Playback GPS tracks on a leaflet timeline with tails

Creates an interactive leaflet htmlwidget with timeline playback and track tails inspired by moveVis-style animations. This function is presentation-oriented and avoids Shiny.

Inspiration: the playback/tail design was informed by the moveVis package (https://github.com/16EAGLE/moveVis).

Usage

grz_playback_gps(
  data,
  lon = "lon",
  lat = "lat",
  datetime = "datetime",
  group = NULL,
  color_by = c("group", "state"),
  state_col = NULL,
  state_colors = c(inactive = "#d7191c", active = "#1a9641"),
  align = TRUE,
  align_interval_mins = "base",
  align_keep_extra = TRUE,
  tail_points = 19L,
  tail_minutes = NULL,
  show_points = TRUE,
  point_radius = 4,
  point_opacity = 0.9,
  point_size_slider = TRUE,
  point_size_min = 1,
  point_size_max = 25,
  slider_position = "bottomleft",
  playback_controls = TRUE,
  playback_steps = 1000L,
  playback_duration_ms = 10000L,
  show_ticks = FALSE,
  enable_keyboard_controls = TRUE,
  wait_to_update_map = FALSE,
  provider = "Esri.WorldImagery",
  popup_fields = c("sensor_id", "datetime"),
  show_legend = TRUE,
  group_palette = "Dark 3",
  max_rows = NULL,
  render_every_n = 1L,
  seed = 1,
  warnings = TRUE,
  progress = TRUE,
  show_loading_overlay = TRUE
)

Arguments

data: Data frame containing GPS rows.
lon: Name of longitude column.
lat: Name of latitude column.
datetime: Name of datetime column.
group: Optional grouping column(s) for track identity and coloring. If NULL, sensor_id is used when present.
color_by: Color mode. "group" (default) colors by track; "state" colors by state_col.
state_col: Optional state column used when color_by = "state".
state_colors: Named colors for state levels.
align: Logical; if TRUE, calls grz_align() before playback.
align_interval_mins: Interval passed to grz_align(interval_mins = ).
align_keep_extra: Logical; passed to grz_align(keep_extra = ).
tail_points: Tail length expressed as number of aligned points. Ignored when tail_minutes is supplied.
tail_minutes: Tail length in minutes. If NULL, inferred from tail_points.
show_points: Logical; draw moving point markers.
point_radius: Point marker radius.
point_opacity: Point marker opacity.
point_size_slider: Logical; show an on-map slider to control point radius during playback.
point_size_min: Minimum value for the point-size slider.
point_size_max: Maximum value for the point-size slider.
slider_position: Position of timeline controls.
playback_controls: Logical; show play/pause/step controls.
playback_steps: Number of playback steps for the timeline.
playback_duration_ms: Minimum playback duration in milliseconds.
show_ticks: Logical; show timeline ticks.
enable_keyboard_controls: Logical; allow keyboard control of playback.
wait_to_update_map: Logical; if TRUE, redraw map only after slider interaction ends.
provider: Tile provider for leaflet::addProviderTiles().
popup_fields: Fields to include in popups.
show_legend: Logical; add legend.
group_palette: HCL palette name used for group colors.
max_rows: Optional maximum rows to render after alignment. If set and exceeded, rows are sampled across groups.
render_every_n: Keep every n-th aligned row per group (>= 1) before building timeline features. Useful for faster rendering.
seed: Random seed for sampling.
warnings: Logical; print warnings for large payloads.
progress: Logical; print stage progress and loop progress bars while building playback features.
show_loading_overlay: Logical; show an on-map loading overlay until timeline layers are ready.

Value

A leaflet htmlwidget.