Sketch to app: 日沼諭史 shows Gemini Canvas build a timer

Hinuma's piece sits at the start of an AI beginner series, and its premise is that text prompting is the hard part for many newcomers. Rather than asking them to get better at describing an app, he inverts the workflow: draw the screen layout first, then let Gemini's Canvas read it.

The trial itself was deliberately minimal — a timer app drawn as four buttons and a time display, in bare black-and-white outlines. Hinuma still added prompt text explaining what each part does, and Gemini filled the gaps: start and stop got distinct colors, a tap sound effect appeared, and arbitrary time setting worked. The drawn layout survived intact.

From there, the output is not trapped in Gemini. Downloading the code or converting it to a Google Sites web app puts it on the same account's Google Drive, reachable from a phone and publishable to other users — which is what makes the sketch-first route usable beyond a one-off demo.