delphi – 如何覆盖调用以在TEdit中显示CapsLock提示窗口？

它是这样的.

>覆盖WndProc.

码

type
  TEdit = class (Vcl.StdCtrls.TEdit)
  protected
    procedure WndProc(var Message: TMessage); override;
  end;

>拦截EM_SHOWBALLOONTIPmessage,你就完成了

码

procedure TEdit.WndProc(var Message: TMessage);
begin
 if Message.Msg = EM_SHOWBALLOONTIP then
   showmessage('Do your thing.')
 else
  inherited;
end;

有关更多信息,请查看MSDN文档：

How do I suppress the CapsLock warning on password edit controls?

这是TEdit的后代,如果使用PasswordChar<>分配某个FOnPasswordCaps事件,则允许在密码编辑控件上抑制CapsLock警告. #0

unit NCREditUnit;

interface

uses
  Vcl.StdCtrls,vcl.Controls,Winapi.Messages,System.Classes;

type
  TNCREdit = class(TEdit)
  private
    FOnPasswordCapsLocked: TNotifyEvent;
    FIsCapsLocked: boolean;
    FOnPasswordCapsFreed: TNotifyEvent;
    FBlockCapsBalloonTip: boolean;
    FValuePasswordChrOnCaps: boolean;
    procedure SetOnPasswordCapsEvents;
    procedure SetOnPasswordCapsFreed(const aValue: TNotifyEvent);
    procedure SetOnPasswordCapsLocked(const aValue: TNotifyEvent);
  protected
    procedure WndProc(var Message: TMessage); override;
    procedure KeyUp(var Key: Word; Shift: TShiftState); override;
    procedure DoEnter; override;
    procedure DoExit; override;
  published
    property BlockCapsBalloonTip: boolean read FBlockCapsBalloonTip write FBlockCapsBalloonTip default False;
    property ValuePasswordChrOnCaps: boolean read FValuePasswordChrOnCaps write FValuePasswordChrOnCaps default True;

//... The usual property declaration of TEdit

    property OnPasswordCapsLocked: TNotifyEvent read FOnPasswordCapsLocked write SetOnPasswordCapsLocked;
    property OnPasswordCapsFreed: TNotifyEvent read FOnPasswordCapsFreed write SetOnPasswordCapsFreed;
  end;


implementation

uses
  Winapi.CommCtrl,Winapi.Windows;

{ TNCREdit }

procedure TNCREdit.DoEnter;
begin
  inherited;
  if FBlockCapsBalloonTip then
    begin
      FIsCapsLocked := Odd(GetKeyState(VK_CAPITAL));
      SetOnPasswordCapsEvents;
    end;
end;

procedure TNCREdit.DoExit;
begin
  if FBlockCapsBalloonTip and (FIsCapsLocked) then
    begin
      FIsCapsLocked := False;
      SetOnPasswordCapsEvents;
    end;
  inherited;
end;

procedure TNCREdit.KeyUp(var Key: Word; Shift: TShiftState);
begin
  if Key = VK_CAPITAL then
    FIsCapsLocked := not FIsCapsLocked;
  SetOnPasswordCapsEvents;
  inherited;
end;

procedure TNCREdit.SetOnPasswordCapsEvents;
begin
  if FIsCapsLocked then
    begin
      if Assigned(FOnPasswordCapsLocked) and
         ((self.PasswordChar <> #0) or ( not FValuePasswordChrOnCaps)) then
      begin
      FOnPasswordCapsLocked(Self);
      end;
    end
  else
    begin
      if Assigned(FOnPasswordCapsLocked) and
         ((self.PasswordChar <> #0) or ( not FValuePasswordChrOnCaps)) then
      begin
      FOnPasswordCapsFreed(Self);
      end;
    end;
end;

procedure TNCREdit.SetOnPasswordCapsFreed(const aValue: TNotifyEvent);
begin
  FOnPasswordCapsFreed := aValue;
  FBlockCapsBalloonTip := True;
end;

procedure TNCREdit.SetOnPasswordCapsLocked(const aValue: TNotifyEvent);
begin
  FOnPasswordCapsLocked := aValue;
  FBlockCapsBalloonTip := True;
end;

procedure TNCREdit.WndProc(var Message: TMessage);
begin
  if (Message.Msg = EM_SHOWBALLOONTIP) and FBlockCapsBalloonTip then Exit; 
  inherited;
end;

end.

Kobik先生制作了一段非常优雅的代码,我认为不应该信任PasteBin,所以我决定在这里添加它.

根据我的理解,它允许您在TPasswordEdit接收焦点时触发的一个事件处理程序中处理TPasswordCapsLockState,失去焦点,在焦点处按下CapsLock键,并在PasswordChar更改时触发可选触发.

使用这种方法,我可以使用OnPasswordCapsLock事件在我的问题中显示/隐藏图像,而不是强迫组件的使用者为每个状态使用两个事件处理程序(顺便说一句非常聪明且不易出错).

也只要LNeedHandle：= FBlockCapsBalloonTip和IsPassword;是真的我有另一个TPasswordEdit的附加功能,它也是在OnPasswordCapsLock中处理OnEnter和OnExit,

那么我能说什么Kobik Je vous轮胎mon chapeau.

type
  TPasswordCapsLockState = (pcsEnter,pcsExit,pcsKey,pcsSetPasswordChar);

  TPasswordCapsLockEvent = procedure(Sender: TObject;
    Locked: Boolean; State: TPasswordCapsLockState) of object;

  TPasswordEdit = class(TCustomEdit)
  private
    FIsCapsLocked: boolean;
    FBlockCapsBalloonTip: boolean;
    FOnPasswordCapsLock: TPasswordCapsLockEvent;
  protected
    procedure WndProc(var Message: TMessage); override;
    procedure KeyUp(var Key: Word; Shift: TShiftState); override;
    procedure DoEnter; override;
    procedure DoExit; override;
    procedure HandlePasswordCapsLock(State: TPasswordCapsLockState); virtual;
    function GetIsPassword: Boolean; virtual;
  public
    property IsPassword: Boolean read GetIsPassword;
  published
    property BlockCapsBalloonTip: boolean read FBlockCapsBalloonTip write FBlockCapsBalloonTip default False;
//... The usual property declaration of TEdit
    property OnPasswordCapsLock: TPasswordCapsLockEvent read FOnPasswordCapsLock write FOnPasswordCapsLock;
  end;

implementation

function TPasswordEdit.GetIsPassword: Boolean;
begin
  Result := ((PasswordChar <> #0) or
   // Edit control can have ES_PASSWORD style with PasswordChar == #0
   // if it was creaed with ES_PASSWORD style
   (HandleAllocated and (GetWindowLong(Handle,GWL_STYLE) and ES_PASSWORD <> 0)));
end;

procedure TPasswordEdit.HandlePasswordCapsLock;
var
  LNeedHandle: Boolean;
begin
  LNeedHandle := FBlockCapsBalloonTip and IsPassword;
  if LNeedHandle then
  begin
    FIsCapsLocked := Odd(GetKeyState(VK_CAPITAL));
    if Assigned(FOnPasswordCapsLock) then
      FOnPasswordCapsLock(Self,FIsCapsLocked,State);
  end;
end;

procedure TPasswordEdit.DoEnter;
begin
  inherited;
  HandlePasswordCapsLock(pcsEnter);
end;

procedure TPasswordEdit.DoExit;
begin
  inherited;
  HandlePasswordCapsLock(pcsExit);
end;

procedure TPasswordEdit.KeyUp(var Key: Word; Shift: TShiftState);
begin
  inherited;
  if Key = VK_CAPITAL then
    HandlePasswordCapsLock(pcsKey);
end;

procedure TPasswordEdit.WndProc(var Message: TMessage);
begin
  if (Message.Msg = EM_SHOWBALLOONTIP) and FBlockCapsBalloonTip and IsPassword then
    Exit;
  // Optional - if password char was changed
  if (Message.Msg = EM_SETPASSWORDCHAR) and Self.Focused then
    HandlePasswordCapsLock(pcsSetPasswordChar);
  inherited;
end;