contextmenu - Dynamically create context menu in QT associated to a toolbutton -


in application have qtoolbutton related presence of usb pen drive. when pen drive inserted show qtoolbutton , create context menu associated content of pen drive.i have different menu dynamically created assigned button.

my code works first time, when create new menu doesn't appear. in last version of code, when show button second time the previous menu (dismount item present) , when click on item doesn't anything.

edit: if use qaction instead of qwidgetaction code works fine. seems related qwidgetaction of qlabel used inside of it.

the following simplified version of code:

/* member variables */ qmenu *m_pqmconmenusb; qlabel m_menuitem;  /* costructor */     ui->tbdriveusb->setcontextmenupolicy(qt::customcontextmenu); m_pqmconmenusb = null; qobject::connect(ui->tbdriveusb, signal(customcontextmenurequested(const qpoint&)),this, slot(showusbcm(const qpoint&))); m_menuitem.setstylesheet("qlabel { background-color : black; color : white; }"); m_menuitem.settext("dismount"); qfont fonte = m_menuitem.font(); fonte.setpixelsize(16); m_menuitem.setfont(fonte); qpalette chepalette = m_menuitem.palette(); m_menuitem.setminimumsize(0,32); chepalette.setcolor(m_menuitem.backgroundrole(), qt::black); chepalette.setcolor(m_menuitem.foregroundrole(), qt::white); m_menuitem.setpalette(chepalette);  /*member functions*/ void  mainwindow::showusbcm(const qpoint& pos) {     // copied example     if (pos != qpoint(0,0)) {         // execute context menu         if (m_pqmconmenusb!=null) m_pqmconmenusb->exec(pos);     } }  void mainwindow::onusbmounted() {     /* static boolean used simulate change in menu content */     static bool trytochange = false;     ui->tbdriveusb->show();     m_pqmconmenusb = new qmenu(this);     qwidgetaction *menuitemw = new qwidgetaction(this);     menuitemw->setdefaultwidget(&m_menuitem);     menuitemw->settext("dismount");     connect(menuitemw,signal(triggered()), this, slot(dodismount()));     m_pqmconmenusb->addaction(menuitemw);     if (trytochange)     {         menuitemw = new qwidgetaction(this);         menuitemw->setdefaultwidget(&m_menuitem);         menuitemw->settext("update");         connect(menuitemw,signal(triggered()), this, slot(update()));         m_pqmconmenusb->addaction(menuitemw);     }     trytochange = !trytochange;     ui->tbdriveusb->setmenu(m_pqmconmenusb); }  void mainwindow::onusbdismounted() {    ui->tbdriveusb->hide();     /* first version of code tries destroy menu following code, doesn't work    /*ui->tbdriveusb->setmenu(null);    qaction *paction;    foreach (paction, m_pqmconmenusb->actions())        paction->disconnect(this);        delete(m_pqmconmenusb);     m_pqmconmenusb = null;*/

}

a useful pattern dynamically populate menu associated qtoolbutton first create menu , attach button, not populate it. connect slot qmenu::abouttoshow() signal. in slot implementation, clear contents of menu , populate needed current state of application.


Comments

Post a Comment

Popular posts from this blog

c++ - CryptStringToBinary API behavior -

i seeing strange behavior cryptstringtobinary cryptography api. please see below code (config: x64 debug): #include "stdafx.h" #include <windows.h> #include <strsafe.h> #include <iostream> #include <exception> void main() { dword dwskip; dword dwflags; dword dwdatalen; //lpcwstr pszinput = l"jaaaaaecaaadzgaaakqaagdnnl1l56bwgfjdgr3rpxtqqqn6daw3usv2emkjym4t"; //this works fine lpcwstr pszinput = l"mytest"; //doesnt work, api returns false,error code 0x0000000d // determine size of byte array , allocate memory. if(! cryptstringtobinary( pszinput, _tcslen( pszinput ) + 1, crypt_string_base64, null, &dwdatalen, &dwskip, &dwflags ) ) { dword dw = getlasterror(); //0x0000000d: data invalid throw std::exception( "error computing byte length." ); } byte *pbytebyte = null; try { ...
Read more

c++ - Correct method for redrawing a layered window -

i have window created ws_ex_layered window style. drawing onto memory bitmap using gdi+, , using updatelayeredwindow update graphical content of layered window. intend use window main window of application, require redraw frequently. seeing layered windows not receive wm_paint windows message [?] , need come appropriate method re-drawing window. optimisation not essential , it's nice have cake , eat too. therefore, in search of "correct" method use. here thoughts far: i guess it's idea render onto off-screen bitmap before bitblt ing or similar. 60 frames rendered per second should (more than?) enough (but how compare other applications' frame rates?). possible solutions: use settimer send wm_timer message on regular basis. useful because through specifying time-out value, can achieve desired frames per second, without requirement measure duration "frame" takes rendered. would cause input or other lags due frequency , speed of m...
Read more

java.util.scanner - How to read and add only numbers to array from a text file -

i'm learning java , have question regarding reading file want read numbers file contains strings well. here example of file: 66.56 "3 java 3-43 5-42 2.1 1 and here coding: public class test { public static void main (string [] args){ if (0 < args.length) { file x = new file(args[0]); try{ scanner in = new scanner( new fileinputstream(x)); arraylist<double> test = new arraylist<>(); while(in.hasnext()){ if(in.hasnextdouble()){ double f=in.nextdouble(); test.add(f);} else {in.next();} } catch(ioexception e) { system.err.println("exception during reading: " + e); } } my problem add 66.56,2.1 , 1 doesn't add 3 after "3 or ignores 3-43 , 5-42 can tell me how skip strings , add doubles here? thanks all said 3 ie; "3, 3-43 , 4-42 strings either u read string , split , check number @ " , - or put in space between characters , integers. jvm after compilation tre...
Read more