Showing custom View under swiped RecyclerView item

Question

First of all, I saw this question: Adding a colored background with text/icon under swiped row when using Android's RecyclerView

However, even though the title states "with text/icon", the answer only covers using Canvas object to draw a rectangle.

Now I have drawing a green rectangle implemented; however I want to make it more obvious what is going to happen by adding "done" button, just like on the following screenshot.

I created a custom view:

public class ChoosePlanView extends LinearLayout{

    public ChoosePlanView(Context context) {
        super(context);
        init();
    }

    public ChoosePlanView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public ChoosePlanView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    private void init(){
        View v = inflate(getContext(), R.layout.choose_plan_view, null);
        addView(v);
    }
}

And the layout is very simple, consisting of green background and the icon:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" 
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/choose_green">

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/doneIcon"
        android:layout_gravity="center_horizontal|right"
        android:src="@mipmap/done"/>

</LinearLayout>

I tried overriding method OnChildDraw:

// ChoosePlanView choosePlanView; <- that was declared and initialized earlier, so I don't have to create a new ChoosePlanView everytime in OnChildDraw();

ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {    

/*
    onMove, onSwiped omitted
*/
  public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
       View itemView = viewHolder.itemView;

       if(dX < 0){
            choosePlanView.invalidate();
            //choosePlanView.setBackgroundResource(R.color.delete_red);
            choosePlanView.measure(itemView.getWidth(), itemView.getHeight());
            choosePlanView.layout(itemView.getRight() + (int) dX, itemView.getTop(), itemView.getRight(), itemView.getBottom());
            c.save();
            c.translate(choosePlanView.getRight() + (int) dX, viewHolder.getAdapterPosition()*itemView.getHeight());

            choosePlanView.draw(c);
            c.restore();
       }

       super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
  }
}

And it kinda works (draws my ChoosePlanView), but there are two problems.

First of all it draws only a small green square wrapping my "done" icon (the red part of the view seen on the screenshot below comes from commented line choosePlanView.setBackgroundResource(R.color.delete_red);). The view has the correct width though, when checked in debugger.

Second thing is where the icon is placed. I specified that I want it to be centered horizontally and always "sticked" to the right side of the view. However it moves, when the RecyclerView item is is swiped, and having red background shows it isn't placed in the center either.

I tried adding line choosePlanView.invalidate(), because I thought that happens, because the view was created earlier, but it seems redrawing changes nothing.

Answer 1

Using the ItemTouchUiUtil interface provides a robust solution to this. It allows you to have a foreground and background view in your ViewHolder and delegate all the swipe handling to the foreground view. Here is an example that I use for swipe right to remove.

In your ItemTouchHelper.Callback :

public class ClipItemTouchHelper extends ItemTouchHelper.SimpleCallback {

    ...

    @Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        if (viewHolder != null){
            final View foregroundView = ((ClipViewHolder) viewHolder).clipForeground;

            getDefaultUIUtil().onSelected(foregroundView);
        }
    }

    @Override
    public void onChildDraw(Canvas c, RecyclerView recyclerView,
                            RecyclerView.ViewHolder viewHolder, float dX, float dY,
                            int actionState, boolean isCurrentlyActive) {
        final View foregroundView = ((ClipViewHolder) viewHolder).clipForeground;

        drawBackground(viewHolder, dX, actionState);

        getDefaultUIUtil().onDraw(c, recyclerView, foregroundView, dX, dY,
                actionState, isCurrentlyActive);
     }

    @Override
    public void onChildDrawOver(Canvas c, RecyclerView recyclerView,
                                RecyclerView.ViewHolder viewHolder, float dX, float dY,
                                int actionState, boolean isCurrentlyActive) {
        final View foregroundView = ((ClipViewHolder) viewHolder).clipForeground;

        drawBackground(viewHolder, dX, actionState);

        getDefaultUIUtil().onDrawOver(c, recyclerView, foregroundView, dX, dY,
                actionState, isCurrentlyActive);
    }

    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder){
        final View backgroundView = ((ClipViewHolder) viewHolder).clipBackground;
        final View foregroundView = ((ClipViewHolder) viewHolder).clipForeground;

        // TODO: should animate out instead. how?
        backgroundView.setRight(0);

        getDefaultUIUtil().clearView(foregroundView);
    }

    private static void drawBackground(RecyclerView.ViewHolder viewHolder, float dX, int actionState) {
        final View backgroundView = ((ClipViewHolder) viewHolder).clipBackground;

        if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
            //noinspection NumericCastThatLosesPrecision
            backgroundView.setRight((int) Math.max(dX, 0));
        }
    }
}

And in your layout file, define the foreground and background views:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/clipRow"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

        <View style="@style/Divider"/>

        <FrameLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/row_selector"
        >

        <RelativeLayout
            android:id="@+id/clipBackground"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:background="@color/swipe_bg"
            tools:layout_width="match_parent">

            <ImageView
                android:layout_width="32dp"
                android:layout_height="32dp"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true"
                android:layout_centerVertical="true"
                android:layout_marginLeft="12dp"
                android:layout_marginStart="12dp"
                android:focusable="false"
                android:src="@drawable/ic_delete_24dp"
                tools:ignore="ContentDescription"/>

        </RelativeLayout>

        <RelativeLayout
            android:id="@+id/clipForeground"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:paddingBottom="@dimen/clip_vertical_margin"
            android:paddingLeft="@dimen/clip_horizontal_margin"
            android:paddingRight="@dimen/clip_horizontal_margin"
            android:paddingTop="@dimen/clip_vertical_margin" >

            <CheckBox
                android:id="@+id/favCheckBox"
                android:layout_width="@dimen/view_image_size"
                android:layout_height="@dimen/view_image_size"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true"
                android:background="@android:color/transparent"
                android:button="@drawable/ic_star_outline_24dp"
                android:clickable="true"
                android:contentDescription="@string/content_favorite"
                />

             ...

        </RelativeLayout>

    </FrameLayout>

</LinearLayout>

Answer 2

Instead of draw over, I believe you should use viewType

Implements getItemViewType(int position) in adapter, returning different types, e.g. 0 for normal, 1 for swipped

and change onCreateViewHolder etc to return different layout on different viewType

Answer 3

For people still finding this default, this is the simplest way.

A simple utility class to add a background, an icon and a label to a RecyclerView item while swiping it left or right.

insert to Gradle

implementation 'it.xabaras.android:recyclerview-swipedecorator:1.2.1'

Override onChildDraw method of ItemTouchHelper class

@Override
public void onChildDraw (Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,float dX, float dY,int actionState, boolean isCurrentlyActive){

    new RecyclerViewSwipeDecorator.Builder(MainActivity.this, c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive)
            .addBackgroundColor(ContextCompat.getColor(MainActivity.this, R.color.my_background))
            .addActionIcon(R.drawable.my_icon)
            .create()
            .decorate();

    super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}

for more info -> https://github.com/xabaras/RecyclerViewSwipeDecorator