Lua Requires Chilkat v11.7.0+

Tile a Watermark Across a PDF Page

See more PDF Watermark Examples

Demonstrates a tiled watermark, which repeats the stamp over the whole page instead of placing it once. Tiling overrides position.align; tile.spacingX and spacingY set the gaps, and tile.stagger offsets alternate rows by half a tile so the pattern does not line up in columns. A faint tiled stamp carrying the name or address is the usual way to mark a document so that a leaked copy can be traced back, and zOrder back keeps it behind the text where it does not hinder reading. Lua

local chilkat = require("chilkat")

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

-- The PDF used in this example is available at long_report.pdf

local pdf = chilkat.Pdf.new()
local success = pdf:load_file("qa_data/pdf/long_report.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

local json = chilkat.JsonObject.new()
json:update_string("type", "text")

-- {date:FORMAT} is replaced per page when the watermark is added.  The other placeholders are
-- {page}, {pages} and {filename}; {{ gives a literal brace.
json:update_string("text", "jdoe@example.com  {date:yyyy-MM-dd}")
json:update_string("id", "trace")
json:update_string("zOrder", "back")
json:update_number("font.size", "14")
json:update_number("opacity", "0.15")
json:update_number("rotation", "30")

json:update_bool("tile.enabled", true)
json:update_number("tile.spacingX", "60")
json:update_number("tile.spacingY", "80")
json:update_bool("tile.stagger", true)

local jsonOut = chilkat.JsonObject.new()
success = pdf:watermark("add", json, jsonOut)
if not success then
    print(pdf.last_error_text)
    return
end

print("id: " .. jsonOut:string_of("id") .. " pages: " .. jsonOut:string_of("pages"))

success = pdf:write_file("qa_output/report_traced.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

-- Sample output:

-- id: trace pages: 1-3