apicaller.pas

来自「delphi开发语言下的源代码分析」· PAS 代码 · 共 42 行

unit ApiCaller;

interface

uses
  Windows, SysUtils;

resourcestring
  SApiCallerError = 'Api Call Error: %s (%d)';

type
  EApiCaller = class(Exception);
  TApiCaller = class
  protected
    procedure CheckThreadError(ErrCode: Integer); overload;
    procedure CheckThreadError(Success: Boolean); overload;
  public
    function GetDC(hwnd: HWND) : HDC;
    // ... 更多的API
  end;

implementation

procedure TApiCaller.CheckThreadError(ErrCode: Integer);
begin
  if ErrCode <> 0 then
    raise EApiCaller.CreateResFmt(@SApiCallerError, [SysErrorMessage(ErrCode), ErrCode]);
end;

procedure TApiCaller.CheckThreadError(Success: Boolean);
begin
  if not Success then
    CheckThreadError(GetLastError);
end;

function TApiCaller.GetDC(hwnd: HWND) : HDC;
begin
  Result := windows.GetDC(hwnd);
  CheckThreadError(Result <> 0);
end;

end.