Preview

Quickly check visual output without full render. preview uses effectcraft-cli render-frame for one PNG per row.

Basic usage

lakreet-swarm preview --template template.ectemplate --data data.csv

Output:

out/preview/1-Budi.png
out/preview/2-Sari.png
out/preview/3-Andi.png
Gallery: out/preview/index.html

Open index.html in browser for a gallery with captions.

Options

Flag	Description	Default
--time	Frame time in seconds	0 (first frame)
--row	Single row (1-based)	All rows
--all	All rows (explicit)	All rows

Examples

Specific time (e.g., 2.5s into video):

lakreet-swarm preview --template t.ectemplate --data d.csv --time 2.5

Single row (row 3):

lakreet-swarm preview --template t.ectemplate --data d.csv --row 3

Custom output folder:

lakreet-swarm preview --template t.ectemplate --data d.csv --out ./my-preview

Gallery

When multiple rows, an index.html is generated:

• Responsive grid (auto columns)
• Lazy-loaded images
• Caption: row number + base name
• Dark theme for video thumbnails

How it works

1. Validates data (same as check)
2. For each row: writes .values.json to .lakreet/values/
3. Calls effectcraft-cli render-frame --template ... --values ... --time ... --out frame.png
4. Generates index.html gallery

Performance

• Much faster than full render (single frame vs entire video)
• Typical: 1–3 seconds per row
• No video encoding overhead

Use cases

• Verify text positioning, font size, colors
• Check media replacement (when available)
• Quick visual QA before batch render
• Share gallery with stakeholders

Next steps

• Your first batch — includes preview step
• Choose output — formats, quality, naming
• Preview reference — all options