One of the first things I yelled about when we were debating switching to a native Android UI for Firefox was add-on support. Using a XUL-based UI meant add-ons were free. The Mozilla platform has support for add-ons baked right in. Moving to a native UI would surely kill our ability to support add-ons, right? Wrong!
Add-ons are an important part of the Firefox story. Native UI builds of Firefox support add-ons. There are some things an add-on developer needs to be aware:
- The add-ons system is the same one used in other Mozilla applications. We did not invent a new add-on system.
- Native UI builds are considered a new application and are not add-on compatible with the XUL versions. The application ID for native UI builds is: {aa3c5121-dab2-40e2-81ca-7ea25febc110}
- There is no visible XUL in the UI, so using overlays to try to add or change UI is useless.
- There is a simple NativeWindow object that allows you to manipulate parts of the native Android UI.
- Services like
nsIPromptServiceandnsIAlertsServiceare implemented to use native Android UI. - Since overlays are useless for UI and JavaScript APIs are available for native UI, you should seriously consider just making a restartless add-on.
NativeWindow
We wanted to give add-on developers some APIs to manipulate the native Android UI, so we create a helper object called NativeWindow. The API is still young, but it gives you access to: Android Menu, Doorhanger Notifications, Context Menus (in web content) and Android popup toast alerts. The object is currently part of the main browser window, but we are considering moving it to a JS module. The basic API is here:
/*
label: menu label
icon: file:// or data: URI for an icon
callback: JS function called when menu is tapped
returns a menu ID that can be used to remove the menu
*/
menuID = NativeWindow.menu.add(label, icon, callback);
NativeWindow.menu.remove(menuID);
/*
message: displayed text
value: string based tag
buttons: array of JS objects used to create buttons in the notification
tabID: tab associated with this notification
options: JS object that has 'persistence' and 'timeout' options
*/
NativeWindow.doorhanger.show(message, value, buttons, tabID, options);
NativeWindow.doorhanger.hide(value, tabID);
/*
label: menu label
selector: JS object that has a 'matches(element)' function. Used to show the menu.
callback: JS function called when menu is tapped
returns a menu ID that can be used to remove the menu
*/
menuID = NativeWindow.contextmenu.add(label, selector, callback);
NativeWindow.contextmenu.add(menuID);
/*
message: displayed text
duration: "short" or "long"; Used for alert timeout
*/
NativeWindow.toast.show(message, duration);
Some examples of what the API can do:
Doorhanger Notification
Menu Item
Context Menu Item
Toast Popup Alert
The NativeWindow API will continue to grow and mature, but I think even now it shows that add-ons can have first-class interactions with the native UI of Firefox. I am looking forward to developers trying it out and helping us push the API forward.