wp-includes/class-wp-image-editor-gd.php:607Returns stream of current image.
$mime_typestringoptionalnullbool public function stream( $mime_type = null ) { list( $filename, $extension, $mime_type ) = $this->get_output_format( null, $mime_type ); switch ( $mime_type ) { case 'image/png': header( 'Content-Type: image/png' ); return imagepng( $this->image ); case 'image/gif': header( 'Content-Type: image/gif' ); return imagegif( $this->image ); case 'image/webp': if ( function_exists( 'imagewebp' ) ) { header( 'Content-Type: image/webp' ); return imagewebp( $this->image, null, $this->get_quality() ); } else { // Fall back to JPEG. header( 'Content-Type: image/jpeg' ); return imagejpeg( $this->image, null, $this->get_quality() ); } case 'image/avif': if ( function_exists( 'imageavif' ) ) { header( 'Content-Type: image/avif' ); return imageavif( $this->image, null, $this->get_quality() ); } // Fall back to JPEG. default: header( 'Content-Type: image/jpeg' ); return imagejpeg( $this->image, null, $this->get_quality() ); } }Introduced in 3.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-image-editor-gd.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.