session-android/src/org/thoughtcrime/securesms/mediasend/MediaSendFragmentPagerAdapter.java

package org.thoughtcrime.securesms.mediasend;

import android.net.Uri;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.view.View;
import android.view.ViewGroup;

import org.thoughtcrime.securesms.scribbles.ImageEditorFragment;
import org.thoughtcrime.securesms.util.MediaUtil;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class MediaSendFragmentPagerAdapter extends FragmentStatePagerAdapter {

  private final List<Media>                         media;
  private final Map<Integer, MediaSendPageFragment> fragments;
  private final Map<Uri, Object>                    savedState;

  MediaSendFragmentPagerAdapter(@NonNull FragmentManager fm) {
    super(fm);
    this.media      = new ArrayList<>();
    this.fragments  = new HashMap<>();
    this.savedState = new HashMap<>();
  }

  @Override
  public Fragment getItem(int i) {
    Media mediaItem = media.get(i);

    if (MediaUtil.isGif(mediaItem.getMimeType())) {
      return MediaSendGifFragment.newInstance(mediaItem.getUri());
    } else if (MediaUtil.isImageType(mediaItem.getMimeType())) {
      return ImageEditorFragment.newInstance(mediaItem.getUri());
    } else if (MediaUtil.isVideoType(mediaItem.getMimeType())) {
      return MediaSendVideoFragment.newInstance(mediaItem.getUri());
    } else {
      throw new UnsupportedOperationException("Can only render images and videos. Found mimetype: '" + mediaItem.getMimeType() + "'");
    }
  }

  @Override
  public int getItemPosition(@NonNull Object object) {
    return POSITION_NONE;
  }

  @NonNull
  @Override
  public Object instantiateItem(@NonNull ViewGroup container, int position) {
    MediaSendPageFragment fragment = (MediaSendPageFragment) super.instantiateItem(container, position);
    fragments.put(position, fragment);

    Object state = savedState.get(fragment.getUri());
    if (state != null) {
      fragment.restoreState(state);
    }

    return fragment;
  }

  @Override
  public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
    MediaSendPageFragment fragment = (MediaSendPageFragment) object;

    Object state = fragment.saveState();
    if (state != null) {
      savedState.put(fragment.getUri(), state);
    }

    super.destroyItem(container, position, object);
    fragments.remove(position);
  }

  @Override
  public int getCount() {
    return media.size();
  }

  List<Media> getAllMedia() {
    return media;
  }

  void setMedia(@NonNull List<Media> media) {
    this.media.clear();
    this.media.addAll(media);
    notifyDataSetChanged();
  }

  Map<Uri, Object> getSavedState() {
    for (MediaSendPageFragment fragment : fragments.values()) {
      Object state = fragment.saveState();
      if (state != null) {
        savedState.put(fragment.getUri(), state);
      }
    }
    return new HashMap<>(savedState);
  }

  void saveAllState() {
    for (MediaSendPageFragment fragment : fragments.values()) {
      Object state = fragment.saveState();
      if (state != null) {
        savedState.put(fragment.getUri(), state);
      }
    }
  }

  void restoreState(@NonNull Map<Uri, Object> state) {
    savedState.clear();
    savedState.putAll(state);
  }

  @Nullable View getPlaybackControls(int position) {
    return fragments.containsKey(position) ? fragments.get(position).getPlaybackControls() : null;
  }
}