
  lpbmi.bmiHeader.biHeight := -srcheader.height;
  lpbmi.bmiHeader.biWidth := srcheader.width;
  lpbmi.bmiHeader.biSizeImage := srcheader.cbSize;
  lpbmi.bmiHeader.biPlanes := 1;
  lpbmi.bmiHeader.biBitCount := 32;
  lpbmi.bmiHeader.biCompression := BI_RGB;

  aDC := GetWindowDC(HWND);
  MyBMP := TBitmap.Create;
  abitmap := 0;
  try
    abitmap := CreateDIBitmap(aDC, lpbmi.bmiHeader, CBM_INIT, srcdata, lpbmi,
      DIB_RGB_COLORS);
    MyBMP.handle := abitmap;

    CallbackDone := True;

  finally
    DeleteDC(aDC);
  end;

  Result := True;
end;

procedure TForm1.CAPTUREClick(Sender: TObject);
var
  filterList: THWNDArray;
  sourceRect: TRect;
begin
  filterList[0] := Form1.handle;

  If (MagSetWindowFilterList(hWndMag, MW_FILTERMODE_EXCLUDE, 1,
    @filterList[0])) Then
  begin

    sourceRect.left := 0;
    sourceRect.top := 0;
    sourceRect.right := desktoprect.width;
    sourceRect.bottom := desktoprect.height;

    CallbackDone := False;

    If (MagSetWindowSource(hWndMag, sourceRect)) Then
      Screen.Cursor := crHourGlass;

    repeat

    until CallbackDone;

    Screen.Cursor := crDefault;

    SaveFileDialog1.Title := 'Save Image File';
    SaveFileDialog1.Filter := 'JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif|Png Image|*.png';
    SaveFileDialog1.DefaultExt := 'bmp';
    SaveFileDialog1.FilterIndex := 2;
    SaveFileDialog1.InitialDir := GetCurrentDir;

    if SaveFileDialog1.Execute then
    begin
      MyBMP.SaveToFile(SaveFileDialog1.FileName);
      MessageDlg('File saved: ' + SaveFileDialog1.FileName, mtInformation,
        [mbOK], 0);
    end
    else
      MessageDlg('Save file was cancelled', mtWarning, [mbOK], 0);

    DeleteObject(abitmap);
    MyBMP.Free;
  end;

end;

procedure TForm1.FormCreate(Sender: TObject);
const
  HOST_CLASSNAME = 'MagnifierHost';
var
  wc: TWndClass;
  hWndHost, desktop: HWND;
begin

 hWndHost := 0;

  wc.lpszClassName := HOST_CLASSNAME;
  wc.lpfnWndProc := @HostWndProc;
  wc.Style := 0;
  wc.hInstance := 0;
  wc.hIcon := 0;
  wc.hCursor := 0;
  wc.hbrBackground := 0;
  wc.lpszMenuName := nil;
  wc.cbClsExtra := 0;
  wc.cbWndExtra := 0;

  desktop := GetDesktopWindow;
  GetWindowRect(desktop, desktoprect);

  if (Winapi.Windows.RegisterClass(wc) <> 0) then

    hWndHost := CreateWindowEx(WS_EX_TOPMOST Or WS_EX_LAYERED Or
      WS_EX_TOOLWINDOW, HOST_CLASSNAME, 'Host Window',
      WS_POPUP Or WS_THICKFRAME Or WS_CLIPCHILDREN, 0, 0, desktoprect.width,
      desktoprect.height, 0, 0, hInstance, nil);

  if (hWndHost <> 0) then
    SetLayeredWindowAttributes(hWndHost, 0, 255, LWA_ALPHA);

  If (MagInitialize) Then
    hWndMag := CreateWindowEx(0, WC_MAGNIFIER, 'MagnifierWindow',
      WS_CHILD Or MS_SHOWMAGNIFIEDCURSOR Or WS_VISIBLE, 0, 0, desktoprect.width,
      desktoprect.height, hWndHost, 0, 0, nil);

  If (hWndMag = 0) Then
    ShowMessage(SysErrorMessage(GetLastError));

  if (MagSetImageScalingCallback(hWndMag, MagImageScalingCallback)) then
    {ShowMessage('MagSetImageScalingCallback registred!'};

  Left := (GetSystemMetrics(SM_CXSCREEN) - width) div 2;
  Top := (GetSystemMetrics(SM_CYSCREEN) - height) div 2;
end;

end.

---

已解决：

 hWndHost := CreateWindowEx(WS_EX_TOPMOST or WS_EX_LAYERED or 
                            WS_EX_TRANSPARENT, HOST_CLASSNAME, 'Host Window',
                            WS_POPUP or WS_CLIPCHILDREN, 0, 0,
                            desktoprect.width, desktoprect.height,
                            0, 0, hInstance, nil);

 hWndHost := CreateWindowEx(WS_EX_TOPMOST or WS_EX_LAYERED or 
                            WS_EX_TRANSPARENT, HOST_CLASSNAME, 'Host Window',
                            WS_POPUP or WS_CLIPCHILDREN, 0, 0,
                            desktoprect.width, desktoprect.height,
                            0, 0, hInstance, nil);