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Add keyboard navigation to an echarts4r chart

ro_e_keyboard_nav.Rd

ro_e_keyboard_nav() attaches JavaScript keyboard event listeners to an echarts4r chart, enabling keyboard-only users to navigate data points and toggle legend series. It is designed to follow ro_e_theme() at the end of an echarts4r pipeline.

Usage

ro_e_keyboard_nav(e, series_keys = NULL, axis = NULL)

Arguments

e

An echarts4r object.

series_keys

Named character vector mapping single-letter key codes to series names, e.g. c(w = "Women", m = "Men", t = "Total"). Names must be single letters (case-insensitive); values must exactly match the series names as used in the chart. Set to NULL (default) to omit legend controls.

axis

Character. Arrow-key direction for tooltip navigation. One of "horizontal" (ArrowLeft / ArrowRight), "vertical" (ArrowUp / ArrowDown), or "both". Default NULL auto-detects from the chart orientation.

Value

The modified echarts4r object, with keyboard navigation attached via htmlwidgets::onRender().

Keyboard controls

Arrow keys: move the tooltip across data points. Direction is auto-detected from chart orientation (left/right for column and line charts; up/down for bar charts), or set explicitly via axis. Letter keys: toggle individual legend series. Controlled by series_keys; nothing is hardcoded. Pass NULL to omit legend controls.

Axis auto-detection

The function inspects the echarts4r object to determine whether echarts4r::e_flip_coords() was applied, and assigns arrow keys accordingly. Override this with the axis argument.

See also

Other echarts4r: ro_e_build_keyboard_nav_js(), ro_e_build_onrender_js(), ro_e_detect_axis_orientation(), ro_e_keyboard_nav_axis_js(), ro_e_keyboard_nav_legend_js(), ro_e_theme(), ro_e_theme_list()

Examples

if (FALSE) { # \dontrun{
library(echarts4r)

data |>
 dplyr::group_by(sex) |>
 e_charts(year) |>
 e_line(value) |>
 e_tooltip(trigger = "axis") |>
 ro_e_theme() |>
 ro_e_keyboard_nav(series_keys = c(w = "Women", m = "Men", t = "Total"))
} # }