Showing TFrame descendant's additional properties on the object inspector

Question

Delphi object inspector doesn't show TFrame descendants's additional properties by design. People tend to suggest using a known trick which is commonly used for showing TForm descendant's properties on the Object inspector. The trick is: registering custom module for TForm descendants to Delphi IDE via design time package like:

RegisterCustomModule(TMyFrame, TCustomModule);

The object inspector can show additional properties of the TFrame Descendant's instance with this way but it loses its frame behaviours while it is embedded in a form. Not redesignable, not possible to implement events for its subcomponents and it accepts child controls (which it musn't). But it behaves normally in its own design area.

Looks like, those behaviours provided by Delphi IDE specially just for TFrame. They problaly are not kind of generic facilities.

Is there any other way to accomplish this without losing frame behaviours ?

I'm using Delphi 2007

Answer 1

No, I don't think this is fully possible.

What I usually do when I have similar needs is to simply install the frame descendant as a component of its own right. But yes, that way you lose a lot of the typical frame behaviour (especially at designtime), e.g. you can no longer manipulate sub-components directly and changes to the frame do no longer automatically propagate to forms that use it at designtime - you have to recompile the runtime package that contains the frame first.

Then again, from an OOP-perspective this isn't too bad. It actually enforces the concept of implementation hiding. You can still expose individual properties and functionality of sub-components via new properties and methods on the frame itself.

Answer 2

Which custom module class are you registering for your frame? Which version of Delphi are you using?

From my experiments with Delphi 2007, the custom module class which seems to work is TFrameModule. This class is contained in delphivclide100.bpl. Since there is no corresponding delphivclide.dcp you have to load it manually:

unit FrameTestReg;

interface

procedure Register;

implementation

uses
  Windows, DesignIntf,
  FrameTest;

procedure Register;
var
  delphivclide: THandle;
  TFrameModule: TCustomModuleClass;
begin
  delphivclide := GetModuleHandle('delphivclide100.bpl');
  if delphivclide <> 0 then
  begin
    TFrameModule := GetProcAddress(delphivclide, '@Vclformcontainer@TFrameModule@');
    if Assigned(TFrameModule) then
      RegisterCustomModule(TTestFrame, TFrameModule);
  end;
end;

end.

My FrameTest unit is very simple, it has no FrameTest.dfm, only the declaration of the new TFrame descendant:

unit FrameTest;

interface

uses
  Forms;

type
  TTestFrame = class(TFrame)
  private
    FHello: string;
  published
    property Hello: string read FHello write FHello;
  end;

implementation

end.

Using TFrameModule class, everything seems to work fine so far. I can create a new descendant of TTestFrame to include in the project and edit its published properties in the Object Inspector, put instances of this new descendant on a form in the IDE, edit their new published properties in the Object Inspector, write event handlers for their child components etc. In the .dfm resource I can see the expected "inline" directive for the instances. I haven't encountered any problem with it so far so perhaps this is the solution.

Answer 3

@TOndrej,

Thank you for the answer. I am using Delphi 2007 and i was using "TCustomModule" to register my frame class. (My question text was updated with those informations) I tried your solution. As far as i understood i need to create a base class ("TBaseFrame") first and define properties in it. "TMyframe" should be derivated from it. And TBaseFrame must be registered to Delphi IDE, not TMyframe.

But there are some handicaps in this method :

• In design time, a TBaseFrame instance is working instead of Tmyframe instance. I overrode additional properties' setter functions in TMyframe but changing those properties in desing time doesn't show affect for TMyFrame. Which is not good for redesignability. But it works OK in runtime.

• I have to maintain two classes with this method.

Answer 4

@Tondrej,

Read comments for the problem, thanks in advance.

frameunit.dfm :

object MyFrame: TMyFrame
  Left = 0
  Top = 0
  Width = 303
  Height = 172
  TabOrder = 0
  object Edit1: TEdit
    Left = 66
    Top = 60
    Width = 151
    Height = 21
    TabOrder = 0
    Text = 'Edit1'
  end
end

---

unit frameunit;

interface

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

type
  TBaseFrame = Class(TFrame)
  protected
    Fstr: string;
    procedure Setstr(const Value: string);virtual;
  published
    Property str:string read Fstr write Setstr;
  End;

  TMyFrame = class(TBaseFrame)
    Edit1: TEdit;
  private
    // This won't be called in designtime. But i need this to be called in designtime
    Procedure Setstr(const Value: string);override;
  end;

implementation

{$R *.dfm}

{ TBaseFrame }

procedure TBaseFrame.Setstr(const Value: string);
begin
  Fstr := Value;
end;

{ TMyFrame }

procedure TMyFrame.Setstr(const Value: string);
begin
  inherited;
  Edit1.Text := Fstr;
  // Sadly this code won't work and Edit1 won't be updated in designtime.
end;

end.

---

unit RegisterUnit;

interface

procedure Register;

implementation

uses
  Windows, DesignIntf, frameunit;

procedure Register;
var
  delphivclide: THandle;
  TFrameModule: TCustomModuleClass;
begin
  delphivclide := GetModuleHandle('delphivclide100.bpl');
  if delphivclide <> 0 then
  begin
    TFrameModule := GetProcAddress(delphivclide, '@Vclformcontainer@TFrameModule@');
    if Assigned(TFrameModule) then
    begin
      RegisterCustomModule(frameunit.TBaseFrame, TFrameModule);
      // Just registering that won't cause Tmyframe to loose its frame behaviours
      // but additional properties won't work well.

      //RegisterCustomModule(frameunit.TMyFrame, TFrameModule);  
      // That would cause Tmyframe to lose its frame behaviours
      // But additional properties would work well.

    end;
  end;
end;


end.