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• Qt - problem appending to QList of QList

  - by bullettime

  I'm trying to append items to a QList at runtime, but I'm running on a error message. Basically what I'm trying to do is to make a QList of QLists and add a few customClass objects to each of the inner lists. Here's my code: widget.h: class Widget : public QWidget { Q_OBJECT public: Widget(QWidget *parent = 0); ~Widget(); public slots: static QList<QList<customClass> > testlist(){ QList<QList<customClass> > mylist; for(int w=0 ; w<5 ; w++){ mylist.append(QList<customClass>()); } for(int z=0 ; z<mylist.size() ; z++){ for(int x=0 ; x<10 ; x++){ customClass co = customClass(); mylist.at(z).append(co); } } return mylist; } }; customclass.h: class customClass { public: customClass(){ this->varInt = 1; this->varQString = "hello world"; } int varInt; QString varQString; }; main.cpp: int main(int argc, char *argv[]) { QApplication a(argc, argv); Widget w; QList<QList<customClass> > list; list = w.testlist(); w.show(); return a.exec(); } But when I try to run the application, it gives off this error: error: passing `const QList<customClass>' as `this' argument of `void List<T>::append(const T&) [with T = customClass]' discards qualifiers I also tried inserting the objects using foreach: foreach(QList<customClass> list, mylist){ for(int x=0 ; x<10 ; x++){ list.append(customClass()); } } The error was gone, but the customClass objects weren't appended, I could verify that by using a debugging loop in main that showed the inner QLists sizes as zero. What am I doing wrong?

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• QList as a function parameter - Linking Error - LNK2019

  - by user2445136

  I have an issue with QList as a function parameter and I'll be glad if you can assist me. I have this code for example: void SpinBoxList_Enable(QList spinBoxList) { foreach(QWidget mWidget,*spinBoxList) mWidget-setEnabled(false); } and in the implemantation file I use the QList variable as a pointer: SpinBoxList_Enable(&controlBoardSpinBoxList); ( controlBoardSpinBoxList is a variable of QList ). The Function ToggleBoards_Slot(bool) is a slot that uses When I compile, I get this error message: 1cmosaixserialnumber.obj : error LNK2019: unresolved external symbol "private: void __cdecl CMosaixSerialNumber::SpinBoxList_Disable(class QList *)" (?SpinBoxList_Disable@CMosaixSerialNumber@@AEAAXPEAV?$QList@PEAVQWidget@@@@@Z) referenced in function "public: void __cdecl CMosaixSerialNumber::ToggleBoards_Slot(bool)" (?ToggleBoards_Slot@CMosaixSerialNumber@@QEAAX_N@Z) 1cmosaixserialnumber.obj : error LNK2019: unresolved external symbol "private: void __cdecl CMosaixSerialNumber::SpinBoxList_Enable(class QList *)" (?SpinBoxList_Enable@CMosaixSerialNumber@@AEAAXPEAV?$QList@PEAVQWidget@@@@@Z) referenced in function "private: void __cdecl CMosaixSerialNumber::on_ControlBoardCheckBox_StateChanged(int)" (?on_ControlBoardCheckBox_StateChanged@CMosaixSerialNumber@@AEAAXH@Z) How can I fix this ? Thanks, EVH671

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• Save QList<int> to QSettings

  - by Tobias

  Hello, I want to save a QList<int> to my QSettings without looping through it. I know that I could use writeArray() and a loop to save all items or to write the QList to a QByteArray and save this but then it is not human readable in my INI file.. Currently I am using the following to transform my QList<int> to QList<QVariant>: QList<QVariant> variantList; //Temp is the QList<int> for (int i = 0; i < temp.size(); i++) variantList.append(temp.at(i)); And to save this QList<Variant> to my Settings I use the following code: QVariant list; list.setValue(variantList); //saveSession is my QSettings object saveSession.setValue("MyList", list); The QList is correctly saved to my INI file as I can see (comma seperated list of my ints) But the function crashes on exit. I already tried to use a pointer to my QSettings object instead but then it crashes on deleting the pointer ..

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• subclassing QList and operator+ overloading

  - by Milen

  I would like to be able to add two QList objects. For example: QList<int> b; b.append(10); b.append(20); b.append(30); QList<int> c; c.append(1); c.append(2); c.append(3); QList<int> d; d = b + c; For this reason, I decided to subclass the QList and to overload the operator+. Here is my code: class List : public QList<int> { public: List() : QList<int>() {} // Add QList + QList friend List operator+(const List& a1, const List& a2); }; List operator+(const List& a1, const List& a2) { List myList; myList.append(a1[0] + a2[0]); myList.append(a1[1] + a2[1]); myList.append(a1[2] + a2[2]); return myList; } int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); List b; b.append(10); b.append(20); b.append(30); List c; c.append(1); c.append(2); c.append(3); List d; d = b + c; List::iterator i; for(i = d.begin(); i != d.end(); ++i) qDebug() << *i; return a.exec(); } , the result is correct but I am not sure whether this is a good approach. I would like to ask whether there is better solution?

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• Best Practice: QT4 QList<Mything*>... on Heap, or QList<Mything> using reference?

  - by Mike Crowe

  Hi Folks, Learning C++, so be gentle :)... I have been designing my application primarily using heap variables (coming from C), so I've designed structures like this: QList<Criteria*> _Criteria; // ... Criteria *c = new Criteria(....); _Criteria.append(c); All through my program, I'm passing pointers to specific Criteria, or often the list. So, I have a function declared like this: QList<Criteria*> Decision::addCriteria(int row,QString cname,QString ctype); Criteria * Decision::getCriteria(int row,int col) which inserts a Criteria into a list, and returns the list so my GUI can display it. I'm wondering if I should have used references, somehow. Since I'm always wanting that exact Criteria back, should I have done: QList<Criteria> _Criteria; // .... Criteria c(....); _Criteria.append(c); ... QList<Criteria>& Decision::addCriteria(int row,QString cname,QString ctype); Criteria& Decision::getCriteria(int row,int col) (not sure if the latter line is syntactically correct yet, but you get the drift). All these items are specific, quasi-global items that are the core of my program. So, the question is this: I can certainly allocate/free all my memory w/o an issue in the method I'm using now, but is there are more C++ way? Would references have been a better choice (it's not too late to change on my side). TIA Mike

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• Qt and finding partial matches in a QList

  - by ExpatEgghead

  I have a struct viz: struct NameKey { std::string fullName; std::string probeName; std::string format; std::string source; } which are held in a QList: QList<NameKey> keyList; what I need to do is find an occurence in keyList of a partial match where the search is for a NameKey that only has two members filled. All the keyList entries are full NameKey's. My current implementation is , well, boring in the extreme with too many if's and conditions. So, If I have a DataKey with a fullName and a format I need to find all the occurences in keyList which match. Any useful Qt/boost things available?

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• Declaration of struct variables in other class when obtained by getters

  - by liaK

  Hi, I am using Qt 4.5 so do C++. I have a class like this class CClass1 { private: struct stModelDetails { QString name; QString code; ..... // only variables and no functions over here }; QList<stModelDetails> m_ModelDetailsList; public: QList<stModelDetails> getModelDetailsList(); ... }; In this I have functions that will populate the m_ModelDetailsList; I have another class say CClassStructureUsage, where I will call the getModelDetailsList() function. Now my need is that I have to traverse the QList and obtain the name, code from each of the stModelDetails. Now the problem is even the CClass1's header file is included it is not able to identify the type of stModelDetails in CClassStructureUsage. When I get the structure list by QList<stModelDetails> ModelList = obj->getModelInformationList(); it says stModelDetails : undeclared identifier. How I can able to fetch the values from the structure? Am I doing anything wrong over here?

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• Qt undocumented method setSharable

  - by soxs060389

  I stumbled about a method which seems to be present in all DataObjects like QList, QQueue, QHash... I even investigated so far i can see the source code of it, which is inline void setSharable(bool sharable) { if (!sharable) detach(); d->sharable = sharable; } in qlist.h (lines 117) but what effect does it have on the QList, QQueue, QHash... ? And is it in any way related to threading? (which sounds reasonable) Thanks for any answer, and please only answer if you got actual knowledge.

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• C++ best practice: Returning reference vs. object

  - by Mike Crowe

  Hi folks, I'm trying to learn C++, and trying to understand returning objects. I seem to see 2 ways of doing this, and need to understand what is the best practice. Option 1: QList<Weight *> ret; Weight *weight = new Weight(cname, "Weight"); ret.append(weight); ret.append(c); return &ret; Option 2: QList<Weight *> *ret = new QList(); Weight *weight = new Weight(cname, "Weight"); ret->append(weight); ret->append(c); return ret; (of course, I may not understand this yet either). Which way is considered best-practice, and should be followed? TIA Mike

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• Lots of pointer casts in QGraphicsView framework and performance

  - by kleimola

  Since most of the convenience functions of QGraphicsScene and QGraphicsItem (such as items(), collidingItems(), childItems() etc.) return a QList you're forced to do lots of qgraphicsitem_cast or static_cast and QGraphicsItem::Type() checks to get hold of the actual items when you have lots of different type of items in the scene. I thought doing lots of subclass casts were not a desirable coding style, but I guess in this case there are no other viable way, or is there? QList<QGraphicsItem *> itemsHit = someItem->collidingItems(Qt::IntersectsItemShape); foreach (QGraphicsItem *item, itemsHit) { if (item->type() == QGraphicsEllipseItem::type()) { QGraphicsEllipseItem *ellipse = qgraphicsitem_cast<QGraphicsEllipseItem *>(item); // do something } else if (item->type() == MyItemSubclass::type()) { MyItemSubClass *myItem = qgraphicsitem_cast<MyItemSubClass *>(item); // do something } // etc } The above qgraphicsitem_cast could be replaced by static_cast since correct type is already verified. When doing lots of these all the time (very dynamic scene), will the numerous casting affect performance beyond the normal if-else evaluation?

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• How does this decorator make a call to the 'register' method?

  - by BryanWheelock

  I'm trying to understand what is going on in the decorator @not_authenticated. The next step in the TraceRoute is to the method 'register' which is also located in django_authopenid/views.py which I just don't understand because I don't see anywhere that register is even mentioned in signin() How is the method 'register' called? def not_authenticated(func): """ decorator that redirect user to next page if he is already logged.""" def decorated(request, *args, **kwargs): if request.user.is_authenticated(): next = request.GET.get("next", "/") return HttpResponseRedirect(next) return func(request, *args, **kwargs) return decorated @not_authenticated def signin(request,newquestion=False,newanswer=False): """ signin page. It manage the legacy authentification (user/password) and authentification with openid. url: /signin/ template : authopenid/signin.htm """ request.encoding = 'UTF-8' on_failure = signin_failure next = clean_next(request.GET.get('next')) form_signin = OpenidSigninForm(initial={'next':next}) form_auth = OpenidAuthForm(initial={'next':next}) if request.POST: if 'bsignin' in request.POST.keys() or 'openid_username' in request.POST.keys(): form_signin = OpenidSigninForm(request.POST) if form_signin.is_valid(): next = clean_next(form_signin.cleaned_data.get('next')) sreg_req = sreg.SRegRequest(optional=['nickname', 'email']) redirect_to = "%s%s?%s" % ( get_url_host(request), reverse('user_complete_signin'), urllib.urlencode({'next':next}) ) return ask_openid(request, form_signin.cleaned_data['openid_url'], redirect_to, on_failure=signin_failure, sreg_request=sreg_req) elif 'blogin' in request.POST.keys(): # perform normal django authentification form_auth = OpenidAuthForm(request.POST) if form_auth.is_valid(): user_ = form_auth.get_user() login(request, user_) next = clean_next(form_auth.cleaned_data.get('next')) return HttpResponseRedirect(next) question = None if newquestion == True: from forum.models import AnonymousQuestion as AQ session_key = request.session.session_key qlist = AQ.objects.filter(session_key=session_key).order_by('-added_at') if len(qlist) > 0: question = qlist[0] answer = None if newanswer == True: from forum.models import AnonymousAnswer as AA session_key = request.session.session_key alist = AA.objects.filter(session_key=session_key).order_by('-added_at') if len(alist) > 0: answer = alist[0] return render('authopenid/signin.html', { 'question':question, 'answer':answer, 'form1': form_auth, 'form2': form_signin, 'msg': request.GET.get('msg',''), 'sendpw_url': reverse('user_sendpw'), }, context_instance=RequestContext(request)) Looking at the request, it seems that account/register/ does reference the register method with 'PATH_INFO': u'/account/register/' Here is the request: <WSGIRequest GET:<QueryDict: {}>, POST:<QueryDict: {u'username': [u'BryanWheelock'], u'email': [u'[email protected]'], u'bnewaccount': [u'Signup']}>, COOKIES:{'__utma': '127460431.1218630960.1266769637.1266769637.1266864494.2', '__utmb': '127460431.3.10.1266864494', '__utmc': '127460431', '__utmz': '127460431.1266769637.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none)', 'sessionid': 'fb15ee538320170a22d3a3a324aad968'}, META:{'CONTENT_LENGTH': '74', 'CONTENT_TYPE': 'application/x-www-form-urlencoded', 'DOCUMENT_ROOT': '/usr/local/apache2/htdocs', 'GATEWAY_INTERFACE': 'CGI/1.1', 'HTTP_ACCEPT': 'application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5', 'HTTP_ACCEPT_CHARSET': 'ISO-8859-1,utf-8;q=0.7,*;q=0.3', 'HTTP_ACCEPT_ENCODING': 'gzip,deflate,sdch', 'HTTP_ACCEPT_LANGUAGE': 'en-US,en;q=0.8', 'HTTP_CACHE_CONTROL': 'max-age=0', 'HTTP_CONNECTION': 'close', 'HTTP_COOKIE': '__utmz=127460431.1266769637.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=127460431.1218630960.1266769637.1266769637.1266864494.2; __utmc=127460431; __utmb=127460431.3.10.1266864494; sessionid=fb15ee538320170a22d3a3a324aad968', 'HTTP_HOST': 'workproject.com', 'HTTP_ORIGIN': 'http://workproject.com', 'HTTP_REFERER': 'http://workproject.com/account/signin/complete/?next=%2F&janrain_nonce=2010-02-22T18%3A49%3A53ZG2KXci&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=id_res&openid.op_endpoint=https%3A%2F%2Fwww.google.com%2Faccounts%2Fo8%2Fud&openid.response_nonce=2010-02-22T18%3A49%3A53Znxxxxxxxxxw&openid.return_to=http%3A%2F%2Fworkproject.com%2Faccount%2Fsignin%2Fcomplete%2F%3Fnext%3D%252F%26janrain_nonce%3D2010-02-22T18%253A49%253A53ZG2KXci&openid.assoc_handle=AOQobUepU4xs-kGg5LiyLzfN3RYv0I0Jocgjf_1odT4RR9zfMFpQVpMg&openid.signed=op_endpoint%2Cclaimed_id%2Cidentity%2Creturn_to%2Cresponse_nonce%2Cassoc_handle&openid.sig=Jf76i2RNhqpLTJMjeQ0nnQz6fgA%3D&openid.identity=https%3A%2F%2Fwww.google.com%2Faccounts%2Fo8%2Fid%3Fid%3DAItxxxxxxxxxs9CxHQ3PrHw_N5_3j1HM&openid.claimed_id=https%3A%2F%2Fwww.google.com%2Faccounts%2Fo8%2Fid%3Fid%3DAItOaxxxxxxxxxxx4s9CxHQ3PrHw_N5_3j1HM', 'HTTP_USER_AGENT': 'Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-US) AppleWebKit/532.9 (KHTML, like Gecko) Chrome/5.0.307.7 Safari/532.9', 'HTTP_X_FORWARDED_FOR': '96.8.31.235', 'PATH': '/usr/bin:/bin', 'PATH_INFO': u'/account/register/', 'PATH_TRANSLATED': '/home/spirituality/webapps/work/spirit_app.wsgi/account/register/', 'QUERY_STRING': '', 'REMOTE_ADDR': '127.0.0.1', 'REMOTE_PORT': '59956', 'REQUEST_METHOD': 'POST', 'REQUEST_URI': '/account/register/', 'SCRIPT_FILENAME': '/home/spirituality/webapps/spirituality/spirit_app.wsgi', 'SCRIPT_NAME': u'', 'SERVER_ADDR': '127.0.0.1', 'SERVER_ADMIN': '[no address given]', 'SERVER_NAME': 'workproject.com', 'SERVER_PORT': '80', 'SERVER_PROTOCOL': 'HTTP/1.0', 'SERVER_SIGNATURE': '', 'SERVER_SOFTWARE': 'Apache/2.2.12 (Unix) mod_wsgi/2.5 Python/2.5.4', 'mod_wsgi.application_group': 'www.workProject.com|', 'mod_wsgi.callable_object': 'application', 'mod_wsgi.listener_host': '', 'mod_wsgi.listener_port': '25931', 'mod_wsgi.process_group': '', 'mod_wsgi.reload_mechanism': '0', 'mod_wsgi.script_reloading': '1', 'mod_wsgi.version': (2, 5), 'wsgi.errors': <mod_wsgi.Log object at 0xb7ce0038>, 'wsgi.file_wrapper': <built-in method file_wrapper of mod_wsgi.Adapter object at 0xb7e94b18>, 'wsgi.input': <mod_wsgi.Input object at 0x999cc78>, 'wsgi.multiprocess': True, 'wsgi.multithread': False, 'wsgi.run_once': False, 'wsgi.url_scheme': 'http', 'wsgi.version': (1, 0)}>

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• Serializing QGraphicsScene contents

  - by Rob

  I am using the Qt QGraphicsScene class, adding pre-defined items such as QGraphicsRectItem, QGraphicsLineItem, etc. and I want to serialize the scene contents to disk. However, the base QGraphicsItem class (that the other items I use derive from) doesn't support serialization so I need to roll my own code. The problem is that all access to these objects is via a base QGraphicsItem pointer, so the serialization code I have is horrible: QGraphicsScene* scene = new QGraphicsScene; scene->addRect(QRectF(0, 0, 100, 100)); scene->addLine(QLineF(0, 0, 100, 100)); ... QList<QGraphicsItem*> list = scene->items(); foreach (QGraphicsItem* item, items) { if (item->type() == QGraphicsRectItem::Type) { QGraphicsRectItem* rect = qgraphicsitem_cast<QGraphicsRectItem*>(item); // Access QGraphicsRectItem members here } else if (item->type() == QGraphicsLineItem::Type) { QGraphicsLineItem* line = qgraphicsitem_cast<QGraphicsLineItem*>(item); // Access QGraphicsLineItem members here } ... } This is not good code IMHO. So, instead I could create an ABC class like this: class Item { public: virtual void serialize(QDataStream& strm, int version) = 0; }; class Rect : public QGraphicsRectItem, public Item { public: void serialize(QDataStream& strm, int version) { // Serialize this object } ... }; I can then add Rect objects using QGraphicsScene::addItem(new Rect(,,,)); But this doesn't really help me as the following will crash: QList<QGraphicsItem*> list = scene->items(); foreach (QGraphicsItem* item, items) { Item* myitem = reinterpret_class<Item*>(item); myitem->serialize(...) // FAIL } Any way I can make this work?

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• How to set QListView Opacity ,setWindowOpacity dosn't work

  - by user63898

  Hi im trying to set opacity to QListView , that sits on QDialog i mange to set the QDialog transperant with setting the :Qt::WA_TranslucentBackground = true but the QList doesn't become transparent with i set the setWindowOpacity to 1 or 0

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• Qt Graphics Scene mouse event propagation

  - by Olorin

  hello i'm learning qt and i'm doing the folowing to add some widgets to a graphics scene void MainWindow::addWidgets(QList<QWidget *> &list, int code) { if(code == CODE_INFO) { QWidget *layoutWidget = new QWidget(); QVBoxLayout *layout = new QVBoxLayout(); foreach(QWidget *w, list) { layout->addWidget(w); this->connect(((ProductInfo*)w), SIGNAL(productClicked()), this, SLOT(getProductDetails())); } layoutWidget->setLayout(layout); this->scene->addWidget(layoutWidget); } } my ProductInfo class processes mouse release and emits a signal void ProductInfo::mouseReleaseEvent(QMouseEvent *e) { QWidget::mouseReleaseEvent(e); emit productClicked(); } the problem is after adding the widgets to the scene they no longer get the mouse release event and don't emit productClicked signal but if i add them to the main window(not to the scene) they work as expected. What am i doing wrong?

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• returning null or throwing an exception?

  - by MoKi

  I have the following types: typedef QPair < QTime , QTime > CalculatedTimeSlotRange; typedef QList < CalculatedTimeSlotRange > CalculatedTimeSlotRangeList; typedef QHash < quint8 , CalculatedTimeSlotRangeList > TimeSlotsTable; I have a function like the following: const CalculatedTimeSlotRangeList* TimeSlots::getCalculatedTimeSlotRangeList(const quint8 id) const { QHashIterator<quint8,CalculatedTimeSlotRangeList> it(mTimeSlotsTable); while (it.hasNext()) { it.next(); if(it.key() == id) { return &it.value(); } } return NULL; } as you can see my function returns a null if it fails to find a key that matches id. Is this correct? or should I just throw an exception if the key does not exist? how should i throw an exception for this situation?

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• Overloading the QDataStream << and >> operators for a user-defined type

  - by Alex Wood

  I have a an object I'd like to be able to read and write to/from a QDataStream. The header is as follows: class Compound { public: Compound(QString, QPixmap*, Ui::MainWindow*); void saveCurrentInfo(); void restoreSavedInfo(QGraphicsScene*); void setImage(QPixmap*); QString getName(); private: QString name, homeNotes, addNotes, expText; Ui::MainWindow *gui; QPixmap *image; struct NMRdata { QString hnmrText, cnmrText, hn_nmrText, hn_nmrNucl, notes; int hnmrFreqIndex, cnmrFreqIndex, hn_nmrFreqIndex, hnmrSolvIndex, cnmrSolvIndex, hn_nmrSolvIndex; }*nmr_data; struct IRdata { QString uvConc, lowResMethod, irText, uvText, lowResText, highResText, highResCalc, highResFnd, highResFrmla, notes; int irSolvIndex, uvSolvIndex; }*ir_data; struct PhysicalData { QString mpEdit, bpEdit, mpParensEdit, bpParensEdit, rfEdit, phyText, optAlpha, optConc, elemText, elemFrmla, notes; int phySolvIndex, optSolvIndex; }*physical_data; }; For all intensive purposes, the class just serves as an abstraction for a handful of QStrings and a QPixmap. Ideally, I would be able to write a QList to a QDataStream but I'm not exactly sure how to go about doing this. If operator overloading is a suitable solution, would writing code like friend QDataStream& operator << (QDataStream&,Compound) { ... } be a potential solution? I'm very open to suggestions! Please let me know if any further clarification is needed.

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• QTableWidget::itemAt() returns seemingly random items

  - by Jordan Milne

  I've just started using Qt, so please bear with me. When I use QTableWidget-getItemAt(), it returns a different item from if I used currentItemChanged and clicked the same item. I believe it's necessary to use itemAt() since I need to get the first column of whatever row was clicked. Some example code is below: MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); QList<QString> rowContents; rowContents << "Foo" << "Bar" << "Baz" << "Qux" << "Quux" << "Corge" << "Grault" << "Garply" << "Waldo" << "Fred"; for(int i =0; i < 10; ++i) { ui->tableTest->insertRow(i); ui->tableTest->setItem(i, 0, new QTableWidgetItem(rowContents[i])); ui->tableTest->setItem(i, 1, new QTableWidgetItem(QString::number(i))); } } //... void MainWindow::on_tableTest_currentItemChanged(QTableWidgetItem* current, QTableWidgetItem* previous) { ui->lblColumn->setText(QString::number(current->column())); ui->lblRow->setText(QString::number(current->row())); ui->lblCurrentItem->setText(current->text()); ui->lblCurrentCell->setText(ui->tableTest->itemAt(current->column(), current->row())->text()); } For the item at 1x9, lblCurrentItem displays "9" (as it should,) whereas lblCurrentCell displays "Quux". Am I doing something wrong?

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• Context Menu on QGraphicsWidget

  - by onurozcelik

  Hi, In my application I have two object type. One is field item, other is composite item. Composite items may contain two or more field items. Here is my composite item implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { //Not carefully thinked about it return QRectF(QPointF(-50,-150),QSizeF(250,250)); } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } My first question is how I can propagate context menu event to specific child. Picture on the above demonstrates one of my possible composite item. If you look on the code above you will see that I print "Test" when context menu event occurs. When I right click on the line symbol I see that "Test" message is printed. But when I right click on the signal symbol "Test" is not printed and I want it to be printed. My second question what cause this behaviour. How do I overcome this.

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• Weird Qt SSL issue -- error "No Error" shows up, nothing else, and if I ignore it, everything works

  - by houbysoft

  The issue is as follows : in my Qt app, I have a QWebView, which I use to load a HTTPS page. Everything worked fine on my development machine, so I'm now trying to get it to run on a test machine. I ran the app, but the page didn't load (the QWebView was blank). After much debugging, I found the problem is that an SSL error shows up, and the sslErrors() signal is fired. Here is my sslErrors() handling code: void blah::sslErrors(QNetworkReply *reply, const QList<QSslError> &errors) { foreach(QSslError error, errors) { qDebug() << error.errorString() << endl; } reply->ignoreSslErrors(); } The only thing the above code prints is: "No error" So there's no error, but unless I call reply->ignoreSslErrors(), the page doesn't load (on the test machine, on my developer computer no error is reported). Huh? Is this a bug? Is it safe to ignore the error, if I make sure it's of the type "No error"?

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• QT QSslError being signaled with the error code set to NoError

  - by Nantucket

  My Problem I compiled OpenSSL into QT to enable OpenSSL support. Everything appeared to go correctly in the compile. However, when I try to use the official HTTP example application that can be found here, everytime I try to download an https page, it will signal two QSslError, each with contents NoError. The types of QSslErrors, including NoError, are documented here, poorly. There is no explanation on why they even included an error type called NoError, or what it means. Bizarrely, the NoError error code seems to be true, as it downloads the remote https document perfectly even while signaling the error. Does anyone have any idea what this means and what could possibly be causing it? Optional Background Reading Here is the relevant part of the code from the example app (this is connected to the network connection's sslErrors signal by the constructor): void HttpWindow::sslErrors(QNetworkReply*,const QList<QSslError> &errors) { QString errorString; foreach (const QSslError &error, errors) { if (!errorString.isEmpty()) errorString += ", "; errorString += error.errorString(); } if (QMessageBox::warning(this, tr("HTTP"), tr("One or more SSL errors has occurred: %1").arg(errorString), QMessageBox::Ignore | QMessageBox::Abort) == QMessageBox::Ignore) { reply->ignoreSslErrors(); } } I have tried the old version of this example, and it produced the same result. I have tried OpenSSL 1.0.0a and 0.9.8o. I have tried tried compiling OpenSSL myself, I have tried using pre-compiled versions of OpenSSL from the net. All produce the same result. If this were my first time using QT with SSL, I would almost think this is the intended result (even though their example application is popping up error warning message windows), if not for the fact that last time I played with QT, using what would now be an old version of QT with an old version of SSL, I distinctly remember everything working fine with no error windows. My system is running Windows 7 x64.

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• Qt: QStackedWidget solution

  - by Martin

  I'm building a Qt application that have about 30 different views (QWidgets). My idea is to use a QStackedWidget to make it easy to switch between the different views in the application. I have two different solutions of how to implement this and use as little memory as possible when the user navigates through the application. Solution 1: Everytime I need to show a view I check if it is already in the stack. (The user might open the same view many times, maybe a view showing an item from a database). If the view is in the stack already it doesn't need to be created again and I can just show the view. The good thing with this solution is that I reuse the views (widgets) so they only need to be created once. This is good as the UI and other stuff should look the same everytime the user show a view, so why not reuse it? The problem with this solution is that every view has childrens. Maybe an object, a QList with objects or other things. A good thing with Qt is that you can use the parent-children mechanism so that the children will be deleted when the parent is deleted. As I never delete the parent (view) I need to handle this myself as the children might need to be deleted from different times when the view is shown. (Maybe the view show a list with objects and the list should be updated from a database each time the view is shown.) Solution 2: Everytime I need to show a QWidget I create a new one and show it. When it is not shown anymore, I delete it from memory. This is a quite easy solution. And as I delete the views when they are not shown both the view and it's children should be deleted from memory so it shouldn't increase memory, am I right? Which one of the solutions do you recommend?

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• C++/Qt - Memory allocation question

  - by HardCoder1986

  Hello! I recently started investigating Qt for myself and have the following question: Suppose I have some QTreeWidget* widget. At some moment I want to add some items to it and this is done via the following call: QList<QTreeWidgetItem*> items; // Prepare the items QTreeWidgetItem* item1 = new QTreeWidgetItem(...); QTreeWidgetItem* item2 = new QTreeWidgetItem(...); items.append(item1); items.append(item2); widget->addTopLevelItems(items); So far it looks ok, but I don't actually understand who should control the objects' lifetime. I should explain this with an example: Let's say, another function calls widget->clear();. I don't know what happens beneath this call but I do think that memory allocated for item1 and item2 doesn't get disposed here, because their ownage wasn't actually transfered. And, bang, we have a memory leak. The question is the following - does Qt have something to offer for this kind of situation? I could use boost::shared_ptr or any other smart pointer and write something like shared_ptr<QTreeWidgetItem> ptr(new QTreeWidgetItem(...)); items.append(ptr.get()); but I don't know if the Qt itself would try to make explicit delete calls on my pointers (which would be disastrous since I state them as shared_ptr-managed). How would you solve this problem? Maybe everything is evident and I miss something really simple?

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• Container item implementation

  - by onurozcelik

  Hi, I am working in Train Traffic Controller software project. My responsibility in this project is to develop the visual railroad GUI. We are implementing the project with Qt. By now I am using QGraphicsLinearLayout to hold my items. I am using the layout because I do not want to calculate coordinates of each item. So far I wrote item classes to add the layout. For instance SwitchItem class symbolizes railroad switch in real world. Each item class is responsible for its own painting and events. So far so good. Now I need a composite item that can contain two or more item. This class is going to be responsible for painting the items contained in it. I need this class because I have to put two or more items inside same layout cell. If I don' t put them in same cell I can' t use layout. See the image below. BlockSegmentItem and SignalItem inside same cell. Here is my compositeitem implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { FieldItem *child; QRectF rect(0,0,0,0); foreach(child,children) { rect = rect.united(child->boundingRect()); } return rect; } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } This code works good with painting but when it comes to item events it is problematic. QGraphicsScene treats the composite item like a single item which is right for layout but not for events. Because each item has its own event implementation.(e.g. SignalItem has its special context menu event.) I have to handle item events seperately. Also I need a composite item implementation for the layout. How can I overcome this dilemma?

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• Using images in QListWidget, is this possible?

  - by Neko

  Hi, again. :) As with the last few times I posted here, I have a question about QT, which I am using to create a chat messenger client. To display the list of online users, I'm using a QListWidget, as created like this: listWidget = new QListWidget(horizontalLayoutWidget); listWidget->setObjectName("userList"); QSizePolicy sizePolicy1(QSizePolicy::Preferred, QSizePolicy::Expanding); sizePolicy1.setHorizontalStretch(0); sizePolicy1.setVerticalStretch(0); sizePolicy1.setHeightForWidth(listWidget->sizePolicy().hasHeightForWidth()); listWidget->setSizePolicy(sizePolicy1); listWidget->setMinimumSize(QSize(30, 0)); listWidget->setMaximumSize(QSize(150, 16777215)); listWidget->setBaseSize(QSize(100, 0)); listWidget->setContextMenuPolicy(Qt::CustomContextMenu); Users are shown by constantly refreshing the list, like this: (Note: There are different channels, with different userlists, so refreshing it is the most efficient thing to do, as far as I know.) void FMessenger::refreshUserlist() { if (currentPanel == 0) return; listWidget = this->findChild<QListWidget *>(QString("userList")); listWidget->clear(); QList<FCharacter*> charList = currentPanel->charList(); QListWidgetItem* charitem = 0; FCharacter* character; foreach(character, charList) { charitem = new QListWidgetItem(character->name()); // charitem->setIcon(QIcon(":/Images/status.png")); listWidget->addItem(charitem); } } This has always worked perfectly. The line that I commented out is the one I have problems with: my current goal is to be able to display a user's online status with an image, which represents whether they are busy, away, available, etc. Using setIcon() does absolutely nothing though, apparently; the items still show up as they used to, without icons. I'm aware that this is probably not the way this function needs to be used, but I have found little documentation about it online, and absolutely no useful examples of implementations. My question is, can anybody help me with fixing this problem? Any help would be appreciated terrifically, like always!

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