queryperffrequ.pas

DelphiWin32核心API参考光盘内容.是学习书籍中的源码,便于学习.

unit QueryPerfFreqU;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  PerformanceFrequency: TLargeInteger;
begin
  {if there is a high resolution performance counter in the hardware...}
  if QueryPerformanceFrequency(PerformanceFrequency) then
    begin
      {...display its frequency...}
      Label1.Caption := 'Performance Frequency Present';
      Label2.Caption := 'Frequency: ' + IntToStr(PerformanceFrequency);
    end
  else
    begin
      {...or display a message}
      Label1.Caption := 'Performance Frequency Not Present';
      Label2.Caption := '';
    end;
end;

end.