libreqr/vendor/endroid/qr-code/README.md

# QR Code

*By [endroid](https://endroid.nl/)*

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This library helps you generate QR codes in a jiffy. Makes use of [bacon/bacon-qr-code](https://github.com/Bacon/BaconQrCode)
to generate the matrix and [khanamiryan/qrcode-detector-decoder](https://github.com/khanamiryan/php-qrcode-detector-decoder)
for validating generated QR codes. Further extended with Twig extensions, generation routes, a factory and a
Symfony bundle for easy installation and configuration. Different writers are provided to generate the QR code
as PNG, SVG, EPS or in binary format.

## Sponsored by

[![Blackfire.io](assets/blackfire.png)](https://www.blackfire.io)

## Installation

Use [Composer](https://getcomposer.org/) to install the library. Also make sure you have enabled and configured the
[GD extension](https://www.php.net/manual/en/book.image.php) if you want to generate images.

``` bash
 composer require endroid/qr-code
```

## Usage: using the builder

```php
use Endroid\QrCode\Builder\Builder;
use Endroid\QrCode\Encoding\Encoding;
use Endroid\QrCode\ErrorCorrectionLevel\ErrorCorrectionLevelHigh;
use Endroid\QrCode\Label\Alignment\LabelAlignmentCenter;
use Endroid\QrCode\Label\Font\NotoSans;
use Endroid\QrCode\RoundBlockSizeMode\RoundBlockSizeModeMargin;
use Endroid\QrCode\Writer\PngWriter;

$result = Builder::create()
    ->writer(new PngWriter())
    ->writerOptions([])
    ->data('Custom QR code contents')
    ->encoding(new Encoding('UTF-8'))
    ->errorCorrectionLevel(new ErrorCorrectionLevelHigh())
    ->size(300)
    ->margin(10)
    ->roundBlockSizeMode(new RoundBlockSizeModeMargin())
    ->logoPath(__DIR__.'/assets/symfony.png')
    ->labelText('This is the label')
    ->labelFont(new NotoSans(20))
    ->labelAlignment(new LabelAlignmentCenter())
    ->validateResult(false)
    ->build();
```

## Usage: without using the builder

```php
use Endroid\QrCode\Color\Color;
use Endroid\QrCode\Encoding\Encoding;
use Endroid\QrCode\ErrorCorrectionLevel\ErrorCorrectionLevelLow;
use Endroid\QrCode\QrCode;
use Endroid\QrCode\Label\Label;
use Endroid\QrCode\Logo\Logo;
use Endroid\QrCode\RoundBlockSizeMode\RoundBlockSizeModeMargin;
use Endroid\QrCode\Writer\PngWriter;
use Endroid\QrCode\Writer\ValidationException;

$writer = new PngWriter();

// Create QR code
$qrCode = QrCode::create('Life is too short to be generating QR codes')
    ->setEncoding(new Encoding('UTF-8'))
    ->setErrorCorrectionLevel(new ErrorCorrectionLevelLow())
    ->setSize(300)
    ->setMargin(10)
    ->setRoundBlockSizeMode(new RoundBlockSizeModeMargin())
    ->setForegroundColor(new Color(0, 0, 0))
    ->setBackgroundColor(new Color(255, 255, 255));

// Create generic logo
$logo = Logo::create(__DIR__.'/assets/symfony.png')
    ->setResizeToWidth(50);

// Create generic label
$label = Label::create('Label')
    ->setTextColor(new Color(255, 0, 0));

$result = $writer->write($qrCode, $logo, $label);

// Validate the result
$writer->validateResult($result, 'Life is too short to be generating QR codes');
```

## Usage: working with results

```php

// Directly output the QR code
header('Content-Type: '.$result->getMimeType());
echo $result->getString();

// Save it to a file
$result->saveToFile(__DIR__.'/qrcode.png');

// Generate a data URI to include image data inline (i.e. inside an <img> tag)
$dataUri = $result->getDataUri();
```

![QR Code](https://endroid.nl/qr-code/default/Life%20is%20too%20short%20to%20be%20generating%20QR%20codes)

### Writer options

Some writers provide writer options. Each available writer option is can be
found as a constant prefixed with WRITER_OPTION_ in the writer class.

* `PdfWriter`
  * `unit`: unit of measurement (default: mm)
  * `fpdf`: PDF to place the image in (default: new PDF)
  * `x`: image offset (default: 0)
  * `y`: image offset (default: 0)
* `PngWriter`
  * `compression_level`: compression level (0-9, default: -1 = zlib default)
* `SvgWriter`
  * `block_id`: id of the block element for external reference (default: block)
  * `exclude_xml_declaration`: exclude XML declaration (default: false)
  * `exclude_svg_width_and_height`: exclude width and height (default: false)
  * `force_xlink_href`: forces xlink namespace in case of compatibility issues (default: false)
* `WebPWriter`
  * `quality`: image quality (0-100, default: 80)

You can provide any writer options like this.

```php
use Endroid\QrCode\Writer\SvgWriter;

$builder->setWriterOptions([
    SvgWriter::WRITER_OPTION_EXCLUDE_XML_DECLARATION => true
]);
```

### Encoding

If you use a barcode scanner you can have some troubles while reading the
generated QR codes. Depending on the encoding you chose you will have an extra
amount of data corresponding to the ECI block. Some barcode scanner are not
programmed to interpret this block of information. To ensure a maximum
compatibility you can use the `ISO-8859-1` encoding that is the default
encoding used by barcode scanners (if your character set supports it,
i.e. no Chinese characters are present).

### Round block size mode

By default block sizes are rounded to guarantee sharp images and improve
readability. However some other rounding variants are available.

* `margin (default)`: the size of the QR code is shrunk if necessary but the size
  of the final image remains unchanged due to additional margin being added.
* `enlarge`: the size of the QR code and the final image are enlarged when
  rounding differences occur.
* `shrink`: the size of the QR code and the final image are
  shrunk when rounding differences occur.
* `none`: No rounding. This mode can be used when blocks don't need to be rounded
  to pixels (for instance SVG).

## Readability

The readability of a QR code is primarily determined by the size, the input
length, the error correction level and any possible logo over the image so you
can tweak these parameters if you are looking for optimal results. You can also
check $qrCode->getRoundBlockSize() value to see if block dimensions are rounded
so that the image is more sharp and readable. Please note that rounding block
size can result in additional padding to compensate for the rounding difference.
And finally the encoding (default UTF-8 to support large character sets) can be
set to `ISO-8859-1` if possible to improve readability.

## Validating the generated QR code

If you need to be extra sure the QR code you generated is readable and contains
the exact data you requested you can enable the validation reader, which is
disabled by default. You can do this either via the builder or directly on any
writer that supports validation. See the examples above.

Please note that validation affects performance so only use it in case of problems.

## Symfony integration

The [endroid/qr-code-bundle](https://github.com/endroid/qr-code-bundle)
integrates the QR code library in Symfony for an even better experience.

* Configure your defaults (like image size, default writer etc.)
* Support for multiple configurations and injection via aliases
* Generate QR codes for defined configurations via URL like /qr-code/<config>/Hello
* Generate QR codes or URLs directly from Twig using dedicated functions
 
Read the [bundle documentation](https://github.com/endroid/qr-code-bundle)
for more information.

## Versioning

Version numbers follow the MAJOR.MINOR.PATCH scheme. Backwards compatibility
breaking changes will be kept to a minimum but be aware that these can occur.
Lock your dependencies for production and test your code when upgrading.

## License

This bundle is under the MIT license. For the full copyright and license
information please view the LICENSE file that was distributed with this source code.