Preview Panel Layout

Preview Panel Layout is the cheapest feedback loop in this pack. It takes an abstract layout and draws it so you can actually see what you're working with - before you've chosen a canvas, margins, or generated a single panel. For the random/mutate workflow this is the node you stare at while hunting for a good page structure.

It's a close cousin of Save Panel Layout - it literally reuses the same rendering code - but aimed at eyeballing rather than archiving. Where Save writes a permanent PNG to your output folder with the layout embedded as metadata, Preview just renders to ComfyUI's temp/preview area. Same picture: panels filled with numbered stamps (the panel order that the cut sequence implies, which the pack treats as the reading order), and the compact cut-tree code printed along the bottom so you can read the structure at a glance.

The inputs are deliberately minimal:

• layout - the PANEL_LAYOUT you want to inspect.
• draw_as - the left-to-right / right-to-left switch, defaulting to LTR. It only affects how the preview is drawn; the underlying data is untouched, which the author's tooltip spells out so you don't go hunting for a data flip that isn't there.

There are no outputs, and the node is marked as an output node (terminal). That's fine - this node's job is to be the last thing on the canvas for a branch you're still exploring.

Two things worth knowing about what you're seeing. First, the preview is drawn without margins and without any panel adjustments - it's the raw cut tree resolved onto a page. If the layout feels cramped or airy here, that's a property of the structure itself, and it'll carry into the real build. Second, because the render goes through matplotlib (the pack's rendering workhorse), preview images are drawn to fit; they're not pixel-accurate to any canvas you have in mind. It's a shape check, not a size check.

Where it slots into the workflow: Random/Grid generator → Preview Panel Layout → like it? → Build Layout Panels with your real canvas and margin. Don't like it? Step the seed. The pattern you'll settle into is a small branch with the preview as the sink, so you can evaluate pages without committing to panel generation each time.

Installing

Part of comfyui-panels by bmad4ever. Via ComfyUI Manager (search "comfyui-panels") and restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/bmad4ever/comfyui_panels

Deps are shapely, matplotlib, opencv-python - no models, no GPU. Watch the pinned shapely version if another pack fights you at import time.