I have A class Named “Student” !
I have a Q Vector From Student class
Now I want To show the form of the 2nd Student in my vector !
but when it shows It is empty , it doesn’t show things the thing in the Ui
What should I do ?! Douse it even can happen ? Or it is not possible in Qt
This is My QVector:
StHead = new QVector <Student> ;
This is My Code :
void MainWindow::StudentSignIn (QString User,QString Pass)
{
///////Sign in things !
int index = StudentSearch(User);
Student* at = StHead->data();
if (at[index].GetPass() == Pass)
emit Hide_StuLog();
at[index].show();
}
Related
I have a QListView that is populated with either a QStandardItemModel or a QStringListModel (based on simplicity of contents... number of columns).
On load, or switching between widgets, I search for the item that should be selected, and try to highlight it.
if (first)
{
m_myListView.setModel(m_standardItemModel);
QList<QStandardItem*> lst = m_standardItemModel->findItems(m_value1, Qt::MatchExactly, 1);
if(!lst.isEmpty())
{
QModelIndex index = lst.at(0)->index();
qDebug() << index.row(); // tells me correct row
//m_myListView.setCurrentIndex(index); // no change if I use
m_myListView.selectionModel()->select(index, QItemSelectionModel::ClearAndSelect);
m_myListView.scrollTo(index);
}
}
else
{
m_myListView.setModel(m_stringListModel);
int i = m_stringListModel->stringList().indexOf(m_value2);
if (i >= 0)
{
QModelIndex index = m_stringListModel->index(i);
m_myListView.selectionModel()->select(index, QItemSelectionModel::ClearAndSelect);
m_myListView.scrollTo(index);
}
}
The m_stringListModel version correctly highlights (and scrolls to item).
The m_standardItemModel version does not highlight row, and does not scroll to item. But in the uses afterwards, it correctly provides the data for selected index:
QModelIndexList indexList = m_myListView.selectionModel()->selectedIndexes();
if (!indexList.isEmpty())
{
QModelIndex index = indexList.first();
if (index.isValid())
{
row = index.row();
data1 = m_standardItemModel->index(row, 1).data().toString();
...
So... it seems that the selection works, but if it does, why do I not see a highlight ? (and the scrollTo() )
Note - the code is pretty giant but I verified for the possibility of reloading the model and possibly losing the selection - and besides, the QStringListModel version works correctly.
Is that a typical behavior of QStandardItemModel, or is there something I must do, like setting a BackgroundRole type data ?
How can I highlight the selection of the list view with the QStandardItemModel applied ?
I see your code, probably you want to select the first element of your model? Let's try:
void MyClass::selectFirstElement() {
const QModelIndex firsIndex = _myModel->index(0,0);
if (index.isValid())
ui->listView->setCurrentIndex(firstIndex);
ui->listView->scrollTo(firstIndex);
}
}
Could you share the m_standardItemModel implementation? Also configure your list correctly:
ui->listView->setSelectionMode(QAbstractItemView::SingleSelection);
ui->listView->setSelectionBehavior(QAbstractItemView::SelectRows); // Or Columns
Check if your QStandarItem has the selection flag enable. See http://doc.qt.io/qt-4.8/qt.html#ItemFlag-enum for more info.
Finally, you could ensure that the index is stored in the correct model by getting the index in the same row & column directly from the model, something like this:
QModelIndex index = lst.at(0)->index();
index = _model->index(index.row(), index.column());
Sorry, for my poor english :S
Because the item found is different than the display item, the list view is unable to select it...
2 solutions: either create a different QModelIndex from the one found, pointing to the display column, or select an entire row containing the desired index:
m_myListView.selectionModel()->select(index, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
I'm using CTreeCtrl to display some data. With each entry in the tree, I have some associated data which I keep in a struct. I save this data with the item by putting the pointer to the struct in the lParam value in each entry in the tree.
This is my add entries code to the tree:
void CClassView::AddElementToTree(Element* _pElement, HTREEITEM _hRoot)
{
HTREEITEM hBranch;
TVINSERTSTRUCT tvInsert;
ZeroMemory(&tvInsert, sizeof(tvInsert));
tvInsert.hParent = _hRoot;
tvInsert.hInsertAfter = NULL;
tvInsert.item.mask = TVIF_TEXT;
WCHAR szText[64] = {'\0'};
tvInsert.item.pszText = szText;
for(std::vector<Element*>::iterator i = _pElement->pChildren.begin(); i != _pElement->pChildren.end(); ++i)
{
wcscpy_s(szText, (*i)->GetName().c_str());
tvInsert.item.lParam = (LPARAM)(*i);
hBranch = m_wndClassView.InsertItem(&tvInsert);
AddElementToTree(*i, hBranch);
}
}
Essentially this function recursively add an element to the tree, with its children. _pElement I pass externally. This is a member variable of my class so I know it is not destroyed unless the program ends.
When the user selects an entry in the tree view, I handle the selchanged message:
void CLayerTree::OnTvnSelchanged(NMHDR *pNMHDR, LRESULT *pResult)
{
LPNMTREEVIEW pNMTreeView = reinterpret_cast<LPNMTREEVIEW>(pNMHDR);
Element* pElement = (Element*)pNMTreeView->itemNew.lParam;
*pResult = 0;
}
pElement is always NULL. I debugged the program and it seems lParam is also zero.
Am I doing anything wrong? I know that the memory of my struct has not been deallocated. Is it something wrong I'm doing adding the entry to the tree?
Any help would be appreciated.
TVIF_PARAM must be set in the mask!
I have this code:
myEdit = QLineEdit()
myQFormLayout.addRow("myLabelText", myEdit)
Now I have to remove the row by reference to myEdit only:
myQformLayout.removeRow(myEdit)
But there is no API for that. I can use .takeAt(), but how can I get the argument? How do I find the label index, or the index of myEdit?
You can just schedule the widget and its label (if it has one) for deletion, and let the form adjust itself accordingly. The label for the widget can be retrieved using labelForField.
Python Qt code:
label = myQformLayout.labelForField(myEdit)
if label is not None:
label.deleteLater()
myEdit.deleteLater()
my solution...
in header file:
QPointer<QFormLayout> propertiesLayout;
in cpp file:
// Remove existing info before re-populating.
while ( propertiesLayout->count() != 0) // Check this first as warning issued if no items when calling takeAt(0).
{
QLayoutItem *forDeletion = propertiesLayout->takeAt(0);
delete forDeletion->widget();
delete forDeletion;
}
This is actually a very good point... there is no explicit reverse function for addRow().
To remove a row you can do the following:
QLineEdit *myEdit;
int row;
ItemRole role;
//find the row
myQFormLayout->getWidgetPosition( myEdit, &row, &role);
//stop if not found
if(row == -1) return;
ItemRole otheritemrole;
if( role == QFormLayout::FieldRole){
otheritemrole = QFormLayout::LabelRole;
}
else if( role == QFormLayout::LabelRole){
otheritemrole = QFormLayout::FieldRole;
}
//get the item corresponding to the widget. this need to be freed
QLayoutItem* editItem = myQFormLayout->itemAt ( int row, role );
QLayoutItem* otherItem = 0;
//get the item corresponding to the other item. this need to be freed too
//only valid if the widget doesn't span the whole row
if( role != QFormLayout::SpanningRole){
otherItem = myQFormLayout->itemAt( int row, role );
}
//remove the item from the layout
myQFormLayout->removeItem(editItem);
delete editItem;
//eventually remove the other item
if( role != QFormLayout::SpanningRole){
myQFormLayout->removeItem(otherItem);
delete otherItem
}
Note that I retrieve all the items before removing them. That's because I don't know if their role will change when an item is removed. This behavior is not specified so I am
playing safe. In qt designer, when you remove an item from a form, the other item on
the row take all the space (which means his role changes...).
Maybe there is a function somewhere and not only I reinvented the wheel but I made a broken one...
Hi
I am creating online quiz in asp.net c#. For that i have one form that displays testlist in dropdownlist & start button. After clicking 2nd form appears, 2nd form shows one label for question, radiobuttonlist for answers ,next & checkbox for review. I am creating array of random question ids in start button click event of the 1stform. when i click next button in 2nd form then next random question appears, i want array of questions those are checked for review. I used code for arrays of values ( eg.10101) 1 for true & 0 for false as follows but i want array of that question ids those are checked:
int[] a = (int[])Session["values"];//this is array of random question ids created in 1st form
int g;
if (chkmark.Checked == true)
{
g = 1;
}
else
{
g = 0;
}
int[] chkarray = new int[Convert.ToInt32(Session["Counter"]) - 1];
int[] temp1 = (int[])Session["arrofchk"];
int k, no;
if (temp1 == null)
no = 0;
else
no = temp.Length;
for (k = 0; k < no; k++)
{
chkarray[k] = temp1[k];
}
chkarray[j] = g;
Personally, i would use a Dictionary<int, bool> for this.
In the key of the dictionary, you can store the random Question ID, in the value of the pair, you can store the checked item state. It might take you more work now to refactor it, but I believe it will save you a lot of time in the end when you want to do more actions on your quiz items.
Using a dictionary - or at least a well chosen collection, I think it will be easier to get the right data back.
For your example, it can work only if the positions of both arrays are the same.
Dictionary<int, bool> quizAnswers = new Dictionary<int, bool>(); // <questionID, checked>
// Fill dictionary with questions and answers
for(int i=0;i<a.length;i++)
{
if(temp1.length > i) // Make sure we don't get an IndexOutOfBoundsException
{
quizAnswers.Add(a[i], temp1[i] == 1);
}
}
// Get Answered question in array ( LINQ )
int[] checkedAnswers = (from KeyValuePair<int, bool> pair in quizAnswers
where pair.Value == true
select pair.Key).ToArray<int>();
The reason I am using a Dictionary here, is because I personally think it's neater than having two separate arrays.
I believe you should implement a Dictionary in your quiz, in stead of those arrays. What if the array indexes don't match, or you want to dynamically add a question to a fixed size array, etc..
It's something to take into consideration. Hope I could help you out.
In the big picture I want to create a frame based application in Bada that has a single UI control - a label. So far so good, but I want it to display a number of my choosing and decrement it repeatedly every X seconds. The threading is fine (I think), but I can't pass the label pointer as a class variable.
//MyTask.h
//...
result Construct(Label* pLabel, int seconds);
//...
Label* pLabel;
//MyTask.cpp
//...
result
MyTask::Construct(Label* pLabel, int seconds) {
result r = E_SUCCESS;
r = Thread::Construct(THREAD_TYPE_EVENT_DRIVEN);
AppLog("I'm in da constructor");
this->pLabel = pLabel;
this->seconds = seconds;
return r;
}
//...
bool
Threading::OnAppInitializing(AppRegistry& appRegistry)
{
// ...
Label* pLabel = new Label();
pLabel = static_cast<Label*>(pForm->GetControl(L"IDC_LABEL1"));
MyTask* task = new MyTask();
task->Construct(&pLabel); // HERE IS THE ERROR no matching for Label**
task->Start();
// ...
}
The problem is that I have tried every possible combination of *, &, and just plain pLabel, known in Combinatorics...
It is not extremely important that I get this (it is just for training) but I am dying to understand how to solve the problem.
Have you tried:
task->Construct(pLabel, 0);
And by that I want to point out that you are missing the second parameter for MyTask::Construct.
No, I haven't. I don't know of a second parameter. But this problem is solved. If I declare a variable Object* __pVar, then the constructor should be Init(Object* pVar), and if I want to initialize an instance variable I should write
Object* pVar = new Object();
MyClass* mClass = new MyClass();
mClass->Construct(pVar);