如何在我的TEdit控件中捕获VK_TAB键并且不让它失去焦点？

Question

在我的TEdit字段中,我在表单中有文本<number1>..<number2>.

我的想法是:

当用户使用TAB另一个控件输入控件时,number1将被选中.

当我的TEdit控件有焦点并且用户TAB再次按下时,我想要number2选择并number1取消选择.

如果当前插入位置位于number2所在的位置,则按下TAB应该正常并将焦点移动到表单上的下一个控件.

我有2个问题.

1. 当"编辑"字段已激活时,我无法按下Tab键.我只能在输入/聚焦此控件时捕获它.

2. 我不知道是否有类似于#0的键,所以我可以把钥匙变成NoOP.

有什么想法,怎么做？

Answer 1

您最好编写自己的TEdit后代来处理WM_GETDLGCODE消息.一般的想法是:

unit Unit1;

interface

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

type
  TMyEdit = class(TEdit)
    procedure WMGetDlgCode(var Message: TWMGetDlgCode); message WM_GETDLGCODE;
  end;

type
  TForm1 = class(TForm)
    Edit2: TEdit;
    procedure FormCreate(Sender: TObject);
    procedure FormKeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
    FMyEdit: TMyEdit;
    FDone: Boolean;
    procedure MyEditEnter(Sender: TObject);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyEdit }

procedure TMyEdit.WMGetDlgCode(var Message: TWMGetDlgCode);
begin
  inherited;
  Message.Result:= Message.Result or DLGC_WANTTAB;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  FMyEdit:= TMyEdit.Create(Self);
  FMyEdit.Left:= 40;
  FMyEdit.Top:= 40;
  FMyEdit.Parent:= Self;
  FMyEdit.Text:= '45..90';
  FMyEdit.OnEnter:= MyEditEnter;
  KeyPreview:= True;
end;

procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char);
begin
  if (Key = #9) and (ActiveControl = FMyEdit) then begin
    if FDone then begin
      Perform(CM_DialogKey, VK_TAB, 0);
    end
    else begin
      FMyEdit.SelStart:= 4;
      FMyEdit.SelLength:= 2;
    end;
    FDone:= not FDone;
    Key:= #0;
  end;
end;

procedure TForm1.MyEditEnter(Sender: TObject);
begin
  FDone:= False;
  FMyEdit.SelStart:= 0;
  FMyEdit.SelLength:= 2;
end;

end.

更新:没有制作TEdit后代类的相同想法:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    procedure Edit2Enter(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormKeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
    FDone: Boolean;
    FOldWndProc: TWndMethod;
    procedure Edit2WindowProc(var Message: TMessage);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Edit2Enter(Sender: TObject);
begin
  FDone:= False;
  Edit2.SelStart:= 0;
  Edit2.SelLength:= 2;
end;

procedure TForm1.Edit2WindowProc(var Message: TMessage);
begin
  if Message.Msg = WM_GETDLGCODE then
    Message.Result:= Message.Result or DLGC_WANTTAB
  else
    if Assigned(FOldWndProc) then FOldWndProc(Message);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  KeyPreview:= True;
  Edit2.Text:= '45..90';
  FOldWndProc:= Edit2.WindowProc;
  Edit2.WindowProc:= Edit2WindowProc;
end;

procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char);
begin
  if (Key = #9) and (ActiveControl = Edit2) then begin
    if FDone then begin
      Perform(CM_DialogKey, VK_TAB, 0);
    end
    else begin
      Edit2.SelStart:= 4;
      Edit2.SelLength:= 2;
    end;
    FDone:= not FDone;
    Key:= #0;
  end;
end;

end.