Solved

New Component

Posted on 1998-10-30
2
165 Views
Last Modified: 2010-04-06
Hi all

i've a problem with creating a new component:
I want to write a ComboBox that filles in all avaible
fonts automatical. her's what I done:

unit FontComboBox;

interface

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

type
  TFontComboBox = class(TComboBox)
  private
    { Private declarations }
  protected
    { Protected declarations }
  public
    constructor Create(AOwner: TComponent);override;
    { Public declarations }
  published
    procedure UpdateFonts;
    { Published declarations }
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Eigene', [TFontComboBox]);
end;

constructor TFontComboBox.Create(AOwner: TComponent);
begin
Inherited Create(AOwner);
UpdateFonts;
end;

procedure TFontComboBox.UpdateFonts;
var
Index: integer;
begin
Clear; <-- Error here
For Index:=0 to Screen.Fonts.Count-1 do
    Items.Add(Screen.Fonts[Index]);
end;
end.

But everytime I create my new component in desgin-time
(I mean by dragging it on a form) or manipulating the items-property at runtime, I get the error-mesage:" Control '' has no parent window"

What's wrong?

regards
rene
0
Comment
Question by:rene100
2 Comments
 
LVL 5

Accepted Solution

by:
inter earned 100 total points
ID: 1345022
The problem is that the inherited Create cannot create the owner windows before exiting the FontCombos Create to solve the problem

1 - Remove UpdateFonts from your Create Method
2 - add the following to your protected declerations

protected
  procedure CreateWnd;override;

3 - add the following to your unit body

procedure TFontComboBox.CreateWnd;
begin
  inherited CreateWnd;
  UpdateFonts;
end;

regards, igor
0
 
LVL 2

Author Comment

by:rene100
ID: 1345023
Ok, it works fine
Thanks a lot!

regards
rene
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…
When you create an app prototype with Adobe XD, you can insert system screens -- sharing or Control Center, for example -- with just a few clicks. This video shows you how. You can take the full course on Experts Exchange at http://bit.ly/XDcourse.

937 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

10 Experts available now in Live!

Get 1:1 Help Now