mirror of
https://github.com/dgtlmoon/changedetection.io.git
synced 2026-05-03 16:21:06 +00:00
dgtlmoon
111 lines
3.6 KiB
Python
111 lines
3.6 KiB
Python
"""
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Preview rendering for SSIM screenshot processor.
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Renders images properly in the browser instead of showing raw bytes.
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"""
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from flask_babel import gettext
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from loguru import logger
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def get_asset(asset_name, watch, datastore, request):
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"""
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Get processor-specific binary assets for preview streaming.
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This function supports serving images as separate HTTP responses instead
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of embedding them as base64 in the HTML template, solving memory issues
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with large screenshots.
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Supported assets:
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- 'screenshot': The screenshot for the specified version
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Args:
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asset_name: Name of the asset to retrieve ('screenshot')
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watch: Watch object
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datastore: Datastore object
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request: Flask request (for version query param)
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Returns:
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tuple: (binary_data, content_type, cache_control_header) or None if not found
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"""
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if asset_name != 'screenshot':
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return None
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versions = list(watch.history.keys())
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if len(versions) == 0:
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return None
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# Get the version from query string (default: latest)
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preferred_version = request.args.get('version')
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timestamp = versions[-1]
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if preferred_version and preferred_version in versions:
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timestamp = preferred_version
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try:
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screenshot_bytes = watch.get_history_snapshot(timestamp=timestamp)
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# Verify we got bytes (should always be bytes for image files)
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if not isinstance(screenshot_bytes, bytes):
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logger.error(f"Expected bytes but got {type(screenshot_bytes)} for screenshot at {timestamp}")
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return None
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# Detect image format using puremagic (same as Watch.py)
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try:
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import puremagic
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detections = puremagic.magic_string(screenshot_bytes[:2048])
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if detections:
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mime_type = detections[0].mime_type
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logger.trace(f"Detected MIME type: {mime_type}")
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else:
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mime_type = 'image/png' # Default fallback
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except Exception as e:
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logger.warning(f"puremagic detection failed: {e}, using 'image/png' fallback")
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mime_type = 'image/png'
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return (screenshot_bytes, mime_type, 'public, max-age=10')
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except Exception as e:
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logger.error(f"Failed to load screenshot for preview asset: {e}")
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return None
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def render(watch, datastore, request, url_for, render_template, flash, redirect):
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"""
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Render the preview page for screenshot watches.
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Args:
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watch: Watch object
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datastore: Datastore object
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request: Flask request
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url_for: Flask url_for function
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render_template: Flask render_template function
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flash: Flask flash function
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redirect: Flask redirect function
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Returns:
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Rendered template or redirect
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"""
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versions = list(watch.history.keys())
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if len(versions) == 0:
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flash(gettext("Preview unavailable - No snapshots captured yet"), "error")
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return redirect(url_for('watchlist.index'))
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# Get the version to display (default: latest)
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preferred_version = request.args.get('version')
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timestamp = versions[-1]
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if preferred_version and preferred_version in versions:
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timestamp = preferred_version
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# Render custom template for image preview
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# Screenshot is now served via separate /processor-asset/ endpoint instead of base64
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# This significantly reduces memory usage by not embedding large images in HTML
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return render_template(
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'image_ssim_diff/preview.html',
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watch=watch,
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uuid=watch.get('uuid'),
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versions=versions,
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timestamp=timestamp,
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current_diff_url=watch['url']
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)
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