This is the second post in the Writing your First Extension series. You can see the full article here: Writing Your First Extension.
Menu items are added via the IPN object provided at extension load time. You add menu items by providing an implementation of IMenuItems. Here is a very simple implementation supporting a single item:
class Menu : public extensions::IMenuItems
{
public:
Menu()
{
memset(&item1, 0, sizeof(item1));
item1.Handler = &MyExtensionFunc;
item1.Title = L"Hello World";
// item1.Type = extensions::miItem;
// item1.UserData = 0;
}
/**
* Get the number of MenuItem instances that can be retrieved.
*/
virtual int GetItemCount() const
{
return 1;
}
/**
* Get an individual MenuItem instance by index.
*/
virtual extensions::MenuItem& GetItem(int index) const
{
if (index == 0)
return const_cast<extensions ::menuitem&>(item1);
}
private:
extensions::MenuItem item1;
};
This very simple implementation adds a single menu item called "Hello World". When the item is selected, the MyExtensionFunc method will be executed by PN.
It might seem like a fair bit of code to add a menu item, but in the next SDK version I’ll provide a general-purpose helper to make this easy. The reason for the interface is to make it easy for you to provide sub-menus. MenuItem instances can contain child items by changing Type to miSubItem and filling in the SubItems member with another instance implementing IMenuItems.
The handler method looks like this:
void MyExtensionFunc(extensions::cookie_t /*cookie*/)
{
g_PN->GetGlobalOutputWindow()->AddToolOutput("Hello World!");
g_PN->ShowOutput();
}
Once you have your handler and IMenuItems implementation, you just need to tell PN about your items. In your init function you need something like this:
bool __stdcall pn_init_extension(int iface_version, extensions::IPN* pn)
{
if(iface_version != PN_EXT_IFACE_VERSION)
return false;
g_PN = pn;
Menu menu;
pn->AddPluginMenuItems(&menu);
return true;
}
Now you have Programmer’s Notepad presenting your commands in the menu and can handle their selection. Next time we’ll look at the other events PN lets you attach to.
