Changeset 56271 for trunk/src/wp-includes/class-wp-image-editor-imagick.php

Timestamp:

07/19/2023 10:33:47 PM (14 months ago)

Author:

antpb

Message:

Media: Adjust PDF upload handling to remove non-opaque alpha channels from previews.

Previously, Imagick uploads of PDF files with non-opaque alpha channels would result in a black background replacing alpha in the generated thumbnail. This patch adds a remove_pdf_alpha_channel() function in the Imagick classes to use a white background instead.

Props gitlost, joemcgill, joedolson, launchinteractive, emirpprime, mwtsn, ceer, maysi, madejackson, 6adminit, costdev, oglekler.
Fixes #39216.

File:

• trunk/src/wp-includes/class-wp-image-editor-imagick.php (modified) (2 diffs)

trunk/src/wp-includes/class-wp-image-editor-imagick.php

@@ -169 +169 @@
             }
 
+            if ( 'pdf' === $file_extension ) {
+                $this->remove_pdf_alpha_channel();
+            }
+
             $this->mime_type = $this->get_mime_type( $this->image->getImageFormat() );
         } catch ( Exception $e ) {
@@ -753 +757 @@
 
     /**
+     * Removes PDF alpha after it's been read.
+     *
+     * @since 6.4.0
+     */
+    protected function remove_pdf_alpha_channel() {
+        $version = Imagick::getVersion();
+        // Remove alpha channel if possible to avoid black backgrounds for Ghostscript >= 9.14. RemoveAlphaChannel added in ImageMagick 6.7.5.
+        if ( $version['versionNumber'] >= 0x675 ) {
+            try {
+                // Imagick::ALPHACHANNEL_REMOVE mapped to RemoveAlphaChannel in PHP imagick 3.2.0b2.
+                $this->image->setImageAlphaChannel( defined( 'Imagick::ALPHACHANNEL_REMOVE' ) ? Imagick::ALPHACHANNEL_REMOVE : 12 );
+            } catch ( Exception $e ) {
+                return new WP_Error( 'pdf_alpha_process_failed', $e->getMessage() );
+            }
+        }
+    }
+
+    /**
      * @since 3.5.0
      * @since 6.0.0 The `$filesize` value was added to the returned array.