My plugin creates custom widgets, How can I programatically add them to existing sidebar widget areas?

Question

OK, I can create the code to add custom widgets to the widgets manager. Check.

My next challenge is to, in the same plugin, during activation, check for the existence of my theme, and if active, pre-populate the widget areas with the custom widgets I've just created.

I hope this makes sense. If I can do this, it will save a ton of time from configuring (and explaining how to configure) my default theme setup, which relies heavily on custom widgets. Things like an optin email form, custom slider widget, etc...

Thanks in advance if anyone can help me here.

Here are my theme's default sidebars...

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'name' => 'Home Sidebar',
        'id' => 'home-sidebar-widget',
    ));

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'name' => 'Home Header Area',
        'id' => 'home-header-widget',
    ));

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'name' => 'Inside Header Area',
        'id' => 'inside-header-widget',
    ));

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'name' => 'Home Footer Area',
        'id' => 'home-footer-widget',
    ));

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'name' => 'Inside Footer Area',
        'id' => 'inside-footer-widget',
    ));

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'name' => 'Inside Sidebar',
        'id' => 'inside-sidebar-widget',
    ));

Answer 1

Sidebars are registered in the option 'sidebars_widgets'. To see what’s in and what not, try this:

add_action( 'wp_footer', 'show_my_sidebars' );

function show_my_sidebars()
{
    $sw = get_option( 'sidebars_widgets' );
    print '<pre>' . htmlspecialchars( print_r( $sw, TRUE ) ) . '</pre>';
}

Sample output:

Array 
(
[sidebar-footer-left] => Array 
( 
[0] => archives-3 
)
[sidebar-footer-right] => Array 
( 
[0] => recent-comments-3 
)[array_version] => 3 
)

So check the option in per activation hook and insert your widgets if they aren’t already in there.

And stop using if ( function_exists('register_sidebar') ). Do you really want to support four years old WP versions?