Delphi - 检测同时按下3个键

Question

我想检测在表单中按下 3 个键，例如 Ctrl+C+N...我需要输入的表单检测始终以 Ctrl 开头，接下来是两个字母。

我该怎么做？

Answer 1

其中一个键到达后，您可以查看另一个键是否已按下。例如:

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if Shift = [ssCtrl] then begin
    case Key of
      Ord('C'):
        if (GetKeyState(Ord('N')) and $80) = $80 then
          ShowMessage('combo');
      Ord('N'):
        if (GetKeyState(Ord('C')) and $80) = $80 then
          ShowMessage('combo');
    end;
  end;
end;

但是，这也会检测例如 N+Ctrl+C，一个不以 < 开头的序列kbd>Ctrl 键。如果这不符合有效的按键组合，您可以借助标志来保留一些按键历史记录。以下内容应仅检测最初以 Ctrl 开头的序列:

type
  TForm1 = class(TForm)
    procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
    procedure FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
  private
    FValidKeyCombo: Boolean;
  end;

...

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if FValidKeyCombo and (Shift = [ssCtrl]) then
    case Key of
      Ord('C'):
        if (GetKeyState(Ord('N')) and $80) = $80 then
          ShowMessage('combo');
      Ord('N'):
        if (GetKeyState(Ord('C')) and $80) = $80 then
          ShowMessage('combo');
    end;
  FValidKeyCombo := (Shift = [ssCtrl]) and (Key in [Ord('C'), Ord('N')]);
end;

procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
  FValidKeyCombo := False;
end;