BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  delete the parent component          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Mike Guest Posted: Fri Dec 26, 2003 5:56 pm    Post subject: delete the parent component Hi, I have written my own componenten, derive from TPanel. That component, has serval comboboxes and one button. My aim is to delete the full instanz of my component, after click the button. Following code would only delete the button, but not the whole componente. void __fastcall TMyComp::ButtonClick(TObject *Sender) { PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(Sender)); } //-------------------------------------------------------------------------- - void __fastcall TForm::WndProc(TMessage &Message) { if(Message.Msg == APPWM_DELETE_COMP) { delete reinterpret_cast<TMyComp*>(Message.LParam); Message.Result = TRUE; } else TForm::WndProc(Message); } //-------------------------------------------------------------------------- - But if i write Sender->Parent or Sender->Owner, this does not help. SO i need anyhow to get the owner of the button, to delete the component. any ideas how to do? mike Back to top Santa Guest Posted: Fri Dec 26, 2003 5:58 pm    Post subject: Re: delete the parent component "Mike" <mikeh (AT) gmx (DOT) de> wrote: Quote: [...] Following code would only delete the button, but not the whole componente. The Sender - as it is in the ButtonClick event - is the button that was clicked. Since you want to delete the Parent of the Sender, You must either PostMessage with the Sender's Parent: void __fastcall TMyComp::ButtonClick(TObject *Sender) { TButton* pButton = static_cast<TButton*>( Sender ); TMyComp* pMyComp = dynamic_cast<TMyComp*>( pButton->Parent ); if( pMyComp ) PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(Sender)); else ShowMessage( "Unable to delete Component" ); } //------------------------------------------------------------- void __fastcall TForm::WndProc(TMessage &Message) { if(Message.Msg == APPWM_DELETE_COMP) { delete reinterpret_cast<TMyComp*>(Message.LParam); Message.Result = TRUE; } else TForm::WndProc(Message); } OR you need to handle all of it in the WndProc: void __fastcall TMyComp::ButtonClick(TObject *Sender) { PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(Sender)); } //------------------------------------------------------------- void __fastcall TForm::WndProc(TMessage &Message) { if(Message.Msg == APPWM_DELETE_COMP) { TButton* pButton = reinterpret_cast<TButton*>(Message.LParam); TMyComp* pMyComp = dynamic_cast<TMyComp*>( pButton->Parent ); if( pMyComp ) { delete pMyComp; Message.Result = TRUE; } else ShowMessage( "Delete MYComp failed" ); } else TForm::WndProc(Message); } Happy Holidays Santa Back to top nicolasr Guest Posted: Fri Dec 26, 2003 6:44 pm    Post subject: Re: delete the parent component Hi, Quote: Following code would only delete the button, but not the whole componente. void __fastcall TMyComp::ButtonClick(TObject *Sender) { PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(Sender)); } //-------------------------------------------------------------------------- - How do you create the button in your component? Does the button have an Owner? Or do you create it with new TButton(NULL)? I assume the Parent is your panel component? Does something like this work: .... TButton* b = dynamic_cast<TButton*>(Sender); PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(b->Parent)); .... Nick Back to top Todd Brylski Guest Posted: Fri Dec 26, 2003 7:08 pm    Post subject: Re: delete the parent component "Mike" <mikeh (AT) gmx (DOT) de> wrote Quote: Hi, I have written my own componenten, derive from TPanel. That component, has serval comboboxes and one button. My aim is to delete the full instanz of my component, after click the button. Following code would only delete the button, but not the whole componente. void __fastcall TMyComp::ButtonClick(TObject *Sender) { PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(Sender)); } You are posting the message to your component, it should go to the Form->Handle. Also you are sending the 'Sender' as your last parameter, that is going to be the Button, you should send a pointer to your component: ::PostMessage( Form1->Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(this); or ::PostMessage( GetParentForm(this)->Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(this); Todd Back to top Remy Lebeau (TeamB) Guest Posted: Fri Dec 26, 2003 8:54 pm    Post subject: Re: delete the parent component "Mike" <mikeh (AT) gmx (DOT) de> wrote Quote: Following code would only delete the button, but not the whole componente. That is because that code was specifically written to do just that. If you want the component to delete itself, then just call 'delete this' in the message handler instead of passing a component pointer as a message parameter. However, with that said, I strongly suggest that you *not* have the component delete itself at all to begin with. You should leave that up to the form to handle instead. You should never delete a component from within its own message handlers, because you have no way of knowing at that time whether the VCL still needs to work with your component after the message handler returns, or if the form or other component is going to try to reference the component later on as a result of another operation. You have a potential of causing access violations and such be having the component delete itself. The easiest way to support what you are asking for is to instead have the component expose an event that is triggered when the component's button is clicked, and then the form can do whatever is needed to delete the component when it is actually safe to do so. For example: #define APPWM_DELETE_COMP (WM_APP + 100) class TMyComp : public TPanel { private: TButton *FButton; TNotifyEvent FOnButtonClick; void __fastcall ButtonClicked(TObject *Sender); //... public: __fastcall TMyComp(TComponent *Owner); __fastcall ~TMyComp(); //... __published: __property TNotifyEvent OnButtonClick = {read=FOnButtonClick, write=FOnButtonClick}; //... }; __fastcall TMyComp::TMyComp(TComponent *Owner) : TPanel(Owner) { FButton = new TButton(this); FButton->Parent = this; FButton->OnClick = ButtonClicked; //... } __fastcall TMyComp::~TMyComp() { //... delete FButton; } void __fastcall TMyComp::ButtonClicked(TObject *Sender) { if( FOnButtonClick ) FOnButtonClick(this); } Then you can do the following: void __fastcall TForm1::MyComp1ButtonClick(TObject *Sender) { PostMessage(Handle, APPWM_DELETE_COMP, 0, reinterpret_cast<int>(Sender)); } void __fastcall TForm1::WndProc(TMessage &Message) { if(Message.Msg == APPWM_DELETE_COMP) { delete reinterpret_cast<TMyComp*>(Message.LParam); Message.Result = TRUE; } else TForm::WndProc(Message); } Gambit Back to top JD Guest Posted: Sat Dec 27, 2003 3:46 pm    Post subject: Re: delete the parent component "Remy Lebeau (TeamB)" <gambit47.no.spam (AT) no (DOT) spam.yahoo.com> wrote: Quote: Please clearify for me how the TNotifyEvent FOnButtonClick; and the __property TNotifyEvent OnButtonClick = {read=FOnButtonClick, write=FOnButtonClick}; declarations work together in regards to if( FOnButtonClick ) FOnButtonClick( this ); ~ JD Back to top Remy Lebeau (TeamB) Guest Posted: Sat Dec 27, 2003 9:48 pm    Post subject: Re: delete the parent component "JD" <nospam (AT) nospam (DOT) com> wrote Quote: Please clearify for me how the snip declarations work together in regards to if( FOnButtonClick ) FOnButtonClick( this ); TNotifyEvent is a typedef for a function pointer: typedef void __fastcall (__closure *TNotifyEvent)(System::TObject* Sender); Thus FOnButtonClick is a simple variable that is a pointer to a class method. Then the code is testing to see if that pointer has been assigned, and if so then it calls the class method that is assigned to it. Gambit Back to top JD Guest Posted: Sun Dec 28, 2003 7:20 pm    Post subject: Re: delete the parent component "Remy Lebeau (TeamB)" <gambit47.no.spam (AT) no (DOT) spam.yahoo.com> wrote: Quote: [...] Then the code is testing to see if that pointer has been assigned, and if so then it calls the class method that is assigned to it. OK, but I don't get how and when it gets assigned. ~ JD Back to top Remy Lebeau (TeamB) Guest Posted: Sun Dec 28, 2003 10:57 pm    Post subject: Re: delete the parent component "JD" <nospam (AT) nospam (DOT) com> wrote Quote: OK, but I don't get how and when it gets assigned. If you look back at my earlier code, you will see that FOnButtonClick is accessed via a property. It is the calling code's responsibility to assign the property when it creates the actual component instance, ie: TMyComp *comp = new TMyComp(this); comp->OnButtonClick = MyComp1ButtonClick; Gambit Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.