淡入小部件或图片进出 - Tkinter

Question

How to fade in/out on a Tkinter Frame
此问题显示您不能使用Tkinter的默认透明度淡入和淡出使用小部件。但是，有没有其他方式，使用PIL或其他方式在Tkinter中淡出小部件（或图片）？ （即调节透明度）

Answer 1

（希望）简单的答案：

#!python3 

import tkinter as tk 
from PIL import Image, ImageTk 
import os 

class App(tk.Tk): 
    def __init__(self): 
     tk.Tk.__init__(self) 
     self.title("Image Fading") 
     self.label = tk.Label(self) 
     self.label.pack() 
     self.load_pictures() 
     self.fadetime = 1 # time between alpha channel changes in ms 
     self.fadestep = 5 # change to alpha channel 
     self.curstep = 0 # the current step through the transparency 

     self.im = None # to hold the raw picture 
     self.photo = None # to hold the tk compatible picture 

     self.after(self.fadetime, self.fade_in) 

    def fade_in(self): 
     if not self.im: 
      self.load_picture() 
     alpha = min(self.curstep * self.fadestep, 255) # clamp to 255 maximum 
     self.im.putalpha(alpha) 
     self.photo = ImageTk.PhotoImage(self.im) 
     self.label.configure(image=self.photo) 
     self.curstep += 1 
     print('fade in: %i' % alpha) 
     if alpha == 255: 
      self.curstep = 0 
      self.after(3000, self.fade_out) # wait three seconds then fade out 
     else: 
      self.after(self.fadetime, self.fade_in) 

    def fade_out(self): 
     alpha = max(255 - self.curstep * self.fadestep, 0) # clamp to 0 minimum 
     self.im.putalpha(alpha) 
     self.photo = ImageTk.PhotoImage(self.im) 
     self.label.configure(image=self.photo) 
     self.curstep += 1 
     print('fade out: %i' % alpha) 
     if alpha == 0: 
      self.curstep = 0 
      self.im = None 
      self.index += 1 # to use next picture 
      if self.index >= len(self.filenames): 
       self.index = 0 
      self.after(3000, self.fade_in) # wait three seconds then load next picture 
     else: 
      self.after(self.fadetime, self.fade_out) 

    def load_picture(self): 
     while True: 
      file = open(self.filenames[self.index], mode='rb') 
      try: # if errors opening file as image, ignore and try next one 
       self.im = Image.open(file) # this is a lazy operation and only reads image header 
       self.im.load() # force image load here 
       file.close() # close the file 
       print('loaded: %s' % self.filenames[self.index]) 
       break 
      except: 
       file.close() 
       self.index += 1 
       if self.index >= len(self.filenames): 
        self.index = 0 

    def load_pictures(self): 
     self.filenames = [] 
     for file in os.listdir(): 
      if file.rsplit('.', 1)[-1] not in ['db', 'py', 'pyw']: 
       self.filenames.append(file) 
     self.index = -1 

if __name__ == '__main__': 
    app = App() 
    app.mainloop() 

这是假定你想淡出每个图像出来，然后下一个中而不是从一个到下一直褪色。 请注意，尽管以最简单的方式（使用putalpha）完成这种淡入/淡出仍然是cpu密集型的，因为每个迭代都转换为ImageTk实例。 那就是为什么我已经把变量的alpha步长和时间来控制它需要被调用的次数。

如果我的假设是错误的，并且您需要从一个直线渐变到下一个，则会更加密集，因为您需要在将图像应用到每个图像后将图像“融合”在一起，然后将结果到ImageTk实例