GratisAIaccessibility · field guide · local-first · no account
viewport mosaic

Estimate Pan Positions on a Magnified Canvas — Free

A fixed canvas can require many viewport positions when magnified. Estimate non-overlapping coverage to expose navigation burden, not to claim a reader will follow a perfect scan path.

The proof surface

Contrast tools check colors and reflow tools adjust text. This examines two-dimensional canvas coverage when a reader must pan instead of reflowing content.

Inputcanvas | content width pixels | content height pixels; square viewport width and height in content pixels
Rare deviceContrast tools check colors and reflow tools adjust text. This examines two-dimensional canvas coverage when a reader must pan instead of reflowing content.
Output artifactviewport positions per row with transparent workings
Cost$0 · local-first · one free run · samples labelled
Sample, not your facts: Illustrative sample: Station map | 1200 | 900; Seating chart | 700 | 500. With square viewport width and height in content pixels set to 400, total is 13.00 viewport positions.

Why the flat version breaks

Dividing area by area

Partial edge tiles can require additional positions.

Using screen pixels at high zoom

The relevant unit is visible content pixels.

Calling coverage usability

Reaching every tile does not establish understanding.

How to work the viewport mosaic

Measure content coordinates

Use the canvas dimensions, not the physical monitor resolution. If magnification changes the visible content area, measure that smaller area in the same coordinate system.

Model a square viewport

Enter the usable square width after controls and browser chrome. For a non-square viewport this instrument is intentionally conservative only if you use its shorter dimension.

Round each direction separately

The 1200 by 900 map needs three columns and three rows at 400 pixels. Multiply rounded column and row counts; dividing total area alone misses partial edge tiles.

Test navigation and orientation

Try the real content with magnification. Record lost context, overlap needed for orientation and controls obscuring content; all can make actual movement exceed this ideal tiling.

What the viewport mosaic replaces

QuestionBeforeVisible working
Dividing area by areaPartial edge tiles can require additional positions.Model a square viewport
Using screen pixels at high zoomThe relevant unit is visible content pixels.Round each direction separately
Calling coverage usabilityReaching every tile does not establish understanding.Test navigation and orientation

A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.

Run it on the samples, right here

FIRST-LOAD

Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.

Ideal geometric coverage, not a usability score or an accessibility standard. It excludes overlap, orientation aids and actual movement paths.

Data note: Everything runs in this browser tab on the viewport mosaic: your canvas | content width pixels | content height pixels stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.

Go deeper: the companion app files the same reading as a scored comparison matrix

The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the viewport mosaic reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.

The viewport mosaic reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.

Open the estimate pan positions on a magnified canvas companion

Boundary

Ideal geometric coverage, not a usability score or an accessibility standard. It excludes overlap, orientation aids and actual movement paths.

What this is built on

Before: Partial edge tiles can require additional positions. After: the viewport mosaic shows the working beside each named row so the reader can change the assumption and inspect the consequence.

Optional AI formatting, not calculation

For this viewport mosaic, use the free AI Studio interface only if available to you, with no paid API key. Manual entry completes the same workflow for free. Supply only fictional or non-sensitive notes. Review its output against the source; never paste unresolved questions into the numeric rows.

Format my non-sensitive notes for a viewport mosaic. Return plain rows only: canvas | content width pixels | content height pixels. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.

Accepted schema: canvas | content width pixels | content height pixels. No AI response is executed as code.