.. _typesoffiles:

File Types
==========

There are many different file types that you will encounter while
developing |project| applications, ui, qrc, qml, pyproject, etc.
Here you can find a simple explanation for
each of them.

Python Files ``.py``
--------------------

Python files are the main format you will be dealing with, while developing
|project| projects.

It is important to note that you can write applications **only** with Python
files, without the need of ``.ui``, ``.qrc``, or ``.qml`` files, however
using other formats will facilitate some processes, and enable new
functionality to your applications.

.. code-block:: python

    class MyWidget(QWidget):
        def __init__(self):
            QWidget.__init__(self)

            self.hello = ["Hallo Welt", "你好，世界", "Hei maailma",
                "Hola Mundo", "Привет мир"]

            self.button = QPushButton("Click me!")
            self.text = QLabel("Hello World")
            self.text.setAlignment(Qt.AlignCenter)
            # ...

User Interface Definition File ``.ui``
--------------------------------------

When using *Qt Widgets Designer*, you can create user interfaces using
Qt Widgets with the WYSIWYG form editor, this interface is represented
as a widget tree using XML. Here is an extract of the beginning of a
``.ui`` file:

.. code-block:: xml

    <?xml version="1.0" encoding="UTF-8"?>
    <ui version="4.0">
     <class>MainWindow</class>
     <widget class="QMainWindow" name="MainWindow">
      <property name="geometry">
       <rect>
        <x>0</x>
        <y>0</y>
        <width>400</width>
        <height>300</height>
       </rect>
      </property>
      <property name="windowTitle">
       <string>MainWindow</string>
      </property>
      <widget class="QWidget" name="centralWidget">

The `pyside6-uic` tool generates Python code from these `.ui` files,
which you can import from your main files, so it is not necessary
for you to include the `.ui` files in your deployed application.

For more details, see :ref:`using_ui_files`.

Resource Collection Files ``.qrc``
----------------------------------

List of binary files that will be used alongside your application.
As an XML-based file, its structure look like this:

.. code-block:: xml

    <!DOCTYPE RCC><RCC version="1.0">
    <qresource>
        <file>images/quit.png</file>
        <file>font/myfont.ttf</file>
    </qresource>
    </RCC>


The `pyside6-rcc` tool generates Python code from these `.qrc` files,
so you are not required to include the listed files in your deployed
application.

For more details, see :ref:`using_qrc_files`.

Qt Modeling Language File ``.qml``
----------------------------------

Graphical QML applications are not related to Qt Widgets applications, and
that is why the usual setup of QML project is a Python file that loads
the QML file, and optionally, elements defined in Python that are exposed
to QML to be used.

You can write ``.qml`` files by hand, but also you can use tools like the
*QML Designer* that is embedded in *Qt Creator*. Additionally, there are commercial
tools like *Qt Design Studio* that allow you to load designs from other design
applications.

Here you can find an example of how a ``.qml`` file looks like.
The code will display a lightgray rectangle, with the "Hello World!"
message on it.

.. code-block:: javascript

    import QtQuick 2.0

    Rectangle {
        id: page
        width: 320;
        height: 480
        color: "lightgray"

        Text {
            id: helloText
            text: "Hello world!"
            y: 30
            anchors.horizontalCenter: page.horizontalCenter
            font.pointSize: 24;
            font.bold: true
        }
    }

Qt Creator Python Project File ``.pyproject``
---------------------------------------------

For *Qt Creator* to load and handle Python based projects, a special file is
needed, because C++ based projects could be handle from ``.qmake`` or
``CMakeLists.txt`` file, which are not used with Python-based projects.

Old versions of *Qt Creator*, provided a simple format with the ``.pyqtc``
extension, which were plain-text files with one-file-per-line::

    library/server.py
    library/client.py
    logger.py
    ...

There were limitations to this format, and further options that might be
added that would not be supported, which was the motivation to create a
``.pyproject`` file, which is a JSON-based file where more options could
be added. Here is an example of such file:

.. code-block:: javascript

    {
        "files": ["library/server.py", "library/client.py", "logger.py", ...]
    }