IconHeaderItemPresenter.java

package com.liskovsoft.smartyoutubetv2.tv.presenter;

import android.content.Context;
import android.graphics.drawable.Drawable;
import androidx.core.content.ContextCompat;
import androidx.leanback.widget.HeaderItem;
import androidx.leanback.widget.ListRow;
import androidx.leanback.widget.PageRow;
import androidx.leanback.widget.Presenter;
import androidx.leanback.widget.RowHeaderPresenter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.liskovsoft.smartyoutubetv2.tv.R;

public class IconHeaderItemPresenter extends RowHeaderPresenter {
    private final int mResId;
    private float mUnselectedAlpha;

    public IconHeaderItemPresenter(int resId) {
        mResId = resId;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup) {
        mUnselectedAlpha = viewGroup.getResources()
                .getFraction(R.fraction.lb_browse_header_unselect_alpha, 1, 1);
        LayoutInflater inflater = (LayoutInflater) viewGroup.getContext()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View view = inflater.inflate(R.layout.icon_header_item, null);
        view.setAlpha(mUnselectedAlpha); // Initialize icons to be at half-opacity.

        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(Presenter.ViewHolder viewHolder, Object item) {
        HeaderItem headerItem;

        if (item instanceof PageRow) {
            headerItem = ((PageRow) item).getHeaderItem();
        } else {
            headerItem = ((ListRow) item).getHeaderItem();
        }

        View rootView = viewHolder.view;
        rootView.setFocusable(true);

        ImageView iconView = rootView.findViewById(R.id.header_icon);
        Drawable icon = ContextCompat.getDrawable(rootView.getContext(), mResId > 0 ? mResId : R.drawable.header_default);
        iconView.setImageDrawable(icon);

        TextView label = rootView.findViewById(R.id.header_label);
        label.setText(headerItem.getName());
    }

    @Override
    public void onUnbindViewHolder(Presenter.ViewHolder viewHolder) {
        // NOP
    }

    // TODO: This is a temporary fix. Remove me when leanback onCreateViewHolder no longer sets the
    // mUnselectAlpha, and also assumes the xml inflation will return a RowHeaderView.
    @Override
    protected void onSelectLevelChanged(RowHeaderPresenter.ViewHolder holder) {
        holder.view.setAlpha(mUnselectedAlpha + holder.getSelectLevel() *
                (1.0f - mUnselectedAlpha));
    }
}