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QT4 TUTORIAL PDF

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A collection of tutorials and walkthrough guides are provided with Qt to help new training material are available as videos, downloadable code, and PDF files. Warning: Be sure to have some knowledge of C++ before starting! Remark: This tutorial series target mainly Qt4. Even if most of these tutorials. C++ GUI Programming with Qt 4. Jasmin Blanchette. Mark Summerfield. In association with Trolltech Press. Upper Saddle River, NJ · Boston · Indianapolis · San.


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QT Presentation By Gabe Rudy Qt: a complete C++ application development . browser: sppn.info • Tutorials. • Examples. • Qt programming books. The tutorials in this document show you how to use Qt Creator to define projects, specify a basic UI, build and package apps, and deploy and. C:\Users\tfj\Documents\COURSES\MUP1\NOTES\Getting Started with Qt (TFJ). Get pass the Hello World state and learn some basic Qt programming idioms.

For this reason, the distinction between slots and "normal" functions has little relevance for us. Signals are ubiquitous in Qt. And of course, you can also define your own. This however is beyond the scope of this tutorial.

Compile your app You now have the basic knowledge for creating a GUI that responds to user input.

Qt Documentation

Say you've written an app. It runs on your computer. How do you give it to other people, so they can run it as well? You could ask the users of your app to install Python and PyQt like we did above, then give them your source code. But that is very tedious and usually impractical. What we want instead is a standalone version of your app.

That is, a binary executable that other people can run on their systems without having to install anything. In the Python world, the process of turning source code into a self-contained executable is called freezing. We will use a new library called fbs that lets you create standalone executables for PyQt apps.

PyQt5 tutorial

To install it, enter the command: pip install fbs. The user need not convert the variables to be output into the strings. Popup 'Variable number of parameters example', var1, var2, "etc" Each new item begins on a new line in the Popup Optional Parameters to a Function Call This feature of the Python language is utilized heavily as a method of customizing windows and window Elements.

Rather than requiring the programmer to specify every possible option for a widget, instead only the options the caller wants to override are specified. Here is the function definition for the Popup function. The details aren't important. What is important is seeing that there is a long list of potential tweaks that a caller can make. However, they don't have to be specified on each and every call. You'll know that dictionaries are being used if you see a key parameter on any Element.

Dictionaries are used in 2 ways: 1. To identify values when a window is read 2. They are the most basic form of communications with the user.

They are named after the type of window they create, a pop-up window. These windows are meant to be short lived while, either delivering information or collecting it, and then quickly disappearing. It's your way of displaying results to a user in the windowed world. Each call to Popup will create a new Popup window. Popup calls are normally blocking. A non-blocking window of Popup discussed in the async section. Just like a print statement, you can pass any number of arguments you wish.

They will all be turned into strings and displayed in the popup window. There are a number of Popup output calls, each with a slightly different look e. PopupYesNo shows a pair of button with Yes and No on them. PopupCancel has a Cancel button, etc.

While these are "output" windows, they do collect input in the form of buttons. The Popup functions return the button that was clicked.

This section can be skipped for now if you only want to program with Qt. If you want to know how Qt works, it is better to read this. Qt provides a meta-object system. To use such meta-object capabilities in an application, one can subclass QObject and mark it so that the meta-object compiler moc can interpret and translate it.

Code produced by moc includes signals and slots signatures, methods that are used to retrieve meta-information from those marked classes, properties handling All this information can be accessed using the following method:. QMetaObject class contains all the methods that deal with meta-objects. When a signal is emitted, the meta-object system is used to compare the signature of the signal, to check the connection, and to find the slot using it's signature.

These macros are actually used to convert the provided method signature into a string that matches the one stored in the meta-object. Creating custom slots and signals is really simple. Slots are like normal methods, but with small decorations around, while signals need little to no implementation at all.

In order to implement a slot, we first need to make the class be able to send signals and have slots see the previous chapter. After that, a slot should be declared in the corresponding section, and implemented as a normal method.

Signals should also be declared in the signals section, and there is no need for them to be implemented. Note that in order to send signals that have parameters, you have to pass them in the signal emission:.

We might want to remove our previous connection that makes the application quit while clicking the button.

Now, we want that, when clicking on the button, the text is changed. More precisely, we want that the button can be checked , and that, when checked, it displays "checked", and when unchecked, it restores "Hello World".

QPushButton does not implement such a specific slot, so we have to implement it on our own. We also add our custom slot. Since we are trying to react from the button being checked, and since the corresponding signal is.

Most of the time, by convention, we implement private and protected slots by prefixing them with "slot". Here, we are not interested in exposing this slot as a public function, we can make it private. The new header is then. We need to make the button checkable, and establish the connection, we have to add this code in the constructor:.

Based on the previous example, we want to close the application if the button is clicked checked or unchecked 10 times.

We first need to implement a counter that will count the number of clicks. These modifications implement it:.

Qt for Beginners

Even if the signal is declared as a method, there is no need to implement it. The meta-object compiler is used to do this. This is because of the meta-object compiler not being run on a class that should have meta-object. Radio button is a standard GUI component.

It is often used to make a unique choice from a list. In Qt, the QRadioButton is used to create radio buttons. All properties of the QPushButton are also the same in the QRadioButton, and everything that was learned in the second chapter can be reused here. By default, QRadioButtons are not grouped, so many of them can be checked at the same time. In order to have the "exclusive" behaviour of many radio buttons, we need to use QButtonGroup. This class can be used like this: We allocate a new button group and attach it to the parent object.

Note that the parent object might be the mainwindow, or "this":. What we want is to create a menu picker. In a window, a list of yummy plates should be displayed with radio buttons, and a push button that is used to select the chosen plate should be displayed.

Here is an example about signals and slots. We are going to write an application with two buttons. The first button should display information about Qt.

You can also add icons on the buttons, or resize them. Obviously, the "Quit" button should be more important, so why not make it bigger? Qt documentation is a very valuable piece of information.

It is the place to find everything related to Qt. But, Qt documentation is not a tutorial on how to use Qt. It is a collection of all information related to classes, as well as some examples.

The goal of this chapter is to introduce you to the documentation as a basis for programming with Qt. Qt documentation on developer network.

It provides the full doc, as well as some DocNotes, that users can add. These DocNotes give more examples and highlight some tricky points. The online documentation also has a quite powerful search engine and contains also all the documentation for all versions of Qt. While the online version requires an internet connection, the DocNotes are still available. If the QtSDK was installed correctly, the documentation that matches the current version of Qt should have been installed, and the Help section of QtCreator should not be empty.

Qt Creator Tutorial

You can also use Qt Assistant , that is a standalone doc browser. If you are running the offline documentation viewer, in either Qt Creator, or Qt Assistant, you will find in the summary that there are documentations for different components of the Qt SDK.

Qt documentation provides a nice introduction of many components, and also the documentation for all the classes in Qt. This list is listed in the page All classes.

Another interesting page is the page that lists All modules. This page provides information about the different components in Qt. The search function is also quite important. If you know the class to use, and want to find the documentation, you can either type the name of this class in the search field online , or in the filter in the index offline. You can also search for methods and enumerations in these fields. Let's take the QTextEdit class as an example.

Jump to: Type MyObject:: T foo const ; void setFoo const T ;. QFont font "Courier" ; button.You can see that Qt Creator automatically generates a class template.

Nearly all UI toolkits have a mechanism to detect a user action, and respond to this action.

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This list is listed in the page All classes. For demonstrations on how to use different Qt technologies, visit the Qt Examples page. If you want to get some information about what these macros do, please read the last section of this chapter.