html-canvas-to-pdf-raku's Introduction

HTML-Canvas-To-PDF-raku

This is a Raku PDF rendering back-end for the HTML::Canvas module.

A canvas may be rendered to either a page, or an XObject form, using a PDF::Content graphics object
This back-end is compatible with PDF::Lite, PDF::Class and PDF::API6.
Supported canvas image formats are PNG, GIF, JPEG and PDF

This back-end is experimental.

This module is an alternative to HTML::Canvas, which is also able to save complete PDF files via Cairo.

It may be useful, for manipulating existing PDF files using the HTML Canvas API, or for integration with Raku PDF modules such as PDF::Lite or PDF::API6.

If this module is installed, the PDF::Content html-canvas() method will automatically render to a graphics stream using the HTML::Canvas::To::PDF back-end. The backend can thus be used on PDF Pages or XObject Forms:

use v6;
# Finish an existing PDF. Add a background color and page numbers

use PDF::Lite;
use PDF::Content;
use PDF::Content::Page;
use HTML::Canvas::To::PDF;

# render to a PDF page
my PDF::Lite $pdf .= open: "examples/render-pdf-test-sheets.pdf";

# use a cache for shared resources such as fonts and images.
# for faster production and smaller multi-page PDF files
my HTML::Canvas::To::PDF::Cache $cache .= new;

my UInt $pages = $pdf.page-count;

for 1 .. $pages -> $page-num {
    my PDF::Content::Page $page = $pdf.page($page-num);
    my PDF::Content $gfx = $page.pre-gfx;
    $gfx.html-canvas: :$cache, -> \ctx {
        ctx.fillStyle = "rgba(0, 0, 200, 0.2)";
        ctx.fillRect(10, 25, $page.width - 20, $page.height - 45);
        ctx.font = "12px Arial";
        ctx.fillStyle = "rgba(50, 50, 200, 0.8)";
        ctx.fillText("Page $page-num/$pages", 550, 15);
    }
}

$pdf.save-as: "examples/demo.pdf";

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