ocr_engine.py

import pytesseract
import mss
import threading
import time
import sys
import os
from PIL import Image, ImageEnhance, ImageOps

class OCREngine:
    def __init__(self, callback, get_region_callback):
        self.callback = callback
        self.get_region_callback = get_region_callback
        self.running = False
        self.thread = None
        self.interval = 1.0  # seconds between captures

        # Attempt to find tesseract
        # If the user has it in PATH, this isn't needed, but often on Windows it's in standard dirs
        self._configure_tesseract()

    def _configure_tesseract(self):
        # Check if tesseract is in PATH
        try:
            pytesseract.get_tesseract_version()
            return
        except pytesseract.TesseractNotFoundError:
            pass

        # Common Windows paths
        paths = [
            r'C:\Program Files\Tesseract-OCR\tesseract.exe',
            r'C:\Program Files (x86)\Tesseract-OCR\tesseract.exe',
            r'C:\Users\\' + os.getlogin() + r'\AppData\Local\Tesseract-OCR\tesseract.exe'
        ]
        for p in paths:
            if os.path.exists(p):
                pytesseract.pytesseract.tesseract_cmd = p
                return
        
        print("Warning: Tesseract not found in standard paths. OCR may fail.")

    def start(self):
        if self.running:
            return
        self.running = True
        self.thread = threading.Thread(target=self._run_loop, daemon=True)
        self.thread.start()

    def stop(self):
        self.running = False
        # Thread will join naturally

    def _run_loop(self):
        with mss.mss() as sct:
            while self.running:
                try:
                    # Get region from UI
                    # Region format: {'top': y, 'left': x, 'width': w, 'height': h}
                    region = self.get_region_callback()
                    
                    if not region or region['width'] < 10 or region['height'] < 10:
                        # Box might be hidden or too small
                        time.sleep(self.interval)
                        continue

                    # mss requires integers
                    monitor = {
                        "top": int(region['top']),
                        "left": int(region['left']),
                        "width": int(region['width']),
                        "height": int(region['height'])
                    }

                    # Capture
                    sct_img = sct.grab(monitor)
                    img = Image.frombytes("RGB", sct_img.size, sct_img.bgra, "raw", "BGRX")

                    # Preprocessing
                    # 1. Grayscale
                    img = img.convert('L')
                    
                    # 2. Resize (Upscale) for better clarity
                    # Using a safe bicubic or lanczos if available
                    img = img.resize((img.width * 3, img.height * 3), Image.Resampling.LANCZOS)
                    
                    # 3. Enhance Contrast
                    enhancer = ImageEnhance.Contrast(img)
                    img = enhancer.enhance(2.0)
                    
                    # 4. Enhance Sharpness
                    enhancer = ImageEnhance.Sharpness(img)
                    img = enhancer.enhance(2.0)

                    # 5. Thresholding (Binarization)
                    # Isolate text (assuming white text on dark background)
                    # Any pixel brighter than 128 becomes 255 (white), else 0 (black)
                    thresh = 100 
                    fn = lambda x : 255 if x > thresh else 0
                    img = img.convert('L').point(fn, mode='1')
                    
                    # 6. Inversion
                    # Convert White-Text/Black-BG -> Black-Text/White-BG for Tesseract
                    img = ImageOps.invert(img.convert('L'))

                    # OCR
                    # --psm 6 usually assumes a single uniform block of text
                    text = pytesseract.image_to_string(img, config='--psm 6')

                    if text.strip():
                        self.callback(text)

                except Exception as e:
                    print(f"OCR Loop Error: {e}")
                
                time.sleep(self.interval)