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Convert device (screen) coordinates to PDF page coordinates

Source: R/api_completion.R
pdf_device_to_page.Rd

Wraps FPDF_DeviceToPage. Given a rendering window of size (size_x, size_y) pixels at top-left (start_x, start_y) with rotation rotate, maps the device pixel (device_x, device_y) to a point in PDF user-space (points).

Usage

pdf_device_to_page(
  page,
  start_x,
  start_y,
  size_x,
  size_y,
  rotate,
  device_x,
  device_y
)

Arguments

page

A pdfium_page from pdf_page_load().

start_x, start_y

Integer — device-pixel position of the display area's top-left.

size_x, size_y

Integer — pixel size of the rendering window.

rotate

Integer — 0, 1, 2, or 3 (clockwise quarter turns). Same convention as PDFium's other rendering functions.

device_x, device_y

Integer — the pixel to convert.

Value

Named numeric vector c(x, y) in PDF points. c(NA, NA) on failure.

Details

Useful when a downstream consumer reports a click position in pixels (e.g. from a Shiny clickOpts event) and you want to translate it back to PDF coordinates for hit-testing against page objects.

See also

pdf_page_to_device() for the inverse.