Build a Drawing Proportion Checker App (2026)

If you’re trying to figure out whether your sketch’s proportions actually match your reference, the fastest fix isn’t hunting for an app that aligns your drawing with a reference image — it’s building the exact tool you need yourself.

Why building your own beats searching for one

Search for a “proportion checker app for drawing” and you’ll mostly find generic photo overlay apps, opacity sliders buried in art software, or clunky blend-mode tricks in editing tools that weren’t made for this. None of them are built specifically to check if your drawing is proportionate against your own reference photos, with your own images, organized your own way.

Auto works differently. You describe what you want, snap or upload a photo, and Auto builds a personal mini-app — a Frame — around that exact need. No app store, no subscription for a tool you’ll use twice a week, no interface cluttered with features you don’t need. Just the thing you asked for, built around how you actually work.

Building a drawing proportions app in Auto

Here’s the walkthrough:

Open Auto and describe the tool. Something like: “I want to compare my sketches against their photo reference to check proportions.” Be specific about your workflow — Auto uses that to shape the Frame.
Ask for what you actually need to do. If you want a place to store every reference and sketch you upload, say so. If you want to align two images to check drawing accuracy by overlaying them on a canvas, ask for that too.
Refine the controls. Want to pick which image is “active” and nudge it with two-finger scroll or pinch-to-zoom to line it up? Tell Auto. It’ll wire up the gestures.
Let it build. Auto writes the actual app in the background. Sometimes it hits a snag and fixes its own code; you just wait a minute and get a working Frame.
Use it immediately. No install step — it’s already yours.

How someone built theirs

One Auto user wanted exactly this: a way to compare sketches against reference photos to judge proportions. They asked Auto to create a Frame with a storage area for every image they uploaded, plus the ability to select one reference and one sketch and overlay them in a canvas view. They specified that they wanted to pick which image was “active” and move or scale it using two-finger scroll and pinch gestures — basically turning their phone into a lightbox with alignment controls.

Partway through, the build hit some TypeScript errors — touch event types not matching up, a component prop mismatch, an undefined variable. Auto caught the failed build, read the error output, and patched the code itself. The user didn’t need to know what a TypeScript error was; they just kept going.

The result, which is now live as a real example called “Sketch Compare,” shows what’s possible: a purpose-built drawing proportions app made from a plain-language description and a few follow-up requests.

FAQ

Do I need to know how to code to build this? No. You describe what you want in plain language, and Auto builds the working app.

Can I check if my drawing is proportionate without drawing software? Yes — the Frame just needs your sketch and reference photos. It overlays them so you can see mismatches directly, no external software required.

What if I want different features than the example? That’s the point of building your own. Ask for grid overlays, opacity control, multiple reference slots, or anything else — it’s shaped around your process, not someone else’s.

Is this a one-time build or can I keep changing it? You can keep refining it any time your workflow changes — just describe the adjustment.