Build the Interactive SVG, or Answer NULL When It Cannot Be Built

should_fallback() answers whether the recorded layers are ones maidr can read. It cannot answer whether the plot can be exported, because that is the exporter's question and the exporter is not consulted until the export runs. When maidr exported through gridSVG, two base R charts failed there on plots that pass the gate – matplot() with "non-numeric argument to binary operator" and symbols() with gridSVG's own "We shouldn't be here!" assertion, both raised inside grid.export() rather than by anything this package computes. The svglite export draws both, but an export can still throw.

Usage

build_interactive_svg(orchestrator, hover_mode = NULL)

Arguments

orchestrator

The orchestrator for the plot being rendered.

hover_mode

The chart's hoverMode: one of "pointermove", "click" or "off", or NULL for getOption("maidr.hover_mode"), and for none when that is unset.

Value

The SVG content, drawn at the orchestrator's canvas_size(), or NULL when the build failed and fallback is enabled.

Details

Left to propagate, those kill the save outright: the caller gets neither the interactive chart nor the static image, and an error naming a package they never called. The lower claim the package makes about a recorded plot is that it is at worst a picture (#216), and an export that throws is no more a reason to break that than a layer it cannot classify.

The whole build is guarded rather than the export alone. From the caller's side the gtable, the data and the SVG are one step – producing the interactive chart – and which of the three threw does not change what they should be given instead.

maidr_set_fallback(enabled = FALSE) is the caller asking for the failure rather than the picture, so the error is re-raised untouched there.

A chart too small to draw at its size (a maidr_chart_draw_error from base_r_drawing_grob()) is re-raised too: its picture is drawn at the same size and would fail the same way.

Before the picture is drawn, the failure is signalled as a condition of class maidr_build_failure, holding it as error. A caller that shows a picture of its own catches that and keeps the failure: a knitted chart is knitr's figure, and the document's build says why.

The chart's hoverMode is written into its schema here, the one place every render path – show(), save_html(), the widget, Shiny, knitr and the console print methods – builds a chart through. It is resolved, and an option set to something else refused, before the build, so the error is not taken for a chart that could not be built.