Custom view in android

I need some valuable advice from you guys... I have a UI where I have to drag objects from one view to another. I have a rough sketch of this UI below

I think I have to create a custom view for this. I have to drag a square and a ball from bag 1 and bag2 [both bags are scrollable, can contain 10 to 60 items each] and drop it to the closet one by one. and later I have to find the number of items in the closet. The items in the closet must开发者_Go百科 be arranged in a well maintained fashion [may be ...like 6 in a row].

• Where should I start?
• How many custom views should I use?
• Is there a simple and effective UI solution for this?

Happy coding..!

I would suggest a design with three different GridView objects laid out inside a ViewGroup that supports dragging objects from one GridView to another. The objects would be custom ImageView subclasses so you'd have a place in code to support a drag-and-drop protocol of some sort and because you'd likely want to associate some data that is specific to your application with the objects being dragged.

As for the drag-and-drop protocol, you could consider an adaptation of the Android Launcher drag-and-drop framework or the current drag-drop classes described on the Android developers' website. I don't have much to say about the current drag-drop classes. I have not tried them yet, but understanding them is on my to-do list. However, I have done an adaptation of the Launcher code, and I have written it up on my blog and posted demo apps and source code there. See Drag-Drop for an Android GridView.

With the framework that originated in the Android Launcher, you have a good set of classes and interfaces to work with. Some of the objects include: DragLayer, DragSource, DropTarget, DragController, DragView. The DragLayer is a custom ViewGroup within which all drag-drop operations occur. It delegates handling of all the touch events to a DragController, which is the object that does the actual moving of objects around on the screen. As it does so, it interacts with DropTarget objects to give the user visual feedback that something is being dragged and that a place to drop something is available. A DropTarget is an object where something can be dropped. A DragSource is the interface for objects that can be dragged within the DragLayer. The Launcher framework is a good one because it gives you a way to think about dragging and dropping and how you want to divide up the responsibilities defined by the framework.

The reason I suggest GridViews for your problem is it sounds like you are thinking that way already. The closet has "maybe 6 in a row" so that could be a GridView with one or more rows depending on how screen space you have. A GridView would also work for the container that holds the squares and circles. If that is a good fit, you could study the code in my drag-drop tutorial and see if that makes it easy for you to move objects from one GridView to another.

In my demo program, I ended up with a custom subclass of ImageView that I called an ImageCell. These are views that are on the grid. An ImageCell allows objects to be dragged from them and onto them. For awhile as I worked on the tutorial, I had a custom GridView class too but ended up with the standard GridView. It sounds like you'd want a custom GridView because it sounds like being in the closet is different than being in the other sections. Having it gives you a convenient place for the methods you have not thought of yet.

I hope some of these suggestions prove useful.

Depends on the Android version you are targeting. For 11 and above you can use the built in drag and drop functionality, otherwise you are pretty much on your own. I would normally advice you to implement some sort of a long press action that might even allow you to select multiple items and move them in batches, which would be a really simple thing to implement.

If you really need DnD you should check out this example, it should give you some idea on how to make your own implementation.

I think that bag1, bag2 and closet can be three instance of the same configurable custom view (let's name it CustomBagView).

CustomBagViews should be responsible for displaying items (using a gridview of imageview for example).

I think those will not need to handle drag & drop directly but they should support

• removing and adding elements
• provide a setOnItemTouched(Interface_class) callback setter.

Then you will need to code a Container custom view (let's name it BagContainerView) that will contain the three bags and handle the dragging & dropping from the bags.

You will provide a handleDrag callback to each bag using CustomBagView.setOnItemTouched, then track the finger motion in it.

When the dragging finishes, you must find where it ends, locate the right 'customBagView' and ask it to add the item to its list.