Images

<?php

declare(strict_types=1);

use PDF\Document\Fonts\StandardFont;
use PDF\Document\Fonts\Type1Font;
use PDF\Document\ResourceDictionary;
use PDF\Document\Resources\Font;
use PDF\Document\Resources\XObject;
use PDF\FileStructure;
use PDF\Graphics\CoordinateSystems\Matrix;
use PDF\Specification\Dictionary\ImageDictionaryTable89;
use PDF\Specification\Dictionary\ImageDictionaryTable89\BitsPerComponentEntry;
use PDF\Specification\Dictionary\ImageDictionaryTable89\ColorSpaceEntry;
use PDF\Specification\Dictionary\ImageDictionaryTable89\HeightEntry;
use PDF\Specification\Dictionary\ImageDictionaryTable89\InterpolateEntry;
use PDF\Specification\Dictionary\ImageDictionaryTable89\SubtypeEntry;
use PDF\Specification\Dictionary\ImageDictionaryTable89\TypeEntry;
use PDF\Specification\Dictionary\ImageDictionaryTable89\WidthEntry;
use PDF\Syntax\ContentStreamsResources\ContentStreams;
use PDF\Syntax\ContentStreamsResources\Operators\BeginTextObject;
use PDF\Syntax\ContentStreamsResources\Operators\ConcatenateMatrix;
use PDF\Syntax\ContentStreamsResources\Operators\EndTextObject;
use PDF\Syntax\ContentStreamsResources\Operators\InlineImage;
use PDF\Syntax\ContentStreamsResources\Operators\InvokeXObject;
use PDF\Syntax\ContentStreamsResources\Operators\MoveTextPosition;
use PDF\Syntax\ContentStreamsResources\Operators\RestoreGraphicsState;
use PDF\Syntax\ContentStreamsResources\Operators\SaveGraphicsState;
use PDF\Syntax\ContentStreamsResources\Operators\SetNonstrokingRGBColor;
use PDF\Syntax\ContentStreamsResources\Operators\SetTextFontAndSize;
use PDF\Syntax\ContentStreamsResources\Operators\ShowText;
use PDF\Syntax\DataStructure\Rectangle;
use PDF\Syntax\DocumentStructure\DocumentCatalog;
use PDF\Syntax\DocumentStructure\PageTree\PageObject;
use PDF\Syntax\DocumentStructure\PageTree\PageTreeNode;
use PDF\Syntax\FileStructure\FileBody;
use PDF\Syntax\FileStructure\FileHeader;
use PDF\Syntax\Filters\FlateDecode;
use PDF\Syntax\Object\BooleanType;
use PDF\Syntax\Object\DictionaryObject\Entry;
use PDF\Syntax\Object\DictionaryType;
use PDF\Syntax\Object\IndirectReference;
use PDF\Syntax\Object\IntegerType;
use PDF\Syntax\Object\NameType;
use PDF\Syntax\Object\NumericType;
use PDF\Syntax\Object\StreamObject;
use PDF\Syntax\Object\StringObject\LiteralString;

require dirname(__DIR__) . '/vendor/autoload.php';

// 1. Build pixels, not a PNG file: each pixel contains three bytes
//    R, G, B. 16 × 16 × 3 = 768 bytes, arranged row by row.
//    The palette contains no ambiguous EI terminator for the inline image.
$palette = [
    [255, 105, 85],
    [255, 204, 96],
    [74, 210, 188],
    [96, 160, 245],
    [181, 133, 235],
    [255, 245, 220],
];
$pixels = '';
for ($y = 0; $y < 16; ++$y) {
    for ($x = 0; $x < 16; ++$x) {
        $colour = $palette[(intdiv($x, 4) + intdiv($y, 4)) % count($palette)];
        $pixels .= chr($colour[0]) . chr($colour[1]) . chr($colour[2]);
    }
}

// 2. Describe samples: /Width and /Height count pixels; 8 bits per
//    component give 256 values; /DeviceRGB expects three components.
//    These entries come from specification Table 89. Interpolate=false
//    preserves the pattern's edges when enlarged.
$width = new WidthEntry(new IntegerType(16));
$height = new HeightEntry(new IntegerType(16));
$bits = new BitsPerComponentEntry(new IntegerType(8));
$colourSpace = new ColorSpaceEntry(new NameType('DeviceRGB'));
$interpolate = new InterpolateEntry(new BooleanType(false));
$imageDictionary = new ImageDictionaryTable89(
    new TypeEntry(new NameType('XObject')),
    new SubtypeEntry(new NameType('Image')),
    $width,
    $height,
    $bits,
    $colourSpace,
    $interpolate,
);

// 3. The image XObject is a separate stream referenced as /Im1 in /XObject.
//    StreamObject compresses pixels with zlib, then produces /Filter
//    /FlateDecode and /Length. Original bytes remain the starting point.
$image = new StreamObject($pixels, $imageDictionary, new FlateDecode());
$helvetica = new Type1Font(StandardFont::Helvetica);
$resources = new ResourceDictionary(
    new Font(new DictionaryType(
        new Entry(new NameType('F1'), new IndirectReference($helvetica)),
    )),
    new XObject(new DictionaryType(
        new Entry(new NameType('Im1'), new IndirectReference($image)),
    )),
);

// 4. The inline image contains its dictionary and bytes directly in
//    the content stream: InlineImage writes BI, ID and EI as one instruction.
//    It has no /Type, /Subtype or entry in /XObject resources.
//    Pixels are raw here: no /Filter is declared.
$inlineImage = new InlineImage(new DictionaryType(
    $width,
    $height,
    $bits,
    $colourSpace,
    $interpolate,
), $pixels);

// 5. A PDF image occupies the unit square. cm transforms it into a
//    216 × 216 point square and translates it. The 16 × 16 pixel resolution
//    therefore does not determine page size. q/Q enclose each cm.
$contents = new StreamObject(new ContentStreams(
    new SetNonstrokingRGBColor(new NumericType(0.08), new NumericType(0.18), new NumericType(0.28)),
    new BeginTextObject(),
    new SetTextFontAndSize(new NameType('F1'), new NumericType(24)),
    new MoveTextPosition(new NumericType(64), new NumericType(714)),
    new ShowText(new LiteralString('Deux representations de la meme image')),
    new SetTextFontAndSize(new NameType('F1'), new NumericType(12)),
    new MoveTextPosition(new NumericType(0), new NumericType(-30)),
    new ShowText(new LiteralString('16 x 16 pixels RGB - 8 bits par composante - affichage 216 x 216 points')),
    new EndTextObject(),
    new BeginTextObject(),
    new SetTextFontAndSize(new NameType('F1'), new NumericType(16)),
    new MoveTextPosition(new NumericType(64), new NumericType(640)),
    new ShowText(new LiteralString('XObject /Im1 + FlateDecode')),
    new EndTextObject(),
    new SaveGraphicsState(),
    new ConcatenateMatrix(new Matrix(
        new NumericType(216),
        new NumericType(0),
        new NumericType(0),
        new NumericType(216),
        new NumericType(64),
        new NumericType(400),
    )),
    new InvokeXObject(new NameType('Im1')),
    new RestoreGraphicsState(),
    new BeginTextObject(),
    new SetTextFontAndSize(new NameType('F1'), new NumericType(16)),
    new MoveTextPosition(new NumericType(332), new NumericType(640)),
    new ShowText(new LiteralString('Image inline BI / ID / EI')),
    new EndTextObject(),
    new SaveGraphicsState(),
    new ConcatenateMatrix(new Matrix(
        new NumericType(216),
        new NumericType(0),
        new NumericType(0),
        new NumericType(216),
        new NumericType(332),
        new NumericType(400),
    )),
    $inlineImage,
    new RestoreGraphicsState(),
    new BeginTextObject(),
    new SetTextFontAndSize(new NameType('F1'), new NumericType(12)),
    new MoveTextPosition(new NumericType(64), new NumericType(370)),
    new ShowText(new LiteralString('Flux separe, reference reutilisable.')),
    new MoveTextPosition(new NumericType(268), new NumericType(0)),
    new ShowText(new LiteralString('768 octets dans le contenu de page.')),
    new MoveTextPosition(new NumericType(-268), new NumericType(-60)),
    new ShowText(new LiteralString('Le nom /Im1 est local aux ressources de la page.')),
    new MoveTextPosition(new NumericType(0), new NumericType(-24)),
    new ShowText(new LiteralString('La matrice fixe la taille et la position ; q/Q isole cette transformation.')),
    new MoveTextPosition(new NumericType(0), new NumericType(-24)),
    new ShowText(new LiteralString('Les deux images utilisent exactement les memes echantillons RGB.')),
    new EndTextObject(),
));

// 6. Connect the page, its tree and catalog; the writer discovers indirect
//    objects and assigns their numbers from this graph.
$page = new PageObject(
    new Rectangle(new NumericType(0), new NumericType(0), new NumericType(612), new NumericType(792)),
    $resources,
    $contents,
);
$pages = (new PageTreeNode())->addKid($page);
$catalog = new DocumentCatalog($pages);
$file = new FileStructure(new FileHeader('1.7'), new FileBody($catalog), new IndirectReference($catalog));
$path = $argv[1] ?? __DIR__ . '/images.pdf';
$file->writeTo($path);
echo $path . PHP_EOL;