如何在TEdit onkeyup事件中将字符更改为星号？

Question

my client requested to me for make a "effect" where each time that release any key of keyboard, change this character to asterisk on field.

How do this in Delphi?

I have in Html + Javascript like this . .js code can be found here .

Answer 1

There is no way to achieve what you want with the standard Delphi controls.

The VCL edit control uses the feature of the underlying Windows EDIT control to mask input characters for "Password" type edit controls. The behaviour is therefore determined by the Windows (OS) control, not Delphi itself.

You could try to get the effect you need by using a non-password field and handling key events to replace characters as required with asterisks or any other masking character, but you would also need to separately maintain the intended content of the edit control.

This would almost certainly be easier to implement as a custom edit control, rather than trying to customize the behaviour of a standard edit control with events.

I suspect that the implementation of a custom control is not the solution you are after however.

Answer 2

The below simulates the behavior of the js code with the difference backspace is also handled.

type
  TForm2 = class(TForm)
    Edit1: TEdit;
    procedure Edit1KeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
  private
    FEditText: string;

procedure TForm2.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
  if Key = ^H then
    SetLength(FEditText, Length(FEditText) - 1)
  else
    FEditText := FEditText + Key;
end;

procedure TForm2.Edit1KeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
  Edit1.Text := StringOfChar('*', Length(Edit1.Text));
  Edit1.SelStart := Length(Edit1.Text);
end;

FEditText is the equivalent of df[0].Value in js code, the actual value that is typed.

Note that there's no option to reset the text, as there is none in the js code.