CustomAdapter.java

package com.devahoy.learn30androidlibraries.day1;

import android.content.Context;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;

import com.devahoy.learn30androidlibraries.R;
import com.etsy.android.grid.util.DynamicHeightImageView;
import com.squareup.picasso.Picasso;

import java.util.Random;

public class CustomAdapter extends ArrayAdapter<String> {

    private LayoutInflater mInflater;
    private Context mContext;

    private static final SparseArray<Double> sPositionHeightRatios =
            new SparseArray<Double>();
    private final Random mRandom;

    static class ViewHolder {
        DynamicHeightImageView imageView;
    }

    public CustomAdapter(final Context context, final int staggeredId) {
        super(context, staggeredId);
        mContext = context;
        mInflater = LayoutInflater.from(context);
        mRandom = new Random();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;

        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.day1_list_item_simple, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.imageView =
                    (DynamicHeightImageView) convertView.findViewById(R.id.image_view);

            convertView.setTag(viewHolder);
        }
        else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        double positionHeight = getPositionRatio(position);

        viewHolder.imageView.setHeightRatio(positionHeight);

        String path = getItem(position);
        Picasso.with(mContext)
                .load(path)
                .error(R.drawable.ic_launcher)
                .placeholder(R.drawable.ic_launcher)
                .into(viewHolder.imageView);


        return convertView;
    }

    private double getPositionRatio(final int position) {
        double ratio = sPositionHeightRatios.get(position, 0.0);
        // if not yet done generate and stash the columns height
        // in our real world scenario this will be determined by
        // some match based on the known height and width of the image
        // and maybe a helpful way to get the column height!
        if (ratio == 0) {
            ratio = getRandomHeightRatio();
            sPositionHeightRatios.append(position, ratio);
        }
        return ratio;
    }

    private double getRandomHeightRatio() {
        return (mRandom.nextDouble() / 2.0) + 1.0; // height will be 1.0 - 1.5 the width
    }
}