zcatpdf/examples/links_demo.zig

//! Links Demo - Demonstrates clickable URL links in PDFs
//!
//! Shows how to create:
//! - Clickable URL links (external websites)
//! - Internal page links (jump to page)
//! - Visual link styling (blue underlined text)

const std = @import("std");
const pdf = @import("zpdf");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    std.debug.print("zpdf - Links Demo\n", .{});

    var doc = pdf.Pdf.init(allocator, .{});
    defer doc.deinit();

    doc.setTitle("Links Demo");
    doc.setAuthor("zpdf");

    // =========================================================================
    // Page 1: External URL Links
    // =========================================================================
    var page1 = try doc.addPage(.{});
    page1.setMargins(50, 50, 50);

    // Title
    try page1.setFont(.helvetica_bold, 24);
    page1.setFillColor(pdf.Color.rgb(41, 98, 255));
    page1.setXY(50, 780);
    try page1.cell(0, 30, "Clickable Links Demo", pdf.Border.none, .center, false);
    page1.ln(50);

    // Description
    try page1.setFont(.helvetica, 12);
    page1.setFillColor(pdf.Color.black);
    const desc =
        \\This PDF demonstrates clickable links. When you view this in a PDF reader,
        \\you can click on the blue underlined text to open URLs in your browser.
    ;
    try page1.multiCell(500, null, desc, pdf.Border.none, .left, false);
    page1.ln(30);

    // Section: External Links
    try page1.setFont(.helvetica_bold, 16);
    page1.setFillColor(pdf.Color.rgb(51, 51, 51));
    try page1.cell(0, 25, "External URL Links", pdf.Border.none, .left, false);
    page1.ln(30);

    try page1.setFont(.helvetica, 12);
    page1.setFillColor(pdf.Color.black);

    // Link 1: Example website
    try page1.cell(0, 18, "Visit the example website: ", pdf.Border.none, .left, false);
    _ = try page1.writeUrlLink("https://example.com", "https://example.com");
    page1.ln(25);

    // Link 2: GitHub
    try page1.cell(0, 18, "Check out Zig on GitHub: ", pdf.Border.none, .left, false);
    _ = try page1.writeUrlLink("Zig Language", "https://github.com/ziglang/zig");
    page1.ln(25);

    // Link 3: Email
    try page1.cell(0, 18, "Send us an email: ", pdf.Border.none, .left, false);
    _ = try page1.writeUrlLink("contact@example.com", "mailto:contact@example.com");
    page1.ln(40);

    // Section: Internal Links
    try page1.setFont(.helvetica_bold, 16);
    page1.setFillColor(pdf.Color.rgb(51, 51, 51));
    try page1.cell(0, 25, "Internal Page Links", pdf.Border.none, .left, false);
    page1.ln(30);

    try page1.setFont(.helvetica, 12);
    page1.setFillColor(pdf.Color.black);
    try page1.cell(0, 18, "Click to jump to: ", pdf.Border.none, .left, false);

    // Internal link to page 2
    const link_text = "Page 2 - More Information";
    const link_width = try page1.drawLink(page1.getX(), page1.getY(), link_text);
    try page1.addInternalLink(1, page1.getX(), page1.getY() - 2, link_width, 16);
    page1.ln(40);

    // Information box
    page1.setFillColor(pdf.Color.rgb(240, 248, 255));
    try page1.fillRect(50, page1.getY() - 80, 495, 80);

    try page1.setFont(.helvetica, 11);
    page1.setFillColor(pdf.Color.rgb(51, 51, 51));
    page1.setXY(60, page1.getY() - 15);
    const info_text =
        \\Note: Link clickability depends on your PDF viewer. Most modern viewers
        \\(Adobe Reader, Preview, Chrome, Firefox) support clickable links.
        \\The blue underlined styling is visual, while the annotation makes it clickable.
    ;
    try page1.multiCell(475, null, info_text, pdf.Border.none, .left, false);

    // =========================================================================
    // Page 2: More Information
    // =========================================================================
    var page2 = try doc.addPage(.{});
    page2.setMargins(50, 50, 50);

    // Title
    try page2.setFont(.helvetica_bold, 24);
    page2.setFillColor(pdf.Color.rgb(41, 98, 255));
    page2.setXY(50, 780);
    try page2.cell(0, 30, "Page 2 - More Information", pdf.Border.none, .center, false);
    page2.ln(50);

    try page2.setFont(.helvetica, 12);
    page2.setFillColor(pdf.Color.black);
    const page2_text =
        \\You navigated here from a clickable internal link!
        \\
        \\Internal links allow you to create table of contents, cross-references,
        \\and navigation within your PDF documents.
        \\
        \\The link annotation stores the target page number and the PDF viewer
        \\handles the navigation when clicked.
    ;
    try page2.multiCell(500, null, page2_text, pdf.Border.none, .left, false);
    page2.ln(30);

    // Link back to page 1
    try page2.cell(0, 18, "Go back to: ", pdf.Border.none, .left, false);
    const back_text = "Page 1 - Links Demo";
    const back_width = try page2.drawLink(page2.getX(), page2.getY(), back_text);
    try page2.addInternalLink(0, page2.getX(), page2.getY() - 2, back_width, 16);
    page2.ln(50);

    // Technical details
    try page2.setFont(.helvetica_bold, 14);
    page2.setFillColor(pdf.Color.rgb(51, 51, 51));
    try page2.cell(0, 20, "How Links Work in PDF", pdf.Border.none, .left, false);
    page2.ln(25);

    try page2.setFont(.helvetica, 11);
    page2.setFillColor(pdf.Color.black);
    const tech_text =
        \\PDF links are implemented using Annotation objects (/Type /Annot /Subtype /Link).
        \\
        \\Each link annotation contains:
        \\- /Rect: The clickable area coordinates [x1, y1, x2, y2]
        \\- /A: Action dictionary for URL links (/S /URI /URI "url")
        \\- /Dest: Destination for internal links (page reference)
        \\- /Border: Border style (we use [0 0 0] for invisible borders)
        \\
        \\The visual styling (blue text + underline) is separate from the annotation.
        \\zpdf's urlLink() and writeUrlLink() methods combine both automatically.
    ;
    try page2.multiCell(500, null, tech_text, pdf.Border.none, .left, false);

    // Add page numbers
    try pdf.Pagination.addPageNumbers(&doc, .{
        .format = "Page {PAGE} of {PAGES}",
        .position = .bottom_center,
    });

    // Footer
    try pdf.Pagination.addFooter(&doc, "Generated with zpdf - Links Demo", .{
        .alignment = .center,
        .font_size = 8,
        .color = pdf.Color.light_gray,
    });

    // Save
    const filename = "links_demo.pdf";
    try doc.save(filename);

    std.debug.print("Created: {s}\n", .{filename});
    std.debug.print("Open in a PDF viewer and click the links!\n", .{});
    std.debug.print("Done!\n", .{});
}