拦截TAB键并禁止它

Question

我需要拦截TEdits上的TAB键盘笔划并以编程方式抑制它们.在某些情况下,我不希望焦点转移到下一个控件.

我尝试在TEdit级别和TForm上使用KeyPreview = true处理KeyPress,KeyDown.我偷看了以下建议:

• 在RichEdit中拦截TAB键
• 如何在不丢失当前位置的情况下使TAB键关闭TComboBox？

但它没有用.事件被触发,比方说,输入键但不是TAB键.

我正在使用Delphi 7.感谢您的帮助.

Answer 1

如果要拦截TAB键行为,则应捕获该CM_DIALOGKEY消息.在此示例中,如果将YouWantToInterceptTab布尔值设置为True,TAB则将使用该键:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
  private
    YouWantToInterceptTab: Boolean;
    procedure CMDialogKey(var AMessage: TCMDialogKey); message CM_DIALOGKEY;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.CMDialogKey(var AMessage: TCMDialogKey);
begin
  if AMessage.CharCode = VK_TAB then
  begin
    ShowMessage('TAB key has been pressed in ' + ActiveControl.Name);

    if YouWantToInterceptTab then
    begin
      ShowMessage('TAB key will be eaten');
      AMessage.Result := 1;
    end
    else
      inherited;        
  end
  else
    inherited;
end;

end.