oubowu / Pancakes

A View-based navigation stack for Android

Pancakes

Pancakes is a View-based navigation stack library for Android. While it does aim to replace some of FragmentManager's functionality, its feature set is not one-to-one with that of FragmentManager, as Views and Fragments are inherently different. Unlike FragmentManager, it also supports the use of Animators for View transitions.

Download

compile 'me.mattlogan.pancakes:pancakes:3.1.0'

Usage

Create a ViewStack instance with a ViewGroup container and a ViewStackDelegate:

ViewStack viewStack = ViewStack.create(container, this);

Create a ViewFactory for each View:

public class RedViewFactory implements ViewFactory {
    @Override
    public View createView(Context context, ViewGroup container) {
        return LayoutInflater.from(context).inflate(R.layout.view_red, container, false);
    }
}

Add a View to your container by pushing a ViewFactory:

viewStack.push(new RedViewFactory());

Call pop() to go back one View:

viewStack.pop();

Or, use an AnimatorFactory along with pushWithAnimation(ViewFactory, AnimatorFactory) and popWithAnimation(AnimatorFactory) to add remove a View with a transition animation.

public class CircularReveal implements AnimatorFactory {
    @Override
    public Animator createAnimator(View view) {
        int cx = view.getWidth() / 2;
        int cy = view.getHeight() / 2;

        int finalRadius = Math.max(view.getWidth(), view.getHeight());

        return ViewAnimationUtils.createCircularReveal(view, cx, cy, 0, finalRadius);
    }
}

You can also call peek() and peekView() to get the ViewFactory and View at the top of the navigation stack.

Add a StackChangedListener (or several!) if you want to be notified of changes in the navigation stack:

viewStack.addStackChangedListener(listener);

You can also remove individual listeners with removeStackChangedListener(StackChangedListener) or remove all of them with clearStackChangedListeners().

Persist ViewFactory instances, in order, across configuration changes:

@Override
public void onSaveInstanceState(Bundle outState) {
    viewStack.saveToBundle(outState, STACK_TAG);
    super.onSaveInstanceState(outState);
}

Rebuild the stack from a Bundle:

if (savedInstanceState != null) {
    viewStack.rebuildFromBundle(savedInstanceState, STACK_TAG);
}

Additionally, you may use View.onSaveInstanceState(Bundle) and View.onRestoreInstanceState(Bundle) to save the state of any View in the navigation stack so long as it has an ID.

Finally, implement ViewStackDelegate.finishStack() to take appropriate action when the stack is finished:

@Override
public void finishStack() {
    finish();
}

See the sample app for an example implementation.

Be careful: because ViewFactory instances are persisted across configuration changes, you should not keep references in a ViewFactory to any objects that should be garbage collected on a configuration change. Keep each ViewFactory as simple as possible.

Tests

Unit tests located in /library/src/test/

License

The MIT License (MIT)

Copyright (c) 2015 Matthew Logan

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.