QOI encoder / decoder

QOI Image encoder and decoder written in pure PHP.

It can encode and decode a few megabytes per second with a small memory footprint.

On x86_64 architectures, it will automatically use the FFI extension to encode the file using the provided C library.

Usage

Convert a PNG file using a stream :

useMKCG\Image\QOI\Codec;
useMKCG\Image\QOI\Driver\Dynamic;
useMKCG\Image\QOI\Writer\StreamWriter;
$inputFilepath = "/foobar.png";
$outputFilepath = "/foobar.qoi";
$context = Dynamic::loadFromFile($inputFilepath);
if ($context) {
$outputFile = fopen($outputFilepath, 'w');
if ($outputFile) {
$writer = newStreamWriter($outputFile);
Codec::encode($context->iterator, $context->descriptor, $writer);
fclose($outputFile);
}
}

Convert a PNG file in-memory :

useMKCG\Image\QOI\Codec;
useMKCG\Image\QOI\Driver\Dynamic;
useMKCG\Image\QOI\Writer\InMemoryWriterFactory;
$inputFilepath = "/foobar.png";
$outputFilepath = "/foobar.qoi";
$context = Dynamic::loadFromFile($inputFilepath);
if ($context) {
$outputFile = fopen($outputFilepath, 'w');
if ($outputFile) {
$writer = (newWriter\InMemoryWriterFactory)->createWriter($context->descriptor);
Codec::encode($context->iterator, $context->descriptor, $writer);
fwrite($outputFile, (string) $writer, $writer->countWritten());
fclose($outputFile);
}
}

Create an image from scratch :

useMKCG\Image\QOI\Codec;
useMKCG\Image\QOI\Colorspace;
useMKCG\Image\QOI\Context;
useMKCG\Image\QOI\ImageDescriptor;
useMKCG\Image\QOI\Writer\StreamWriter;
$outputFilepath = "/white.qoi";
$width = 800;
$height = 600;
$channels = 3;
$context = newContext(
newImageDescriptor($width, $height, $channels, Colorspace::SRGB),
(function() use ($width, $height, $channels) {
$size = $width * $height * $channels;
for ($i = 0; $i < $size; $i++) {
yield [ 255, 255, 255, 255 ];
}
})(),
);
$outputFile = fopen($outputFilepath, 'w');
if ($outputFile) {
$writer = newStreamWriter($outputFile);
Codec::encode($context->iterator, $context->descriptor, $writer);
fclose($outputFile);
}

Decode a QOI image

useMKCG\Image\QOI\Codec;
functioncreateFileIterator($filepath): \Generator
{
$bytes = file_get_contents($filepath);
for ($i = 0; $i < strlen($bytes); $i++) {
yield$bytes[$i];
}
};
$filepath = "/input.qoi";
$reader = Codec::decode(createFileIterator($filepath));
$width = $reader->descriptor->width;
$height = $reader->descriptor->height;
$channels = $reader->descriptor->channels;
$pixels = iterator_to_array($reader->iterator);

Convert a QOI image

useMKCG\Image\QOI\Codec;
useMKCG\Image\QOI\Format;
useMKCG\Image\QOI\Driver\Dynamic;
functioncreateFileIterator($filepath): \Generator
{
$handler = fopen($filepath, 'r');
while (($bytes = fread($handler, 8192)) !== false) {
for ($i = 0; $i < strlen($bytes); $i++) {
yield$bytes[$i];
}
}
fclose($handler);
};
$filepath = "/input.qoi";
$reader = Codec::decode(createFileIterator($filepath));
Dynamic::convertInto($reader, "/output.png", Format::PNG);
// Important: you need to create another reader$reader = Codec::decode(createFileIterator($filepath));
Dynamic::convertInto($reader, "/output.jpg", Format::JPG);

Drivers

Name	Requirements	Description
Dynamic	at least one of the ext	Manipulates images using the appropriate PHP image extension
Gd	ext-gd	gd use only 7 bits for the alpha channel instead of 8
Imagick	ext-imagick	imagick must have been compiled against ImageMagick >= 6.4.0
Vips	ext-vips

Supported images format

Driver GdImage : png and jpeg only

Driver Imagick : any image format that can be loaded by \Imagick