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.NET Forum / Languages / Managed C++ / June 2005Event related to a runtime created component.
Hello! I am developping a Visual C++ .NET 2003 multiple forms application. My problem is: When running my application, I click a button and a new main menu item is created. Ok. Now I want to relate an event to the click of this new item created. How do I create an event related to a component that is created in runtime? If somebody could help me anyway I thank very much. Hello, > Hello! > I am developping a Visual C++ .NET 2003 multiple forms application. My [quoted text clipped - 3 lines] > component that is created in runtime? > If somebody could help me anyway I thank very much. m_NewComponent->EventName += new ComponentsEventHandler ( this, EventHandlingMethodName ); void EventHandlingMethodName ( object* source, YourComponentsEventArgs* ea ) { //handle event } your couuld take a look into the FormDesigners InitalizeComponents Method to see how events are registered there... Try following: class MyForm : public Windows::Forms::Form { // ... void ButtonHandler(Object* psender, EventArgs *pevent) { MenuItem* pitem = new MenuItem; pitem->Text = S"My Menu Item"; pitem->Click += new EventHandler(this, &MyForm::NewMenuItemHandler); // you need // this? m_pmainmenu->MenuItems->Item[0]->Add(pitem); } void NewMenuItemHandler(Object* psender, EventArgs* pevent) { // handle your event here } // ... }; Hope that helps. Ismail Thanks very much! That worked! But now another problem came up: If I create in runtime, for exemple, 20 items. Afterwards, when I click in one of these items, the event will occur, ok. It is the same for any of these items. But I need also to obtain the 'Text' and 'Checked' properties of the clicked new item. How could I obtain the properties of that new specific item that suffered the click? These would solve my problem at all. Thanks once more. Hello ! When writing an event handler, the prototype has two parameters: the sender of the event, and the arguments related to the event. The sender, in this case, is the menu item on which the event occurred. This can be judged by looking at pitem->Click += new EventHandler(this, &MyForm::NewMenuItemHandler); When the click handler fires, you can take a look at the properties of the object that is passed as an argument. Try casting it into a MenuItem pointer, and checking the Text property to see which menu item it was that fired the event. Then do handling/check status querying accordingly.. -Antti Keskinen ------------------------------ > Thanks very much! That worked! > But now another problem came up: [quoted text clipped - 4 lines] > of that new specific item that suffered the click? These would solve my > problem at all. Thanks once more. Thank you! But I don't find a way to casting the object passed as argument into a main Menu pointer. Could you suggest me any way? Hi Marcelo, try: void MyForm::m_mniMyMenuItem_Click(System::Object * sender, System::EventArgs * e) { MenuItem* mni = dynamic_cast<MenuItem*>(sender); if ( mni->Text->Equals ( "ExpectedText" ) ) { //do your stuff here... } } Greets, Sebastian > Thank you! But I don't find a way to casting the object passed as > argument into a main Menu pointer. Could you suggest me any way? It worked! With this operator I can get all the properties of the component that suffered the event. That's what I wanted. Thanks very much, really! You're welcome, I'd like to suggest you to learn something about casting... it is an essential practice in object oriented languages. Take Care: using dynamic_cast<Type*>(Object) might return NULL (0) if the cast failes.... that means if you cast some object to a type that it is not related too it(inherited from). If you are familiar with exception handling, you could use try { TargetType* target = __try_cast<TargetType*>(source); } catch (InvalidCastException* ice) { //do some error handling } dynmic_cast returns NULL for invalid casts, __try_cast throws an Exception. Greets, Sebastian Dau > It worked! With this operator I can get all the properties of the > component that suffered the event. That's what I wanted. Thanks very > much, really! Thank you for the suggestion. Could you help me in one more thing? I am working with 2 forms. For exemple, here : profileToMenu = new MenuItem(profileName); profileToMenu->Click += new System::EventHandler(this, &ConnectionPreferences::RunTimeItem_Click); a menu item is created and related to the RunTimeItem_Click event od the ConnectionPreferences class . Now, if I create a menuItem in another Form, let us say "Form1" class, how would I relate the click of this menu item (which is in Form1) to the same event RunTimeItem_Click of the ConnectionPreferences Form? menuInForm1 = new MenuItem(profileName); menuInForm1 ->Click += new System::EventHandler(this */(???)*/, &ConnectionPreferences::RunTimeItem_Click */(???)*/); Greetings, Marcelo Schio > Thank you for the suggestion. > Could you help me in one more thing? I am working with 2 forms. For [quoted text clipped - 15 lines] > > Greetings, Marcelo Schio Quick and dirty: public __gc class Form2 : public Windows::Forms { //... public: void Form1_MenuItem1_OnClick ( Object* sender , EventArgs* ea ) { //react on event } }; public class Form1 : Windows::Forms { //... void InitForm2 ( ) { Form2* form2 = new Form2 (); menuInForm1 = new MenuItem(profileName); menuInForm1 ->Click += new System::EventHandler(form2 , &Form2::Form1_MenuItem1_OnClick ); } }; This is the idea of it very straight forward, hopefully helpful. Greets, Sebastian Dau Thank you once more! It worked perfectly. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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