Python – Adding double tap on any widget in kivy

Kivy is a platform-independent GUI tool in Python. It can run on Android, IOS, Linux and Windows, etc. This is the only GUI library from python which can independently run on an android device even we can use it on Raspberry Pi also.  It is an open-source Python library for the rapid development of applications that make use of innovative user interfaces, such as multi-touch apps. Its graphic engine is built over OpenGL ES 2 and has fast graphics pipeline. If you are new to kivy you can learn from this link.

In this article, we will develop a GUI window using kivy framework of python, and we will add an image on this window(you can follow the same pattern for implementing double-tap event on other widgets also) and we will add a double-tap event on this image.

A basic approach to implement double-tap on image widget

1. Import image widget from kivy package
2. Import touchbehaviour from kivy package
3. Import kivy app
4. Import boxlayout from kivy package
5. Add widget
6. Extend the class
7. Return layout
8. Run an instance of the class

Code: 

Python3

# importing image widget of kivy framework
from kivy.uix.image import Image

# importing Touch behaviour event from kivy framework
from kivymd.uix.behaviors import TouchBehavior
from kivy.app import App

# importing boxlayout for our application
from kivy.uix.boxlayout import BoxLayout

# attaching touch behaviour with image widget
class ImageWithDoubleTouch(Image, TouchBehavior):

    # event for double-tap
    def on_double_tap(self, instance, *args):
        print("wow!! you have double clicked an image named "+self.source)

# this will connect MainWindow which we have
# created in ui.kv with main.py file
class MainWindow(BoxLayout):
    pass
"""
Note:- keep in mind that our .kv file name was ui.kv so our rendering
class(class which will render our application) name
should be like uiApp otherwise we will not get the desired output!!
"""

# this is the main class which will render
# the whole application
class uiApp(App):

    # method which will render our application
    def build(self):
        return MainWindow()

# running the application
uiApp().run()

kivy Code:

#window which contains our image

<MainWindow>:

   BoxLayout:

       # adding our ImageWithDoubleTouch widget that we have created in main.py file

       ImageWithDoubleTouch:

           # adding path of image file

           source:”gfg.png”

Output: