This is a note for https://class.coursera.org/interactivepython-005
In week two, I have learned:
1.event-drvien programing
4 event types:
Input: button, textbox
Keyborad: key up, key down
Mouse: click, drag
Timer
example:
# Example of a simple event-driven program # CodeSkulptor GUI module
import simplegui # Event handler
def tick():
print "tick!" # Register handler
timer = simplegui.create_timer(1000, tick) # Start timer
timer.start()
2. global variables
when you want to change the global variables, use global, ifelse you don't need global.(不需更改全局变量，只是想使用全局变量的值的时候，不需要声明global)
3. simpleGUI
Program structure with 7 steps:
①Globals (state)
②Helper functions
③Classes
④Define event handlers
⑤Create a frame
⑥Register event handlers
⑦Start frame & timers
# SimpleGUI program template # Import the module
import simplegui # Define global variables (program state)
counter = 0
# Define "helper" functions
def increment():
global counter
counter = counter + 1 # Define event handler functions
def tick():
increment()
print counter def buttonpress():
global counter
counter = 0 # Create a frame
frame = simplegui.create_frame("SimpleGUI Test", 100, 100)
frame.add_button("Click me!", buttonpress)
# Register event handlers
timer = simplegui.create_timer(1000, tick) # Start frame and timers
frame.start()
timer.start()
Simple Calculator
Data
Store
Operand
Operations
Swap
Add
Subtract
Multiple
Divide
Computation
Store = store operation operand
# calculator with all buttons import simplegui # intialize globals
store = 0
operand = 0 # event handlers for calculator with a store and operand def output():
"""prints contents of store and operand"""
print "Store = ", store
print "Operand = ", operand
print "" def swap():
""" swap contents of store and operand"""
global store, operand
store, operand = operand, store
output() def add():
""" add operand to store"""
global store
store = store + operand
output() def sub():
""" subtract operand from store"""
global store
store = store - operand
output() def mult():
""" multiply store by operand"""
global store
store = store * operand
output() def div():
""" divide store by operand"""
global store
store = store / operand
output() def enter(t):
""" enter a new operand"""
global operand
operand = int(t)
output() # create frame
f = simplegui.create_frame("Calculator",300,300) # register event handlers and create control elements
f.add_button("Print", output, 100)
f.add_button("Swap", swap, 100)
f.add_button("Add", add, 100)
f.add_button("Sub", sub, 100)
f.add_button("Mult", mult, 100)
f.add_button("Div", div, 100)
f.add_input("Enter", enter, 100) # get frame rolling
f.start()