Lua Requires Chilkat v11.7.0+

Add an Image (Logo) Watermark to a PDF

See more PDF Watermark Examples

Demonstrates an image watermark placed in a corner of every page. The image is a PNG or JPEG given either by path ("image.path") or, as here, as base64 in the JSON itself ("image.base64"), which suits a server that keeps its logo in a database rather than on disk. PNG transparency is kept. Giving only a width keeps the aspect ratio, and the units member says those numbers are inches rather than points. 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 four_pages.pdf

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

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

-- A small PNG logo, base64 encoded.  Use "image.path" instead to name a PNG or JPEG file:
--    ignore = json.UpdateString("image.path","logo.png");
json:update_string("image.base64", "iVBORw0KGgoAAAANSUhEUgAAAGAAAAAgCAYAAADtwH1UAAAApElEQVR42u3a7QmAIBgAYTdpo/ZphhZti6IBylLrlXoO/G3cIeFHSgAAFDKM08rCy8Jzg6Ug8UJ0JF+EDuSXRGgxX8+jufxlTk0nFuCCiF360aidXICMiDP5uQgCXAxQI782ggAHEu7IP4sgQOcBIMA35ItgBQhQEqBmtbX6xl//hAUI3gcIELwTFiD4LEiA4NNQAYLvA+BGzJ0wvIrwLggA8DgbwPbrr8c7+lkAAAAASUVORK5CYII=")

-- The size to draw it at.  Give only the width and the height follows the aspect ratio.
json:update_string("units", "in")
json:update_number("image.width", "1.5")

-- Bottom-right, half an inch in from the page edges.
json:update_string("position.align", "bottomRight")
json:update_number("position.margin", "0.5")
json:update_number("opacity", "0.85")
json:update_string("id", "logo")

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/four_pages_logo.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

-- Sample output:

-- id: logo pages: 1-4