Python Kivy线画布（Canvas）用法实例

Kivy是Python中与平台无关的GUI工具。由于它可以在Android, IOS, Linux和Windows等操作系统上运行。它基本上是用于开发Android应用程序, 但这并不意味着它不能在桌面应用程序上使用。

????Kivy教程–通过示例学习Kivy。

线条画布 Line是一个顶点画布指令。它允许绘制通过点的线。此代码显示如何使用/绘制扩展线图, 例如圆形, 椭圆形, 矩形和Bezier等。

Basic Approach:1) import kivy 2) import kivy App 3) import Gridlayout 4) import widget 5) set minimum version(optional) 6) Create as much as widget class as needed 7) create the App class 8) return the widget/layout etc class 9) Run an instance of the class

实施方法：
＃Main.py

# kivy Lines Demo# 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# The GridLayout arranges children in a matrix. # It takes the available space and # divides it into columns and rows, # then adds widgets to the resulting "cells". from kivy.uix.gridlayout import GridLayout # Widgets are elements of # a graphical user interface that # form part of the User Experience. from kivy.uix.widget import Widget############################################## # Classes form Different types of line aswidgetsclass LineEllipse1(Widget): passclass LineEllipse2(Widget): passclass LineEllipse3(Widget): passclass LineCircle1(Widget): passclass LineCircle2(Widget): passclass LineCircle3(Widget): passclass LineCircle4(Widget): passclass LineRectangle(Widget): passclass LineBezier(Widget): pass# Create the App class class LineApp(App): def build( self ):# Assign the number of coloumn, spacing and padding root = GridLayout(cols = 3 , padding = 50 , spacing = 100 )# Adding the widgets root.add_widget(LineEllipse1()) root.add_widget(LineEllipse2()) root.add_widget(LineEllipse3()) root.add_widget(LineCircle1()) root.add_widget(LineCircle2()) root.add_widget(LineCircle3()) root.add_widget(LineCircle4()) root.add_widget(LineRectangle()) root.add_widget(LineBezier()) return root# Run the App class if __name__ = = '__main__' : LineApp().run()

Line.kv文件：

# Line.kv file of the code# Creating Different types of Lines(or shapes through line)############################################ Row 1:# Ellipse(1st row 1st element)< LineEllipse1> :# Creating Canvas canvas: Color: rgba: 1 , . 1 , . 1 , . 9 # Ellipse Creation Line: width: 2. ellipse: ( self .x, self .y, self .width, self .height)# Label the figure Label: center: root.center text: 'Ellipse'############################################# Ellipse from 90 to 180((1st row 2nd element))< LineEllipse2> : canvas: Color: rgba: 1 , . 1 , . 1 , . 9 Line: width: 2. ellipse: ( self .x, self .y, self .width, self .height, 90 , 180 ) Label: center: root.center text: 'Ellipse from 90 to 180'############################################# Ellipse from 90 to 720, 10 segments(1st row 3rd element)< LineEllipse3> : canvas: Color: rgba: 1 , . 1 , . 1 , . 9 Line: width: 2. ellipse: ( self .x, self .y, self .width, self .height, 90 , 720 , 10 ) Label: center: root.center text: 'Ellipse from 90 to 720, 10 segments' halign: 'center'############################################# Circle(2nd row 1st element) < LineCircle1> : canvas: Color: rgba: . 1 , 1 , . 1 , . 9 Line: width: 2. circle: ( self .center_x, self .center_y, min ( self .width, self .height) /2 ) Label: center: root.center text: 'Circle'############################################# Circle from 90 to 180(2nd row 2nd element) < LineCircle2> : canvas: Color: rgba: . 1 , 1 , . 1 , . 9 Line: width: 2. circle: ( self .center_x, self .center_y, min ( self .width, self .height) /2 , 90 , 180 ) Label: center: root.center text: 'Circle from 90 to 180'############################################ # Circle from 90 to 180, 10 segments(1st row 3rd element) < LineCircle3> : canvas: Color: rgba: . 1 , 1 , . 1 , . 9 Line: width: 2. circle: ( self .center_x, self .center_y, min ( self .width, self .height) /2 , 90 , 180 , 10 ) Label: center: root.center text: 'Circle from 90 to 180, 10 segments' halign: 'center'############################################# Circle from 0 to 360 (3rd row 1st element) < LineCircle4> : canvas: Color: rgba: . 1 , 1 , . 1 , . 9 Line: width: 2. circle: ( self .center_x, self .center_y, min ( self .width, self .height) /2 , 0 , 360 ) Label: center: root.center text: 'Circle from 0 to 360' halign: 'center'############################################# Rectangle (3rd row 2nd element) < LineRectangle> : canvas: Color: rgba: . 1 , . 1 , 1 , . 9 Line: width: 2. rectangle: ( self .x, self .y, self .width, self .height) Label: center: root.center text: 'Rectangle'############################################# Bezier (3rd row 3rd element) < LineBezier> : canvas: Color: rgba: . 1 , . 1 , 1 , . 9 Line: width: 2. bezier: ( self .x, self .y, self .center_x - 40 , self .y + 100 , self .center_x + 40 , self .y - 100 , self .right, self .y) Label: center: root.center text: 'Bezier'

输出如下：