Magento - Add custom Filter options (dropdown) for payment method

Question

I have a module that adds a payment method column to the Sales > Orders grid.

$this->addColumn('method', array(
                'header' => Mage::helper('sales')->__('Payment<br />Method'),
                'index' => 'method',
                'renderer'  => 'Artizara_Ordergridadditions_Block_Catalog_Product_Renderer_Payment',
                'filter_index' => 'sfop.method', // refers to a declaration above
                type'  => 'options',
                'options' => array(0=>'Option 1',1=>'Option2'), // how would I get the keys to match to the renderer options???
        ));

Renderer code (below):

public function render(Varien_Object $row) {
    $value =  $row->getData($this->getColumn()->getIndex());

    switch ($value) {
    case 'authorizenet':
        $value = 'Credit Card (Authorize.net)';
        $span = '';
        break;
    case 'paypal_express':
        $value = 'Paypal Express';
        $span = '';
        break;
    case 'checkmo':
        $value = 'Check/Money Order';
        $span = '';
        break;
    case 'free':
        $value = 'No Payment Required';
        $span = '';
        break;
    default:
        $value = 'Unknow Payment Method';
        $span = 'style="color:red;"';
    }

    return '<span ' . $span . '>' . $value . '</span>';
}

Simply want to be able to make a dropdown prepopulated with the renderer options for filtering in the grid.

Note: If I add the text field method for filtering, you have to put in the original keys from the database (e.g. - checkmo, paypal_express, authorizenet, etc).

I'd like to be able to show the renderer values for each in the dropdown...(how)?

EDIT 7/20/12

I've tried two following ways below but not working yet...

'options' => array(
                    array('value' => 'authorizenet', 'label' => 'Credit Card (Authorize.net)'),
                    array('value' => 'paypal_express', 'label' => 'Paypal Express'),
                    array('value' => 'checkmo', 'label' => 'Check/Money Order'),
                    array('value' => 'free', 'label' => 'No Payment Required'),
                ),

Just gets me a dropdown populated with 4 options as follows:

Array
Array
Array
Array

I've tried it also like this:

'options' => array(
                    array => ('value' => 'authorizenet', 'label' => 'Credit Card (Authorize.net)'),
                    array => ('value' => 'paypal_express', 'label' => 'Paypal Express'),
                    array => ('value' => 'checkmo', 'label' => 'Check/Money Order'),
                    array => ('value' => 'free', 'label' => 'No Payment Required'),
                ),

But I get an error:

Parse error: syntax error, unexpected T_DOUBLE_ARROW, expecting '('

Answer 1

Use an option hash with the values you use in your renderer :

'options' => array(
   'authorizenet' => 'Credit Card (Authorize.net)',
   [..]
)

On a side note, you may be interested by the Enhanced Admin Grids extension I develop (page on Magento Connect), the latest version available on github has brought a custom columns system that allows to add new columns without rewrites and with quite some possibilities.
And as a basis, it comes with a payment method column for the orders grid.