Preview a Directory Tree as a Mermaid Diagram

Writes an HTML page that renders tree_to_mermaid() output as an SVG diagram in a web browser. The page loads Mermaid from its public CDN, so rendering requires an internet connection. Browser opening is always suppressed in non-interactive sessions, including package checks and automated jobs.

Usage

view_mermaid(
  path = NULL,
  file = tempfile("printtree-mermaid-", fileext = ".html"),
  title = "Directory tree",
  theme = c("default", "neutral", "dark", "forest", "base"),
  open = interactive(),
  pan_zoom = TRUE,
  save = NULL,
  ...
)

Arguments

path

Character. Directory path, project name, or .Rproj file. If NULL, uses the current directory.

file

Character. HTML output path. By default, a temporary file is used.

title

Character. Page title and heading.

theme

Mermaid theme: "default", "neutral", "dark", "forest", or "base".

open

Logical. Open the generated page when running interactively. Browser opening is skipped when interactive() is false, even if this is explicitly set to TRUE.

pan_zoom

Logical. Enable pan/zoom controls for navigating large diagrams (via the svg-pan-zoom library).

save

Character or NULL. If given, render the diagram to an image file instead of the HTML page: one of "png", "jpeg" (or "jpg"), or "pdf". Requires the webshot2 package and a Chrome/Chromium browser. When save is given, file is treated as the image output path; if file was not explicitly supplied, the path is derived from title and the save extension. A missing extension is appended; a conflicting extension is an error. PNG/JPEG capture only the diagram element; PDF uses print CSS to hide the viewer UI.

...

Additional arguments passed to tree_to_mermaid(), such as direction, ignore, max_depth, git_colors, or subgraph.

Value

Invisibly, the generated HTML file path (or the image path when save is given).

Examples

demo <- file.path(tempdir(), "printtree-view-demo")
if (dir.exists(demo)) unlink(demo, recursive = TRUE)
dir.create(file.path(demo, "R"), recursive = TRUE)
file.create(file.path(demo, "R", "hello.R"))
#> [1] TRUE
file.create(file.path(demo, "README.md"))
#> [1] TRUE

preview <- view_mermaid(demo, open = FALSE)
file.exists(preview)
#> [1] TRUE