如何在 Delphi 屏幕键盘窗体中使用窗口焦点消息

Question

我的应用程序中需要一个内置的屏幕数字键盘。由于各种原因，我无法使用 TMS 软件 或其他商业组件产品。我对下面所示的基于按钮的解决方案感到非常满意，但我还不知道如何解决焦点切换问题，即单击按钮会激活键盘表单，并且我失去了我想要的角色的焦点控制。如果我将键盘按钮保留在目标表单内，我的解决方案就有效，但我想要一个独立于表单的解决方案。有没有办法禁用按钮激活或知道焦点来自哪里，以便我可以使用类似 Scree.ActiveControl :=?? 的东西？把它放回去？

Answer 1

您可以在键盘上使用 TSpeedButton 来执行此任务。 TSpeedButton 不支持 Focus。但表格确实如此。这很丑陋，即使你将焦点放回主窗体，焦点也会在两个窗体之间闪烁。所以我会尝试创建一个没有焦点的表单。

名为 WS_EX_NOACTIVATE 的标志可用于创建一个窗口（窗体），当用户单击它时，该窗口不会成为前台窗口。此外，当用户最小化或关闭前台窗口时，系统不会将此窗口置于前台。

要创建不可激活的窗体，请重写 CreateParams 方法：

procedure TMainForm.CreateParams(var Params: TCreateParams) ;
 //const WS_EX_NOACTIVATE = $8000000;
 begin
   inherited;
   Params.ExStyle := Params.ExStyle + WS_EX_NOACTIVATE;
 end;

当 Delphi 创建窗体时，Create 方法调用 CreateWindowEx API 函数来创建实际的窗口。

在执行 CreateWindowEx 之前，会调用 CreateParams 方法 - CreateParams 允许您在创建窗口时更改窗口的默认样式以满足您的特定需要。

Answer 2

我不知道如何创建带有框架的窗口，当您单击它时，该框架无法聚焦，因此下面的窗口是无边框的。正如 Andreas 提到的，使用 TSpeedButtons。

type
  TKeypadForm = class(TForm)
    SpeedButton1: TSpeedButton;
    procedure SpeedButton1Click(Sender: TObject);
  private
    procedure CreateParams(var Params: TCreateParams); override;
    procedure WMMouseActivate(var Message: TWMMouseActivate); message WM_MOUSEACTIVATE;
  end;

procedure TKeypadForm.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  Params.Style := WS_POPUP or WS_THICKFRAME;
end;

procedure TKeypadForm.WMMouseActivate(var Message: TWMMouseActivate);
begin
  Message.Result := MA_NOACTIVATE;
end;

procedure TKeypadForm.SpeedButton1Click(Sender: TObject);
begin
  PostMessage(GetFocus, WM_KEYDOWN, VK_NUMPAD1, MakeLong(0, MapVirtualKey(VK_NUMPAD1, 0)));
end;

这是显示键盘窗口的方法

procedure TForm18.Edit1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  case Key of
    VK_RETURN: ShowWindow(KeypadForm.Handle, SW_SHOWNOACTIVATE);
    VK_ESCAPE: ShowWindow(KeypadForm.Handle, SW_HIDE);
  end;
end;

Answer 3

我的最终解决方案如下。这将创建一个带有边框的数字键盘，并且 - 是的 - 如果单击边框或调整大小，它确实会激活，但单击按钮不会窃取目标窗体/控件的焦点。简单地使用 CreateParams 对我来说不起作用 - 它似乎需要 WMMouseActivate 消息。

我将其与我发现的例程结合起来，该例程将密钥发布到操作系统，而不仅仅是集中控制。请注意，下面的代码假设来自祖先表单的一些简单支持用于设置默认大小和位置。感谢您的帮助。

unit UArtScreenKeyboardForm;

interface

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

type
  TArtScreenKeyboardForm = class(TArtBaseForm)
    procedure FormShow(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormCreate(Sender: TObject);
    procedure WMMouseActivate(var Message: TWMMouseActivate); message WM_MOUSEACTIVATE;
    procedure FormResize(Sender: TObject);
  private
    { Private declarations }
    procedure DoOnbuttonClick(ASender: TObject);
    procedure DrawButtons;
  protected
    procedure SetDefaultSizeAndPosition; override;
  public
    { Public declarations }
  end;



procedure ArtScreenKeyboardForm_Show;
procedure ArtScreenKeyboardForm_Hide;


implementation

{$R *.DFM}

uses
  UArtLibrary;

type
  TButtonKind = (
    bk0,
    bk1,
    bk2,
    bk3,
    bk4,
    bk5,
    bk6,
    bk7,
    bk8,
    bk9,
    bkPlus,
    bkMinus,
    bkDel,
    bkDiv,
    bkMul,
    bkEquals,
    bkDecPt,
    bkEnter );

const
  ButtonCaptions : array[TButtonKind] of string = (
    '0',
    '1',
    '2',
    '3',
    '4',
    '5',
    '6',
    '7',
    '8',
    '9',
    '+',
    '-',
    'Back',
    '/',
    '*',
    '=',
    '.',
    'Enter' );

  ScanCodes : array[TButtonKind] of cardinal = (
    Ord( '0' ),
    Ord( '1' ),
    Ord( '2' ),
    Ord( '3' ),
    Ord( '4' ),
    Ord( '5' ),
    Ord( '6' ),
    Ord( '7' ),
    Ord( '8' ),
    Ord( '9' ),
    VK_ADD,
    VK_SUBTRACT,
    8, {BACKSPACE}
    VK_DIVIDE,
    VK_MULTIPLY,
    Ord( '=' ),
    Ord( '.' ),
    VK_RETURN );


var
  ArtScreenKeyboardForm: TArtScreenKeyboardForm = nil;


procedure PostKeyEx32(key: Word; const shift: TShiftState; specialkey: Boolean) ;
 {
Parameters :
* key : virtual keycode of the key to send. For printable keys this is simply the ANSI code (Ord(character)) .
* shift : state of the modifier keys. This is a set, so you can set several of these keys (shift, control, alt, mouse buttons) in tandem. The TShiftState type is declared in the Classes Unit.
* specialkey: normally this should be False. Set it to True to specify a key on the numeric keypad, for example.

Description:
Uses keybd_event to manufacture a series of key events matching the passed parameters. The events go to the control with focus. Note that for characters key is always the upper-case version of the character. Sending without any modifier keys will result in a lower-case character, sending it with [ ssShift ] will result in an upper-case character!
}
type
  TShiftKeyInfo = record
    shift: Byte ;
    vkey: Byte ;
  end;

  ByteSet = set of 0..7 ;

const
  shiftkeys: array [1..3] of TShiftKeyInfo =
    ((shift: Ord(ssCtrl) ; vkey: VK_CONTROL),
    (shift: Ord(ssShift) ; vkey: VK_SHIFT),
    (shift: Ord(ssAlt) ; vkey: VK_MENU)) ;
var
  flag: DWORD;
  bShift: ByteSet absolute shift;
  j: Integer;
begin
  for j := 1 to 3 do
  begin
    if shiftkeys[j].shift in bShift then
      keybd_event(shiftkeys[j].vkey, MapVirtualKey(shiftkeys[j].vkey, 0), 0, 0) ;
  end;
  if specialkey then
    flag := KEYEVENTF_EXTENDEDKEY
  else
    flag := 0;

 keybd_event(key, MapvirtualKey(key, 0), flag, 0) ;
  flag := flag or KEYEVENTF_KEYUP;
  keybd_event(key, MapvirtualKey(key, 0), flag, 0) ;

 for j := 3 downto 1 do
  begin
    if shiftkeys[j].shift in bShift then
      keybd_event(shiftkeys[j].vkey, MapVirtualKey(shiftkeys[j].vkey, 0), KEYEVENTF_KEYUP, 0) ;
  end;
end;




procedure TArtScreenKeyboardForm.DoOnbuttonClick(ASender: TObject);
var
  Btn : TSpeedButton;
  Kind : TButtonKind;
begin
  Btn := ASender as TSpeedButton;
  Kind := TButtonKind(StrToIntDef( Copy( Btn.Name, 4, MaxStrLen ), 0 ));
  PostKeyEx32( ScanCodes[Kind], [], False );

  // As suggested also:
  //PostMessage(GetFocus, WM_KEYDOWN, Ord('A'), 0 );
  // PostMessage(GetFocus, WM_KEYDOWN, VK_NUMPAD1, MakeLong(0, MapVirtualKey(VK_NUMPAD1, 0)));



end;



procedure TArtScreenKeyboardForm.WMMouseActivate(var Message: TWMMouseActivate);
begin
  Message.Result := MA_NOACTIVATE;
end;

procedure ArtScreenKeyboardForm_Show;
begin
  If ArtScreenKeyboardForm = nil then
    begin
    ArtScreenKeyboardForm := TArtScreenKeyboardForm.Create( Application );
    ArtScreenKeyboardForm.Show;
    end;

 Application.ProcessMessages;
end;





procedure ArtScreenKeyboardForm_Hide;
begin
 If ArtScreenKeyboardForm <> nil then
   begin
   ArtScreenKeyboardForm.Free;
   ArtScreenKeyboardForm := nil;
   end;
end;


procedure TArtScreenKeyboardForm.FormShow(Sender: TObject);
begin
  DrawButtons;
end;

procedure TArtScreenKeyboardForm.SetDefaultSizeAndPosition;
begin
  inherited;
  Width := 300;
  PlaceControl( Self, cpWorkAreaTopLeft );
end;

procedure TArtScreenKeyboardForm.FormClose(Sender: TObject;
  var Action: TCloseAction);
begin
  Action := caFree;
  ArtScreenKeyboardForm := nil;
end;


procedure TArtScreenKeyboardForm.FormCreate(Sender: TObject);
begin
  Constraints.MinWidth  := 200;
  Constraints.MinHeight := (120 * 5)  div 4;
end;


procedure TArtScreenKeyboardForm.DrawButtons;

  procedure AddButton( ATop, ALeft, AWidth, AHeight : integer; AKind : TButtonKind );

    function WidthPix( AValue : integer ) : integer;
    begin
      Result := AValue * (ClientWidth div 4);
    end;

    function HeightPix( AValue : integer ) : integer;
    begin
      Result := AValue * (ClientHeight div 5);
    end;

  var
    Button : TSpeedButton;
  begin
    Button := TSpeedButton.Create( Self );
    Button.Parent := Self;

    Button.Left := WidthPix( ALeft );
    Button.Top  := HeightPix( ATop );
    Button.Width := WidthPix( AWidth );
    Button.Height := HeightPix( AHeight );
    Button.Visible := True;

    Button.Name := Format( 'btn%d', [Ord( AKind )] );
    Button.Caption := ButtonCaptions[ AKind ];

    button.OnClick := DoOnbuttonClick;
  end;



var
  I : integer;
begin
  Height := (Width * 5) div 4;

  ApplyScreenIconTitleFontToFont( Font );

  Font.Size := Font.Size + ((Height-250) div 30);

  Font.Style := Font.Style + [fsBold];
  Font.Color := clGray;

  For I := ComponentCount-1 downto 0 do
    If Components[I] is TSpeedButton then
      Components[I].Free;

  Addbutton( 0, 0, 1, 1, bkDel      );
  Addbutton( 0, 1, 1, 1, bkEquals   );
  Addbutton( 0, 2, 1, 1, bkDiv      );
  Addbutton( 0, 3, 1, 1, bkMul      );

  Addbutton( 1, 0, 1, 1, bk7        );
  Addbutton( 1, 1, 1, 1, bk8        );
  Addbutton( 1, 2, 1, 1, bk9        );
  Addbutton( 1, 3, 1, 1, bkMinus    );

  Addbutton( 2, 0, 1, 1, bk4        );
  Addbutton( 2, 1, 1, 1, bk5        );
  Addbutton( 2, 2, 1, 1, bk6        );
  Addbutton( 2, 3, 1, 1, bkPlus     );

  Addbutton( 3, 0, 1, 1, bk1        );
  Addbutton( 3, 1, 1, 1, bk2        );
  Addbutton( 3, 2, 1, 1, bk3        );
  Addbutton( 3, 3, 1, 2, bkEnter    );

  Addbutton( 4, 0, 2, 1, bk0        );
  Addbutton( 4, 2, 1, 1, bkDecPt    );
end;

procedure TArtScreenKeyboardForm.FormResize(Sender: TObject);
begin
  DrawButtons;
end;

initialization
finalization
  FreeAndNil( ArtScreenKeyboardForm );
end.