Although the Python language is very versatile, it is still a bit wrong to use it to develop apps. Therefore, apps developed with Python should be used as coding exercises or for self-entertainment. In addition, the current modules in this area are not particularly mature, and bugs More, all in all, advise Jun Mo to enter lightly.
Preparation
Using Python to develop apps requires the use of a module of Python - kivy, kivy is an open source, cross-platform Python development framework for developing and using innovative applications. In short, this is a Python desktop program development framework (similar to wxpython and other modules). The powerful thing is that kivy supports linux, mac, windows, android, and ios platforms, which is why this module is needed for app development.
Although kivy is cross-platform, if you want to use Python code on different platforms, you need to package the Python code into an executable program for the corresponding platform. Fortunately, there is a packaging tool project under the kivy project – buildozer, which is officially recommended Packaging tools, because they are relatively simple and have a high degree of automation, other projects such as: Python-for-android can also play a similar role, so I won’t introduce them here.
Build kivy development environment
The kivy development environment needs to be installed on the pc. Here is a demonstration of the installation process under mac and linux.
install kivy for mac
Install some dependencies:
brew install pkg-config sdl2 sdl2_image sdl2_ttf sdl2_mixer gstreamer
Install cython and kivy:
pip install cython==0.25
pip install kivy
If an error is reported when installing kivy, use the following method to install kivy:
git clone https://github.com/kivy/kivy
python setup.py install
Test after installation:
$python
Python 2.7.10 (default, Jul 15 2017, 17:16:57)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.31)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>> import kivy
[INFO ] [Logger ] Record log in /Users/didi/.kivy/logs/kivy_18-05-08_4.txt
[INFO ] [Kivy ] v1.10.1.dev0, git-5f6c66e, 20180507
[INFO ] [Python ] v2.7.10 (default, Jul 15 2017, 17:16:57)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.31)]
Note: If no error is reported when importing the kivy module, the installation is successful.
install kivy for centos7
Install dependencies first:
yum install \
make \
mercurial \
automake \
gcc \
gcc-c++ \
SDL_ttf-devel \
SDL_mixer-devel \
khrplatform-devel \
mesa-libGLES \
mesa-libGLES-devel \
gstreamer-plugins-good \
gstreamer \
gstreamer-python \
mtdev-devel \
python-devel \
python-pip \
java-devel
Install cython and kivy:
pip install Cython==0.20
pip install kivy
Centos installation kivy reference: https://kivy.org/docs/installation/installation-linux.html#using-software-packages
Note: Other ways to install kivy can be moved: https://kivy.org/#download (requires over the wall)
Develop your first Python app with kivy
After installing kivy, you can develop the app program. Here is a demonstration of the hello-world program. The more complicated usage of kivy is not the focus of this article, and it will be introduced later.
Create a main.py file and write:
#! -*- coding:utf-8 -*-
from kivy.app import App
class HelloApp(App):
pass
if __name__ == '__main__':
HelloApp().run()
Create a hello.kv file and write:
Label:
text: 'Hello, World! I am nMask'
Brief description: main.py is the entry function, which defines a HelloApp class, which inherits kivy.app; the hello.kv file is a kivy program, which is equivalent to defining the interface style, etc. The naming rule of this file is lowercase for the class name and app is removed.
Run your first Python app
python main.py
operation result:
Install the buildozer tool
Through the above coding, I created my first python app program, which can run directly on mac, linux, and windows platforms, so how to make it run on Android or Apple phones? We know that to run on Android, it needs to be packaged into an apk installation program, so we need to use the buildozer tool mentioned above (buildozer tool can package kivy programs, support android, ios, etc.), the installation process of buildozer is relatively simple :
pip install buildozer
Use the buildozer tool to package the kivy program into an apk
Run in the python project directory:
buildozer init
A successful run will create a configuration file buildozer.spec, you can change the name of the app by modifying the configuration file, and then run:
buildozer android debug deploy run
Running the above command will generate a cross-platform installation package, which is applicable to Android, ios, etc. If it is used for Android, use the python-for-android project.
When running the above command for the first time, it will automatically download the necessary files such as Android SDK in the system, as shown in the figure below. (The process needs to go over the wall, and there are many dependencies that need to be downloaded)
Explanation: Here we only demonstrate packaging into apk files. The iso platform can be studied by yourself. Reference document: https://github.com/kivy/buildozer.
python apk program test
If the above steps are run successfully, an apk file should be generated in the bin directory under the project directory, similar to the following:
Then download the apk to the Android phone and install it. The test results are as follows:
open app
buildozer instructions
Usage:
buildozer [--profile <name>] [--verbose] [target] <command>...
buildozer --version
Available targets:
android Android target, based on python-for-android project
ios iOS target, based on kivy-ios project
android_old Android target, based on python-for-android project (old toolchain)
Global commands (without target):
distclean Clean the whole Buildozer environment.
help Show the Buildozer help.
init Create a initial buildozer.spec in the current directory
serve Serve the bin directory via SimpleHTTPServer
setdefault Set the default command to run when no arguments are given
version Show the Buildozer version
Target commands:
clean Clean the target environment
update Update the target dependencies
debug Build the application in debug mode
release Build the application in release mode
deploy Deploy the application on the device
run Run the application on the device
serve Serve the bin directory via SimpleHTTPServer
Target "android_old" commands:
adb Run adb from the Android SDK. Args must come after --, or
use --alias to make an alias
logcat Show the log from the device
Target "ios" commands:
list_identities List the available identities to use for signing.
xcode Open the xcode project.
Target "android" commands:
adb Run adb from the Android SDK. Args must come after --, or
use --alias to make an alias
logcat Show the log from the device
p4a Run p4a commands. Args must come after --, or use --alias
to make an alias
Pitpoints in the buildozer packaging process
If you encounter an error during the packaging process, you can modify the log_level in the buildozer.spec configuration file to 2, and then run it again to see the specific error message.
报错：You might have missed to install 32bits libs
This error is the error reported by me when I run it on centos7, to the effect that the system lacks some 32-bit dependent files.
solution:
yum -y install --skip-broken glibc.i686 arts.i686 audiofile.i686 bzip2-libs.i686 cairo.i686 cyrus-sasl-lib.i686 dbus-libs.i686 directfb.i686 esound-libs.i686 fltk.i686 freeglut.i686 gtk2.i686 hal-libs.i686 imlib.i686 lcms-libs.i686 lesstif.i686 libacl.i686 libao.i686 libattr.i686 libcap.i686 libdrm.i686 libexif.i686 libgnomecanvas.i686 libICE.i686 libieee1284.i686 libsigc++20.i686 libSM.i686 libtool-ltdl.i686 libusb.i686 libwmf.i686 libwmf-lite.i686 libX11.i686 libXau.i686 libXaw.i686 libXcomposite.i686 libXdamage.i686 libXdmcp.i686 libXext.i686 libXfixes.i686 libxkbfile.i686 libxml2.i686 libXmu.i686 libXp.i686 libXpm.i686 libXScrnSaver.i686 libxslt.i686 libXt.i686 libXtst.i686 libXv.i686 libXxf86vm.i686 lzo.i686 mesa-libGL.i686 mesa-libGLU.i686 nas-libs.i686 nss_ldap.i686 cdk.i686 openldap.i686 pam.i686 popt.i686 pulseaudio-libs.i686 sane-backends-libs-gphoto2.i686 sane-backends-libs.i686 SDL.i686 svgalib.i686 unixODBC.i686 zlib.i686 compat-expat1.i686 compat-libstdc++-33.i686 openal-soft.i686 alsa-oss-libs.i686 redhat-lsb.i686 alsa-plugins-pulseaudio.i686 alsa-plugins-oss.i686 alsa-lib.i686 nspluginwrapper.i686 libXv.i686 libXScrnSaver.i686 qt.i686 qt-x11.i686 pulseaudio-libs.i686 pulseaudio-libs-glib2.i686 alsa-plugins-pulseaudio.i686 python-matplotli
Reference: https://ask.fedoraproject.org/en/question/9556/how-do-i-install-32bit-libraries-on-a-64-bit-fedora/
Error: Error compiling Cython file
The error roughly means that there is an error in the cython file. It may be that the cython module is not installed, or there is a problem with the version. solution:
pip install cython==0.25
Error: IOError: [Errno 2] No such file or directory….. This is the last step of packaging, when copying the apk file to the bin directory of the project, it is a bug in buildozer.
solution:
Modify the /usr/local/lib/python2.7/dist-packages/buildozer/tagets/android.py file:
Import at the beginning of the file:
from distutils.version import LooseVersion
Replace the code below line 786: XXX found how the apk name is really built from the title with:
__sdk_dir = self.android_sdk_dir
build_tools_versions = os.listdir(join(__sdk_dir, 'build-tools'))
build_tools_versions = sorted(build_tools_versions, key=LooseVersion)
build_tools_version = build_tools_versions[-1]
gradle_files = ["build.gradle", "gradle", "gradlew"]
is_gradle_build = any((exists(join(dist_dir, x)) for x in gradle_files)) and build_tools_version >= ’25.0'
buildozer virtual machine
Kivy officially launched a buildozer virtual machine image, which has installed buildozer and some dependent files to provide a platform for buildozer packaging and testing. Since I used buildozer to package on the mac before, I kept reporting errors, and it was still unsuccessful when I switched to centos, so I downloaded this virtual machine, and the test results are as follows:
Virtual machine download address: http://txzone.net/files/torrents/kivy-buildozer-vm-2.0.zip
Note: For friends who cannot solve the dependency problem, you can use this virtual machine for program packaging. It is recommended to use your own local machine for the development environment.
kivy development example
Because the focus of this article is to introduce how to use kivy+buildozer to develop a python app, so the kivy development process and app functions are simplified.