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Overlay custom graphics on a pdf

Source: R/pdf_add_overlay.R
pdf_add_overlay.Rd

pdf_add_overlay() calls grid_fn on selected pages to draw custom graphics on top.

Usage

pdf_add_overlay(input, output = NULL, ..., grid_fn = grid::grid.null)

Arguments

input

Input pdf filename.

output

Output pdf filename. NULL defaults to tempfile(fileext = ".pdf").

...

Passed to pdf_apply().

grid_fn

A zero-argument function called to draw graphics on selected pages. Defaults to grid::grid.null().

Value

output pdf file name invisibly. As a side effect creates a pdf with overlaid graphics.

See also

pdf_apply() which this function wraps and pdf_add_cropmarks(), pdf_add_crosshairs(), pdf_add_lines(), and pdf_add_rects() for specific applications. pdf_overlay_stamp() alternatively adds the contents of a stamp pdf file.

Examples

f1 <- pdf_create_blank(length = 2L, paper = "letter")
f2 <- pdf_add_overlay(f1, pages = "all", dpi = 75,
                      grid_fn = function() {
                        grid::grid.text("DRAFT", gp = grid::gpar(col = "red",
                                        fontsize = 72, alpha = 0.3))
                      })
unlink(f1)
unlink(f2)