I just switched from QTableWidget to QTableView. Calling the method setSortingEnabled before filling the table slows the construction really down. So if I use QTableWidget I first fill the table and then I call setSortingEnabled.
My problem with QTableView is that I do not know how to find out that the Table is filled, resp. when to call setSortingEnabled without loosing performance.
Is there any signal I can handle, or any slot to override ?
Related
There is a dictionary taken from JSON file, that is represented by QTreeView QStandardItemModel.
A user can reorganize QTreeView(add, delete, drag-n-drop) and rename items.
The goal is: call function that reads changed QTreeView, makes the dictionary and writes it to initial JSON file.
I can do it by pressing a QPushButton after changes occurred or by binding that function to every change e.g. call function when an item is deleted, call function when an item is added, call a function when an item is renamed and so on.
Is there any way to call a function if any of changes occur? Is there such a signal that corresponds to all of the mentioned changes?
The rowsMoved and itemChanged signals do what you think they do. See http://doc.qt.io/qt-4.8/qstandarditemmodel.html
As #vahancho suggests in the comments, you should connect to the layoutChanged signal. All models should emit this immedaitely after making any changes which could affect the view. So this will include sorting and filtering, as well as re-ordering, editing, deleting, etc.
The dataChanged signal is similar, but only really useful if you want to monitor specific items.
In my program I use QTableView and QAbstractTableModel that are connected. Model doesn't contain data. When view needs data to show it calls QAbstractTableModel::data and model uses another object to get data and return. At some point data in that object is going changed. Model doesn't know what has changed so dataChanged is not called.
I need that only visible part of data (that is shown in view) goes updated. It should get new data from model. I am trying to achieve that by calling update() or repaint() functions of view but it doesn't help. I am thinking that it should call paintEvent of tableview but it is not called.
How is it possible to make view update visible part of data? I don't want to update whole data that is huge.
Your wishes brokes Qt MVC logic. But if you need workaround - you may do next call to update visible area: emit dataChanged( QModelIndex(), QModelIndex() );
I'm implementing a Model/View for a tree like structure, and I've decided to try the QStandardItemModel on which I want to wrap on it a specific class, (which I call here "appSpecificClass").
Basically, I want part of that class (like names, or some data), to be shown in the model, and when I change the model (in edit role, or drag and drop), I want that to have consequences on the appSpecificClass (which is, when I change a name that is showing on the model, the name on the object associated with the model's item of the appSpecificClass also changes).
So, I started from subclassing the QStandardItem by a appSpecificItem, which only has a pointer to the appSpecificClass. When I construct the appSpecificItem, the text and icons are called from appSpecificClass and everything works fine.
However, when change data from appSpecificItem, naturally it does not change the appSpecificClass, because so far I didn't found any way of interacting with the appSpecificItem's pointer via overloading a virtual function (or else)
Does anyone knows how to do this/if this is possible? What can I do such that if for instance the signal
QStandardItemModel::itemChanged ( QStandardItem * item )
is emitted, I can change a the appSpecificItem's pointer.
If not, is there any good tutorial about implementing a Model from scratch? I've tried myself some, but it is not an easy task. Ideally I would like a QStandardItemModel like model, but a little more abstraction on it (such that I can put my appSpecificClass on it).
I'm trying to write a script for an application developed with Qt, using javascript for the business logic and a .ui file for the GUI, but I'm facing two problems.
In the ui I declared a QComboBox, to which I successfully connect javascript functions to handle
signals such as editTextChanged, etc. I was wondering I cannot populate the combobox from within
javascript code, because the addItem function is not exposed to script-side code.
combobox.editTextChanged[action](ComboBoxChanged); // OK (action is "connect" or "disconnect")
combobox.addItem("element 1"); // Error!
Is there any (other) way to do this?
I need to show a set of items (strings) in a table-like component. I tried using a QTableView and
QTableWidget but I cannot insert or get items. For example, from javascript I cannot access the
setModel function of a QTableView (if at least I could create a QAbstractItemModel from
script...), neither I can access the item(row,col) function of a QTableWidget class, to set an
item's text. Is there any way to show a table of strings to the user, let edit them and retrieve
the modified contents?
Thanks in advance.
Antonio
Because the addItem() function isn't a slot, you'll need an intermediate public slot to handle the transaction. It'll be the same with the other functions you are trying to get at as well.
How can I autocommit data from QTableWidget, that is in editing state, when I fire some command?
Assume, that there is some grid and data in it (editable thorough delegate that fires QComboBox editor). So, one starting to select option in combo, but do not finish editing, then hit some button, that executes action, that uses data from that combo, but new choise is not committed yet :\
How can I programmatically finish editing in table?
I mean some not strict 'loop all items and finish editing' way, that I consider as bad and ugly.
OOPS: worked too much, so, haven't realised, that there could be only one pending editor at time. Question is still here.
There is a protected slot named "commitData" in the tableWidget. You can inherit from tableWidget, then add your own public method (or slot) and send a signal (or simply call commitData method) from there.
There is one problem. You'll need to provide the editor object, but tableWidget gives you no way to get the pointer you need.
If you're using your own createEditor method, you can save the pointer to the editor somewhere, where your method can get it. It's a hack, but it's the only way i know.
The current editor does not seem to be accessible from outside of the view, but its content is committed when the current model index changes. So a simple way to force a commit seems to be to call
table->setCurrentIndex (QModelIndex ())
plus restoring your previous current index afterwards if the widget is not discarded yet.
This is quite an old question but it still came up quite high on Google so just in case anyone else needs the answer QTableView has a protected method
void currentChanged(const QModelIndex ¤t, const QModelIndex &previous)
which causes the data to be commited and QTableWidget is built on QTableView so that should still work. I found this info on the Qt Forum.