[Book Tools] Calculate Text Growth

BTTextGrowth answers one question: "if this text is laid out at the minimum font size, how much would it need to grow to fill the region it's meant to occupy?" The answer comes back as a percentage - 0 to 100 - and there's no image output at all. It's a measurement node, and measurements are what you feed into logic when you want a workflow to make decisions instead of you.

How it works

You give it text, the mask_width and mask_height of the region the text should fill, a min_font_size to measure at, and the usual font, padding, line_height_factor. It lays the text out at that minimum size (word-wrapping it within the effective width), measures the resulting width and height, and computes how far short it is:

• width_ratio = (text_width / mask_width) / 2
• height_ratio = (text_height / mask_height) / 2
• take the larger of the two as the growth ratio
• if that ratio is below 0.5 → return 0
• otherwise return min(100, int((growth_ratio - 0.5) * 200))

In plain terms: if the text already fits at minimum size, you get 0; the more the text overflows the region, the higher the percentage climbs, capped at 100.

The one output is growth_percentage, an INT. It's a pure calculation - no image passes through - so you'll wire it into logic nodes, not into a Save Image.

Why a beginner would use it

The obvious home is the loop family. A page renderer that's supposed to end a book when the text no longer fits can do this: measure the growth percentage with BTTextGrowth, compare it against a threshold with a comparison node, and feed the result into BTEndQueue (same pack) to stop the batch. No one sits watching the queue; the workflow stops itself when the text stops fitting.

It's also useful for scaling: multiply the percentage into a scale/zoom value so a title grows to fill its panel across a series of pages. Think of it as a font-fit estimator you can react to, rather than the auto-fit the overlay nodes do internally.

The usual caveats

The font input defaults to the Linux path /usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf, which doesn't exist on Windows - the calculation quietly uses PIL's default font and your growth numbers will be off. Point it at a real font (BTDownloadFont is the pack's built-in helper) so the estimate matches what the overlay nodes will actually draw. And remember mask_width / mask_height are the dimensions of the region the text should fill, not the image size - padding is on top of that.

Installing

cd ComfyUI/custom_nodes
git clone https://github.com/Big-Idea-Technology/ComfyUI-Book-Tools
# restart ComfyUI

Or via ComfyUI Manager: search "ComfyUI-Book-Tools". The pack installs with no models and no extra pip dependencies beyond what ComfyUI already ships.