FairEmail/app/src/main/java/eu/faircode/email/AdapterImage.java

package eu.faircode.email;

/*
    This file is part of FairEmail.

    FairEmail is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    FairEmail is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with FairEmail.  If not, see <http://www.gnu.org/licenses/>.

    Copyright 2018-2019 by Marcel Bokhorst (M66B)
*/

import android.content.Context;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import androidx.annotation.NonNull;
import androidx.lifecycle.LifecycleOwner;
import androidx.recyclerview.widget.DiffUtil;
import androidx.recyclerview.widget.ListUpdateCallback;
import androidx.recyclerview.widget.RecyclerView;

public class AdapterImage extends RecyclerView.Adapter<AdapterImage.ViewHolder> {
    private Context context;
    private LayoutInflater inflater;
    private LifecycleOwner owner;

    private List<EntityAttachment> all = new ArrayList<>();
    private List<EntityAttachment> filtered = new ArrayList<>();

    public class ViewHolder extends RecyclerView.ViewHolder {
        View itemView;
        ImageView image;
        TextView caption;

        ViewHolder(View itemView) {
            super(itemView);

            this.itemView = itemView;
            image = itemView.findViewById(R.id.image);
            caption = itemView.findViewById(R.id.caption);
        }

        private void bindTo(EntityAttachment attachment) {
            if (attachment.available) {
                Drawable d = BitmapDrawable.createFromPath(
                        EntityAttachment.getFile(context, attachment.id).getAbsolutePath());
                if (d == null)
                    image.setImageResource(R.drawable.baseline_broken_image_24);
                else
                    image.setImageDrawable(d);
            } else
                image.setImageResource(R.drawable.baseline_image_24);

            caption.setText(attachment.name);
        }
    }

    AdapterImage(Context context, LifecycleOwner owner) {
        this.context = context;
        this.inflater = LayoutInflater.from(context);
        this.owner = owner;
        setHasStableIds(true);
    }

    public void set(@NonNull List<EntityAttachment> attachments) {
        Log.i("Set images=" + attachments.size());

        Collections.sort(attachments, new Comparator<EntityAttachment>() {
            @Override
            public int compare(EntityAttachment a1, EntityAttachment a2) {
                return a1.sequence.compareTo(a2.sequence);
            }
        });

        all = attachments;

        DiffUtil.DiffResult diff = DiffUtil.calculateDiff(new MessageDiffCallback(filtered, all));

        filtered.clear();
        filtered.addAll(all);

        diff.dispatchUpdatesTo(new ListUpdateCallback() {
            @Override
            public void onInserted(int position, int count) {
                Log.i("Inserted @" + position + " #" + count);
            }

            @Override
            public void onRemoved(int position, int count) {
                Log.i("Removed @" + position + " #" + count);
            }

            @Override
            public void onMoved(int fromPosition, int toPosition) {
                Log.i("Moved " + fromPosition + ">" + toPosition);
            }

            @Override
            public void onChanged(int position, int count, Object payload) {
                Log.i("Changed @" + position + " #" + count);
            }
        });
        diff.dispatchUpdatesTo(this);
    }

    private class MessageDiffCallback extends DiffUtil.Callback {
        private List<EntityAttachment> prev;
        private List<EntityAttachment> next;

        MessageDiffCallback(List<EntityAttachment> prev, List<EntityAttachment> next) {
            this.prev = prev;
            this.next = next;
        }

        @Override
        public int getOldListSize() {
            return prev.size();
        }

        @Override
        public int getNewListSize() {
            return next.size();
        }

        @Override
        public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
            EntityAttachment a1 = prev.get(oldItemPosition);
            EntityAttachment a2 = next.get(newItemPosition);
            return a1.id.equals(a2.id);
        }

        @Override
        public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
            EntityAttachment a1 = prev.get(oldItemPosition);
            EntityAttachment a2 = next.get(newItemPosition);
            return a1.equals(a2);
        }
    }

    @Override
    public long getItemId(int position) {
        return filtered.get(position).id;
    }

    @Override
    public int getItemCount() {
        return filtered.size();
    }

    @Override
    @NonNull
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new ViewHolder(inflater.inflate(R.layout.item_image, parent, false));
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        EntityAttachment attachment = filtered.get(position);
        holder.bindTo(attachment);
    }
}