Large Power Automate flows can extend beyond the viewport, making documentation and review difficult when screenshots must be captured and combined manually.
PA Flow Capture is a Firefox extension that captures a defined flow canvas and exports a stitched PNG.
The extension detects the flow designer canvas, then lets you place two anchors with Ctrl + click to define the exact capture bounds. From there it moves the viewport tile-by-tile, pauses for settle timing, and captures each frame.
Raw captures almost always produce visible join lines because of anti-aliasing and tiny movement differences between frames. The background stitcher runs on OffscreenCanvas and uses horizontal seam matching (grayscale SAD) to line up edges and reduce visible artifacts.
// rough flow
for (const tile of tiles) {
await scrollTo(tile);
await settle();
const shot = await captureVisibleTab();
frames.push(cropToViewport(shot));
}
const finalImage = stitchWithSeamMatching(frames);
This is a Manifest V3 extension with a popup UI, content script for in-page capture orchestration, and background worker for image processing. No build system needed, so iteration is fast when tuning capture timing.
The focus is predictable capture boundaries and readable output for large flows; capture time will vary with the page and chosen settings.
Source code is available on GitHub with local run instructions through about:debugging in Firefox.