wp_get_webp_info( string $filename )

Source

File: wp-includes/media.php

function wp_get_webp_info( $filename ) {
	$width  = false;
	$height = false;
	$type   = false;

	if ( 'image/webp' !== wp_get_image_mime( $filename ) ) {
		return compact( 'width', 'height', 'type' );
	}

	try {
		$handle = fopen( $filename, 'rb' );
		if ( $handle ) {
			$magic = fread( $handle, 40 );
			fclose( $handle );

			// Make sure we got enough bytes.
			if ( strlen( $magic ) < 40 ) {
				return compact( 'width', 'height', 'type' );
			}

			// The headers are a little different for each of the three formats.
			// Header values based on WebP docs, see https://developers.google.com/speed/webp/docs/riff_container.
			switch ( substr( $magic, 12, 4 ) ) {
				// Lossy WebP.
				case 'VP8 ':
					$parts  = unpack( 'v2', substr( $magic, 26, 4 ) );
					$width  = (int) ( $parts[1] & 0x3FFF );
					$height = (int) ( $parts[2] & 0x3FFF );
					$type   = 'lossy';
					break;
				// Lossless WebP.
				case 'VP8L':
					$parts  = unpack( 'C4', substr( $magic, 21, 4 ) );
					$width  = (int) ( $parts[1] | ( ( $parts[2] & 0x3F ) << 8 ) ) + 1;
					$height = (int) ( ( ( $parts[2] & 0xC0 ) >> 6 ) | ( $parts[3] << 2 ) | ( ( $parts[4] & 0x03 ) << 10 ) ) + 1;
					$type   = 'lossless';
					break;
				// Animated/alpha WebP.
				case 'VP8X':
					// Pad 24-bit int.
					$width = unpack( 'V', substr( $magic, 24, 3 ) . "\x00" );
					$width = (int) ( $width[1] & 0xFFFFFF ) + 1;
					// Pad 24-bit int.
					$height = unpack( 'V', substr( $magic, 27, 3 ) . "\x00" );
					$height = (int) ( $height[1] & 0xFFFFFF ) + 1;
					$type   = 'animated-alpha';
					break;
			}
		}
	} catch ( Exception $e ) {
	}

	return compact( 'width', 'height', 'type' );
}