如何在Kivy的Python文件中为Button控件显示图片

Let's walk through the problems in your current code and get that image button working properly:

1. Invalid Image Source #

Your source=('Image') is not a valid image reference. This should be the full filename or relative path of your actual image file (like 'button_icon.png'), not just the word "Image". The parentheses here are also unnecessary—you only need to pass a string directly.

2. Broken on_press Binding #

on_press="Screen" won’t work because Kivy expects a callable function/method for this event, not a plain string. You need to define a method that handles the button press (like switching screens, which it looks like you’re aiming for) and bind that method to the button.

3. Missing Size Configuration (Critical for Visibility) #

If you don’t set size_hint or size for the Button, it will default to a tiny size, and your image won’t be visible. Adding these properties ensures the button is large enough to display your image.

Corrected Working Example #

Here’s a full, tested code snippet that fixes all these issues:

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen

class MainScreen(Screen):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        # Create the image button with proper configuration
        img_button = Button(
            source='my_button_image.png',  # Replace with your image's actual path/name
            pos_hint={"x":0.3, "top":0.3},
            size_hint=(0.2, 0.1),  # Adjust relative size to your needs
            on_press=self.switch_to_target_screen  # Bind to your press handler
        )
        self.add_widget(img_button)
    
    def switch_to_target_screen(self, instance):
        # Logic to switch screens (adjust based on your ScreenManager setup)
        self.manager.current = 'target_screen'

class TargetScreen(Screen):
    pass

class MyApp(App):
    def build(self):
        sm = ScreenManager()
        sm.add_widget(MainScreen(name='main'))
        sm.add_widget(TargetScreen(name='target_screen'))
        return sm

if __name__ == '__main__':
    MyApp().run()

Key Tips to Troubleshoot Further: #

• Image Path Check: Ensure your image file is in the same folder as your Python script, or use a relative path like 'assets/button_icon.png' if it’s in a subfolder. Kivy supports PNG, JPG, and other common image formats.
• Screen Setup: The switch_to_target_screen method assumes you’re using a ScreenManager (since you referenced "Screen" in your original code). If you’re not using screens, replace this method with whatever action you want the button to trigger.
• Size Tweaks: Use size=(200, 50) for fixed pixel dimensions if you don’t want relative sizing with size_hint.

If the image still doesn’t show up, double-check that the filename is spelled correctly (case-sensitive on most systems) and that the image file isn’t corrupted.

内容的提问来源于stack exchange，提问作者Adam Kamil