From e47623cdf6ca68a459575d0134d5f1618c43156f Mon Sep 17 00:00:00 2001
From: Zankaria <zankaria.auxa@mailu.io>
Date: Sat, 22 Mar 2025 01:40:30 +0100
Subject: [PATCH] GdMediaHandler.php: correct exif orientation if possible

---
 inc/Service/Media/GdMediaHandler.php | 44 ++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 5 deletions(-)

diff --git a/inc/Service/Media/GdMediaHandler.php b/inc/Service/Media/GdMediaHandler.php
index 6defcd05..e51200ba 100644
--- a/inc/Service/Media/GdMediaHandler.php
+++ b/inc/Service/Media/GdMediaHandler.php
@@ -1,7 +1,7 @@
 <?php
 namespace Vichan\Service\Media;
 
-use Vichan\Data\ThumbGenerationResult;
+use Vichan\Data\{Exif, ThumbGenerationResult};
 use Vichan\Functions\{Fs, Mime};
 
 
@@ -13,6 +13,7 @@ class GdMediaHandler implements MediaHandler {
 
 
 	private bool $strip_redraw;
+	private ImageMetadataReader $image_metadate_reader;
 
 
 	private static function imageCreateFrom(string $file, string $mime): mixed {
@@ -33,7 +34,7 @@ class GdMediaHandler implements MediaHandler {
 		return false;
 	}
 
-	public static function imageSaveTo(mixed $gd, string $file, string $mime) {
+	private static function imageSaveTo(mixed $gd, string $file, string $mime) {
 		// Somebody should tune the quality and speed values...
 		// Won't be me.
 		switch ($mime) {
@@ -53,8 +54,7 @@ class GdMediaHandler implements MediaHandler {
 		return false;
 	}
 
-	private static function createCanvas(string $mime, int $width, int $height) {
-		$gd = \imagecreatetruecolor($width, $height);
+	private static function enableTransparency(mixed $gd, string $mime) {
 		switch ($mime) {
 			case 'image/png':
 				\imagecolortransparent($gd, \imagecolorallocatealpha($gd, 0, 0, 0, 0));
@@ -66,6 +66,11 @@ class GdMediaHandler implements MediaHandler {
 				\imagesavealpha($gd, true);
 				break;
 		}
+	}
+
+	private static function createCanvas(string $mime, int $width, int $height) {
+		$gd = \imagecreatetruecolor($width, $height);
+		self::enableTransparency($gd, $mime);
 		return $gd;
 	}
 
@@ -130,8 +135,9 @@ class GdMediaHandler implements MediaHandler {
 	 * @param bool $strip_redraw If the EXIF metadata should be stripped by redrawing it.
 	 *                           May cause the loss of color profiles. Orientation is still handled.
 	 */
-	public function __construct(bool $strip_redraw) {
+	public function __construct(bool $strip_redraw, ImageMetadataReader $image_metadate_reader) {
 		$this->strip_redraw = $strip_redraw;
+		$this->image_metadate_reader = $image_metadate_reader;
 	}
 
 	public function supportsMime(string $mime): bool {
@@ -145,10 +151,38 @@ class GdMediaHandler implements MediaHandler {
 	}
 
 	public function openHandle(string $file_path, string $file_mime, int $file_kind): mixed {
+		$metadata = $this->image_metadate_reader->getMetadata($file_path);
+		if ($file_mime !== $file_mime) {
+			throw new \RuntimeException("Mime mismatch on '$file_path'");
+		}
+
 		$gd = self::imageCreateFrom($file_path, $file_mime);
 		if ($gd === false) {
 			throw new \RuntimeException("Could not open '$file_path'");
 		}
+
+		// Fix the orientation once and for all.
+		if ($metadata->exif_orientation !== null) {
+			$degrees = Exif::exifOrientationDegrees($metadata->exif_orientation);
+			$flipped = Exif::exifOrientationIsFlipped($metadata->exif_orientation);
+
+			if ($degrees !== 0) {
+				self::enableTransparency($gd, $file_mime);
+				$gd_other = \imagerotate($gd, $degrees, \imagecolorallocatealpha($gd, 0, 0, 0, 127));
+				\imagedestroy($gd);
+				if ($gd_other === false) {
+					throw new \RuntimeException("Error while correcting rotation of '$file_path'");
+				}
+				$gd = $gd_other;
+			}
+
+			if ($flipped) {
+				if (!\imageflip($gd, \IMG_FLIP_HORIZONTAL)) {
+					throw new \RuntimeException("Error while correcting flipping of '$file_path'");
+				}
+			}
+		}
+
 		return [ $gd, $file_path, $file_mime, $file_kind ];
 	}