暂停 for 循环以等待按钮按下

Question

I am trying to build an image classifier and I need to manually assign classifications for a training dataset, so I build a file browser /media window app in tkinter to display images and assign them classifications via a button click. To iterate over the files, I am using a for loop, but I need it to pause and wait for that input. Here is my code:

def setKnownData(self):
    training_sample = self.dataset.sample(frac = .1)
    print(training_sample)                                                                                
    for i, row in training_sample.iterrows():                                              
        print(row)                                                                                
        global img                                                                                       
        file = Image.open(row['ID'])                                                            
        resized = file.resize((500,600))                                                            
        img = ImageTk.PhotoImage(resized)                                                  
        self.media_window.create_image(0,0, anchor = 'nw', image = img)                           
        self.event_var.get()                                                                    
        while True:                                              
            if self.event_var.get() == 0:                                                         
                print(self.event_var.get())                                                          
                return                                        
            if self.event_var.get() == 1:                                                      
                training_sample.loc[row]['class'] = 'cartoon'                                            
                break                                                                     
            elif self.event_var.get() ==2:                                                       
                training_sample.loc[row]['class'] = 'photo'                                   
                break
            self.event_var.set(0)
        
def stateSwitch(self, action):
    print('state switching....')
    if action == 'toon':
        print(self.event_var.get())
        self.event_var.set(1)
        print('classification: TOON', self.event_var.get())
    elif action == 'photo':
        self.event_var.set(2)
        print('classification: PHOTO')

I've exausted every combination of IntVar, tkinter, and for loop searches and can't find a viable solution, so I apologize if this is a repeat question. How can I pause this for loop, wait for a putton press, and then proceed to the next image in the list?

Answer 1

You need to shift your thinking away from pausing the loop. That's procedural programming, but GUIs are work much better as "event driven programming", where the entire program is just endlessly waiting for an event (like a button press) to happen. The means no loops, besides the tkinter mainloop. And it means making a new function for every event.

def setKnownData(self):
    training_sample = self.dataset.sample(frac = .1)
    print(training_sample)
    self.training_sample = training_sample.iterrows()

def on_button_click(self):                                                      
    i, row = next(self.training_sample)                            
    print(row)                                                                                
    global img                                                                                       
    file = Image.open(row['ID'])                                                            
    resized = file.resize((500,600))                                                            
    img = ImageTk.PhotoImage(resized)                                                  
    self.media_window.create_image(0,0, anchor = 'nw', image = img)                           
    self.event_var.get()                                                                    
    while True:                                              
        if self.event_var.get() == 0:                                                         
            print(self.event_var.get())                                                          
            return                                        
        if self.event_var.get() == 1:                                                      
            training_sample.loc[row]['class'] = 'cartoon'                                            
            break                                                                     
        elif self.event_var.get() ==2:                                                       
            training_sample.loc[row]['class'] = 'photo'                                   
            break
        self.event_var.set(0)