FragmentStackNavigationController.cs

/*
* MIT License
*
* Copyright (c) 2019 Randall
*
* 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.
*/

using System.Collections.Generic;
using System.Linq;
using Android.OS;
using Android.Support.V4.App;
using Android.Views;
using Android.Widget;

namespace Controls
{
 public class FragmentStackNavigationController : Fragment
 {
 #region Fields

 private const string PUSH_ENTER_ANIM_KEY = "push enter animation";
 private const string PUSH_EXIT_ANIM_KEY = "push exit animation";
 private const string POP_ENTER_ANIM_KEY = "pop enter animation";
 private const string POP_EXIT_ANIM_KEY = "pop exit animation";
 private const string FRAGMENT_STACK_SIZE_KEY = "fragment stack size";

 private static int FRAGMENT_CONTAINER_ID = View.GenerateViewId();

 private readonly Queue<Fragment> addQueue = new Queue<Fragment>();
 private readonly Stack<Fragment> fragmentsStack = new Stack<Fragment>();

 #endregion

 #region Properties

 public IEnumerable<Fragment> Fragments => this.fragmentsStack.Reverse();

 #endregion

 #region Methods

 public static FragmentStackNavigationController Create(
 int pushEnterAnimation,
 int pushExitAnimation,
 int popEnterAnimation,
 int popExitAnimation)
 {
 var args = new Bundle();
 args.PutInt(PUSH_ENTER_ANIM_KEY, pushEnterAnimation);
 args.PutInt(PUSH_EXIT_ANIM_KEY, pushExitAnimation);
 args.PutInt(POP_ENTER_ANIM_KEY, popEnterAnimation);
 args.PutInt(POP_EXIT_ANIM_KEY, popExitAnimation);

 var fragment = new FragmentStackNavigationController();
 fragment.Arguments = args;

 return fragment;
 }

 public override void OnCreate(Bundle savedInstanceState)
 {
 base.OnCreate(savedInstanceState);

 if (savedInstanceState != null)
 {
 var fragmentCount = savedInstanceState.GetInt(FRAGMENT_STACK_SIZE_KEY);
 for (int i = 0; i < fragmentCount; ++i)
 {
 var fragment = this.ChildFragmentManager.GetFragment(
 savedInstanceState,
 FragmentStackNavigationController.CreateFragmentKeyForIndex(i)
 );

 this.fragmentsStack.Push(fragment);
 }
 }
 }

 public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
 {
 var fragmentContainer = new LinearLayout(this.Context);
 fragmentContainer.Id = FRAGMENT_CONTAINER_ID;
 fragmentContainer.Orientation = Orientation.Vertical;
 fragmentContainer.LayoutParameters = new ViewGroup.LayoutParams(
 ViewGroup.LayoutParams.WrapContent,
 ViewGroup.LayoutParams.WrapContent
 );

 if (addQueue.Count > 0 && savedInstanceState == null)
 {
 var rootFragment = this.addQueue.Dequeue();
 this.ChildFragmentManager
 .BeginTransaction()
 .Add(FRAGMENT_CONTAINER_ID, rootFragment)
 .Commit();

 while (this.addQueue.Count > 0)
 {
 var nextFragment = this.addQueue.Dequeue();
 this.AddChildFragment(nextFragment);
 }
 }

 return fragmentContainer;
 }

 public override void OnSaveInstanceState(Bundle outState)
 {
 base.OnSaveInstanceState(outState);
 outState.PutInt(FRAGMENT_STACK_SIZE_KEY, this.Fragments.Count());

 for (int i = 0; i < this.Fragments.Count(); ++i)
 {
 this.ChildFragmentManager.PutFragment(
 outState,
 FragmentStackNavigationController.CreateFragmentKeyForIndex(i),
 this.Fragments.ElementAt(i)
 );
 }
 }

 public bool Pop()
 {
 if (this.ChildFragmentManager.BackStackEntryCount > 0)
 {
 this.ChildFragmentManager.PopBackStack();
 this.fragmentsStack.Pop();
 return true;
 }

 return false;
 }

 public void Push(Fragment fragment)
 {
 this.fragmentsStack.Push(fragment);

 if (!this.IsAdded)
 {
 this.addQueue.Enqueue(fragment);
 return;
 }

 this.AddChildFragment(fragment);
 }

 private void AddChildFragment(Fragment fragment)
 {
 this.ChildFragmentManager
 .BeginTransaction()
 .SetCustomAnimations(
 this.Arguments.GetInt(PUSH_ENTER_ANIM_KEY),
 this.Arguments.GetInt(PUSH_EXIT_ANIM_KEY),
 this.Arguments.GetInt(POP_ENTER_ANIM_KEY),
 this.Arguments.GetInt(POP_EXIT_ANIM_KEY)
 )
 .Replace(FRAGMENT_CONTAINER_ID, fragment)
 .AddToBackStack(null)
 .Commit();
 }

 private static string CreateFragmentKeyForIndex(int index)
 {
 return $"fragment {index}";
 }

 #endregion
 }
}