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Registering a descendant form

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Dov Landau

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Jan 21, 1998, 3:00:00 AM1/21/98

Hello,
I would like to enhance the standard Delphi form.
I do it by creating a new component, that inherits from TForm and by adding
particular property in the "published" section.
My problem is:
How can I register the new component in the VCL, without causing it to
appear in the Componets pallete. Instead I like it in the object
repository, in a manner that it will be defined as the default form (when I
select "New form" from the menu, or press the "New form" Speed button).
Any advance will be appreciated.
TIA
Dov Landau
dla...@netvision.net.il
ISRAEL

DRR

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Jan 21, 1998, 3:00:00 AM1/21/98

This is an example from an old listing

From - Mon Jan 12 12:06:23 1998
Path: newslist.borland.com!for...@borland.com
From: "Erik B. Berry" <ebe...@sync-link.com.SPAM>
Newsgroups: borland.public.delphi.vcl.components.writing
Subject: Re: TForm descendent
Date: Tue, 04 Nov 1997 09:31:50 -0800
Organization: Synchronics, Inc <http://www.sync-link.com>
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References: <01bce8fb$9fbeacc0$030000c0@mickes>
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Michael Lebert wrote:

> I tried to add a TMyForm to the object repository, but that way I can't
see
> the properties I added to TMyForm in the object inspector during design
> time instead only the properties belonging to TForm show up.

Here is the correct way to do this. You have to create a expert to
register the form as follows:

John Crouch <jcr...@mail.EXPOCARD.com> wrote in article
<64990FEABFBCD011B5CC0020AF3BE3C5F76B@NTSERVER>...
> We have created this very nice form with all sorts of nice components on
> it and nice functionality. We placed it in the Repository and our users
> (other programmers) just add it to their application by using the
> File|New command.
>
> One feature we do not have with this setup is the ability for the user
> to change some of the properties of the form in the object inspector. I
> think we have to make it a component to do this.
>
John,
In Delphi 3.0 (which I hope you are using as this information only
applies to 3.0) there is a new approach which you can use that I will
try
to briefly describe. The idea is to use a custom module to create a new
form class that has new properties etc. This can be done by registering
a
classtype with the IDE by calling RegisterCustomModule (in the expert
API).
With a custom module you can add your own new properties to forms which
will appear in the object inspector. The mechanism to get this to work
is
as follows:

- Create a unit that declares your new form class descending from
TCustomForm
- Create an expert that will generate a new instance of the above class
in
the IDE
- Install the expert in the IDE by including the expert unit below in a
new
package and simply install the package.

Once you have followed these steps you will have a new item on the Forms
page of the File|New dialog which will be your new form class.

I hope all of this isn't too confusing.

Here is the "simple" example of how to get this to work:

The new form class unit:
>>>> Begin unit <<<<<<
unit myForm;

interface

uses Messages, Windows, SysUtils, Classes, Controls, Forms;

type
TMyForm = class(TCustomForm)
private
FNewProp: String;
protected
public
published
property NewProp: String read FNewProp write FNewProp; // ex. of a
new form property
property ActiveControl;
property Align;
property AutoScroll;
property BorderStyle;
property BorderIcons;
property Caption stored True;
property ClientHeight;
property ClientWidth;
property Color;
property DragCursor;
property DragMode;
property Enabled;
property Font;
property Height stored True;
property HorzScrollBar;
property KeyPreview;
property ParentColor;
property ParentCtl3D;
property ParentFont;
property ParentShowHint;
property PixelsPerInch;
property PopupMenu;
property PrintScale;
property Scaled;
property ShowHint;
property TabStop;
property VertScrollBar;
property Width stored True;
property OnActivate;
property OnClick;
property OnClose;
property OnCloseQuery;
property OnCreate;
property OnDblClick;
property OnDestroy;
property OnDeactivate;
property OnDragDrop;
property OnDragOver;
property OnHide;
property OnHelp;
property OnKeyDown;
property OnKeyPress;
property OnKeyUp;
property OnMouseDown;
property OnMouseMove;
property OnMouseUp;
property OnPaint;
property OnResize;
property OnShow;
end;

implementation

end.
>>>> end unit <<<<

Here is the expert necessary to create instances of this class from the
IDE:
>>>> begin expert <<<<
unit newmod;

interface

procedure Register;

implementation

uses Windows, SysUtils, Classes, Controls, Forms, ExptIntf, ToolIntf,
VirtIntf,
IStreams, DsgnIntf, MyForm;

type
TMyFormExpert = class(TIExpert)
function GetName: string; override;
function GetComment: string; override;
function GetGlyph: HICON; override;
function GetStyle: TExpertStyle; override;
function GetState: TExpertState; override;
function GetIDString: string; override;
function GetAuthor: string; override;
function GetPage: string; override;
function GetMenuText: string; override;
procedure Execute; override;
end;

{ TMyFormExpert }

function TMyFormExpert.GetName: string;
begin
Result := 'My Form';
end;

function TMyFormExpert.GetComment: string;
begin
Result := 'Custom form';
end;

function TMyFormExpert.GetGlyph: HICON;
begin
Result := LoadIcon(HInstance, '');
end;

function TMyFormExpert.GetStyle: TExpertStyle;
begin
Result := esForm;
end;

function TMyFormExpert.GetState: TExpertState;
begin
Result := [esEnabled];
end;

function TMyFormExpert.GetIDString: string;
begin
Result := 'MyForm.Expert';
end;

function TMyFormExpert.GetAuthor: string;
begin
Result := 'Borland';
end;

function TMyFormExpert.GetPage: string;
begin
Result := 'Forms';
end;

function TMyFormExpert.GetMenuText: string;
begin
Result := '';
end;

FormDfmSource = 'object %s: T%0:s end';

procedure TMyFormExpert.Execute;
var
UnitIdent, Filename: string;
FormName: string;
CodeStream: TIStream;
DFMStream: TIStream;
DFMString, DFMVCLStream: TStream;
begin
if not ToolServices.GetNewModuleName(UnitIdent, FileName) then Exit;
FormName := 'MyForm' + Copy(UnitIdent, 5, 255);
CodeStream :=
TIStreamAdapter.Create(TStringStream.Create(Format(FormUnitSource,
[UnitIdent, FormName])), True);
try
CodeStream.AddRef;
DFMString := TStringStream.Create(Format(FormDfmSource,
[FormName]));
try
DFMVCLStream := TMemoryStream.Create;
try
ObjectTextToResource(DFMString, DFMVCLStream);
DFMVCLStream.Position := 0;
except
DFMVCLStream.Free;
end;
DFMStream := TIStreamAdapter.Create(DFMVCLStream, True);
try
DFMStream.AddRef;
ToolServices.CreateModuleEx(FileName, FormName, 'TMyForm', '',
CodeStream, DFMStream, [cmAddToProject, cmShowSource,
cmShowForm,
cmUnNamed, cmMarkModified]);
finally
DFMStream.Free;
end;
finally
DFMString.Free;
end;
finally
CodeStream.Free;
end;
end;

procedure Register;
begin
RegisterCustomModule(TMyForm, TCustomModule);
RegisterLibraryExpert(TMyFormExpert.Create);
end;

end.
>>>> end expert <<<<

To get the expert installed you have to add the unit to a package and
install the package. Once this is complete your new form class will be
available from the File|New dialog.
--

-Steve
Delphi QA
(To email me remove "-nojunkmail-" from my address)

Erik

Dov Landau wrote in message <01bd2651$5698c1a0$LocalHost@default>...

Christopher Mah

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Jan 21, 1998, 3:00:00 AM1/21/98

Dov Landau wrote:
>
> Hello,
> I would like to enhance the standard Delphi form.
> I do it by creating a new component, that inherits from TForm and by adding
> particular property in the "published" section.
> My problem is:
> How can I register the new component in the VCL, without causing it to
> appear in the Componets pallete. Instead I like it in the object
> repository, in a manner that it will be defined as the default form (when I
> select "New form" from the menu, or press the "New form" Speed button).
> Any advance will be appreciated.
> TIA
> Dov Landau
> dla...@netvision.net.il
> ISRAEL

Right click on your form and select "Add to repository." I don't think
this will be registered as your default form. But you should be able to
select this form when you select File|New.

Cheerios,
Chris.

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