Google’s documented way to turn a paper sketch into a testable Gemini Canvas prototype is to upload a photo, select Canvas, ask Gemini to write the code, then try and refine the result in Preview. It’s a practical route from an app idea on paper to an interactive first pass. Google’s instructions describe the process for app mock-ups, habit trackers and game boards.

From sketch photo to Canvas preview

A Gemini interface shows a hand-drawn app sketch, the prompt “Can you code this app?” and the Canvas control.

Start with a photo of your drawing. Google’s November 5, 2026 instructions lay out the steps in this order:

  1. Photograph your sketch. Use a drawing of the app idea you want to explore. Google gives app mock-ups, habit trackers and game boards as examples.
  2. Upload the photo to Gemini. This gives Gemini the drawing as the starting point for the prototype.
  3. Select Canvas. Choose Canvas in Gemini for the coding task.
  4. Ask Gemini to code the app. Google’s example prompt is “Can you code this app?” You can describe the result you want in your own words, too.
  5. Try the result in Preview. Inspect the generated interface and test its visible controls.
  6. Request a refinement. Ask for a specific change to a color, font or feature, then check the updated preview.
Treat each Preview pass as a test: try an interaction, request one change, then check that interaction again.

Test the preview, then refine it

Watch Google Workspace’s English-language demonstration of the sign-up prototype, sample input and interface refinements.

Google Workspace’s demonstration, published October 27, 2025, shows a hand-drawn event sign-up form turned into a prototype. The presenter enters sample information with generated code beside the preview, then asks Gemini to make the submit button green and add a dietary-restriction dropdown.

Use your sketch as a checklist while trying the prototype: check that the controls you drew are present, enter sample information where the interface asks for it, and try the actions you requested. After a change, revisit the controls it could affect. The preview is the place in Google’s documented workflow to inspect and refine the generated prototype.

Workspace restrictions in Google’s May 2025 notice

In its May 20, 2025 notice, Google said the Canvas features described there were limited to users over 18. It also said apps containing Workspace data could not be previewed. Workspace users opening a link shared by a personal-account user could open it, but could not take further actions such as asking Gemini to refine the content. Google Workspace Updates’ notice described those terms for that rollout.