capture
plot.capture
Render an HTML page to a static file with a headless browser, from a figure spec.
A panel that shows a live web view — a knowledge-graph browser, a JavaScript force layout, the platform’s own UI — has no matplotlib equivalent, and a screenshot someone took once drifts silently from the page it claims to show. An image panel carrying a capture: recipe re-renders its source on every build instead, so the committed raster is a build product like any other and the page is what is under version control.
Resolution is a device pixel ratio rather than a dpi: the page is laid out in CSS pixels and rasterised at device_scale_factor times that, so text and vector art in the page come out at the scale factor’s full resolution. The default puts a panel-width capture above what a journal asks of a raster figure.
Attributes
| Name | Description |
|---|---|
| DEFAULT_SCALE | Device pixel ratio when the recipe names none, so a default capture is already above print resolution. |
| DEFAULT_WIDTH | Viewport width in CSS pixels when the recipe names none. |
Functions
| Name | Description |
|---|---|
| capture | Render source to path with a headless Chromium, honouring a RenderSpec, and return the path written. |
| is_stale | Whether path has to be re-captured: it is missing, its local source has changed, or it was taken with a different recipe. |
| recipe_sidecar | Where the recipe a capture was taken with is recorded, beside the file it produced. |
capture
plot.capture.capture(source, path, spec=None, *, base_dir=None, force=False)Render source to path with a headless Chromium, honouring a RenderSpec, and return the path written.
A capture whose output is already newer than its local source is skipped, so re-running a build does not re-launch a browser for a page nothing has touched; force takes the shot regardless. A remote source has no mtime to compare, so it is captured once and then only on force.
is_stale
plot.capture.is_stale(path, source_path, recipe=None)Whether path has to be re-captured: it is missing, its local source has changed, or it was taken with a different recipe.
The recipe counts because it decides what the file is: raising device_scale_factor or changing the viewport with the page untouched must re-render, or the spec says one thing and the committed raster is another. Split out from :func:capture so the decision is testable without a browser, and so a build can report what it is about to re-render.
recipe_sidecar
plot.capture.recipe_sidecar(path)Where the recipe a capture was taken with is recorded, beside the file it produced.