Python|使用 .kv 文件在 Kivy 中添加图像

Kivy 是Python中一个独立于平台的 GUI 工具。因为它可以在Android、IOS、linux、Windows等平台上运行，基本上是用来开发Android应用的，但并不代表不能在Desktops应用上使用。

Kivy Tutorial – Learn Kivy with Examples.

图像小部件：

Image 小部件用于显示图像。要使用图像小部件，您必须导入：

from kivy.uix.image import Image, AsyncImage (not necessary while working with .kv file)

因为模块 kivy.uix.image 具有与图像相关的所有功能。
图像可以通过两种类型加载到应用程序：

1) Synchronous Loading: Loading image from the system (must be from the folder in which .py and .kv file is saved) 
2) Asynchronous Loading: To load an image asynchronously (for example from an external webserver) 

注意：默认情况下，图像居中并适合小部件边界框。如果您不想这样，可以将allow_stretch设置为 True 并将keep_ratio设置为 False。

Basic Approach to create multiple layout in one file:
1) import kivy
2) import kivyApp
3) import image
4) import BoxLayout
5) set minimum version(optional)
6) Create the Layout class
7) Create App class
8) Create .kv file:
          1) Add BoxLayout
          2) Add Label
          3) Add Image
          4) Resizing, Positioning etc of Image 
9) return instance of the layout class
10) Run an instance of the class

所以在下面的代码中，我们将解释如何加载同步和异步图像。还有如何用更多的东西调整图像的大小、定位、标签等。
.py 文件 –

Python3

## Sample Python application demonstrating the 
## working with images in Kivy using .kv file 
   
##################################################
# import kivy module   
import kivy 
     
# base Class of your App inherits from the App class.   
# app:always refers to the instance of your application  
from kivy.app import App
   
# this restrict the kivy version i.e 
# below this kivy version you cannot 
# use the app or software 
kivy.require('1.9.0')
 
# BoxLayout arranges children in a vertical or horizontal box.
# or help to put the children at the desired location.
from kivy.uix.boxlayout import BoxLayout
  
# to change the kivy default settings we use this module config
from kivy.config import Config
  
# 0 being off 1 being on as in true / false
# you can use 0 or 1 && True or False
Config.set('graphics', 'resizable', True)
 
# creating the root widget used in .kv file
class Imagekv(BoxLayout):
    '''
        no need to do anything here as
        we are building things in .kv file
    '''
    pass
 
# class in which name .kv file must be named My.kv.
class MyApp(App):
    # define build() function
    def build(self):
        # returning the instance of Imagekv class
        return Imagekv()
 
# run the App
if __name__ == '__main__':
    MyApp().run()

.kv 文件实现 –

Python3

# How to use images in kivy using .kv
 
# root widget od Imagekv Class
:
 
    # Giving orientation to Box Layout
    orientation:'vertical'
 
###############################################
  
    # Adding Box Layout
    BoxLayout:
         
        padding:5
 
        # Adding image from the system
        Image:
            source: 'download.jpg'
 
            # Giving the size of image
            size_hint_x: 0.4
 
            # allow stretching of image
            allow_stretch: True
             
        # Giving Label to images
        Label:
            text:"Python"
            font_size:11
            bold:True
 
        Label:
            text:"Programing Language"
            font_size:10
             
###############################################
  
   # Drawing the line between the multiples
    Label:
        canvas.before:
            Color:
                rgba: (1, 1, 1, 1)
            Rectangle:
                size: self.size
                pos: self.pos
        size_hint_y: None
        height: 1
 
################################################
  
    # Another Box Layout
    BoxLayout:
        padding:5
        Image:
            source:"downloading.jpg"
            size_hint_x: 0.4
            allow_stretch: True
 
        Label:
            text:"Image"
            font_size:11
            bold:True
 
        Label:
            text:"Python Image"
            font_size:10
             
#############################################
  
    # Drawing the line between the multiples
    Label:
        canvas.before:
            Color:
                rgba: (1, 1, 1, 1)
            Rectangle:
                size: self.size
                pos: self.pos
        size_hint_y: None
        height: 1
         
###############################################
  
    # Adding next Box Layout
    BoxLayout:
        padding:5
 
        # To load an image asynchronously
        # (for example from an external webserver)
        AsyncImage:
            source: 'http://kivy.org/logos/kivy-logo-black-64.png'
            width: 100
            allow_stretch: True
 
        Label:
            text:" Asynchronous Image "
            font_size:11
            bold:True
 
        Label:
            text:"Kivy Logo"
            font_size:10
 
####################################################
             
    # Drawing the line between the multiples
    Label:
        canvas.before:
            Color:
                rgba: (1, 1, 1, 1)
            Rectangle:
                size: self.size
                pos: self.pos
        size_hint_y: None
        height: 1
 
#####################################################
  
    # LAst Box Layout
    BoxLayout:
        padding:5
         
        AsyncImage:
            size_hint_y: None
            source: 'http://kivy.org/slides/kivypictures-thumb.jpg'
            width: 100
            allow_stretch: True
 
        Label:
            text:"Asynchronous Image "
            font_size:11
            bold:True
 
        Label:
            text:" Webserver image "
            font_size:10

输出：