ImageFormatReader: add iamge format readers

inc/Service/Media/GdImageFormatReader.php

@@ -0,0 +1,18 @@
+<?php
+namespace Vichan\Service\Media;
+
+
+class GdImageFormatReader implements ImageFormatReader {
+	/**
+	 * getimagesize() is agnostic of any image metadata.
+	 * If e.g. the Exif Orientation flag is set to a value which rotates the image by 90 or 270 degress, index 0 and 1
+	 * are swapped, i.e. the contain the height and width, respectively.
+	 */
+	public function getSizes(string $file_path): array {
+		$ret = \getimagesize($file_path);
+		if ($ret === false) {
+			throw new \RuntimeException("Could not read image sizes of '$file_path'");
+		}
+		return $ret;
+	}
+}

inc/Service/Media/ImageFormatReader.php

@@ -0,0 +1,11 @@
+<?php
+namespace Vichan\Service\Media;
+
+
+interface ImageFormatReader {
+	/**
+	 * @param string $file_path Image file path.
+	 * @return array An array with width and height.
+	 */
+	public function getSizes(string $file_path): array;
+}

inc/Service/Media/MagickImageFormatReader.php

@@ -0,0 +1,33 @@
+<?php
+namespace Vichan\Service\Media;
+
+
+class MagickImageFormatReader implements ImageFormatReader {
+	private string $prefix;
+
+	public static function createImageMagickReader(): MagickImageFormatReader {
+		return new self('');
+	}
+
+	public static function createGraphicsMagickReader(): MagickImageFormatReader {
+		return new self('gm ');
+	}
+
+	private function __construct(string $prefix) {
+		$this->prefix = $prefix;
+	}
+
+	public function getSizes(string $file_path): array {
+		$arg = escapeshellarg("$file_path[0]");
+		$ret_exec = shell_exec_error("{$this->prefix}identify -format \"%w %h\" $arg");
+
+		if (!\is_string($ret_exec)) {
+			throw new \RuntimeException("Error while executing identify");
+		}
+		$ret_match = \preg_match('/^(\d+) (\d+)$/', $ret_exec, $m);
+		if (!$ret_match) {
+			throw new \RuntimeException("Could not parse identify output");
+		}
+		return [ $m[1], $m[2] ];
+	}
+}