Question

I am trying to resize an image in wordpress using this code

if ( function_exists( 'add_image_size' ) ) {
    add_image_size( 'My Thumbnail', 300, 100, true ); //(cropped)
}

add_filter('image_size_names_choose', 'my_image_sizes');
function my_image_sizes($sizes) {
        $addsizes = array(
                "new-size" => __( "New Size")
                );
        $newsizes = array_merge($sizes, $addsizes);
        return $newsizes;
}

but the radio button for the New Size is disabled on the media uploader so its uncheckable.
I am using wordpress version 3.4.2.Why does it fail?.

Answer 1

I discovered that i hadn’t installed php-gd so i did it in ubuntu like

sudo apt-get install php5-gd

then added this code in the functions.php

if ( function_exists( 'add_image_size' ) ) {
    add_image_size( 'new-size', 300, 100, true ); //(cropped)
}

add_filter('image_size_names_choose', 'my_image_sizes');
function my_image_sizes($sizes) {
        $addsizes = array(
                "new-size" => __( "New Size")
                );
        $newsizes = array_merge($sizes, $addsizes);
        return $newsizes;
}

and it worked.