如何将Delphi XE圆角窗口代码适配Delphi 2007并兼容Win7/8

一、适配Delphi 2007及更早版本的修改方法 #

原代码无法在Delphi 2007及更早版本编译的核心原因是命名空间差异和部分API声明兼容性问题，具体修改点如下：

1. 移除Winapi命名空间前缀
   Delphi 2007及更早版本不使用Winapi.命名空间，直接引用原始单元名：

interface
uses
  Windows; // 替换Winapi.Windows

implementation
uses
  Dwmapi; // 替换Winapi.Dwmapi

2. 手动添加缺失的API声明
   部分旧版本Delphi的Dwmapi单元未包含DwmSetWindowAttribute的声明，需在代码中手动添加函数原型：

// 在implementation段的常量定义后添加
function DwmSetWindowAttribute(hwnd: HWND; dwAttribute: DWORD; pvAttribute: Pointer; cbAttribute: DWORD): HRESULT; stdcall; external 'Dwmapi.dll';

3. 类型与常量兼容检查
   原代码中的Cardinal类型在Delphi 2007中可正常使用，所有常量定义无需修改。

修改后的完整单元代码：

unit delphi_rounded_corners;

interface
uses
  Windows;

type TRoundedWindowCornerType = (RoundedCornerDefault, RoundedCornerOff, RoundedCornerOn, RoundedCornerSmall);

procedure SetRoundedCorners(const TheHandle: HWND; const CornerType: TRoundedWindowCornerType);

implementation
uses
  Dwmapi;

const
  DWMWCP_DEFAULT    = 0; // 让系统决定是否启用圆角
  DWMWCP_DONOTROUND = 1; // 强制禁用圆角
  DWMWCP_ROUND      = 2; // 适当情况下启用圆角
  DWMWCP_ROUNDSMALL = 3; // 适当情况下启用小半径圆角

  DWMWA_WINDOW_CORNER_PREFERENCE = 33; // 控制顶级窗口圆角策略的属性ID

// 旧版Delphi需手动添加该函数声明
function DwmSetWindowAttribute(hwnd: HWND; dwAttribute: DWORD; pvAttribute: Pointer; cbAttribute: DWORD): HRESULT; stdcall; external 'Dwmapi.dll';

procedure SetRoundedCorners(const TheHandle: HWND; const CornerType: TRoundedWindowCornerType);
var
  DWM_WINDOW_CORNER_PREFERENCE: Cardinal;
begin
  case CornerType of
    RoundedCornerOff:     DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_DONOTROUND;
    RoundedCornerOn:      DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_ROUND;
    RoundedCornerSmall:   DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_ROUNDSMALL;
  else
    DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_DEFAULT;
  end;
  DwmSetWindowAttribute(TheHandle, DWMWA_WINDOW_CORNER_PREFERENCE, @DWM_WINDOW_CORNER_PREFERENCE, sizeof(DWM_WINDOW_CORNER_PREFERENCE));
 end;
end.

二、Windows 7/8的兼容处理：必须动态调用DLL #

Windows 7和8的DWM组件不支持DWMWA_WINDOW_CORNER_PREFERENCE（属性ID33），直接调用会返回运行时错误，因此必须通过动态加载DLL+系统版本判断实现兼容，修改方案如下：

unit delphi_rounded_corners;

interface
uses
  Windows;

type TRoundedWindowCornerType = (RoundedCornerDefault, RoundedCornerOff, RoundedCornerOn, RoundedCornerSmall);

procedure SetRoundedCorners(const TheHandle: HWND; const CornerType: TRoundedWindowCornerType);

implementation

type
  TDwmSetWindowAttribute = function(hwnd: HWND; dwAttribute: DWORD; pvAttribute: Pointer; cbAttribute: DWORD): HRESULT; stdcall;

const
  DWMWCP_DEFAULT    = 0;
  DWMWCP_DONOTROUND = 1;
  DWMWCP_ROUND      = 2;
  DWMWCP_ROUNDSMALL = 3;

  DWMWA_WINDOW_CORNER_PREFERENCE = 33;

procedure SetRoundedCorners(const TheHandle: HWND; const CornerType: TRoundedWindowCornerType);
var
  hDwmApi: HMODULE;
  DwmSetWindowAttribute: TDwmSetWindowAttribute;
  DWM_WINDOW_CORNER_PREFERENCE: Cardinal;
  OSVersionInfo: TOSVersionInfo;
begin
  // 仅在Windows 11及以上版本执行圆角设置（Win11内部版本号从22000开始）
  OSVersionInfo.dwOSVersionInfoSize := SizeOf(TOSVersionInfo);
  GetVersionEx(OSVersionInfo);
  if (OSVersionInfo.dwMajorVersion < 10) or (OSVersionInfo.dwMajorVersion = 10) and (OSVersionInfo.dwBuildNumber < 22000) then
    Exit;

  // 动态加载Dwmapi.dll
  hDwmApi := LoadLibrary('Dwmapi.dll');
  if hDwmApi = 0 then Exit;
  try
    @DwmSetWindowAttribute := GetProcAddress(hDwmApi, 'DwmSetWindowAttribute');
    if Assigned(DwmSetWindowAttribute) then
    begin
      case CornerType of
        RoundedCornerOff:     DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_DONOTROUND;
        RoundedCornerOn:      DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_ROUND;
        RoundedCornerSmall:   DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_ROUNDSMALL;
      else
        DWM_WINDOW_CORNER_PREFERENCE := DWMWCP_DEFAULT;
      end;
      DwmSetWindowAttribute(TheHandle, DWMWA_WINDOW_CORNER_PREFERENCE, @DWM_WINDOW_CORNER_PREFERENCE, sizeof(DWM_WINDOW_CORNER_PREFERENCE));
    end;
  finally
    FreeLibrary(hDwmApi);
  end;
end;
end.

关键说明 #

• 通过系统版本判断，仅在Win11及以上版本执行圆角逻辑，避免Win7/8下的无效调用
• 动态加载Dwmapi.dll，避免静态链接导致的Win7/8下DLL加载失败问题
• 即使在Win11环境中，若函数获取失败（极端情况），也不会影响程序正常运行

内容的提问来源于stack exchange，提问作者Tom