Изучение Python Kivy в одной статье! Основы Kivy

Python обладает большим набором библиотек для разработки графического интерфейса. Ранее мы уже знакомились с TKinter, а также PyQT5. Сейчас мы рассмотрим принцип работы с библиотекой Kivy.

Зачем изучать Kivy?

Разрабатывать программы можно на разных языках программирования. Даже при помощи JavaScript и библиотеки Electron это также можно делать. В то же время, создавать крупные ПК проекты на JS не охота, ибо язык медленный и не столь удобный. Использовать Swift или C# тоже не хочется, так как в этом случае разработка будет вестись лишь под одну операционную систему.

Можно делать проекты на Java, React Native или на Flutter. Все они хороши, но все же еще хорошим и крупным игроком является Python вместе со своими библиотеками. Он обеспечивает разработку кроссплатформенных программ с хорошей скоростью выполнения. И еще приятным бонусом является само написание программы, ведь синтаксис языка Python хороший.

Для языка Python сфера полноценных проектов не первостепенно важна, но все же язык предоставляет отличные возможности для разработки полноценных программ под разные операционные системы.

Информация относительно Kivy

Фреймворк Kivy разрабатывается с 2011 года. С момента релиза на его основе было построено много проектов под платформу Андирод.

Если сравнивать Kivy с другими библиотеками языка Питон по набору функций, то среди крупных конкурентов можно выделить PyQT . Все прочие библиотеки явно будут уступать по функционалу.

Важно отметить, что Kivy имеет большой набор уже готовых проектов, которые вы можете использовать для построения своих программ.

Установка Kivy

Для установки Kivy вам потребуется стандартный пакетный менеджер pip и программа для написания кода. Для получения пакетного менеджера выполните установку Python на ваш компьютер, при чем установите Питон именно версии 3.7. Он лучше остальных подходит под Kivy.

Чтобы выполнить установку пропишите в терминале команду pip install kivy и далее библиотека будет готова к использованию.

Создание проекта

Ниже представлен код готового приложения на Kivy. Полная информация относительно Питон Киви находится в обучающем видео в конце этой статьи.

Видео на эту тему

Детальный разбор Python Kivy вы можете просмотреть на видео ниже. В видеоуроке показан разбор библиотеки и её возможностей.

Дополнительный курс

На нашем сайте также есть углубленный курс по изучению языка Питон . В ходе огромной программы вы изучите не только язык Питон, но также научитесь создавать веб сайты за счёт веб технологий и фреймворка Джанго. За курс вы изучите массу нового и к концу программы будете уметь работать с языком Питон, создавать на нём полноценные приложения на основе библиотеки Kivy, а также создавать веб сайты на основе библиотеки Джанго.

Installing Kivy¶

Installation for Kivy version 2.0.0. Read the changelog here . For other Kivy versions, select the documentation from the dropdown on the top left.

Kivy 2.0.0 officially supports Python versions 3.6 — 3.9.

Using pip¶

The easiest way to install Kivy is with pip , which installs Kivy using either a pre-compiled wheel , if available, otherwise from source (see below).

Kivy provides pre-compiled wheels for the supported Python versions on Windows, OS X, Linux, and RPi. Alternatively, installing from source is required for newer Python versions not listed above or if the wheels do not work or fail to run properly.

Setup terminal and pip¶

Before Kivy can be installed, Python and pip needs to be pre-installed . Then, start a new terminal that has Python available . In the terminal, update pip and other installation dependencies so you have the latest version as follows (for linux users you may have to substitute python3 instead of python and also add a —user flag in the subsequent commands outside the virtual environment):

Create virtual environment¶

Create a new virtual environment for your Kivy project. A virtual environment will prevent possible installation conflicts with other Python versions and packages. It’s optional but strongly recommended:

Create the virtual environment named kivy_venv in your current directory:

Activate the virtual environment. You will have to do this step from the current directory every time you start a new terminal. This sets up the environment so the new kivy_venv Python is used.

For Windows default CMD, in the command line do:

If you are in a bash terminal on Windows, instead do:

If you are in linux, instead do:

Your terminal should now preface the path with something like (kivy_venv) , indicating that the kivy_venv environment is active. If it doesn’t say that, the virtual environment is not active and the following won’t work.

Install Kivy¶

Finally, install Kivy using one of the following options:

Pre-compiled wheels¶

The simplest is to install the current stable version of kivy and optionally kivy_examples from the kivy-team provided PyPi wheels. Simply do:

This also installs the minimum dependencies of Kivy. To additionally install Kivy with audio/video support, install either kivy[base,media] or kivy[full] . See Kivy’s dependencies for the list of selectors.

For the Raspberry Pi, you must additionally install the dependencies listed in source dependencies before installing Kivy above.

From source¶

If a wheel is not available or is not working, Kivy can be installed from source with some additional steps. Installing from source means that Kivy will be installed from source code and compiled directly on your system.

First install the additional system dependencies listed for each platform: Windows , OS X , Linux , RPi .

With the dependencies installed, you can now install Kivy into the virtual environment.

To install the stable version of Kivy, from the terminal do:

To install the latest cutting-edge Kivy from master, instead do:

If you want to install Kivy from a different branch, from your forked repository, or from a specific commit (e.g. to test a fix from a user’s PR) replace the corresponding components of the url.

For example to install from the stable branch, the url becomes https://github.com/kivy/kivy/archive/stable.zip . Or to try a specific commit hash, use e.g. https://github.com/kivy/kivy/archive/3d3e45dda146fef3f4758aea548da199e10eb382.zip

Pre-release, pre-compiled wheels¶

To install a pre-compiled wheel of the last pre-release version of Kivy, instead of the current stable version, add the —pre flag to pip:

This will only install a development version of Kivy if one was released to PyPi. Instead, one can also install the latest cutting-edge Nightly wheels from the Kivy server with:

It is done in two steps, because otherwise pip may ignore the wheels on the server and install an older pre-release version from PyPi.

For the Raspberry Pi, remember to additionally install the dependencies listed in source dependencies before installing Kivy above.

Development install¶

If you want to edit Kivy before installing it, or if you want to try fixing some Kivy issue and submit a pull request with the fix, you will need to first download the Kivy source code. The following steps assumes git is pre-installed and available in the terminal.

The typical process is to clone Kivy locally with:

This creates a kivy named folder in your current path. Next, install the additional system dependencies listed for each OS: Windows , OS X , Linux , RPi .

Then change to the kivy directory and install Kivy as an editable install:

Now, you can use git to change branches, edit the code and submit a PR. Remember to compile Kivy each time you change cython files as follows:

Or if using bash or on Linux, simply do:

To run the test suite, simply run:

or in bash or Linux:

Checking the demo¶

Kivy should now be installed. You should be able to import kivy in Python or, if you installed the Kivy examples, run the demo (on Windows):

or in bash or Linux:

The exact path to the Kivy examples directory is also stored in kivy.kivy_examples_dir .

The 3d monkey demo under kivy-examples/3Drendering/main.py is also fun to see.

Installation using Conda¶

If you use Anaconda, you can install Kivy with its package manager Conda using:

Do not use pip to install kivy if you’re using Anaconda, unless you’re installing from source.

Installing Kivy’s dependencies¶

Kivy supports one or more backends for its core providers. E.g. it supports glew, angle, and sdl2 for the graphics backend on Windows. For each category (window, graphics, video, audio, etc.), at least one backend must be installed to be able to use the category.

To facilitate easy installation, we provide extras_require groups that will install selected backends to ensure a working Kivy installation. So one can install Kivy more simply with e.g.«pip install kivy[base,media,tuio]«. The full list of selectors and the packages they install is listed in setup.py. The exact packages in each selector may change in the future, but the overall goal of each selector will remain as described below.

We offer the following selectors:

not including video/audio.

media : Only the video/audio dependencies required for Kivy to

be able to play media.

full : All the typical dependencies required for Kivy to run, including video/audio and

most optional dependencies.

dev : All the additional dependencies required to run Kivy in development mode

(i.e. it doesn’t include the base/media/full dependencies). E.g. any headers required for compilation, and all dependencies required to run the tests and creating the docs.

tuio : The dependencies required to make TUIO work (primarily oscpy).

The following selectors install backends packaged as wheels by kivy under the Kivy_deps namespace. They are typically released and versioned to match specific Kivy versions, so we provide selectors to facilitate installation (i.e. instead of having to do pip install kivy kivy_deps.sdl2==x.y.z , you can now do pip install kivy[sdl2] to automatically install the correct sdl2 for the Kivy version).

(currently only on Windows)

angle : A alternate OpenGL backend, if it’s available

(currently only on Windows)

sdl2 : The window/image/audio backend, if it’s available (currently only on Windows,

on OSX and Linux it is already included in the main Kivy wheel).

glew : A alternate OpenGL backend, if it’s available (currently only on Windows)

Following are the kivy_deps dependency wheels:

kivy_deps.gstreamer is an optional dependency which is only needed for audio/video support. We only provide it on Windows, for other platforms it must be installed independently. Alternatively, use ffpyplayer instead.

kivy_deps.glew and kivy_deps.angle are for OpenGL. You can install both, that is no problem. It is only available on Windows. On other platforms it is not required externally.

One can select which of these to use for OpenGL using the KIVY_GL_BACKEND environment variable: By setting it to glew (the default), angle_sdl2 , or sdl2 . Here, angle_sdl2 is a substitute for glew but requires kivy_deps.sdl2 be installed as well.

kivy_deps.sdl2 is for window/images/audio and optionally OpenGL. It is only available on Windows and is included in the main Kivy wheel for other platforms.

Python glossary¶

Here we explain how to install Python packages, how to use the command line and what wheels are.

Installing Python¶

Kivy is written in Python and as such, to use Kivy, you need an existing installation of Python. Multiple versions of Python can be installed side by side, but Kivy needs to be installed as package under each Python version that you want to use Kivy in.

To install Python, see the instructions for each platform: Windows , OS X , Linux , RPi .

Once Python is installed, open the console and make sure Python is available by typing python —version .

How to use the command line¶

To execute any of the pip or wheel commands given here, you need a command line (here also called console, terminal, shell or bash, where the last two refer to Linux style command lines) and Python must be on the PATH.

The default command line on Windows is the command prompt, short cmd. The quickest way to open it is to press Win+R on your keyboard. In the window that opens, type cmd and then press enter.

Alternative Linux style command lines on Windows that we recommend are Git for Windows or Mysys.

Note, the default Windows command line can still be used, even if a bash terminal is installed.

To temporarily add your Python installation to the PATH, simply open your command line and then use the cd command to change the current directory to where python is installed, e.g. cd C:\Python37 .

If you have installed Python using the default options, then the path to Python will already be permanently on your PATH variable. There is an option in the installer which lets you do that, and it is enabled by default.

If however Python is not on your PATH, follow the these instructions to add it:

What is pip and what are wheels¶

In Python, packages such as Kivy can be installed with the python package manager, named pip (“python install package”).

When installing from source, some packages, such as Kivy, require additional steps, like compilation.

Contrary, wheels (files with a .whl extension) are pre-built distributions of a package that has already been compiled. These wheels do not require additional steps when installing them.

When a wheel is available on pypi.org (“Python Package Index”) it can be installed with pip . For example when you execute python -m pip install kivy in a command line, this will automatically find the appropriate wheel on PyPI.

When downloading and installing a wheel directly, use the command python -m pip install , for example:

What are nightly wheels¶

Every day we create a snapshot wheel of the current development version of Kivy (‘nightly wheel’). You can find the development version in the master branch of the Kivy Github repository.

As opposed to the last stable release (which we discussed in the previous section), nightly wheels contain all the latest changes to Kivy, including experimental fixes. For installation instructions, see Pre-release, pre-compiled wheels .

Using the latest development version can be risky and you might encounter issues during development. If you encounter any bugs, please report them.