Source
File: wp-includes/class-wp-image-editor-gd.php
public function crop( $src_x, $src_y, $src_w, $src_h, $dst_w = null, $dst_h = null, $src_abs = false ) {
// If destination width/height isn't specified,
// use same as width/height from source.
if ( ! $dst_w ) {
$dst_w = $src_w;
}
if ( ! $dst_h ) {
$dst_h = $src_h;
}
$dst = wp_imagecreatetruecolor( $dst_w, $dst_h );
if ( $src_abs ) {
$src_w -= $src_x;
$src_h -= $src_y;
}
if ( function_exists( 'imageantialias' ) ) {
imageantialias( $dst, true );
}
imagecopyresampled( $dst, $this->image, 0, 0, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h );
if ( is_resource( $dst ) ) {
imagedestroy( $this->image );
$this->image = $dst;
$this->update_size();
return true;
}
return new WP_Error( 'image_crop_error', __( 'Image crop failed.' ), $this->file );
}