I think you are good, but you don’t need to use other functions. You have all in
File: wp-includes/media.php
For instance, you may _wp_get_image_size_from_meta to get the image dimensions, so you don’t need to use something like this:
$size = getimagesize($file);
$width = $size[0];
$height = $size[1];
$mime = $size['mime'];
To get the image dimensions and type.
On the other hand, it is not clear why not using add_image_size
File: wp-includes/media.php
256: /**
257: * Register a new image size.
258: *
259: * Cropping behavior for the image size is dependent on the value of $crop:
260: * 1. If false (default), images will be scaled, not cropped.
261: * 2. If an array in the form of array( x_crop_position, y_crop_position ):
262: * - x_crop_position accepts 'left' 'center', or 'right'.
263: * - y_crop_position accepts 'top', 'center', or 'bottom'.
264: * Images will be cropped to the specified dimensions within the defined crop area.
265: * 3. If true, images will be cropped to the specified dimensions using center positions.
266: *
267: * @since 2.9.0
268: *
269: * @global array $_wp_additional_image_sizes Associative array of additional image sizes.
270: *
271: * @param string $name Image size identifier.
272: * @param int $width Image width in pixels.
273: * @param int $height Image height in pixels.
274: * @param bool|array $crop Optional. Whether to crop images to specified width and height or resize.
275: * An array can specify positioning of the crop area. Default false.
276: */
277: function add_image_size( $name, $width = 0, $height = 0, $crop = false ) {
278: global $_wp_additional_image_sizes;
279:
280: $_wp_additional_image_sizes[ $name ] = array(
281: 'width' => absint( $width ),
282: 'height' => absint( $height ),
283: 'crop' => $crop,
284: );
285: }
You can set the $crop option to true, and create thumbnails of 16:9 ratio. This organizes your images to particular size.
You can add multiple times:
add_image_size( 'andy1', 160, 90 , true);
add_image_size( 'andy2', 1600, 900, true);
And if possible thumbnails will be created, and in a way you like.
If you work with image srcset attribute this comes handy.