Prevent transparency loss in AVIF by falling back to WebP on older ImageMagick #2245
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| <?php | ||
| /** | ||
| * WordPress Image Editor Class for Image Manipulation through Imagick | ||
| * for transparency detection | ||
| * | ||
| * @package webp-uploads | ||
| * | ||
| * @since n.e.x.t | ||
| */ | ||
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| // @codeCoverageIgnoreStart | ||
| if ( ! defined( 'ABSPATH' ) ) { | ||
| exit; // Exit if accessed directly. | ||
| } | ||
| // @codeCoverageIgnoreEnd | ||
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| if ( class_exists( 'WebP_Uploads_Image_Editor_Imagick_Base' ) ) { | ||
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| /** | ||
| * WordPress Image Editor Class for Image Manipulation through Imagick | ||
| * for transparency detection. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @see WP_Image_Editor | ||
| */ | ||
| class WebP_Uploads_Image_Editor_Imagick extends WebP_Uploads_Image_Editor_Imagick_Base { | ||
| /** | ||
| * The current instance of the image editor. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @var WebP_Uploads_Image_Editor_Imagick|null $current_instance The current instance. | ||
| */ | ||
| public static $current_instance = null; | ||
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| /** | ||
| * Stores already checked images for transparency. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @var array<string, bool> Associative array with file paths as keys and transparency detection results as values. | ||
| */ | ||
| private static $checked_images = array(); | ||
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| /** | ||
| * Load the image and set the current instance. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @return WP_Error|true True on success, WP_Error on failure. | ||
| */ | ||
| public function load() { | ||
| // @phpstan-ignore-next-line -- Parent class is created via class_alias at runtime. | ||
| $result = parent::load(); | ||
| if ( ! is_wp_error( $result ) ) { | ||
| self::$current_instance = $this; | ||
| } | ||
| return $result; | ||
| } | ||
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| /** | ||
| * Get the file path of the image. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @return string The file path of the image. | ||
| */ | ||
| public function get_file(): string { | ||
| if ( property_exists( $this, 'file' ) && is_string( $this->file ) ) { | ||
| return $this->file; | ||
| } | ||
| return ''; | ||
| } | ||
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| /** | ||
| * Looks for transparent pixels in the image. | ||
| * If there are none, it returns false. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @return bool|WP_Error True or false based on whether there are transparent pixels, or an error on failure. | ||
| */ | ||
| public function has_transparency() { | ||
| if ( ! property_exists( $this, 'image' ) || ! $this->image instanceof Imagick ) { | ||
| return new WP_Error( 'image_editor_has_transparency_error_no_image', __( 'Transparency detection no image found.', 'webp-uploads' ) ); | ||
| } | ||
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| $file_path = $this->get_file(); | ||
| if ( isset( self::$checked_images[ $file_path ] ) ) { | ||
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| return self::$checked_images[ $file_path ]; | ||
| } | ||
| $transparency = false; | ||
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| try { | ||
| /* | ||
| * Check if the image has an alpha channel if false, then it can't have transparency so return early. | ||
| * | ||
| * Note that Imagick::getImageAlphaChannel() is only available if Imagick | ||
| * has been compiled against ImageMagick version 6.4.0 or newer. | ||
| */ | ||
| if ( is_callable( array( $this->image, 'getImageAlphaChannel' ) ) ) { | ||
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| if ( Imagick::ALPHACHANNEL_UNDEFINED === $this->image->getImageAlphaChannel() ) { | ||
| self::$checked_images[ $file_path ] = false; | ||
| return false; | ||
| } | ||
| } | ||
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| // Use mean and range to determine if there is any transparency more efficiently. | ||
| if ( is_callable( array( $this->image, 'getImageChannelMean' ) ) && is_callable( array( $this->image, 'getImageChannelRange' ) ) ) { | ||
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|
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| $rgb_mean = $this->image->getImageChannelMean( Imagick::CHANNEL_ALL ); | ||
| $alpha_range = $this->image->getImageChannelRange( Imagick::CHANNEL_ALPHA ); | ||
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| if ( isset( $rgb_mean['mean'], $alpha_range['maxima'] ) ) { | ||
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| $maxima = (int) $alpha_range['maxima']; | ||
| $mean = (int) $rgb_mean['mean']; | ||
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| if ( 0 > $maxima || 0 > $mean ) { | ||
| // For invalid values assume no transparency. | ||
| $transparency = false; | ||
| } elseif ( 0 === $maxima && 0 === $mean ) { | ||
| // Alpha channel is all zeros AND no RGB content indicates fully transparent image. | ||
| $transparency = true; | ||
| } elseif ( 0 === $maxima && $mean > 0 ) { | ||
| // Alpha maxima of 0 with RGB content present indicates no real alpha channel exists (hence fully opaque). | ||
| $transparency = false; | ||
| } elseif ( 0 < $maxima && 0 < $mean ) { | ||
| // Non-zero alpha values with RGB content present indicates some transparency. | ||
| $transparency = true; | ||
| } | ||
| } | ||
| } else { | ||
| // Fallback to walk through the pixels and look for transparent pixels. | ||
| $w = $this->image->getImageWidth(); | ||
| $h = $this->image->getImageHeight(); | ||
| for ( $x = 0; $x < $w; $x++ ) { | ||
| for ( $y = 0; $y < $h; $y++ ) { | ||
| $pixel = $this->image->getImagePixelColor( $x, $y ); | ||
| $color = $pixel->getColor( 2 ); | ||
| if ( $color['a'] < 255 ) { | ||
| $transparency = true; | ||
| break 2; | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| self::$checked_images[ $file_path ] = $transparency; | ||
| return $transparency; | ||
| } catch ( Exception $e ) { | ||
| /* translators: %s is the error message */ | ||
| return new WP_Error( 'image_editor_has_transparency_error', sprintf( __( 'Transparency detection failed: %s', 'webp-uploads' ), $e->getMessage() ) ); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -21,12 +21,16 @@ | |
| * @since 2.0.0 Added support for AVIF. | ||
| * @since 2.2.0 Added support for PNG. | ||
| * | ||
| * @param string|null $filename Optional. The filename. Default null. | ||
| * @return array<string, array<string>> An array of valid mime types, where the key is the mime type and the value is the extension type. | ||
| */ | ||
| function webp_uploads_get_upload_image_mime_transforms( ?string $filename = null ): array { | ||
| // Check the selected output format. | ||
| $output_format = webp_uploads_get_image_output_format(); | ||
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| if ( 'avif' === $output_format && ( ! webp_uploads_mime_type_supported( 'image/avif' ) || webp_uploads_check_image_transparency( $filename ) ) ) { | ||
| $output_format = 'webp'; | ||
| } | ||
|
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| $default_transforms = array( | ||
| 'image/jpeg' => array( 'image/' . $output_format ), | ||
|
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@@ -512,3 +516,110 @@ function webp_uploads_get_attachment_file_mime_type( int $attachment_id, string | |
| $mime_type = $filetype['type'] ?? get_post_mime_type( $attachment_id ); | ||
| return is_string( $mime_type ) ? $mime_type : ''; | ||
| } | ||
|
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| /** | ||
| * Checks if Imagick has AVIF transparency support. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @param string|null $version Optional Imagick version string. If not provided, the version will be retrieved from the Imagick class. | ||
| * @return bool True if Imagick has AVIF transparency support, false otherwise. | ||
| */ | ||
| function webp_uploads_imagick_avif_transparency_supported( ?string $version = null ): bool { | ||
| $supported = false; | ||
| $imagick_version = $version; | ||
|
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| if ( null === $imagick_version && extension_loaded( 'imagick' ) && class_exists( 'Imagick' ) ) { | ||
| $imagick_version = Imagick::getVersion(); | ||
| $imagick_version = $imagick_version['versionString']; | ||
| } | ||
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| if ( null !== $imagick_version && '' !== $imagick_version && (bool) preg_match( '/\d+(?:\.\d+)+(?:-\d+)?/', $imagick_version, $matches ) ) { | ||
| $imagick_version = $matches[0]; | ||
| } | ||
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| if ( null === $imagick_version || '' === $imagick_version ) { | ||
| return false; | ||
| } | ||
|
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| $supported = version_compare( $imagick_version, '7.0.25', '>=' ); | ||
|
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| /** | ||
| * Filters whether Imagick has AVIF transparency support. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @param bool $supported Whether AVIF transparency is supported. | ||
| */ | ||
| return (bool) apply_filters( 'webp_uploads_imagick_avif_transparency_supported', $supported ); | ||
| } | ||
|
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| /** | ||
| * Checks if an image has transparency when AVIF output is configured and AVIF transparency support is missing. | ||
| * | ||
| * @since n.e.x.t | ||
| * | ||
| * @param string|null $filename The uploaded file name. | ||
| * @return bool Whether the image has transparency. | ||
| */ | ||
| function webp_uploads_check_image_transparency( ?string $filename ): bool { | ||
| static $processed_images = array(); | ||
|
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| if ( 'avif' !== webp_uploads_get_image_output_format() || webp_uploads_imagick_avif_transparency_supported() ) { | ||
| return false; | ||
| } | ||
|
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| if ( ! class_exists( 'WebP_Uploads_Image_Editor_Imagick' ) ) { | ||
| // Calls filter `wp_image_editors` internally which makes sure `webp_uploads_set_image_editors` is called. | ||
| wp_image_editor_supports(); | ||
| } | ||
|
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| if ( ! class_exists( 'WebP_Uploads_Image_Editor_Imagick' ) ) { | ||
| return false; | ||
| } | ||
|
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| /* | ||
| * When WordPress generates subsizes (thumbnail, medium, large, etc.), the 'image_editor_output_format' | ||
| * filter is triggered without a filename parameter. In these cases, we need to retrieve the filename | ||
| * from the current editor instance that was used to load the original image. This allows us to perform | ||
| * the transparency check on the source file even when generating derivative sizes. | ||
| */ | ||
| if ( null === $filename ) { | ||
| if ( null === WebP_Uploads_Image_Editor_Imagick::$current_instance ) { | ||
| return false; | ||
| } | ||
| $file = WebP_Uploads_Image_Editor_Imagick::$current_instance->get_file(); | ||
| if ( '' === $file ) { | ||
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|
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| return false; | ||
| } | ||
| $filename = $file; | ||
| } | ||
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| if ( ! is_string( $filename ) || ! file_exists( $filename ) ) { | ||
| return false; | ||
| } | ||
|
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| if ( isset( $processed_images[ $filename ] ) ) { | ||
| return $processed_images[ $filename ]; | ||
| } | ||
| $processed_images[ $filename ] = false; | ||
|
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| $editor = wp_get_image_editor( | ||
| $filename, | ||
| array( | ||
| 'methods' => array( | ||
| 'get_file', | ||
| 'has_transparency', | ||
| ), | ||
| ) | ||
| ); | ||
|
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| if ( is_wp_error( $editor ) || ! $editor instanceof WebP_Uploads_Image_Editor_Imagick ) { | ||
| return false; | ||
| } | ||
|
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| $has_transparency = $editor->has_transparency(); | ||
| $processed_images[ $filename ] = is_wp_error( $has_transparency ) ? false : $has_transparency; | ||
|
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| return $processed_images[ $filename ]; | ||
| } | ||
|
Comment on lines
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+625
There was a problem hiding this comment. The new transparency checking functionality lacks test coverage. The repository has comprehensive test coverage for other functions (test-helper.php, test-load.php, etc.), but no tests are present for webp_uploads_imagick_avif_transparency_supported(), webp_uploads_check_image_transparency(), or the WebP_Uploads_Image_Editor_Imagick::has_transparency() method. Given the complexity and critical nature of this transparency detection logic, unit tests should be added to verify correct behavior.
Member
There was a problem hiding this comment. @copilot open a new pull request to add test coverage based on this feedback
Member
There was a problem hiding this comment. hmmm... copilot seems to have ignored me :( I'll give Claude a try locally...
Contributor
Author
There was a problem hiding this comment. I think it's because this PR uses a branch from a fork 🤔.
Contributor
Author
There was a problem hiding this comment. I’m still working on some feedback from Copilot. Once that’s done, I’ll write the tests. |
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