关于Python 3.6.2下运行SDL2的问题及Kivy学习中的脚本报错咨询

Hey there! Let's break down your two technical issues and walk through common fixes and troubleshooting steps.

SDL2 can be tricky to get running smoothly on older Python versions like 3.6.2—here are the most common pitfalls and how to fix them:

• Missing or misconfigured SDL2 libraries
  If you're using pysdl2 (the official Python binding), you need to make sure the SDL2 binaries are accessible to Python:

  • On Windows: Place SDL2.dll in your Python installation's Scripts folder, or add its directory to your system PATH.
  • On Linux: Install system-level dependencies with sudo apt-get install libsdl2-dev (Debian/Ubuntu) or equivalent for your distro.
  • On macOS: Use Homebrew to install SDL2 with brew install sdl2.
    You can also explicitly set the DLL path in your script before importing sdl2:

  import os
  os.environ['PYSDL2_DLL_PATH'] = '/path/to/your/sdl2/bin/directory'
  import sdl2
  

• Incompatible binding versions
  Not all pysdl2 versions support Python 3.6.2. Stick to pysdl2==0.9.7—this release is confirmed to work with Python 3.6. Install it with:

  pip install pysdl2==0.9.7
  

• Conflicting system libraries
  If your system has multiple versions of SDL2 installed, Python might load the wrong one. On Linux, use ldd your_script.py to check which SDL2 library is being linked. On Windows, use Dependency Walker to verify the DLL path. Uninstall old versions or prioritize the correct path in your environment variables.

Since you mentioned script errors but didn't share specifics, let's cover a few common beginner issues with concrete examples to help you spot your problem:

Example 1: Missing self in the build method #

Problematic Script:

from kivy.app import App
from kivy.uix.label import Label

class MyApp(App):
    def build():  # Oops—missing the required `self` parameter
        return Label(text='Hello Kivy')

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

Error Message:

TypeError: build() takes 0 positional arguments but 1 was given

Fix: Add self to the build method definition:

def build(self):
    return Label(text='Hello Kivy')

Example 2: Missing Kivy dependencies #

Error Message:

ImportError: No module named 'kivy.core.window.window_sdl2'

Fix: Kivy relies on SDL2 under the hood, so you need to install all required system dependencies:

• On Linux: Install with sudo apt-get install libsdl2-dev libsdl2-image-dev libsdl2-mixer-dev libsdl2-ttf-dev
• On Windows: Install the Visual C++ Redistributable for Visual Studio 2015-2019
• Reinstall a Kivy version compatible with Python 3.6.2:

  pip install kivy==1.11.1
  

Example 3: Invalid KV syntax #

If you're using a .kv file, indentation and syntax mistakes are common. For example:
Bad KV File:

<MyLabel>:
text: "Hello"  # Missing indentation

Error Message:

kivy.lang.parser.ParserException: Parser: File "", line 2:
...
text: "Hello"
^
IndentationError: unexpected indent

Fix: Indent properties under the widget class:

<MyLabel>:
    text: "Hello"

If your issue doesn't match these examples, sharing your exact script and full error traceback would let us pinpoint the problem faster!

内容的提问来源于stack exchange，提问作者psalrod