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Convert bitmap pixel coordinates to PDF page-space points

Source: R/render.R
pdf_bitmap_to_page.Rd

Inverse of pdf_bitmap_from_page(). Translates pixel positions in a pdfium_bitmap (returned by pdf_render_page()) to PDF user-space points on the source page. Wraps FPDF_DeviceToPage with the render-geometry that produced the bitmap pre-populated from the bitmap's attributes.

Usage

pdf_bitmap_to_page(bitmap, x, y)

Arguments

bitmap

A pdfium_bitmap from pdf_render_page(). Must carry render-geometry metadata (older pdf_render_page_with_matrix() output doesn't).

x, y

Numeric vectors of pixel positions on the bitmap. Recycled to a common length.

Value

A two-column tibble with columns x and y in PDF user-space points (origin at the page's bottom-left).

See also

pdf_bitmap_from_page() for the inverse, pdf_device_to_page() for the underlying primitive.

Examples

fixture <- system.file("extdata", "fixtures", "shapes.pdf",
  package = "pdfium"
)
if (nzchar(fixture)) {
  doc <- pdf_doc_open(fixture)
  bmp <- pdf_render_page(doc, dpi = 72)
  # Map two bitmap pixel positions back to PDF page-space points.
  pdf_bitmap_to_page(bmp, x = c(0, 100), y = c(0, 100))
  pdf_doc_close(doc)
}