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https://github.com/dgtlmoon/changedetection.io.git
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dgtlmoon
99 lines
3.8 KiB
Python
99 lines
3.8 KiB
Python
# Pages with a vertical height longer than this will use the 'stitch together' method.
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# - Many GPUs have a max texture size of 16384x16384px (or lower on older devices).
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# - If a page is taller than ~8000–10000px, it risks exceeding GPU memory limits.
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# - This is especially important on headless Chromium, where Playwright may fail to allocate a massive full-page buffer.
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from loguru import logger
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from changedetectionio.content_fetchers import SCREENSHOT_MAX_HEIGHT_DEFAULT, SCREENSHOT_DEFAULT_QUALITY
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def stitch_images_worker_raw_bytes(pipe_conn, original_page_height, capture_height):
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"""
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Stitch image chunks together in a separate process.
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Uses spawn multiprocessing to isolate PIL's C-level memory allocation.
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When the subprocess exits, the OS reclaims ALL memory including C-level allocations
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that Python's GC cannot release. This prevents the ~50MB per stitch from accumulating
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in the main process.
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Trade-off: Adds 35MB resource_tracker subprocess, but prevents 500MB+ memory leak
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in main process (much better at scale: 35GB vs 500GB for 1000 instances).
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Args:
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pipe_conn: Pipe connection to receive data and send result
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original_page_height: Original page height in pixels
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capture_height: Maximum capture height
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"""
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import os
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import io
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import struct
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from PIL import Image, ImageDraw, ImageFont
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try:
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# Receive chunk count as 4-byte integer (no pickle!)
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count_bytes = pipe_conn.recv_bytes()
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chunk_count = struct.unpack('I', count_bytes)[0]
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# Receive each chunk as raw bytes (no pickle!)
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chunks_bytes = []
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for _ in range(chunk_count):
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chunks_bytes.append(pipe_conn.recv_bytes())
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# Load images from byte chunks
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images = [Image.open(io.BytesIO(b)) for b in chunks_bytes]
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del chunks_bytes
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total_height = sum(im.height for im in images)
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max_width = max(im.width for im in images)
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# Create stitched image
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stitched = Image.new('RGB', (max_width, total_height))
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y_offset = 0
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for im in images:
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stitched.paste(im, (0, y_offset))
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y_offset += im.height
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im.close()
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del images
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# Clip stitched image to capture_height (chunks may overshoot by up to step_size-1 px)
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if total_height > capture_height:
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stitched = stitched.crop((0, 0, max_width, capture_height))
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# Draw caption only if page was trimmed
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if original_page_height > capture_height:
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draw = ImageDraw.Draw(stitched)
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caption_text = f"WARNING: Screenshot was {original_page_height}px but trimmed to {capture_height}px because it was too long"
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padding = 10
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try:
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font = ImageFont.truetype("arial.ttf", 35)
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except IOError:
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font = ImageFont.load_default()
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bbox = draw.textbbox((0, 0), caption_text, font=font)
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text_width = bbox[2] - bbox[0]
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text_height = bbox[3] - bbox[1]
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draw.rectangle([(0, 0), (max_width, text_height + 2 * padding)], fill=(255, 255, 255))
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text_x = (max_width - text_width) // 2
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draw.text((text_x, padding), caption_text, font=font, fill=(255, 0, 0))
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# Encode and send
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output = io.BytesIO()
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stitched.save(output, format="JPEG", quality=int(os.getenv("SCREENSHOT_QUALITY", SCREENSHOT_DEFAULT_QUALITY)), optimize=True)
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result_bytes = output.getvalue()
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stitched.close()
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del stitched
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output.close()
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del output
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pipe_conn.send_bytes(result_bytes)
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del result_bytes
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except Exception as e:
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logger.error(f"Error in stitch_images_worker_raw_bytes: {e}")
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error_msg = f"error:{e}".encode('utf-8')
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pipe_conn.send_bytes(error_msg)
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finally:
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pipe_conn.close()
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