Changeset 65367 for trunk/src/wp-admin/includes/image-edit.php

Timestamp:

11/10/2026 01:33:13 AM (23 hours ago)

Author:

desrosj

Message:

Media: Use imageflip() to flip images with GD.

WP_Image_Editor_GD::flip() and the deprecated _flip_image_resource() mirrored images by copying them with imagecopyresampled() and negative source dimensions. With the GD 2.4.0 bundled in PHP 8.6, this produces an all-black image. It affects flips in the image editor, and also JPEG uploads with an EXIF orientation of 2, 3 or 4, which WP_Image_Editor::maybe_exif_rotate() flips.

Both functions now flip the image in place with imageflip(), and the output stays the same as before. Palette images are still converted to truecolor, alpha blending is turned off and alpha saving on, and the resolution and interlacing are reset to GD's defaults of 96 DPI and off. This matches what rotate(), crop() and resize() produce. Whether every operation should keep the source image's resolution and interlacing will be decided in a follow-up ticket.

When no valid image is loaded, flip() now returns a WP_Error instead of throwing a TypeError.

Props sanjith2023, rumancodes, arshidkv12, dhruvang21, abhishekfdd, desrosj.
Fixes #66113.

File:

• trunk/src/wp-admin/includes/image-edit.php (modified) (2 diffs)

trunk/src/wp-admin/includes/image-edit.php

@@ -566 +566 @@
  *
  * @since 2.9.0
+ * @since 7.2.0 Switched to using imageflip() instead of imagecopyresampled() with negative dimensions.
  * @deprecated 3.5.0 Use WP_Image_Editor::flip()
  * @see WP_Image_Editor::flip()
@@ -578 +579 @@
         _deprecated_function( __FUNCTION__, '3.5.0', 'WP_Image_Editor::flip()' );
 
-        $w   = imagesx( $img );
-        $h   = imagesy( $img );
-        $dst = wp_imagecreatetruecolor( $w, $h );
-
-        if ( is_gd_image( $dst ) ) {
-                $sx = $vert ? ( $w - 1 ) : 0;
-                $sy = $horz ? ( $h - 1 ) : 0;
-                $sw = $vert ? -$w : $w;
-                $sh = $horz ? -$h : $h;
-
-                if ( imagecopyresampled( $dst, $img, 0, 0, $sx, $sy, $w, $h, $sw, $sh ) ) {
-                        if ( PHP_VERSION_ID < 80000 ) { // imagedestroy() has no effect as of PHP 8.0.
-                                imagedestroy( $img );
-                        }
-
-                        $img = $dst;
-                }
-        }
+        if ( ! is_gd_image( $img ) ) {
+                return $img;
+        }
+
+        // Keep returning a truecolor image, like the previous implementation did. imagewebp() rejects palette images.
+        if ( ! imageistruecolor( $img ) && ! imagepalettetotruecolor( $img ) ) {
+                return $img;
+        }
+
+        // Match the alpha settings of the previous implementation's copy, including when no axis is flipped.
+        imagealphablending( $img, false );
+        imagesavealpha( $img, true );
+
+        /*
+         * imageflip() changes the image in place, so the image keeps its current resolution and interlace setting.
+         * _rotate_image_resource() and _crop_image_resource() copy into a new image, which resets them to GD's defaults:
+         * 96 DPI and no interlacing. Reset them here too, so a flip gives the same result as the other edits.
+         *
+         * @link https://core.trac.wordpress.org/ticket/66113
+         */
+        imageresolution( $img, 96, 96 );
+        imageinterlace( $img, 0 );
+
+        if ( ! $horz && ! $vert ) {
+                return $img;
+        }
+
+        if ( $horz && $vert ) {
+                $mode = IMG_FLIP_BOTH;
+        } elseif ( $horz ) {
+                $mode = IMG_FLIP_VERTICAL;
+        } else {
+                $mode = IMG_FLIP_HORIZONTAL;
+        }
+
+        imageflip( $img, $mode );
 
         return $img;