Apply Map Themes from a Portable XML to a QGIS Project

Read a <rfp-themes> document produced by rfp_qgs_theme_export() and insert its visibility-preset nodes into a destination .qgs file. Layer names in the portable document are resolved back to the destination's layer ids by name match; group nodes are copied verbatim.

Usage

rfp_qgs_theme_apply(
  path,
  themes_file,
  themes = NULL,
  on_missing_layer = c("warn", "error", "skip"),
  backup = TRUE
)

Arguments

path: Character. Path to the destination .qgs project file.
themes_file: Character. Path to the portable <rfp-themes> XML produced by rfp_qgs_theme_export().
themes: Character vector of theme names to apply from themes_file. If NULL (default), all themes in the file are applied.
on_missing_layer: How to handle layers referenced by a theme that don't exist in the destination project. One of "warn" (default — skip the layer, return a row in the result tibble), "error" (raise), or "skip" (silent skip, still recorded in the tibble).
backup: Logical. Write a <path>.bak copy of the destination before modifying. Default TRUE.

Value

Invisible tibble with one row per applied theme: theme, layers_applied (int), layers_missing (int), missing (chr — comma-joined names of layers not found in the destination).

Details

Errors loudly when the destination has duplicate layer names (the dff bug class — name-based remap can't be safe), or when a theme being applied already exists in the destination. Use rfp_qgs_themes() + QGIS Desktop to remove an existing preset first if you want to replace.

Examples

if (FALSE) { # \dontrun{
# Round-trip a theme from one project to another
rfp_qgs_theme_export("source.qgs", themes = "Floodplain")
rfp_qgs_theme_apply("destination.qgs", "source_themes.xml")
} # }