變數類別

變數類別基本概念

就是把Widget控件的參數以變數處理時，必須借助tkinker模組的變數類別

x = IntVar()
x = DoubleVar()
x = StringVar()
x = BooleanVar()

get() 與 set()

做出按鈕顯示及收回的效果

from tkinter import *

def btn_hit():
    global msg_on
    if msg_on == False:
        msg_on = True
        x.set("我顯示出來囉")
    else:
        msg_on = False
        x.set(" ")

# 這邊如果使用get......
# if x.get == "":
#    x.set("我顯示出來囉")
# else:
#    x.set("")

root = Tk()
root.title("Python-tkinter")
msg_on = False

x = StringVar()

label = Label(root, textvariable = x, 
              fg = "blue", bg = "lightyellow",
              width = 25, height = 2)

label.pack()

btn = Button(root, text = "點我", command = btn_hit)
btn.pack()

root.mainloop()

結果

追蹤模式trace()使用 w

更改時更動輸出結果

from tkinter import *

def callback(*args):
    print("顯示更動: ", xE.get())


root = Tk()
root.title("Python-tkinter")

xE = StringVar()
entry = Entry(root, textvariable = xE)
entry.pack(padx = 5, pady = 10)

xE.trace("w", callback)


root.mainloop()

結果

當然也可以同步顯示

def callback(*args):
    xL.set(xE.get())
    print("顯示更動: ", xE.get())


xL = StringVar()
label = Label(root, textvariable = xL)
xL.set("同步顯示")
label.pack(pady = 5, padx = 10)

結果

追蹤模式trace()使用 r

• 這是讀取追蹤，要按下按鈕才會出現……

  from tkinter import *
  
  
  def callbackW(*args):
      xL.set(xE.get())
  
  def callbackR(*args):
      print("資料被讀取")
  
  def hit():
      print("讀取資料: ", xE.get())
  
  root = Tk()
  root.title("Python-tkinter")
  
  xE = StringVar()
  entry = Entry(root, textvariable = xE)
  entry.pack(pady = 5, padx = 10)
  xE.trace("w", callbackW)
  xE.trace("r", callbackR)
  
  xL = StringVar()
  label = Label(root, textvariable = xL)
  xL.set("同步顯示")
  label.pack(pady = 5, padx = 10)
  
  btn = Button(root, text = "讀取", command = hit)
  btn.pack(pady = 5)
  
  root.mainloop()

結果

callback方法參數

def callbackW(name, index, mode):
    xL.set(xE.get())
    print("name = %r, index = %r, mode = %r" % (name, index, mode))

結果