Android Open Source - android-virtual-layout Backstack

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License

The source code is released under:

MIT License

Java Source Code

package trikita.anvil.example;
//  ww w .j a  v a2 s . c  o m
import android.content.Context;
import android.os.Bundle;
import android.os.Parcelable;
import android.util.SparseArray;
import android.view.View;

import java.util.ArrayDeque;
import java.util.ArrayList;

import static trikita.anvil.Render.*;

//
// Custom backstack implementation to use views instead of
// activities/fragments.
//
// Saves stack of views in a bundle, each view can also save its state to a
// nested bundle.
//
public class Backstack {

  // Bundle keys
  final static String KEY_CLASSNAME = "className";
  final static String KEY_STATE = "state";
  final static String KEY_BACKSTACK = "backstack";

  Listener listener;
  Context context;
  ArrayDeque<Bundle> backstack = new ArrayDeque<>();

  interface Listener {
    void setContentView(View toView);
  }

  public Backstack(Context c, Listener l) {
    this.context = c;
    this.listener = l;
  }

  public void navigate(View v) {
    Bundle b = new Bundle();
    b.putString(KEY_CLASSNAME, v.getClass().getName());
    SparseArray<Parcelable> state = new SparseArray<>();
    v.saveHierarchyState(state);
    b.putSparseParcelableArray(KEY_STATE, state);
    backstack.push(b);
    listener.setContentView(v);
  }

  public int size() {
    return backstack.size();
  }

  public boolean back() {
    backstack.pop();
    if (backstack.size() == 0) {
      return false;
    } else {
      View v = createView(backstack.peek());
      listener.setContentView(v);
    }
    render();
    return true;
  }

  public void load(Bundle b) {
    for (Parcelable p : b.getParcelableArrayList(KEY_BACKSTACK)) {
      if (p instanceof Bundle) {
        navigate(createView((Bundle) p));
      }
    }
  }

  public void save(Bundle b) {
    ArrayList<Parcelable> backstackState = new ArrayList<>(backstack.size());
    for (Bundle entry : backstack) {
      backstackState.add(0, entry);
    }
    b.putParcelableArrayList(KEY_BACKSTACK, backstackState);
  }

  private View createView(Bundle b) {
    try {
      String className = b.getString(KEY_CLASSNAME);
      View v = (View)
        Class.forName(className).getConstructor(Context.class).newInstance(context);
      SparseArray<Parcelable> state = b.getSparseParcelableArray(KEY_STATE);
      if (state != null) {
        v.restoreHierarchyState(state);
      }
      return v;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }
}

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