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Mosaic Node ​

Purpose & Use Cases ​

The mosaic node provides manual positioning of multiple images on a canvas with precise coordinate control. It creates composite images by placing images at specific positions, supporting both normalized (0-1) and pixel coordinates for flexible layout creation.

Real-World Applications:

  • Custom Layouts: Create precise image arrangements with exact positioning
  • Template-Based Designs: Position images according to predefined layout templates
  • Overlay Compositions: Layer images at specific positions for complex compositions
  • Dashboard Assembly: Position charts and data visualizations with pixel precision
  • Print Design: Create exact layouts for brochures, posters, and marketing materials

Mosaic Demo

Input/Output Specification ​

Inputs ​

  • Image Array: Array of image objects to position on canvas
  • Position Configuration: Position mappings defined in node configuration
  • Canvas Parameters: Canvas dimensions and background settings

Outputs ​

  • Composite Image: Single image with positioned elements on canvas
  • Fixed Canvas Size: Canvas dimensions as configured
  • Format Options: Raw image object or encoded file formats

Configuration Options ​

Input/Output Paths ​

  • Input From: msg.payload (default), flow.*, global.*
  • Output To: msg.payload (default), flow.*, global.*

Canvas Configuration ​

Canvas Dimensions ​

  • Canvas Width: Width of output canvas in pixels
  • Canvas Height: Height of output canvas in pixels
  • Sources: Number, msg.*, flow.*, global.*

Background Settings ​

  • Background Color: Color for empty canvas areas
  • Default: Black
  • Formats: RGB (rgb(255,0,0))

Positioning System ​

Coordinate System ​

  • Normalized Mode: Values from 0.0 to 1.0 (relative to canvas dimensions)
  • Pixel Mode: Absolute pixel coordinates

Position Configuration ​

  • Position Mappings: Array of position configurations in node editor
  • Array Index: Which image from input array to position
  • X/Y Coordinates: Position on canvas (normalized or pixel)
  • Per-Image Control: Individual positioning for each image

Output Format Options ​

  • Raw: Standard image object (fastest for processing chains)
  • JPEG: Compressed with quality control
  • PNG: Lossless with transparency support
  • WebP: Modern format with excellent compression

Performance Notes ​

C++ Backend Processing ​

  • Optimized Canvas Composition: Efficient positioning and placement on fixed canvas
  • Memory Management: Pre-allocated canvas with optimal memory usage
  • Batch Placement: All images positioned in single C++ operation
  • Coordinate Validation: Automatic bounds checking and position validation

Position Processing ​

  • Coordinate Transformation: Efficient conversion between normalized and pixel coordinates
  • Bounds Checking: Automatic validation of positions within canvas boundaries
  • Layer Management: Proper handling of image placement order and overlaps

Real-World Examples ​

Custom Dashboard Layout ​

javascript
// In function node: set specific positions for dashboard elements

  { arrayIndex: 0, x: 0, y: 0 }      // Chart at top-left
  { arrayIndex: 1, x: 400, y: 0 }    // KPI at top-right
  { arrayIndex: 2, x: 0, y: 300 }   // Graph at bottom-left  
  { arrayIndex: 3, x: 400, y: 300 }   // Table at bottom-right
[Dashboard Elements] → [Function: Set Positions] → [Mosaic: 800x600 canvas] → [Dashboard]

Template-Based Layout ​

javascript
// Predefined layout template positions

  { arrayIndex: 0, x: 0.1, y: 0.1 }   // Normalized coordinates
  { arrayIndex: 1, x: 0.6, y: 0.1 }    // 10% and 60% from left
  { arrayIndex: 2, x: 0.1, y: 0.6 }     // 10% and 60% from top
[Content Images] → [Function: Apply Template] → [Mosaic: Normalized coords] → [Layout]

Overlay Composition ​

[Base Image] → [Array-In: pos=0] ┐
[Logo Overlay] → [Array-In: pos=1] ├→ [Function: Set Positions] → [Mosaic: Canvas] → [Branded Image]
[Text Overlay] → [Array-In: pos=2] ┘

Position logos and text overlays at specific coordinates.

javascript
// Precise positioning for print layout
canvasWidth = 1200;  // Print width
canvasHeight = 1800; // Print height
  { arrayIndex: 0, x: 100, y: 100 }   // Header image
  { arrayIndex: 1, x: 100, y: 400 }   // Content image
  { arrayIndex: 2, x: 100, y: 1200 }  // Footer image

Common Issues & Troubleshooting ​

Position Configuration Errors ​

  • Issue: Images not appearing or positioned incorrectly
  • Solution: Verify arrayIndex values match input array length
  • Validation: Check that positions array contains valid coordinates

Coordinate System Confusion ​

  • Issue: Images appearing in wrong locations
  • Solution: Verify normalized vs. pixel coordinate mode matches your values
  • Normalized: Use 0-1 values for relative positioning
  • Pixel: Use absolute coordinates within canvas bounds

Canvas Size Problems ​

  • Issue: Images clipped or positioned outside visible area
  • Solution: Ensure canvas dimensions accommodate all positioned images
  • Planning: Calculate required canvas size based on image positions and sizes

Position Array Mismatches ​

  • Issue: ArrayIndex references non-existent images
  • Result: Images ignored with warnings logged
  • Solution: Validate arrayIndex values against input array length