Question

I have a desktop-like application which has 2 controllers: ‘Desktop’ which represents desktop icons and ‘Taskbar’ which represents the taskbar where you find buttons to minimize/restore windows already opened, like MS Windows is working.

The problem I currently have is the approach to “how should I display the window”. Infact after doubleclicking the icon, I should create a window, and this could happen both on Desktop controller or on Taskbar controller (or maybe directly on the viewport, because they can be dragged anywhere). However, when I create a window, a new button should be created on the taskbar to minimize/restore it.

Because of this, I thought about handling window in the taskbar controller, however I don’t know how to reach the Taskbar controller from the Desktop controller.

I have 3 ideas in my mind at the moment:

1. The Desktop controller directly adds the button to the TaskbarView, but in this way I’m feeling like violating MVC pattern. Also I need to specify TaskbarView in Desktop views.
2. The Desktop controller after icon doubleclick fires a custom event on the Taskbar controller. In this case the taskbar opens the windows and adds the button, this approach is quite linear but I don’t know how to reference a controller from another controller (in this case, from Desktop to Taskbar)
3. The Ext.Application register for itemdblclick event on Desktop controller. When this event is fired, it redirects (or call a custom event) on Taskbar controller. After this everything keeps going like point 2. In this way I centralize the Routing functionality (like rails), however could also happen that Application object becomes really big. Also I’m using it as a “gigant controller” to route everything, but this is not really a big problem, thinking about rails it does something similar.
4. The application should not be split in 2 controllers (so Desktop and Taskbar should be one) and everything will be fine. I don’t think this approach is correct.

So, my questions are:

• Which approach should I use: 1,2,3,4 (or specify if there is something different)?
• What a window should belongs to: Desktop controller, Taskbar controller, something else?

Thanks for any answer

Answer 1

I have a similar setup to you. Personally I would go with choice 2. There is a couple ways to deal with this. One is to have a parent that contains both the Desktop and task bar as its children and it can manage the communication between the two. You can create custom events which the parent listens for and directs them to the correct children.

So for example the parent creates both the task bar and desktop and it listen for icon click events on the desktop. When a click event on the icon occurs the parent receives the events and then internally determines what need to be done. In this case it knows that it needs to call the task bar and create the button for the opened window on it.

You could also look at using a a Mediator design pattern in JavaScript to register senders and listeners. So you could sent it up that the desktop is a sender of icon click events and the task bar is a listener of these events. The click on the icon will send an event to all the listeners of it set in the mediator. This way you don’t need a parent to manage it. But personal I like the parent better.