historical-ocr / app.py
milwright's picture
modularize + nest scripts; reduce technical debt
94e74f0
# Standard library imports
import os
import json
import sys
import time
import base64
import io
import logging
from pathlib import Path
from datetime import datetime
# Configure logging
logging.basicConfig(level=logging.INFO,
format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)
# Third-party imports
import streamlit as st
# Local application/module imports
from preprocessing import convert_pdf_to_images, preprocess_image
from ocr_processing import process_file
from ui.ui_components import (
ProgressReporter,
create_sidebar_options,
display_results,
create_file_uploader,
display_about_tab,
display_previous_results,
display_document_with_images
)
from utils import get_base64_from_image, handle_temp_files, format_timestamp
from error_handler import handle_ocr_error, check_file_size
from constants import (
MAX_FILE_SIZE_MB,
MAX_PAGES,
DOCUMENT_TYPES,
DOCUMENT_LAYOUTS,
CUSTOM_PROMPT_TEMPLATES,
LAYOUT_PROMPT_ADDITIONS
)
from structured_ocr import StructuredOCR
from config import MISTRAL_API_KEY
from utils.image_utils import create_results_zip
# Set favicon path
favicon_path = os.path.join(os.path.dirname(__file__), "static/favicon.png")
# Set page configuration
st.set_page_config(
page_title="Historical OCR",
page_icon=favicon_path if os.path.exists(favicon_path) else "πŸ“œ",
layout="wide",
initial_sidebar_state="collapsed",
)
# ========================================================================================
# CRITICAL WARNING TO ALL AI MODELS AND DEVELOPERS:
# DO NOT MODIFY THE STATE MANAGEMENT LOGIC IN THIS APPLICATION WITHOUT FULL UNDERSTANDING
# OF STREAMLIT'S EXECUTION MODEL.
#
# This state management implementation has been carefully designed to work with Streamlit's
# unique execution flow. The app runs from top to bottom on EVERY interaction, and state
# must be explicitly managed through st.session_state.
#
# The current implementation uses:
# 1. A dedicated close_document() callback function triggered by the button's on_click
# 2. A flag-based approach (close_clicked) to handle cleanup on the next run cycle
# 3. Early cleanup detection and st.rerun() to ensure clean UI rendering
#
# Previous approaches using direct state manipulation or conditional rendering based on
# reset flags led to persistent UI elements and resource leaks.
#
# Consult https://docs.streamlit.io/library/advanced-features/session-state for details.
# ========================================================================================
def reset_document_state():
"""Reset only document-specific state variables
This function explicitly resets all document-related variables to ensure
clean state between document processing, preventing cached data issues.
"""
st.session_state.sample_document = None
st.session_state.original_sample_bytes = None
st.session_state.original_sample_name = None
st.session_state.original_sample_mime_type = None
st.session_state.is_sample_document = False
st.session_state.processed_document_active = False
st.session_state.sample_document_processed = False
st.session_state.sample_just_loaded = False
st.session_state.last_processed_file = None
st.session_state.selected_previous_result = None
# Keep temp_file_paths but ensure it's empty after cleanup
if 'temp_file_paths' in st.session_state:
st.session_state.temp_file_paths = []
def init_session_state():
"""Initialize session state variables if they don't already exist
This function follows Streamlit's recommended patterns for state initialization.
It only creates variables if they don't exist yet and doesn't modify existing values.
"""
# Initialize persistent app state variables
if 'previous_results' not in st.session_state:
st.session_state.previous_results = []
if 'temp_file_paths' not in st.session_state:
st.session_state.temp_file_paths = []
if 'auto_process_sample' not in st.session_state:
st.session_state.auto_process_sample = False
if 'close_clicked' not in st.session_state:
st.session_state.close_clicked = False
if 'active_tab' not in st.session_state:
st.session_state.active_tab = 0
# Initialize document-specific state variables
if 'last_processed_file' not in st.session_state:
st.session_state.last_processed_file = None
if 'sample_just_loaded' not in st.session_state:
st.session_state.sample_just_loaded = False
if 'processed_document_active' not in st.session_state:
st.session_state.processed_document_active = False
if 'sample_document_processed' not in st.session_state:
st.session_state.sample_document_processed = False
if 'sample_document' not in st.session_state:
st.session_state.sample_document = None
if 'original_sample_bytes' not in st.session_state:
st.session_state.original_sample_bytes = None
if 'original_sample_name' not in st.session_state:
st.session_state.original_sample_name = None
if 'is_sample_document' not in st.session_state:
st.session_state.is_sample_document = False
if 'selected_previous_result' not in st.session_state:
st.session_state.selected_previous_result = None
def close_document():
"""Called when the Close Document button is clicked
This function handles proper cleanup of resources and state when closing a document.
It uses Streamlit's callback mechanism which ensures the state change happens
at the correct time in Streamlit's execution cycle.
WARNING: Do not replace this with inline button handling using if st.button():
That approach breaks Streamlit's execution flow and causes UI artifacts.
"""
logger.info("Close document button clicked")
# Clean up temp files first
if 'temp_file_paths' in st.session_state and st.session_state.temp_file_paths:
logger.info(f"Cleaning up {len(st.session_state.temp_file_paths)} temporary files")
handle_temp_files(st.session_state.temp_file_paths)
# Reset all document-specific state variables to prevent caching issues
reset_document_state()
# Set flag for having cleaned up - this will trigger a rerun in main()
st.session_state.close_clicked = True
def show_example_documents():
"""Show example documents section"""
st.header("Sample Documents")
# Add a simplified info message about examples and CSS in the same markdown block
# to reduce spacing between elements
st.markdown("""
This app can process various historical documents:
- Historical photographs, maps, and manuscripts
- Handwritten letters and documents
- Printed books and articles
- Multi-page PDFs
<style>
/* Make the selectbox container match the full column width */
.main .block-container .element-container:has([data-testid="stSelectbox"]) {
width: 100% !important;
max-width: 100% !important;
margin-top: -12px !important; /* Reduce space between text and selectbox */
}
/* Make the actual selectbox control take the full width */
.stSelectbox > div > div {
width: 100% !important;
max-width: 100% !important;
}
/* Tighten spacing in the sample documents tab */
.main .block-container [data-testid="stVerticalBlock"] > div:nth-child(n+2) {
margin-top: 0.5rem !important;
}
</style>
""", unsafe_allow_html=True)
# Sample document URLs dropdown with clearer label
sample_urls = [
"Select a sample document",
"https://huggingface.co/spaces/milwright/historical-ocr/resolve/main/input/a-la-carte.pdf",
"https://huggingface.co/spaces/milwright/historical-ocr/resolve/main/input/magician-or-bottle-cungerer.jpg",
"https://huggingface.co/spaces/milwright/historical-ocr/resolve/main/input/handwritten-letter.jpg",
"https://huggingface.co/spaces/milwright/historical-ocr/resolve/main/input/magellan-travels.jpg",
"https://huggingface.co/spaces/milwright/historical-ocr/resolve/main/input/milgram-flier.png",
"https://huggingface.co/spaces/milwright/historical-ocr/resolve/main/input/recipe.jpg",
]
sample_names = [
"Select a sample document",
"Restaurant Menu (PDF)",
"The Magician (Image)",
"Handwritten Letter (Image)",
"Magellan Travels (Image)",
"Milgram Flier (Image)",
"Historical Recipe (Image)"
]
# Initialize sample_document in session state if it doesn't exist
if 'sample_document' not in st.session_state:
st.session_state.sample_document = None
selected_sample = st.selectbox("Select a sample document from `~/input`", options=range(len(sample_urls)), format_func=lambda i: sample_names[i])
if selected_sample > 0:
selected_url = sample_urls[selected_sample]
# Add process button for the sample document with consistent styling
if st.button("Load Sample Document", key="load_sample_btn"):
try:
import requests
from io import BytesIO
with st.spinner(f"Downloading {sample_names[selected_sample]}..."):
response = requests.get(selected_url)
response.raise_for_status()
# Extract filename from URL
file_name = selected_url.split("/")[-1]
# Create a BytesIO object from the downloaded content
file_content = BytesIO(response.content)
# Store as a UploadedFile-like object in session state
class SampleDocument:
def __init__(self, name, content, content_type):
self.name = name
self._content = content
self.type = content_type
self.size = len(content)
def getvalue(self):
return self._content
def read(self):
return self._content
def seek(self, position):
# Implement seek for compatibility with some file operations
return
def tell(self):
# Implement tell for compatibility
return 0
# Determine content type based on file extension
if file_name.lower().endswith('.pdf'):
content_type = 'application/pdf'
elif file_name.lower().endswith(('.jpg', '.jpeg')):
content_type = 'image/jpeg'
elif file_name.lower().endswith('.png'):
content_type = 'image/png'
else:
content_type = 'application/octet-stream'
# Reset any document state before loading a new sample
if st.session_state.processed_document_active:
# Clean up any temporary files from previous processing
if st.session_state.temp_file_paths:
handle_temp_files(st.session_state.temp_file_paths)
# Reset all document-specific state variables
reset_document_state()
# Save download info in session state
st.session_state.sample_document = SampleDocument(
name=file_name,
content=response.content,
content_type=content_type
)
# Store original bytes for reprocessing with proper MIME type handling
st.session_state.original_sample_bytes = response.content
st.session_state.original_sample_name = file_name
st.session_state.original_sample_mime_type = content_type
# Set state flags
st.session_state.sample_just_loaded = True
st.session_state.is_sample_document = True
# Generate a unique identifier for the sample document
st.session_state.last_processed_file = f"{file_name}_{len(response.content)}"
# Set a flag to show redirect message
st.session_state.redirect_to_processing = True
st.rerun()
except Exception as e:
st.error(f"Error downloading sample document: {str(e)}")
st.info("Please try uploading your own document instead.")
else:
# If no sample is selected, clear the sample document in session state
st.session_state.sample_document = None
def process_document(uploaded_file, left_col, right_col, sidebar_options):
"""Process the uploaded document and display results"""
if uploaded_file is None:
return
# Check file size (cap at 50MB)
file_size_mb = len(uploaded_file.getvalue()) / (1024 * 1024)
if file_size_mb > MAX_FILE_SIZE_MB:
with left_col:
st.error(f"File too large ({file_size_mb:.1f} MB). Maximum file size is {MAX_FILE_SIZE_MB}MB.")
return
# Check if this is a new file (different from the last processed file)
current_file_identifier = f"{uploaded_file.name}_{len(uploaded_file.getvalue())}"
# Make sure last_processed_file is initialized
if 'last_processed_file' not in st.session_state:
st.session_state.last_processed_file = None
if st.session_state.last_processed_file != current_file_identifier:
# Reset processed_document_active if a new file is uploaded
st.session_state.processed_document_active = False
# Process button - flush left with similar padding as file browser
with left_col:
# Create a process button with minimal spacing to the uploader
st.markdown('<div style="padding: 0.2rem 0; min-width: 170px; margin-top: -10px; overflow: visible;">', unsafe_allow_html=True)
process_button = st.button("Process Document", key="process_document_btn")
st.markdown('</div>', unsafe_allow_html=True)
# Handle sample document recreation if needed
if process_button and st.session_state.processed_document_active and st.session_state.original_sample_bytes is not None:
# Recreate the uploaded file from stored bytes
from io import BytesIO
import mimetypes
# Determine mime type based on file extension
file_ext = os.path.splitext(st.session_state.original_sample_name)[1].lower()
if file_ext == '.pdf':
mime_type = 'application/pdf'
elif file_ext in ['.jpg', '.jpeg']:
mime_type = 'image/jpeg'
elif file_ext == '.png':
mime_type = 'image/png'
else:
mime_type = mimetypes.guess_type(st.session_state.original_sample_name)[0] or 'application/octet-stream'
# Create a synthetic file-like object with the same interface as UploadedFile
uploaded_file = type('obj', (object,), {
'name': st.session_state.original_sample_name,
'getvalue': lambda: st.session_state.original_sample_bytes,
'read': lambda: st.session_state.original_sample_bytes,
'seek': lambda x: None,
'type': mime_type
})
# Empty container for progress indicators - will be filled during processing
# Positioned right after the process button for better visibility
progress_placeholder = st.empty()
# Image preprocessing preview - show if image file and preprocessing options are set
# Remove the document active check to show preview immediately after selection
if (any(sidebar_options["preprocessing_options"].values()) and
uploaded_file.type.startswith('image/')):
st.markdown("**Preprocessed Preview**")
try:
# Create a container for the preview
with st.container():
processed_bytes = preprocess_image(uploaded_file.getvalue(), sidebar_options["preprocessing_options"])
# Convert image to base64 and display as HTML to avoid fullscreen button
img_data = base64.b64encode(processed_bytes).decode()
img_html = f'<img src="data:image/jpeg;base64,{img_data}" style="width:100%; border-radius:4px;">'
st.markdown(img_html, unsafe_allow_html=True)
# Show preprocessing metadata in a well-formatted caption
meta_items = []
# Only include document type in the list if actual preprocessing is applied
has_active_preprocessing = (
sidebar_options["preprocessing_options"].get("grayscale", False) or
sidebar_options["preprocessing_options"].get("denoise", False) or
sidebar_options["preprocessing_options"].get("contrast", 0) != 0 or
sidebar_options["preprocessing_options"].get("rotation", 0) != 0
)
# Only show document type if there's actual preprocessing being applied
if has_active_preprocessing and sidebar_options["preprocessing_options"].get("document_type", "standard") != "standard":
meta_items.append(f"Document type ({sidebar_options['preprocessing_options']['document_type']})")
if sidebar_options["preprocessing_options"].get("grayscale", False):
meta_items.append("Grayscale")
if sidebar_options["preprocessing_options"].get("denoise", False):
meta_items.append("Denoise")
if sidebar_options["preprocessing_options"].get("contrast", 0) != 0:
meta_items.append(f"Contrast ({sidebar_options['preprocessing_options']['contrast']})")
if sidebar_options["preprocessing_options"].get("rotation", 0) != 0:
meta_items.append(f"Rotation ({sidebar_options['preprocessing_options']['rotation']}Β°)")
# Only show "Applied:" if there are actual preprocessing steps
if meta_items:
meta_text = "Applied: " + ", ".join(meta_items)
st.caption(meta_text)
except Exception as e:
st.error(f"Error in preprocessing: {str(e)}")
st.info("Try using grayscale preprocessing for PNG images with transparency")
# Container for success message (will be filled after processing)
metadata_placeholder = st.empty()
# Check if this is an auto-processing situation
auto_processing = st.session_state.auto_process_sample and not st.session_state.processed_document_active
# Show a message if auto-processing is happening
auto_processing_message = st.empty()
if auto_processing:
auto_processing_message.info("Automatically processing sample document...")
# Determine if we should process the document
# Either process button was clicked OR auto-processing is happening
should_process = process_button or auto_processing
if should_process:
# Reset auto-process flag to avoid processing on next rerun
if st.session_state.auto_process_sample:
st.session_state.auto_process_sample = False
# Move the progress indicator reference to just below the button
progress_reporter = ProgressReporter(progress_placeholder).setup()
try:
# Process the document, capturing both result and temp file paths
# Modified to pass existing temp_file_paths to avoid resource leaks
existing_temp_paths = []
if 'temp_file_paths' in st.session_state:
existing_temp_paths = st.session_state.temp_file_paths
result = process_file(
uploaded_file=uploaded_file,
use_vision=sidebar_options["use_vision"],
preprocessing_options=sidebar_options["preprocessing_options"],
progress_reporter=progress_reporter,
pdf_dpi=sidebar_options.get("pdf_dpi", 150),
max_pages=sidebar_options.get("max_pages", 3),
pdf_rotation=sidebar_options.get("pdf_rotation", 0),
custom_prompt=sidebar_options.get("custom_prompt", ""),
perf_mode=sidebar_options.get("perf_mode", "Quality"),
use_segmentation=sidebar_options.get("use_segmentation", False)
)
# Ensure temp_file_paths in session state is updated with any new paths
# This is critical for proper resource cleanup when document is closed
if 'has_images' in result and result['has_images']:
logger.info("Document has images, ensuring temp files are tracked")
if 'temp_file_paths' not in st.session_state:
st.session_state.temp_file_paths = []
# Handle text-only OCR results (like the Milgram flier)
if ('ocr_contents' in result and
'raw_text' in result['ocr_contents'] and
len(result['ocr_contents']) <= 2 and # Only raw_text and possibly one other field
'has_images' not in result):
logger.info("Text-only OCR detected, handling as special case")
# Ensure raw_text is properly formatted as markdown
raw_text = result['ocr_contents']['raw_text']
# If we don't have other structured content, set a placeholder title
if 'title' not in result['ocr_contents']:
result['ocr_contents']['title'] = "Document Text"
# Display success message at the top of results, before any previews
with left_col:
# First show the success message (full width)
st.success("**Document processed successfully**")
# Then show the close button (also full width, positioned to left)
st.button("Close Document",
key="close_document_btn",
type="secondary",
on_click=close_document)
# Add a small spacer
st.markdown("<div style='height: 10px;'></div>", unsafe_allow_html=True)
# Display results
display_results(result, right_col, sidebar_options.get("custom_prompt", ""))
# Set processed_document_active to True when a new document is processed
st.session_state.processed_document_active = True
# Clear the auto-processing message
auto_processing_message.empty()
# Store information about this processed file to track when new files are uploaded
if uploaded_file is not None:
st.session_state.last_processed_file = current_file_identifier
# Store the result in the previous results list
# Add timestamp to result for history tracking
result_copy = result.copy()
result_copy['timestamp'] = format_timestamp()
# Store if this was a sample document
if 'is_sample_document' in st.session_state and st.session_state.is_sample_document:
result_copy['sample_document'] = True
# Add to session state, keeping the most recent 20 results
st.session_state.previous_results.insert(0, result_copy)
if len(st.session_state.previous_results) > 20:
st.session_state.previous_results = st.session_state.previous_results[:20]
except Exception as e:
st.error(f"Error processing document: {str(e)}")
# Log the error
import logging
logging.error(f"Document processing error: {str(e)}", exc_info=True)
def main():
"""Main application function"""
# Initialize session state
init_session_state()
# Handle any required cleanup at the start of execution
# CRITICAL: This two-phase state cleanup pattern is essential for Streamlit's execution model.
# When close_clicked is True, we need to restart the app's execution with a clean slate.
# DO NOT REMOVE OR MODIFY this pattern as it ensures proper UI cleanup.
if st.session_state.get('close_clicked', False):
# Reset the flag - cleanup has been handled
st.session_state.close_clicked = False
# Don't do anything else in this run - force a clean restart
st.rerun()
# Initialize new flag for redirecting to processing tab
if 'redirect_to_processing' not in st.session_state:
st.session_state.redirect_to_processing = False
# Apply custom CSS
from ui.layout import load_css
load_css()
# Create sidebar options
sidebar_options = create_sidebar_options()
# Create main layout with tabs - simpler, more compact approach
tab_names = ["Document Processing", "Sample Documents", "Learn More"]
main_tab1, main_tab2, main_tab3 = st.tabs(tab_names)
with main_tab1:
# Create a two-column layout for file upload and results with minimal padding
st.markdown('<style>.block-container{padding-top: 1rem; padding-bottom: 0;}</style>', unsafe_allow_html=True)
# Using a 2:3 column ratio gives more space to the results column
left_col, right_col = st.columns([2, 3])
with left_col:
# Create file uploader
uploaded_file = create_file_uploader()
# If a real file is uploaded, clear any sample document
if uploaded_file is not None and 'sample_document' in st.session_state:
st.session_state.sample_document = None
st.session_state.is_sample_document = False
# Check if we have a sample document loaded (only if no real file uploaded)
elif ('sample_document' in st.session_state and
st.session_state.sample_document is not None):
# Use the sample document instead of the uploaded file
uploaded_file = st.session_state.sample_document
# Just reset the sample document loading flags after it's been used
if st.session_state.sample_just_loaded:
st.session_state.sample_just_loaded = False
st.session_state.sample_document_processed = True
st.session_state.auto_process_sample = True
# Only process document if available
if uploaded_file is not None:
process_document(uploaded_file, left_col, right_col, sidebar_options)
with main_tab2:
# Sample Documents tab
# Show redirect message if a sample was just loaded
if st.session_state.get('redirect_to_processing', False):
st.success("**Sample document loaded!** Please switch to the **Document Processing** tab to view and process it.")
# Clear the flag after showing the message
st.session_state.redirect_to_processing = False
show_example_documents()
# Previous results tab temporarily removed
with main_tab3:
# About tab
display_about_tab()
# Run the application
if __name__ == "__main__":
main()