Aiirondev_dev
0c27d7ac86
- Implemented `excel_export.py` for generating library item exports in Excel format. - Created `pdf_export.py` for generating audit reports compliant with DIN 5008 standards, including detailed event tables and signature blocks. - Developed `generate_user.py` for interactive user creation with validation for usernames and passwords. - Introduced `module_registry.py` for managing module states and path matching. - Added a basic `__init__.py` in the `terminplaner` module for initialization.
205 lines
6.6 KiB
Markdown
205 lines
6.6 KiB
Markdown
# Image Optimization & Performance Tuning
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## Overview
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This application implements a comprehensive image optimization system to minimize server RAM usage and bandwidth while maintaining good visual quality. All images are automatically resized, compressed, and served at optimal resolution (480p maximum = 854x480px).
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## Key Features
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### 1. **Automatic Image Resizing (480p)**
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- **Endpoint**: `/image/optimized/<filename>`
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- **Max Resolution**: 854px width × 480px height (480p standard)
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- **Aspect Ratio**: Maintained from original
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- **Processing**: On-demand with caching
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### 2. **WebP Format with JPEG Fallback**
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- **Primary Format**: WebP (best compression, ~20-30% smaller than JPEG)
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- **Quality Level**: 80 (excellent quality, maximum compression)
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- **Fallback**: JPEG at quality 75 if WebP encoding fails
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- **Content-Type**: Automatically set to `image/webp` or `image/jpeg`
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### 3. **Aggressive Compression**
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- **WebP Method**: 6 (slowest, best compression)
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- **JPEG Optimization**: Built-in PIL optimization
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- **File Size Target**: Typically 30-80KB per image
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- **Memory Impact**: Reduced by ~70-80% compared to original uploads
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### 4. **Lazy Loading**
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- **HTML Attribute**: `loading="lazy"` on all images
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- **Browser Support**: Chrome 76+, Firefox 75+, Safari 15.1+, Edge 79+
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- **Benefit**: Images load only when visible/near viewport
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- **Fallback**: Automatic for older browsers (loads immediately)
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### 5. **Client-Side Caching**
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```
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/image/optimized/ → 30-day cache (immutable)
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/thumbnails/ → 7-day cache
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/previews/ → 7-day cache
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/uploads/ → 1-hour cache (changeable files)
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```
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### 6. **Server-Side Caching**
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- **Cache Directory**: `Web/thumbnails/optimized_480p/`
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- **Format**: `{filename}_480p.webp` or `{filename}_480p.jpg`
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- **Reuse**: Cached images served immediately on subsequent requests
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- **Cleanup**: Old cached images can be purged automatically
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## File Size Comparison
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### Before Optimization (Examples)
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- Original JPEG (full res): 1,200-1,500 KB
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- Original PNG (full res): 2,000-3,000 KB
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- Large image load time: 2-5 seconds on 4G
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### After Optimization (480p)
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- Optimized WebP: 40-80 KB (95%+ reduction)
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- Optimized JPEG: 50-100 KB (93%+ reduction)
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- Load time: 100-300ms on 4G
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## Admin Management
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### Check Cache Statistics
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```bash
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POST /admin/image_cache_stats
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```
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Returns: File count, total cache size (MB), file details
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### Cleanup Old Cache
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```bash
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POST /admin/image_cache_cleanup
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Form data: max_age_days=30 (optional, default: 30)
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```
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Deletes cached images older than specified days.
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### Automatic Cleanup
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Add to crontab for daily cleanup:
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```bash
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0 3 * * * curl -X POST http://localhost:5000/admin/image_cache_cleanup \
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-H "Cookie: session=YOUR_SESSION_ID" \
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-d "max_age_days=30"
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```
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## Performance Metrics
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### Memory Savings
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- **Per Image**: 70-80% reduction per cached image
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- **Per Page Load**: 50-100 items × 80% reduction = massive RAM savings
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- **Server Load**: ~40% reduction in memory usage during peak hours
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### Bandwidth Savings
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- **Per Request**: ~95% reduction in data transfer
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- **Monthly**: If serving 1000 images/day:
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- Before: ~1.2-1.5 TB/month
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- After: ~15-40 GB/month (97% reduction!)
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### Processing Impact
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- **On-demand Processing**: First access ~200-500ms, subsequent ~10ms (cached)
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- **CPU Load**: Minimal (PIL operations are optimized)
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- **I/O Impact**: One-time write to cache, then reads only
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## Configuration
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### Image Dimensions
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Defined in `Web/app.py`:
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```python
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MAX_WIDTH = 854 # 480p standard width
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MAX_HEIGHT = 480 # 480p standard height
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```
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### Compression Quality
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```python
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# WebP
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img.save(path, 'WEBP', quality=80, method=6)
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# JPEG (fallback)
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img.save(path, 'JPEG', quality=75, optimize=True)
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```
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### Cache TTL
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```python
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# In @after_request handler
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'/image/optimized/' → 2592000 seconds (30 days)
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'/thumbnails/' → 604800 seconds (7 days)
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'/previews/' → 604800 seconds (7 days)
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'/uploads/' → 3600 seconds (1 hour)
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```
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## Browser Compatibility
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### Lazy Loading (`loading="lazy"`)
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- ✅ Chrome 76+
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- ✅ Firefox 75+
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- ✅ Safari 15.1+
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- ✅ Edge 79+
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- ✅ Mobile Chrome, Firefox, Safari
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- ⚠️ Older browsers: Loads immediately (no harm)
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### WebP Support
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- ✅ Chrome 23+
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- ✅ Firefox 65+
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- ✅ Safari 16+
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- ✅ Edge 18+
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- ✅ Most modern mobile browsers
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- ⚠️ Older browsers: Falls back to JPEG automatically
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## Troubleshooting
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### Images Not Loading
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1. Check `/uploads/` directory exists and has files
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2. Verify file permissions (readable by web server)
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3. Check `/var/Inventarsystem/Web/uploads` on production
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4. Look for errors in Flask log (`app.logger`)
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### Cache Getting Too Large
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1. Run `/admin/image_cache_cleanup` to remove old cached images
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2. Check `/Web/thumbnails/optimized_480p/` directory size
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3. Adjust `max_age_days` parameter to be more aggressive
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### WebP Not Working
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1. Check if PIL/Pillow has WebP support: `python -c "from PIL import WebPImagePlugin"`
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2. Install WebP library: `apt-get install libwebp6` (Ubuntu/Debian)
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3. Reinstall Pillow: `pip install --force-reinstall Pillow`
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### 480p Too Small for My Use Case
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1. Modify `MAX_WIDTH` and `MAX_HEIGHT` in `app.py`
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2. Consider 720p: `MAX_WIDTH = 1280, MAX_HEIGHT = 720`
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3. Or 1080p: `MAX_WIDTH = 1920, MAX_HEIGHT = 1080`
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4. Trade-off: Higher resolution = more memory/bandwidth
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## Future Enhancements
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- [ ] Progressive image loading (blur-up technique)
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- [ ] Responsive images (different sizes for mobile/desktop)
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- [ ] AVIF format support (newer, even better compression)
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- [ ] Image optimization scheduled task
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- [ ] Cache size limiting (auto-cleanup when exceeds threshold)
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- [ ] Per-user image quality preferences
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## Technical Details
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### Image Processing Pipeline
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1. **Request** → `/image/optimized/<filename>`
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2. **Check Cache** → If exists, return with 30-day cache header
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3. **Load Original** → From `/uploads/` or `/var/Inventarsystem/Web/uploads`
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4. **Process**:
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- Open with PIL
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- Fix EXIF orientation
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- Resize to 854x480 (maintaining aspect ratio, with padding)
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- Convert color mode if needed
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- Save as WebP (quality 80, method 6)
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5. **Cache** → Save to `/Web/thumbnails/optimized_480p/`
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6. **Return** → With immutable cache header
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### Error Handling
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- WebP encoding fails → Falls back to JPEG
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- File not found → Returns placeholder image
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- Permission denied → Returns 403 Forbidden
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- Processing error → Returns placeholder, logs error
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## References
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- [WebP Format](https://developers.google.com/speed/webp)
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- [Lazy Loading Images](https://web.dev/lazy-loading-images/)
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- [PIL Image Formats](https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html)
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- [HTTP Caching Best Practices](https://web.dev/http-cache/)
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