changing size image within the content

Question

I'm trying to get my images inside the post may larger than 800px ;

For this I took a function that resizes image here and I'm trying to create a function to my thumb inside the post come with size that put to resize , more the problem is that is not resizing

function resizeThumb($html, $post_id, $post_thumbnail_id, $size, $attr){
$image = get_post_thumbnail_id();
$thumb = vt_resize( $image, '', 850, 600, true );
$html = '<img src="' . $thumb[url] . '" alt="' . $alt . '" class="img-responsive" />';
return $html;
} 
add_filter( 'post_thumbnail_html', 'resizeThumb', 10, 5 );

Could anyone help me in this code please ?

Answer 1

Have you looked at using add_image_size? Check it out here.

It will allow you to crop images various ways. It will also allow you to use the standard the_post_thumbnail and pass it your custom image size when you go to output this on the front-end.

I also just noticed that you said inside the content. One way would be to take the above function and wrap it into a shortcode. Then you could pass the shortcode the needed arguments to output the correct size image.