How to apply android layout animation only to children above a certain index?

问题

I have a ListView containing a series of notes.

Currently I use a layout animation to slide all the notes in from the side when the list first loads; this works perfectly.

However, I'm trying to figure out how to apply a layout animation only to list items below a certain point. Say I delete an item on the list: I'd like all items below it to shift up into the deleted note's old spot.

I've tried finding a way to customize the animation delays or interpolators by child index but haven't found anything appropriate for this location. Is there a way to do this using a custom layout animation (such as extending LayoutAnimationController) or would I have to do this low level and animate each view individually?

Any suggestions?

回答1:

Create your animation and call it in your list OnItemClickListener. After that you might use the adapter's notifyDataSetChanged to refresh the list content.

In this example, I created a method called removeListItem with receives the row you want to remove and the position of that row in you list content array.

public class MainActivity extends ListActivity implements OnItemClickListener{

ArrayList<String> values;
ArrayAdapter<String> adapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    values = generateMockData(50);

    adapter = new ArrayAdapter<String>(
            this, android.R.layout.simple_list_item_1, values);

    setContentView(R.layout.activity_main);

    getListView().setAdapter(adapter);
    getListView().setOnItemClickListener(this);
}

private ArrayList<String> generateMockData(int number) {

    ArrayList<String> result = new ArrayList<String>();

    for(int i = 0; i < number; i++)
        result.add(""+i+" "+ (int)Math.random() * 13);

    return result;
}

private void removeListItem(View rowView, final int positon) {

    Animation anim = AnimationUtils.loadAnimation(this,
            android.R.anim.slide_out_right);
    anim.setDuration(500);
    rowView.startAnimation(anim);

    new Handler().postDelayed(new Runnable() {

        public void run() {

            values.remove(positon);//remove the current content from the array

            adapter.notifyDataSetChanged();//refresh you list

        }

    }, anim.getDuration());

}

public void onItemClick(AdapterView<?> arg0, View row, int position, long arg3) {

       if(position == YOUR_INDEX) //apply your conditions here!
          removeListItem(row,position);
}

回答2:

I had a very similar problem and was able to find a solution with a simple View subclass that allows you to use a layout animation controller to animate only the views that you specify. Please see this link:

Can LayoutAnimationController animate only specified Views

回答3:

In your layout xml, try adding:

<ListView  
  android:id="@android:id/list"
  ... 
  android:animateLayoutChanges="true"/>

This will automatically animate insertions and deletions from your listview.
If you have a custom animation, named anim_translate_left, use instead:

<ListView  
  android:id="@android:id/list"
  ... 
  android:animateLayoutChanges="@anim/anim_translate_left"/>

Source: Google API's

来源：https://stackoverflow.com/questions/4658416/how-to-apply-android-layout-animation-only-to-children-above-a-certain-index

标签

android

listview

animation

android-listview

layout-animation