Change caption and attributes of ShowMessage dialog

Question

In Delphi can you change the caption of the ShowMessage dialog because by default it is taking my exe name.

And can I change the background color, size of the same?

Solution 1

You can create your own custom dialogs by using delphi's CreateMessageDialog function.

Example below:

var
  Dlg: TForm;
begin
  Dlg := CreateMessageDialog('message', mtInformation, [mbOk], mbOK);
  // Treat Dlg like any other form

  Dlg.Caption := 'Hello World';

  try
    // The message label is named 'message'
    with TLabel(Dlg.FindComponent('message')) do
    begin
      Font.Style := [fsUnderline];

      // extraordinary code goes here
    end;

    // The icon is named... icon
    with TPicture(Dlg.FindComponent('icon')) do
    begin
      // more amazing code regarding the icon
    end;

    Dlg.ShowModal;
  finally
    Dlg.Free;
  end;

and of course you can insert other components aswell into that form dynamically.

Solution 2

The dialog will use the contents of Application.Title as the caption. So you could set this before calling ShowMessage.

However, if you want to show multiple dialogs with different captions, it would be more convenient to call the Windows MessageBox function. Certainly if you have an older version of Delphi this will result in a more native feel to your dialog.

procedure MyShowMessage(const Msg, Caption: string);
begin
  MessageBox(GetParentWindowHandleForDialog, PChar(Msg), PChar(Caption), MB_OK);
end;

function GetParentWindowHandleForDialog: HWND;
begin
  //we must be careful that the handle we use here doesn't get closed while the dialog is showing
  if Assigned(Screen.ActiveCustomForm) then begin
    Result := Screen.ActiveCustomForm.Handle;
  end else if Assigned(Application.MainForm) then begin
    Result := Application.MainFormHandle;
  end else begin
    Result := Application.Handle;
  end;
end;

If you wish to control color and size then the most obvious option is to create your own dialog as a TForm descendent.

Comments

[Shirish11]

i cant find MianWindowHandle in BDS 2006 having a custom form as a dialog box seem to be an option

[David Heffernan]

I misremembered. It's MainFormHandle in Delphi. I'm answering too many WinForms questions!!!

[Shirish11]

but it violates the Showmodal property of Showmessages

[David Heffernan]

Sorry, I can't understand that comment.

[Shirish11]

when u display a MessageDialog box using a Showmessage the control of the aplication goes to the Showmessage Dialog but in this case the control is still with the application when the MessageBox is called

[David Heffernan]

Windows MessageBox is modal also. A TForm descdendant can be modal by showing it with ShowModal. Both options I present can operator modally.

[Shirish11]

let us continue this discussion in chat

[Peter Turner]

@David I had to write this for an internal app because some of the tech guys here wanted to have red buttons on important warning messages. It's essentially a hook that can draw on the 'canvas' of the dialog you pop up. You can draw in the place where the comments are.

[David]

I never knew FindComponent existed. +1!