Loading an image in custom WordPress plugin - php

Question

I created my custom plugin and want to add custom logo, but somehow it keeps redirecting me to wrong dir, this is error I get:
GET http://localhost/logo.png 404 (Not Found)
Here is what I tried so far:
$plugin_dir = str_replace( $base_url, ABSPATH, $plugins_url );
$plugin_dir = plugins_url();
$plugin_dir = plugin_dir_path( __FILE__ );
$plugin_dir = WP_CONTENT_DIR . '/plugins';
$plugin_dir = plugins_url( '/', __FILE__ );
Here is my add action:
function kalbos_modifymenu() {
add_menu_page('Kalbos', //page title
'Kalbos', //menu title
'manage_options', //capabilities
'kalbos_list', //menu slug
'kalbos_list', //function
$plugin_dir . 'logo.png',
'5'
);
}
add_action('admin_menu','kalbos_modifymenu');
However icon is working when i move my logo to wp-admin/logo.png dir because thats where my logo path goes even if i set it go to my plugin folder

Answer 1

plugins_url will (my emphasis):
Retrieves the absolute URL to the plugins or mu-plugins directory (without the trailing slash) or, when using the $path argument, to a specific file under that directory. You can either specify the $path argument as a hardcoded path relative to the plugins or mu-plugins directory, or conveniently pass __FILE__ as the second argument to make the $path relative to the parent directory of the current PHP script file.
So, the following will point exactly to your plugin directory with an ending slash:
$plugin_dir = plugins_url( '/', __FILE__ );
// results in http://localhost/wp-content/plugins/YOUR_PLUGIN/
And to target the logo, use:
$plugin_dir . 'logo.png'
Another example, to make a shortcut to your images folder:
$plugin_img = plugins_url( '/images/', __FILE__ );
// results in http://localhost/wp-content/plugins/YOUR_PLUGIN/images/

Answer 2

Try to add an other slash to /plugins like this: /plugins/ and also close your quotes on the same line. At the moment you have it like 'plugins; but the correct is '/plugins';