This is an abstract class that every payment button widget will inherit from.
Because every payment button is, after all, a button, this class inherits from Widget_Button
in order to keep it as close as possible to the default button widget ( and of course to avoid unnecessary code duplications ).
This class is responsible for creating the universal sections && controls of the payment buttons. In addition, it has some abstract functions to make sure that every payment button will work as it should.
Use the register_account_section() function in order to add the API controls for your payment provider.
See widgets/paypal-button.php for reference.
Use the register_sandbox_controls() function if you need more sandbox controls than the default sandbox_mode switch.
By default, they will be registered just after the switch.
Use the after_product_type() function when you need to add something after the product type select-box. This is useful when you want to add a
note to the user.
See widgets/paypal-button.php for reference.
The currencies list defaults to PayPal's supported currencies, so when you extend it, make sure that this list is also supported in the payment method you are using, or override it with the appropriate one.
The get_custom_message( $id ) returns a custom message that is set in the Custom Messages control under the Additional Settings section, and will default to
the default errors messages that returned from get_default_error_messages().
You can override this function in order to extend the default custom messages. Don't forget to extend the register_settings_section() and register_messages_style_section() functions as well.
You should use is_sandbox() to determine if it's on sandbox mode.