Android's leanback library provides a few standard ways to customize a RowFragment, both the Rows and the Cards themselves, but I'm not sure how to add custom elements outside of what is provided on the framework.
What I am specifically trying to achieve is to add a FooterItem to a row, similar to how a each Row has a a HeaderItem.
I'd like to get the existing functionality in ListRowView / ListRowPresenter, but I'm not sure how to do it "properly".
As with almost all things with Leanback, there's more than one way to skin the cat.
We needed to customize the ListRow to add more padding to the header. We've achieved this level of customization by overriding onBindRowViewHolder of ListRowPresenter, grabbing the View for the header (via View header = holder.getHeaderViewHolder().view;). And then we changed the height of it with header.getLayoutParams().height = rowItem.getRowHeaderHeight();.
With this same technique, you could dynamically add your footer view to holder.view (with addView).
Another approach would be following the what the documentation for RowPresenter recommends. The relevant quote is:
When a subclass of RowPresenter adds UI widgets, it should subclass RowPresenter.ViewHolder and override createRowViewHolder(ViewGroup) and initializeRowViewHolder(ViewHolder). The subclass must use layout id "row_content" for the widget that will be aligned to the title of any HeadersFragment that may exist in the parent fragment.
So with this new recommended approach, you'll basically be supplying your own xml. I believe you can even subclass ListRowPresenter. To see how the code works, look at ListRowView to see that it inflates the xml for R.layout.lb_list_row. And then it just uses the view for R.id.row_content.
Then that'll be the actual view that's supplied by holder.view and then you can set text on it and do whatever you want.
Let me know if you need any further clarification.
Related
I'm working on an android project where I have a set of views (2 TextViews and some checkboxes in a checkbox group) to replicate many time in the same activity.
Is it possible to define the layout only for one set and instantiate it many time?
Also, the views are grouped in a Relative layout, is it possible to position the without the id attributes (to avoid id duplication)?
I would use a ListView for this. Even if you got like 5 items it workd fine. If you got many more items it still works perfect. Take a look at this example.
You can do this by defining the fields you want to reuse in their own xml. you can then use the 'include' tag for where you want them to display.
http://developer.android.com/training/improving-layouts/reusing-layouts.html
You do need to define the id's to position them in the relative layout. What is your concern about replicating the id's.
The other thing worth mentioning is how to use findById() when using 'include'. You can put a id on the include tag (which is effectively the relative layout viewgroup). Find that group first (Cast to viewgroup) and then do a findbyId on that group for what ever view you are after.
I want to create a custom view with some text and two buttons all on one line. I need to be able to add multiple (any number) of these views to an existing layout dynamically (needs to be able to scroll). I want to pass a custom object to the view and set the text and buttons. I need access to the button event handlers from the activity. I've looked a little into custom views but I'm still at a loss for how to do what I want. I'm used to .NET custom controls, and I'm looking for the same effect. Any help or example code would be greatly appreciated.
What you want is custom compound view. You should write you own class (usually extending one of the layouts) and whole behavior, inflate the layout the way you want etc.
More of it: http://developer.android.com/guide/topics/ui/custom-components.html
This one helped me a lot too: http://javatechig.com/android/creating-custom-and-compound-views-in-android-tutorial
If you use list activity or list fragment, you will automatically have the many features you have asked for. You only need to create a adapter class for your listview. You can define your layout for your row view(buttons, text etc..) Try to look at the examples on the web for cusom adapter and lists.
I want to create a pocket reference application. So, much of the content would be texts, linkbuttons and images.
I wonder where is a good place to put all of the contents. I could place it hard-coded on the source code, So, when a user click a linkbutton, a new view will be opened and in the source code I specify the TextView and setText, etc. But I think it's not a good idea. Can I put the content in an xml file or in a database? Which one is better for this case?
I see that we are encouraged to put layout in main.xml. But, from what I read, the xml layout is static, what if I want to put some TextView, but I don't know how many TextView would be displayed, because the content would be loaded dynamically/programmatically?
Thank you.
Not sure it this is what you meant:
You can initialize your application ui by an android xml file layout.
to inflate, you use this method.
in your activity's onCreate()-Method or even later, you can then get the TextViews or whatever you want by calling findViewById(R.id.textview). Note that this method will search all over the layout xml file for the specified id and though blocks the ui thread while searching. if your textview is very near at bottom and many other elements come before it, this can take some time.
if you want to build your own layout dynamically, you have to do this programmatically of course.
for general layout declaring, refer this tutorial on android dev guide.
You could write the textView in a xml layout and inflate it dynamically in the activity as many times you want
View view = getLayoutInflater().inflate(R.layout.scroll_project, null);
//then add the view in linear layout as
layout.add(view);
I'm reading the book 'Hello, Android'. In the Sudoku example, it uses a options menu. It needs a MenuInflater that we use to read the menu definition from XML and turns it into a real view.
To use button, textview, or many other views, I don't need to inflate them.
My question is, in what situations, I need inflaters? Why doesn't Android treat menus like other views?
You need an inflater at every place that you want to dynamically create a view out of an XML file.
Activity layouts are automatically inflated when you call setContentView() as they're always required.
But when the menu is required — which is only when the user first presses the Menu button — the XML-defined layout needs to be manually inflated.
Similarly, if you have a ListView, you don't know in advance what rows will exist, so we have to inflate a View from XML for each row in the list, as they're required.
Inflaters are mainly used for parsing Xml layout into view objects. As mentioned above the inflation is needed for making a link between the UI defined in the Xml for manipulating and making developer.
Whenever UI Updation is needed we need inflation and UI Updation is done through view object and developer can dynamically create view and add to existing view.
Hence inflation helps developer to change behaviour of UI in xml layout according to specified condition in a program.
With inflation, we are able define controllers in MVC for each xml layout where xml is view.
Menu is also a view it has to inflated In certain code such setContentView(specifiedLayout) includes inflation
But in earlier version it was not like this it was like setContextView(getInflater().inflate(specifiedLayout))
for ease of programming,android developers have incorporated inflation in setContentview() and there are lot scenarios like add view to layout addView(),etc..In most cases inflation has incorporated in code that why most of beginner does know inflation concept and has difficulties in understanding inflation in android.
I have to dynamically add a list of views (the views use RelativeLayout). Can I do this by specifying the view definition in xml and instantiate multiple objects off it? This gives the usual benefits of separating the view part from the code (for e.g., making it easy for the UI guys to alter things) or Is going the ArrayAdapter the suggested/only route?
are you saying that you want to do this?
View v1 = (View) findViewById(R.id.someView);
View v2 = (View) findViewById(R.id.someView);
If you do this, you will merely have 2 references to the same view; it does not create two separate View objects. However, if you want to make a vertical list of views, look into ListActivity. in this case you will make a layout xml that will be used for every item in the list. you will need to implement a ListAdapter, or use a SimpleArrayAdapter.
does that help?