Use compression level instead of quality

Author: endroid

README.md

@@ -113,10 +113,32 @@ $dataUri = $result->getDataUri();
 
 ### 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;
 
-$builder->setWriterOptions([SvgWriter::WRITER_OPTION_EXCLUDE_XML_DECLARATION => true]);
+$builder->setWriterOptions([
+    SvgWriter::WRITER_OPTION_EXCLUDE_XML_DECLARATION => true
+]);
 ```
 
 ### Encoding

src/Writer/PngWriter.php

@@ -13,17 +13,17 @@
 
 final class PngWriter extends AbstractGdWriter
 {
-    public const WRITER_OPTION_QUALITY = 'quality';
+    public const WRITER_OPTION_COMPRESSION_LEVEL = 'compression_level';
 
     public function write(QrCodeInterface $qrCode, LogoInterface|null $logo = null, LabelInterface|null $label = null, array $options = []): ResultInterface
     {
-        if (!isset($options[self::WRITER_OPTION_QUALITY])) {
-            $options[self::WRITER_OPTION_QUALITY] = -1;
+        if (!isset($options[self::WRITER_OPTION_COMPRESSION_LEVEL])) {
+            $options[self::WRITER_OPTION_COMPRESSION_LEVEL] = -1;
         }
 
         /** @var GdResult $gdResult */
         $gdResult = parent::write($qrCode, $logo, $label, $options);
 
-        return new PngResult($gdResult->getMatrix(), $gdResult->getImage(), $options[self::WRITER_OPTION_QUALITY]);
+        return new PngResult($gdResult->getMatrix(), $gdResult->getImage(), $options[self::WRITER_OPTION_COMPRESSION_LEVEL]);
     }
 }