Make a fun captcha generator using wxPython: from scratch

1. Introduction

2. Text

The application scenarios of CAPTCHA are mainly in scenarios where user identity needs to be verified or to prevent malicious attacks, as follows List several common application scenarios:

• User login verification: Use CAPTCHA when the user logs in to prevent automated robots from logging into the account.

• Website registration verification: Use CAPTCHA to prevent automated robots from registering accounts.

• Web crawler restrictions: Some websites may restrict crawler access. Using CAPTCHA can prevent malicious crawler attacks.

• Email filter spam: Use CAPTCHA to prevent automated robots from sending spam.

• Online Surveys: Use CAPTCHA to ensure the accuracy and credibility of online survey results.

• Website comments: Use CAPTCHA to prevent automated bots from posting malicious comments on your website.

• Authentication: Use CAPTCHA to ensure that only real users can access sensitive information or resources.

In general, the application scenarios of CAPTCHA are very wide in scenarios where user identity needs to be verified or to prevent automated robot attacks.

3. Example analysis

import wx
import random
import string
from PIL import Image, ImageDraw, ImageFont
 
 
class MyFrame(wx.Frame):
    def __init__(self, parent):
        super().__init__(parent, title="CAPTCHA Generator", size=(300, 200))
        panel = wx.Panel(self)
        button = wx.Button(panel, label="Generate CAPTCHA", pos=(0, 0))
        self.Bind(wx.EVT_BUTTON, self.on_button_click, button)
        # 创建一个静态图片控件
        self.static_bitmap = wx.StaticBitmap(panel, -1, size=(200, 80), pos=(40, 60))
    def on_button_click(self, event):
        # Set the dimensions of the image
        IMAGE_WIDTH = 200
        IMAGE_HEIGHT = 80
 
        # Generate a random string of characters to use as the CAPTCHA text
        captcha_text = ''.join(random.choices(string.ascii_uppercase + string.digits, k=6))
 
        # Create a blank image and get a drawing context
        image = Image.new('RGB', (IMAGE_WIDTH, IMAGE_HEIGHT), color = (255, 255, 255))
        draw = ImageDraw.Draw(image)
 
        # Generate a random color for the text
        text_color = (random.randint(0, 255), random.randint(0, 255), random.randint(0, 255))
 
        # Load a TrueType font file to use for the text
        font = ImageFont.truetype('arial.ttf', 36)
 
        # Draw the CAPTCHA text on the image
        x0, y0, x1, y1 = draw.textbbox((0, 0), captcha_text, font=font)
        text_width = x1 - x0
        text_height = y1 - y0
        x = (IMAGE_WIDTH - text_width) / 2
        y = (IMAGE_HEIGHT - text_height) / 2
        draw.text((x, y), captcha_text, fill=text_color, font=font)
 
        # Add some noise to the image by drawing randomly placed dots
        for i in range(500):
            x = random.randint(0, IMAGE_WIDTH - 1)
            y = random.randint(0, IMAGE_HEIGHT - 1)
            draw.point((x, y), fill=(random.randint(0, 255), random.randint(0, 255), random.randint(0, 255)))
 
        # Save the image as a PNG file with the CAPTCHA text as the filename
        image.save(captcha_text + '.png', 'PNG')
        # 加载PNG图片文件并显示在静态图片控件中
        bitmap = wx.Bitmap(captcha_text + '.png', wx.BITMAP_TYPE_PNG)
        self.static_bitmap.SetBitmap(bitmap)
if __name__ == '__main__':
    app = wx.App()
    frame = MyFrame(None)
    frame.Show(True)
    app.MainLoop()

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