Zig 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. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // 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

    const pdf = try chilkat.Pdf.init();
    defer pdf.deinit();
    pdf.loadFile("qa_data/pdf/long_report.pdf") catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    json.updateString("type", "text") catch {};

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

    json.updateBool("tile.enabled", true) catch {};
    json.updateNumber("tile.spacingX", "60") catch {};
    json.updateNumber("tile.spacingY", "80") catch {};
    json.updateBool("tile.stagger", true) catch {};

    const json_out = try chilkat.JsonObject.init();
    defer json_out.deinit();
    pdf.watermark("add", json, json_out) catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("id: {s} pages: {s}\n", .{ try json_out.stringOf(alloc, "id"), try json_out.stringOf(alloc, "pages") });

    pdf.writeFile("qa_output/report_traced.pdf") catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    // Sample output:

    // id: trace pages: 1-3
}