windows - SPI_SETDISABLEOVERLAPPEDCONTENT

Question

我有功能

function bgSetDisableOverlappedContent(CAA: BOOL; var ErrorCode: DWORD; ErrorText: string): Boolean;  
begin
  errorCode := ERROR_SUCCESS;
  ErrorText := '';  
  if not GetOSVersion >= 60 then
    Exit;
  Result := SystemParametersInfo(SPI_SETDISABLEOVERLAPPEDCONTENT, 0, @CAA, 0);
  if not Result then
  begin
    ErrorCode := GetLastError;
    ErrorText := GetErrorText(ErrorCode);
  end;
end;

并准确地调用它

procedure TForm1.Button3Click(Sender: TObject);
var
  CAA: BOOL;
  OS: TUsableInOS;
  ErrorCode: DWORD;
  ErrorText: string;
begin
  CAA := False;
  if bgSetDisableOverlappedContent(CAA, ErrorCode, ErrorText) then
    ShowMessage('Success');
end;

但是，当我再次检查下一个代码时

function bgGetDisableOverlappedContent(var CAA: BOOL; OS: TUsableInOS; ErrorCode: DWORD; ErrorText: string): Boolean;
begin
  errorCode := ERROR_SUCCESS;
  ErrorText := '';
  os := tosVistaUp;   
  if not GetOSVersion >= 60 then
    Exit;   
  Result := SystemParametersInfo(SPI_GETDISABLEOVERLAPPEDCONTENT, 0, @CAA, 0);   
  if not Result then
  begin
    ErrorCode := GetLastError;
    ErrorText := GetErrorText(ErrorCode);
  end;
end;
function GetOSVersion: Integer;
var
  OSVersionInfo : TOSVersionInfo;
begin
  Result:= 0;
  FillChar(OsVersionInfo, Sizeof(OsVersionInfo), 0);
  OSVersionInfo.dwOSVersionInfoSize := SizeOf(OSVersionInfo);
  if GetVersionEx(OSVersionInfo) then
  begin
    if OSVersionInfo.dwPlatformId = VER_PLATFORM_WIN32_NT then
    begin
      if (OsVersionInfo.dwMajorVersion = 5) and ((OsVersionInfo.dwMinorVersion = 0)) then
         Result:= 50; //2000
      if (OsVersionInfo.dwMajorVersion = 5) and ((OsVersionInfo.dwMinorVersion = 1)) then
         Result:= 51; //XP
      if (OsVersionInfo.dwMajorVersion = 5) and ((OsVersionInfo.dwMinorVersion = 2)) then
         Result:= 52; //2003, 2003 R2
      if (OsVersionInfo.dwMajorVersion = 6) and ((OsVersionInfo.dwMinorVersion = 0)) then
         Result:= 60; //Vista, Windows Server 2008
      if (OsVersionInfo.dwMajorVersion = 6) and ((OsVersionInfo.dwMinorVersion = 1)) then
         Result:= 61; //Server 2008 R2, 7
    end;
  end;
end;

CAA 的结果再次为真，即使我完全设置了 CAA := False；我正在使用 Win 7。Result of Result := SystemParametersInfo(SPI_SETDISABLEOVERLAPPEDCONTENT, 0, @CAA, 0);是 True，但 SPI_GETDISABLEOVERLAPPEDCONTENT 为 CAA 返回 True，即使在它被设置为 False 之前的步骤中也是如此。

procedure TForm1.Button3Click(Sender: TObject);
var
  CAA: BOOL;
  OS: TUsableInOS;
  ErrorCode: DWORD;
  ErrorText: string;
  Res: Bool;
begin
  CAA := False;
{  if bgSetDisableOverlappedContent(CAA, ErrorCode, ErrorText) then
    ShowMessage('Success'); }
  Res := SystemParametersInfo(SPI_SETDISABLEOVERLAPPEDCONTENT,
                                 0,
                                 @CAA,
                                 0);

  Res := SystemParametersInfo(SPI_GETDISABLEOVERLAPPEDCONTENT,
                                 0,
                                 @CAA,
                                 0);
  if Caa then
    ShowMessage('True')
  else
    ShowMessage('False');
end;

CAA 是正确的。

你有什么想法吗？

提前致谢博扬

Answer 1

主要问题是，当传递 SPI_SETDISABLEOVERLAPPEDCONTENT 时，您打算传递一个 BOOL 变量，但您传递的是一个指向 BOOL 的指针. documentation说:

The pvParam parameter is a BOOL variable. Set pvParam to TRUE to disable overlapped content, or FALSE to enable overlapped content.

这意味着您设置属性的代码需要像这样:

SystemParametersInfo(SPI_SETDISABLEOVERLAPPEDCONTENT, 0, Pointer(CAA), 0)

---

您的 GetOSVersion 是一场灾难。抱歉听起来很刺耳!对于 Windows 8 及更高版本，它返回 0。而且您的代码在运算符优先级方面存在问题。你写:

if not GetOSVersion >= 60 then

and operator precedence means that is interpreted as

if (not GetOSVersion) >= 60 then

由于 GetOSVersion 返回一个带符号的值，(not GetOSVersion) >= 60 的计算结果为 False，与 Windows 版本无关。那是因为 not GetOSVersion 总是 <= 0。

您需要逻辑否定而不是按位否定。所以你应该写

if not (GetOSVersion >= 60) then

或等效

if GetOSVersion < 60 then

实际上有一个内置函数可以做到这一点。它称为 CheckWin32Version。像这样调用它:

if not CheckWin32Version(6, 0) then
  exit;

---

你的函数的其余部分有点乱。您按值传递 ErrorText，然后分配给它。大概您打算调用者接收该值。除非您通过 var，否则不会发生这种情况。

我个人会像这样编写您的程序:

procedure bgSetDisableOverlappedContent(CAA: BOOL);
begin
  if CheckWin32Version(6, 0) then
    if not SystemParametersInfo(SPI_SETDISABLEOVERLAPPEDCONTENT, 0, Pointer(CAA), 0) then
      RaiseLastOSError;
end;

我认为最好将 SystemParametersInfo 中的错误转换为异常，因为这是一种特殊情况。我反对你实际生成对 SystemParametersInfo 的调用失败。在这种情况下，没有必要为根本不会发生的事情构建错误代码返回机制。检查错误并转换为运行时异常。这使得调用代码变得非常简单。

您的按钮点击处理程序可以更简单:

procedure TForm1.Button3Click(Sender: TObject);
begin
  bgSetDisableOverlappedContent(False);
end;

而且 getter 函数也比必要的复杂得多。我会这样:

function bgGetDisableOverlappedContent: Boolean;
var
  CAA: BOOL;
begin
  if not CheckWin32Version(6, 0) then
  begin
    Result := False;//or True, I don't know, you decide
    exit;
  end;
  if not SystemParametersInfo(SPI_GETDISABLEOVERLAPPEDCONTENT, 0, @CAA, 0) then
    RaiseLastOSError;
  Result := CAA;
end;