We need a tree view with File system and check boxes in QT. Is there any way to achieve that?
The tree we need would look something like below:
UPDATE:
I am able to achieve it with subclass of QFileSystemModel. Still have few challenges, but at least subclass is working. Below is the code if anyone needs it. Below is the link to the code -
https://drive.google.com/file/d/1qViZ3iEW2pV2th0jQhzneDL14SEhIgS0/view?usp=sharing
The pending work is to apply a wait cursor (or make treeview uneditable when the check/uncheck is taking place).
PS: It will take a lot of time if root node is checked.
Well, all of that can be achieved with minimal customizations of built-in classes, actually those checkboxes is almost the only thing that has to be done yourself.
QFileSystemModel already provides a proper model for displaying the current filesystem contents, it can be subclassed
As for QML, the best demo is already provided by Qt, check the File System Browser Example. This example uses some deprecaded Qt functionality, but still it shows the basic concept.
The modern techniqes can be also found in the answers to the following question: Qt File Browser based on QML
Hopefully, all that helps you, good luck!
Related
In general, is the order in which I add my widgets into each other, the same order I access them back?
Example:
If I have a bunch of QPushButton in a QHBoxLayout, and this layout in a Window::ui,
can I access those button by simply ui->button_name? or Do I must do ui->layout->itemAt(idx)?
EDIT: My question aims to find an easy way to access elements that are deep into the hierarchy, like a label in a frame, inside a layout, inside a frame, inside the window etc...
PS: Also, I would really appreciate any documentations about good practices of GUI architecture!
Use ui->object_name you don;t need to worry about the layout!
It's possible to redesign the layout, eg. for different platforms, without changing any of the C++ code.
There are a couple of good books on Qt and the sample code is very good.
C++ GUI Programming with Qt 4
Advanced Qt Programming
I want to use a custom widget in the GUI-Designer of Qt-Creator IDE.
So i created a class which inherits from Qt's QWidget. It worked to place
it on a QMainWindow programaticaly, but have to do my work in the desiger
where it does not appear as an option in the kist of components.
I googled to find a solution for problem an found an manual on, who guesses, the
Qt doc page ( https://doc.qt.io/archives/qt-4.7/designer-creating-custom-widgets.html
and https://doc.qt.io/archives/qt-4.7/designer-creating-custom-widgets.html).
I tried to follow it but doesn't work.
Does someone know an other way to do this or can give a hint where i can search
for problems following this tutorial?
Thanks in advance.
Codierknecht
There is a different example in the examples section of the Qt documentation that I think is a lot clearer.
Custom Widget Plugin Example
It was a little unclear to me when reading the tutorial where the Q_EXPORT_PLUGIN2() macro goes, but having full example code and project alleviates that.
If you are like me, the analog clock example didn't do it for you, in which case I found just one better tutorial. It may be on the kde site but I you dont need kde to do it, it just explains how to make the custom widget a plugin so you can add it into Qt Designer, rather than having to code it in, which is the norm when you just add a widget to your project and customize the class. I hope this page helps you like it helped me, get in the right direction of writing a single Qt Designer (or multiple) plugin:
Writing Qt Designer Plugins
If this link ever becomes dead, just do a search for the link itself, usually that will turn up the original page in someone's cache, as they do in the other examples above (the dead links in the above answers that just take you to main area and not to the pages originally intended).
Im just pondering best practice with an application I'm developing. Its a simple one window application using qt creator. It's just going to start a QProcess and show the output in a QTextEdit box. To do this there needs to be a bit of processing between the output of the QProcess and the QTextEdit but i dont know where i should do this, should i create a new class to do that or add member functions and extra signals and slots to my main window? I dont want mainwindow to become bloated and hard to read but equally i dont want to have more source files than really I need.
Any thoughts?
The main window class can very easily get bloated with all kinds of functionality. I've dealt with that myself, so it's a very real trouble.
Really, though, this is not so much of QT question as it is an object-oriented design question. The key is that your output window does not need to be a part of QMainWindow, so it probably shouldn't be. Make the display a widget, and insert it onto the main window. That is much more flexible, as if you ever need to move that output pane for any reason, it won't be coupled to a specific part of the program.
The logic that feeds data into that output pane should also get its own class, separating the responsibility for displaying the output from the responsibility for acquiring the output.
For reference on the concepts behind my suggestion, see the Single Responsibility Principle and the separation of concerns.
Also - you may wish to have a read at this link to model view delegate information which is how I tend to develop in Qt. Like the person above says - this is more a question of good OO design.
I wanted to consult with the sages here regarding Qt and skinning, get your opinion and chart a path for my development. My requirements are as follows:
My Qt/C++ application (cross platform with Mac, Windows and Linux versions) needs to have modular skins.
A skin is defined as a set of one or more elements: - Window background texture - Look/feel of UI controls such as edit boxes, drop down, radio buttons, buttons etc. - Look/feel of window "caption", resize grips etc.
Skins will be installed with the application installer, allowing the user to choose which one he/she wants to use. Users should be able to change skins on the fly.
Can I go the QML route? should this be custom and based on simple resources which are built into the application? Any design advice will be appreciated.
Thanks.
If I understood you correctly then stylesheet is the best way forward. You can create stylesheets similar to CSS and then pass them as command line option to your application or load on invocation to style your application at runtime. That way you can create multiple stylesheets each having a different look and feel and allow user to load them at will. Since its CSS it doesn't need any new learning and you can keep all your styling outside your source code.
Here are a list of resources that can get you up and running quickly:
http://blog.qt.io/blog/2007/11/27/theming-qt-for-fun-and-profit/
http://doc.qt.io/qt-5/stylesheet.html
I haven't played with QML yet, but you could also create a custom QStyle implementation that supports your resource format. Note that you'd lose style sheet support if you went this route.
Changing window captions is a little trickier if you want portability.
QML, if I understand correctly, doesn't really skin the widgets, it mainly deals with GUI layout etc etc.
QStyle is used to change the looks. It is a bit low-level though, and requires programming, so if you want to load different user-created skins (from an XML or so) it might be tricky to support extensive skinning. Chaining colors and a few items are easy enough though. (There might be someone else who've done something you could re-use.. not sure.)
For modifying widgets, use QStyle::polish(). You could use that to change the background picture (if it's a top-level window, or of a certain class). There are numerous repaint method to change almost every part of every widget.
Store/load the style using QSettings, by reading and setting the desired Style just after QApplication but before your main window is constructed.
Every time I start a project with some graphical toolkit, one of the first conflicts happen with the decision of how to deal with the visual design and the widget layout: A graphical tool or handcoding?
This is a quite tricky/subjective question because most people will decide based on personal preference. It also depends greatly on the quality of the graphical tool. In this case I would like to focus just on the latest version of the QT library. I do not intend to discuss which method is better. I am convinced that the best answer is: depends on the project.
What I want is a reference to a good non biased article, based on experience after several projects. The article should just describe the tradeoffs of both choices
I started with doing everything hand-coded, and of late have been switching to using Qt Designer for most forms. Here are some benefits for each position:
Using Qt Designer
The biggest time saver for me is managing complex layouts; it saves a lot of tedious coding. Simply (very roughly) arrange your widgets, select them, right-click, and put them in the correct type of layout. Especially as layouts become nested, this is so much easier.
It tends to keep your implementation files cleaner instead of filling them with all the boilerplate layout code. I'm type-A, so I like that.
If you are translating your application, it is possible to send your translators the .ui files so they can see on your GUI where the text they are translating will be. (Assuming they are using Qt Linguist.)
Hand-coding
Control. If you have a layout where you need to instantiate / initialize the controls in a very particular order, or dynamically create the controls based on other criteria (database lookup, etc.), this is the easiest way.
If you have custom widgets, you can kind-of-sort-of use the Designer, adding the closest built-in QWidget from which your class derived and then "upgrading" it. But you won't see a preview of your widget unless you make it a designer plugin in a separate project, which is way too much work for most use cases.
If you have custom widgets that take parameters in their constructor beyond the optional QWidget parent, Designer can't handle it. You have no choice but to add that control manually.
Miscellaneous
I don't use the auto-connect SLOTS and SIGNALS feature (based on naming convention such as "on_my_button_clicked".) I have found that I almost invariably have to set up this connection at a determinate time, not whenever Qt does it for me.
For QWizard forms, I have found that I need to use a different UI file for each page. You can do it all in one, but it becomes very awkward to communicate between pages in any kind of custom way.
In summary, I start with Qt Designer and let it take me as far as it can, then hand-code it from there. That's one nice thing about what Qt Designer generates--it is just another class that becomes a member of your class, and you can access it and manipulate it as you need.
My answer is based on two years developing biochemistry applications using PyQt4 (Python bindings to Qt 4) and OpenGL. I have not done C++ Qt, because we only used C++ for performance-critical algorithms. That said, the PyQt4 API greatly resembles Qt4, so much here still applies.
Qt Designer
Good
Exploration. Discover what widgets are available, the names for those widgets, what properties you can set for each, etc.
Enforces separation of UI logic from application logic.
Bad
If you need to add or remove widgets at run-time, you have to have that logic in code. I think it's a bad idea to put your UI logic in two places.
Making changes to nested layouts. When a layout has no widgets in it, it collapses, and it can be really hard to drag and drop a widget in to the location you want.
Hand coding
Good
Fast if you are very familiar with Qt.
Best choice if you need to add or remove widgets at run-time.
Easier than Qt Designer if you have your own custom widgets.
With discipline, you can still separate UI layout from behavior. Just put your code to create and layout widgets in one place, and your code to set signals and slots in another place.
Bad
Slow if you are new to Qt.
Does not enforce separation of layout from behavior.
Tips
Don't just jump into creating your windows. Start by quickly sketching several possible designs, either on paper or using a tool like Balsamiq Mockups. Though you could do this in Qt Designer, I think it is too tempting to spend a lot of time trying to get your windows to look just right before you've even decided if it is the best design.
If you use Qt Designer for PyQt, you have the extra step of running pyuic4 to compile your *.ui files to Python source files. I found it easy to forget this step and scratch my head for a second why my changes didn't work.
If you code your UI by hand, I suggest putting your layout code in one place and your signals and slots in another place. Doing this makes it easier to change the way your widgets are arranged on a window without affecting any of your application logic. Or you can change some behavior without having to wade through all the layout code.
Enjoy Qt! Now that I am using Java Swing for work, I miss it.
I tend to layout dialogs using the designer but I do all the event handling stuff in the main code. I also do all the main windows, toolbars, menus in direct code.
The designer is just frustrating - a pity since decent drag and drop sizer based designers have been around for more than a decade
It depends on the number of different windows/panels you need for your application. If the number is small, use a graphical tool. It is much faster to get a few windows designed perfectly. If the number is large, the graphical tool can (and should) only be used for prototypes. You need to code the layout to be able to make application-wide changes at acceptable cost.
That includes creating a model of how the UI of the application works and dynamically adding and removing widgets at runtime. For an excellent example of such a model (in a different environment), take a look at the glamour model for creating object browsers.
I object to the suggestion that it is tricky/subjective (at least more than other development choices). It is easy to come up with criteria to decide on. Personal experience and preference are important for that, as they decide when the number of different windows should be considered small. The same goes for tool quality.
My personal opinion (just personal), all GUI based development distracts me too much, my imagination or my mind works very bad when i'm seeing gui objects, i prefer to hand-coding most the time because my imagination works better, you know, is like you were reading a book with no images... when i see nothing else than code its looks like i finish faster...
Second reason, i like c++ so much, so I see the good side of hand-coding, is that I keep my c++ practice no matter if I'm writing something redundant... Coding skill is improved when you only use text... Indeed, i could use nano or vim, but that is too far slow for debuging.
Hand-coding here ++vote
I use a combination of both:
I find for x,y coordinates, Designer is the way to go.
A lot of the other UI properties etc can be set in your code.
I think trying to do UI completely by hand-coding would be a very time consuming project. It's not as simple as setting up HTML tables.
Yes version 4 is bad, but people at work who have used version 3 said it was REALLY bad. Lots of crashing.
I, along with my fellow QTers, are truly hoping that version 5 will be an improvement.
I know this is an old question, but I hope this helps! One man's experience.