Example E025 : transparency

<?php

declare(strict_types=1);

/**
 * E025_transparency.php
 *
 * @since       2026-04-26
 * @category    Library
 * @package     Pdf
 * @author      Nicola Asuni <info@tecnick.com>
 * @copyright   2002-2026 Nicola Asuni - Tecnick.com LTD
 * @license     https://www.gnu.org/copyleft/lesser.html GNU-LGPL v3 (see LICENSE)
 * @link        https://github.com/tecnickcom/tc-lib-pdf
 *
 * This file is part of tc-lib-pdf software library.
 */

// NOTE: local file reads (images, fonts, attachments) are restricted to an allowlist of
// trusted paths that covers this package tree, so run the examples in place. To read assets
// from other locations, list them in the 'allowedPaths' entry of the fileOptions constructor
// parameter (see E047_remote_resources_security.php).

// NOTE: run make fonts in the project root to generate the dependencies and example fonts.

// autoloader when using Composer
require __DIR__ . '/../vendor/autoload.php';

// define fonts directory
\define('K_PATH_FONTS', \realpath(__DIR__ . '/../vendor/tecnickcom/tc-lib-pdf-font/target/fonts'));

$pdf = new \Com\Tecnick\Pdf\Tcpdf(
    unit: \Com\Tecnick\Pdf\Page\Unit::Millimeter,
    isunicode: true,
    subsetfont: false,
    compress: true,
    mode: \Com\Tecnick\Pdf\PdfConformance::None,
    objEncrypt: null,
);

$pdf->setCreator('tc-lib-pdf');
$pdf->setAuthor('Nicola Asuni');
$pdf->setSubject('tc-lib-pdf example: 025');
$pdf->setTitle('Object transparency');
$pdf->setKeywords('TCPDF tc-lib-pdf example object transparency alpha extgstate');
$pdf->setPDFFilename('025_transparency.pdf');
$pdf->setViewerPreferences(['DisplayDocTitle' => true]);
$pdf->enableDefaultPageContent();

$setFont = static function (\Com\Tecnick\Pdf\Tcpdf $pdf, string $family, string $style, int $size): array {
    $font = $pdf->font->insert($pdf->pon, $family, $style, $size, 0.0, 1.0);
    $pdf->page->addContent($font['out']);
    return $font;
};

$getRectStyle = static fn(string $strokeColor, string $fillColor): array => [
    'all' => [
        'lineWidth' => 2.0,
        'lineCap' => 'square',
        'lineJoin' => 'miter',
        'dashArray' => [],
        'dashPhase' => 0,
        'lineColor' => $strokeColor,
        'fillColor' => $fillColor,
    ],
];

// Insert one neutral font before addPage() so page context has a valid current font.
$pdf->font->insert($pdf->pon, 'helvetica', '', 10, 0.0, 1.0);

$page = $pdf->addPage();

$setFont($pdf, 'helvetica', '', 12);
$pdf->page->addContent($pdf->getTextCell(
    'You can set the transparency of PDF objects using graph->getAlpha().',
    15,
    20,
    180,
    0,
    valign: \Com\Tecnick\Pdf\TextVAlign::Top,
    halign: \Com\Tecnick\Pdf\TextHAlign::Left,
    drawcell: false,
));

// Opaque red square.
$pdf->page->addContent($pdf->graph->getRect(
    30.0,
    40.0,
    60.0,
    60.0,
    'DF',
    $getRectStyle('rgb(127,0,0)', 'rgb(255,0,0)'),
));

// Semi-transparent objects.
$pdf->page->addContent($pdf->graph->getAlpha(0.5));

$pdf->page->addContent($pdf->graph->getRect(
    50.0,
    60.0,
    60.0,
    60.0,
    'DF',
    $getRectStyle('rgb(0,127,0)', 'rgb(0,255,0)'),
));

$pdf->page->addContent($pdf->graph->getRect(
    70.0,
    80.0,
    60.0,
    60.0,
    'DF',
    $getRectStyle('rgb(0,0,127)', 'rgb(0,0,255)'),
));

$imagePath = __DIR__ . '/images/tcpdf_logo.jpg';
if (\is_file($imagePath)) {
    $imageId = $pdf->image->add($imagePath);
    $pdf->page->addContent($pdf->image->getSetImage($imageId, 90.0, 100.0, 60.0, 60.0, $page['height']));
}

// Restore full opacity.
$pdf->page->addContent($pdf->graph->getAlpha(1.0));

$rawpdf = $pdf->getOutPDFString();
$pdf->renderPDF(rawpdf: $rawpdf);