Ticket #24380: 24380.4.diff

src/wp-includes/class-wp-image-editor-gd.php

@@ -384 +384 @@
                                 imagetruecolortopalette( $image, false, imagecolorstotal( $image ) );
 
                         /*
-                         * Invert the 1-100 quality scale and constrain it to 0-9,
-                         * as per imagepng()'s peculiar quality parameter.
+                         * Convert quality value (1-100) to the 0-9 scale needed for GD.
+                         *  0 = no compression
+                         *  1 = worst compression
+                         *  9 = best compression
+                         * -1 = use default zlib compression
                          */
-                        $compression_level = floor( ( 101 - $this->quality ) * 0.09 );
+                        $compression_level = floor( $this->quality / 10 );
 
+                        if ( $compression_level > 9 ) {
+                                $compression_level = 9;
+                        } elseif ( -1 != $compression_level && $compression_level < 0 ) {
+                                $compression_level = 0;
+                        }
                         if ( ! $this->make_image( $filename, 'imagepng', array( $image, $filename, $compression_level ) ) ) {
                                 return new WP_Error( 'image_save_error', __('Image Editor Save Failed') );
                         }

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

@@ -241 +241 @@
                                         $this->quality = $this->default_quality;
                                 }
                         }
-                }
+                } elseif ( 'image/png' == $this->mime_type ) {
+                        /**
+                         * Filter the PNG compression level.
+                         *
+                         * @since 4.0.0
+                         *
+                         * @param int $quality Compression level. Falls between 1 (worst compression)
+                         *                     and 100 (best but slowest compression).
+                         */
+                        $quality = apply_filters( 'png_compression_level', $quality );
+                }
 
                 return $this->quality;
         }