Pyglet Hello World: 你的第一个 Python 游戏窗口

Before we sprinkle any Pyglet magic, let’s make sure the foundation is solid. You'll need Python 3.7 or newer—most systems will have it, but it’s always worth a quick check. Pop open your terminal or command prompt and ask Python what it's been up to:

python --version

If you don't see Python 3.x.x, a quick trip to python.org will sort you out. Once Python's confirmed, let's carve out a nice, clean workspace with a virtual environment:

# Navigate to your project folder, then create it:
python -m venv .venv

And then, like waving a wand, activate it. Your terminal prompt should gain a little (.venv) prefix, a subtle nod that you're now in your isolated wonderland:

# On macOS/Linux
source .venv/bin/activate

# On Windows (use Command Prompt)
.venv\Scripts\activate

With your virtual environment humming along, bringing Pyglet into your project is as simple as, well, installing a package. Just one command, and pip handles the rest, fetching Pyglet from the Python Package Index and tucking it neatly into your isolated project space.

Type this into your *activated* terminal:

pip install pyglet

You'll see a flurry of text as Pyglet and any necessary sub-dependencies get downloaded and installed. Once it settles down, you're officially ready to start making windows appear! It's kind of like setting up a easel and getting your paints ready for the first brushstroke.

Every great visual application starts with a canvas, and in Pyglet, that's a window. It's the most basic element, yet it opens up a world of possibilities. Let's create a new file, say main.py, and give it the simplest window-making incantation.

Copy and paste this snippet into your main.py file:

import pyglet

# Create a window
window = pyglet.window.Window(width=800, height=600, caption='Hello Pyglet!')

# Run the application
pyglet.app.run()

Now, save that file and run it from your *activated* terminal:

python main.py

You should see a rather plain, empty window pop up with "Hello Pyglet!" in its title bar. A humble start, perhaps, but quite the achievement!

That little chunk of code in the last step did quite a lot, actually. Let's pull back the curtain on those two lines that brought your window to life.

• import pyglet: This line is our entry point, simply telling Python we intend to use the Pyglet library. Think of it as opening your toolbox.
• window = pyglet.window.Window(...): Here, we're creating an instance of Pyglet's Window class. We've passed in a few arguments:
  • width and height: These set the dimensions of your window in pixels.
  • caption: This is the text that appears in the window's title bar, acting as its name tag.
  You can get fancier with other options, like `resizable=True` or `fullscreen=True`, but for a "Hello World," these suffice.
• pyglet.app.run(): This is the grand maestro. It starts Pyglet's main event loop. Essentially, it puts your application in a waiting state, listening for things like mouse clicks, key presses, or even the operating system saying, "Hey, redraw this window!" Without this line, your window would flash and disappear faster than you can say "Pyglet."

It's a foundational pattern for almost any Pyglet application—set up your stage, then tell the show to start running.

An empty window is a bit like an empty stage—functional, but lacking character. Let's throw some text onto it to truly declare our presence. Pyglet provides a handy Label class for just this purpose, making text display surprisingly easy.

Update your main.py to look like this:

import pyglet

window = pyglet.window.Window(800, 600, caption='Hello Pyglet!')

# Create a Label object
hello_label = pyglet.text.Label(
    'Hello World!',
    font_name='Times New Roman',
    font_size=36,
    x=window.width//2, y=window.height//2,
    anchor_x='center', anchor_y='center',
    color=(255, 255, 255, 255) # RGBA: white, opaque
)

# This is a decorator to register a function as an event handler
@window.event
def on_draw():
    window.clear() # Clear the window first
    hello_label.draw() # Then draw our label

pyglet.app.run()

Run this new version of main.py. Now, smack dab in the middle of your window, you should see "Hello World!" in all its glory. It's a bit like adding the headline to your masterpiece.

You just saw @window.event and on_draw()—these are crucial for anything visual in Pyglet. The event loop we mentioned earlier isn't just for user input; it also dictates when your window needs to redraw itself. That's where on_draw comes in.

• @window.event: This Python decorator is Pyglet's way of saying, "Hey, whenever the `window` object needs to handle an 'event' called `on_draw`, this function is the one to call." It's like telling the stage manager exactly who handles the "curtain call" event.
• def on_draw():: This function contains all the instructions for what should be visible on your window *at that moment*. It's called automatically whenever the window needs to refresh its display—be it after being minimized, resized, or simply because it's time for the next frame of animation.
• window.clear(): Before drawing anything new, it's good practice to wipe the slate clean. This clears the entire window, preventing old drawings from lingering like ghostly remnants.
• hello_label.draw(): Finally, we tell our `hello_label` object to draw itself onto the cleared window. Drawing order matters, so whatever you draw last will appear on top.

Understanding on_draw is key. It's the central hub for all rendering. Every graphical element, from text to images to complex 3D models, will eventually make its way through this function to be displayed. Consider it the beating heart of your application's visual output.

A static image is nice, but interactive experiences are where the fun really begins. Pyglet, being an event-driven framework, makes handling user input a breeze. Let's add a simple keyboard handler to make our window respond to a key press—say, closing the window when you hit Escape.

Add this new event handler to your main.py, right below your on_draw function:

# ... (previous code for window and label) ...

@window.event
def on_draw():
    window.clear()
    hello_label.draw()

# Import the keys module for checking key presses
import pyglet.window.key as key

@window.event
def on_key_press(symbol, modifiers):
    if symbol == key.ESCAPE:
        pyglet.app.exit() # Close the application

pyglet.app.run()

Run the script again, and try hitting the `Escape` key. Poof! Your window should vanish. The on_key_press function is another special event handler, listening for those moments when a user's fingers dance across the keyboard. It's like having a little attendant backstage, ready to perform an action when a specific cue is given.

Keyboards are great, but sometimes a good old click is what's needed. Pyglet gives us a similar event handler for mouse input. Let's make our "Hello World!" label change its message whenever you click the mouse button.

Add the following on_mouse_press function to your main.py:

# ... (previous code) ...

# Keep track of click count
click_count = 0

@window.event
def on_mouse_press(x, y, button, modifiers):
    global click_count # We need to modify the global variable
    click_count += 1
    hello_label.text = f'You clicked {click_count} times!'

# ... (on_key_press and pyglet.app.run() remain the same) ...

When you run this, clicking anywhere in the window will update the text. Notice how on_mouse_press gets information about where the click happened (x, y coordinates), which button was pressed, and any modifier keys (like Shift or Ctrl). It's a miniature surveillance system for your mouse, always ready to report back.

So, we've covered the basics: a window, some text, and a couple of ways to respond to user input. Let's put it all together into one coherent "Hello World" script that truly demonstrates Pyglet's elegance. This consolidated version is what you'd typically start with for any new interactive Pyglet project.

Here’s the complete, polished version of main.py:

import pyglet
import pyglet.window.key as key # For keyboard events

# 1. Setup the window
window = pyglet.window.Window(width=800, height=600, caption='Pyglet Interactive Hello World', resizable=True)

# 2. Prepare visual elements
click_count = 0
hello_label = pyglet.text.Label(
    'Hello World!',
    font_name='Arial',
    font_size=28,
    x=window.width//2, y=window.height//2,
    anchor_x='center', anchor_y='center',
    color=(255, 255, 255, 255) # White text
)

# 3. Define event handlers

@window.event
def on_draw():
    window.clear()
    hello_label.draw()

@window.event
def on_key_press(symbol, modifiers):
    if symbol == key.ESCAPE:
        pyglet.app.exit()
    elif symbol == key.SPACE:
        hello_label.text = "Spacebar pressed! Hello again!"
    elif symbol == key.BACKSPACE:
        hello_label.text = "Back to basics: Hello World!"


@window.event
def on_mouse_press(x, y, button, modifiers):
    global click_count
    click_count += 1
    hello_label.text = f'Mouse clicked {click_count} times!'

# Update label position if window resizes
@window.event
def on_resize(width, height):
    hello_label.x = width // 2
    hello_label.y = height // 2
    print(f"Window resized to {width}x{height}") # For debugging

# 4. Run the application
pyglet.app.run()

Now, save this version and run it. Try clicking the mouse, pressing `Space`, `Backspace`, and `Escape`. You've essentially built a tiny interactive demo, a small but mighty example of how Pyglet lets you choreograph actions and reactions on your screen. It’s like conducting a mini-orchestra, where every event is a note and your code is the score.

You've officially created your very first Pyglet "Hello World" application! From a blank canvas to an interactive display, you've seen the core components in action: creating windows, displaying text, and responding to user input. This foundation is surprisingly robust for building much more complex things.

Where do you go from here? The world—or at least the Pyglet world—is your oyster:

• Images and Sprites: Bring your games to life by loading and drawing images. Pyglet handles various formats with ease.
• Animation: Move things around! Use Pyglet's clock for timed events and create smooth animations.
• Audio and Video: Add sound effects, background music, or even embed videos directly into your applications.
• Game Loop & Batching: For more complex projects, you'll delve into efficient rendering techniques and managing many objects.
• Input Devices: Beyond mouse and keyboard, explore joystick and gamepad support.

Think of this "Hello World" as the first gentle push on a swing. You've got the momentum now; the next steps are all about how high you want to go. Keep tinkering, keep exploring, and enjoy bringing your Python creations to life with Pyglet!