How to save UI state of a QT application? - qt

I have a software with different components ( button, slider, ...). I want to save all components state (clicked, slider value, ..).
I heard there is QSettings which can save state. But in my software, i can't know which components exists because i create them "randomly" at runtime.
Looking for a solution to be able to save the whole ui state. Thanks.
EDIT :
My question wasn't clear so i will explain a bit futher, i don't need to save state between 2 sessions of the application, i just need to save state for later without restarting the software. I can get the list of ui components using findChildren for exemple.

Related

Redux creating new objects on ui

Creating an application that uses redux state quite seriously.
While passing values between the UI components and the reducers. The immutability has become a problem.
1) The cycle problem - I have forms that create JSON objects - which are then used by reducers to maintain the model. The next time you use a form, it is set to the earlier state,.. and either gives error or updates the previous attribute along with itself. Is there someway to capture things in non redux state and then pass it to the states for process?
2) Redux returns or reducers become extremely unmanageable on scale. I have started using immer for this. Is this a good choice?
Are you using Reactjs for creating the forms?
To benefit most from immutabilitiy it is best if your design embraces it also.
What I mean: Develop a form which just displays your data. (a pure form, or FormPure)
Then wrap this form / component by another component which holds the state of the form to be displayed and actually displays the data through the pure form. And allows you to just edit it.
The hierarchy would look like: App > Form > FormPure
Components
Form:
Connected to Redux
May have its own state.
FormPure:
Does not know about redux
Only displays data provided from its parent (in react via props and communicated via callbacks up)
When the user hits the Save Button then the connected Component (Form) may dispatch an action to update the state in redux.
This way you may build your FormPure in isolation separately from any data, and just bring it to live as needed.
You may consider using Storybook for nicely designing your components.
For 2: Yes immer is reasonably fine to use, just make sure you are not overusing it by creating to large object trees, as described in the documentation.
Also make sure to turn off autofreezing when deploying it to production.
Hint: immer uses Proxy make sure your target platform supports them, or make sure to switch then to the ES5 implementation which is considerably slower (see, immer docs)

What's the best way to chain Dialogs in QT?

In my app, I have a project features but it needs a chain of dialogs to work.
At start, the user must either open an existing project or create a new one and when creating a new project, the user must specify a folder.
So there is a first dialog for the choice between new or existing project and another one opens to select a folder in the case of a new project.
Right now, I call the exec_() method on the first one, and do everything inside (creating the second dialog, using it, ect). the direct consequence : it is messy as it uses side effects.
So the question is : It is possible to cleanly chain dialogs in QT ?
Take a look at QWizard clas:
A wizard (also called an assistant on Mac OS X) is a special type of
input dialog that consists of a sequence of pages. A wizard's purpose
is to guide the user through a process step by step. Wizards are
useful for complex or infrequent tasks that users may find difficult
to learn.
Sounds to me like "state machine" is your friend.
http://www.drdobbs.com/cpp/state-machine-design-in-c/184401236
https://en.wikipedia.org/wiki/Automata-based_programming
In your case, you'd start your state machine from an initial state that runs dialog 1.
You run dialog 1, and when it returns from exec(), determine and
update your machine to a new state.
Then run the appropriate dialog for the new state. And so on, until you get to a state that is the end of your dialog chain.
This allows you to have the flexibility in your dialog chain where the next dialog is conditional to what the user selects in the previous dialog, while keeping the logic of the states outside of the dialogs and in a central location.
It's basically a switch statement in a while loop, but a very useful one for managing non-linear / conditional flow in your program.
Hope this helps.

Communication between multiple dialogs in Qt, using signals and slots or references

Im developing a Qt GUI application, with multiple QDialog's open at any given time.
These dialogs need to communicate and notify with each other when special data is received on a separate network thread.
Usually a dialog will hold a reference to at least one other dialog, and thus can communicate using this.
My question is whether to use this reference to call a function in a another dialog, or emit a signal and absorb that signal in a slot in another dialog? Im aware that this might be a preference - but I would still like to get some input on this.
I suggest you start by looking at Qt's Model View Programming. Based on the Model View Controller design pattern, you would be better off separating data (the model) and the view of that data.
If you follow Qt's Model View Programming, you'll find that when the model containing your data changes, the view(s) are notified and react accordingly. You shouldn't need to message from one dialog to another.

Save current state of entire GUI in Qt?

I have an app written in Qt that has many widgets, including lists, tables, trees, line edits, etc. As the user progresses through the app, they may need to save the current state, leave, and come back later to pick up where they left off. I do not have a the data separate from the GUI (all data is stored in the widgets themselves). I have found a way to loop through all the widgets and save the current state, but it takes a significant amount of time. Is there a faster or built in way to save the current state of the GUI? I am trying to avoid re-writing the code to have a data model that is only represented by the GUI due to limited time available.
Is Qt's session management what you're looking for?
You can save every param on its actual change, or when user leaves the page, not on exit. And don't try to save every parameter of every widget, use smarter algorithm
As a good crossplatform and flexible way to save state of your GUI is to use Qt's mechanism -- QSettings (official documentation).
But, really, there are re-writing moments, which you can't avoid.

Notes and remarks over the GUI

I am developing a flex application for collaborative data analysis. To present the data my application uses standard and custom components (grids, charts etc.).
I want to deliver the feature that allows users making notes over the GUI of my application. So, other users will see they notes late on.
At the moment my question is: How can be implemented mechanism that allows making notes over the GUI? All suggestions and examples are welcome?
There are a lot of ways to approach this. ( Check out Buzzword, MS Word, and Acrobat all for slightly different approaches of note taking on a document--I assume an application GUI could use any of the same approaches ).
I'd start by saying that the click event bubbles:
http://livedocs.adobe.com/flex/3/langref/flash/display/InteractiveObject.html#event:click
So, listen for the click event on every child of your main application file. When you receive that click event you can provide some business logic as to whether or not you want to add a comment /note on the component that was clicked. Then you just some "note" component for collecting and displaying the note data. You an position them based on the x, y values of the click event.
So, actually my problem is much easier then I expected (thank for great design of Flex).
I decided to utilize PopUpManager functionality for my task. It does everything I need at the moment.

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