src/Tizen.NUI.Components/Controls/Navigation/Navigator.cs

   1 /*
   2  * Copyright(c) 2021 Samsung Electronics Co., Ltd.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  *
  16  */
  17
  18 using System;
  19 using System.Collections.Generic;
  20 using System.ComponentModel;
  21 using Tizen.NUI.BaseComponents;
  22 using Tizen.NUI.Binding;
  23
  24 namespace Tizen.NUI.Components
  25 {
  26     /// <summary>
  27     /// PoppedEventArgs is a class to record <see cref="Navigator.Popped"/> event arguments which will be sent to user.
  28     /// </summary>
  29     /// <since_tizen> 9 </since_tizen>
  30     public class PoppedEventArgs : EventArgs
  31     {
  32         /// <summary>
  33         /// Page popped by Navigator.
  34         /// </summary>
  35         /// <since_tizen> 9 </since_tizen>
  36         public Page Page { get; internal set; }
  37     }
  38
  39     /// <summary>
  40     /// The Navigator is a class which navigates pages with stack methods such as Push and Pop.
  41     /// </summary>
  42     /// <remarks>
  43     /// With Transition class, Navigator supports smooth transition of View pair between two Pages
  44     /// by using <see cref="PushWithTransition(Page)"/> and <see cref="PopWithTransition()"/> methods.
  45     /// If current top Page and next top Page have <see cref="View"/>s those have same TransitionTag,
  46     /// Navigator creates smooth transition motion for them.
  47     /// Navigator.Transition property can be used to set properties of the Transition such as TimePeriod and AlphaFunction.
  48     /// When all transitions are finished, Navigator calls a callback methods those connected on the "TransitionFinished" event.
  49     /// </remarks>
  50     /// <example>
  51     /// <code>
  52     /// Navigator navigator = new Navigator()
  53     /// {
  54     ///     TimePeriod = new TimePeriod(500),
  55     ///     AlphaFunction = new AlphaFunction(AlphaFunction.BuiltinFunctions.EaseInOutSine)
  56     /// };
  57     ///
  58     /// View view = new View()
  59     /// {
  60     ///     TransitionOptions = new TransitionOptions()
  61     ///     {
  62     ///         /* Set properties for the transition of this View */
  63     ///     }
  64     /// };
  65     ///
  66     /// ContentPage newPage = new ContentPage()
  67     /// {
  68     ///     Content = view,
  69     /// };
  70     ///
  71     /// Navigator.PushWithTransition(newPage);
  72     /// </code>
  73     /// </example>
  74     /// <since_tizen> 9 </since_tizen>
  75     public class Navigator : Control
  76     {
  77         /// <summary>
  78         /// TransitionProperty
  79         /// </summary>
  80         [EditorBrowsable(EditorBrowsableState.Never)]
  81         public static readonly BindableProperty TransitionProperty = BindableProperty.Create(nameof(Transition), typeof(Transition), typeof(Navigator), null, propertyChanged: (bindable, oldValue, newValue) =>
  82         {
  83             var instance = (Navigator)bindable;
  84             if (newValue != null)
  85             {
  86                 instance.InternalTransition = newValue as Transition;
  87             }
  88         },
  89         defaultValueCreator: (bindable) =>
  90         {
  91             var instance = (Navigator)bindable;
  92             return instance.InternalTransition;
  93         });
  94
  95         private const int DefaultTransitionDuration = 500;
  96
  97         //This will be replaced with view transition class instance.
  98         private Animation curAnimation = null;
  99
 100         //This will be replaced with view transition class instance.
 101         private Animation newAnimation = null;
 102
 103         private TransitionSet transitionSet = null;
 104
 105         private Transition transition = new Transition()
 106         {
 107             TimePeriod = new TimePeriod(DefaultTransitionDuration),
 108             AlphaFunction = new AlphaFunction(AlphaFunction.BuiltinFunctions.Default),
 109         };
 110
 111         private bool transitionFinished = true;
 112
 113         //TODO: Needs to consider how to remove disposed window from dictionary.
 114         //Two dictionaries are required to remove disposed navigator from dictionary.
 115         private static Dictionary<Window, Navigator> windowNavigator = new Dictionary<Window, Navigator>();
 116         private static Dictionary<Navigator, Window> navigatorWindow = new Dictionary<Navigator, Window>();
 117
 118         private List<Page> navigationPages = new List<Page>();
 119
 120         /// <summary>
 121         /// Creates a new instance of a Navigator.
 122         /// </summary>
 123         /// <since_tizen> 9 </since_tizen>
 124         public Navigator() : base()
 125         {
 126             Layout = new AbsoluteLayout();
 127         }
 128
 129         /// <inheritdoc/>
 130         [EditorBrowsable(EditorBrowsableState.Never)]
 131         public override void OnInitialize()
 132         {
 133             base.OnInitialize();
 134
 135             SetAccessibilityConstructor(Role.PageTabList);
 136         }
 137
 138         /// <summary>
 139         /// An event fired when Transition has been finished.
 140         /// </summary>
 141         /// <since_tizen> 9 </since_tizen>
 142         public event EventHandler<EventArgs> TransitionFinished;
 143
 144         /// <summary>
 145         /// An event fired when Pop of a page has been finished.
 146         /// </summary>
 147         /// <remarks>
 148         /// When you free resources in the Popped event handler, please make sure if the popped page is the page you find.
 149         /// </remarks>
 150         /// <since_tizen> 9 </since_tizen>
 151         public event EventHandler<PoppedEventArgs> Popped;
 152
 153         /// <summary>
 154         /// Returns the count of pages in Navigator.
 155         /// </summary>
 156         /// <since_tizen> 9 </since_tizen>
 157         public int PageCount => navigationPages.Count;
 158
 159         /// <summary>
 160         /// Transition properties for the transition of View pair having same transition tag.
 161         /// </summary>
 162         /// <since_tizen> 9 </since_tizen>
 163         public Transition Transition
 164         {
 165             get
 166             {
 167                 return GetValue(TransitionProperty) as Transition;
 168             }
 169             set
 170             {
 171                 SetValue(TransitionProperty, value);
 172                 NotifyPropertyChanged();
 173             }
 174         }
 175         private Transition InternalTransition
 176         {
 177             set
 178             {
 179                 transition = value;
 180             }
 181             get
 182             {
 183                 return transition;
 184             }
 185         }
 186
 187         /// <summary>
 188         /// Pushes a page to Navigator.
 189         /// If the page is already in Navigator, then it is not pushed.
 190         /// </summary>
 191         /// <param name="page">The page to push to Navigator.</param>
 192         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 193         /// <since_tizen> 9 </since_tizen>
 194         public void PushWithTransition(Page page)
 195         {
 196             if (!transitionFinished)
 197             {
 198                 Tizen.Log.Error("NUI", "Transition is still not finished.\n");
 199                 return;
 200             }
 201
 202             if (page == null)
 203             {
 204                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 205             }
 206
 207             //Duplicate page is not pushed.
 208             if (navigationPages.Contains(page)) return;
 209
 210             var topPage = Peek();
 211
 212             if (!topPage)
 213             {
 214                 Insert(0, page);
 215                 return;
 216             }
 217
 218             navigationPages.Add(page);
 219             Add(page);
 220             page.Navigator = this;
 221
 222             //Invoke Page events
 223             page.InvokeAppearing();
 224             topPage.InvokeDisappearing();
 225
 226             transitionSet = CreateTransitions(topPage, page, true);
 227             transitionSet.Finished += (object sender, EventArgs e) =>
 228             {
 229                 if (page is DialogPage == false)
 230                 {
 231                    topPage.SetVisible(false);
 232                 }
 233
 234                 // Need to update Content of the new page
 235                 ShowContentOfPage(page);
 236
 237                 //Invoke Page events
 238                 page.InvokeAppeared();
 239                 topPage.InvokeDisappeared();
 240                 NotifyAccessibilityStatesChangeOfPages(topPage, page);
 241             };
 242             transitionFinished = false;
 243         }
 244
 245         /// <summary>
 246         /// Pops the top page from Navigator.
 247         /// </summary>
 248         /// <returns>The popped page.</returns>
 249         /// <exception cref="InvalidOperationException">Thrown when there is no page in Navigator.</exception>
 250         /// <since_tizen> 9 </since_tizen>
 251         public Page PopWithTransition()
 252         {
 253             if (!transitionFinished)
 254             {
 255                 Tizen.Log.Error("NUI", "Transition is still not finished.\n");
 256                 return null;
 257             }
 258
 259             if (navigationPages.Count == 0)
 260             {
 261                 throw new InvalidOperationException("There is no page in Navigator.");
 262             }
 263
 264             var topPage = Peek();
 265
 266             if (navigationPages.Count == 1)
 267             {
 268                 Remove(topPage);
 269
 270                 //Invoke Popped event
 271                 Popped?.Invoke(this, new PoppedEventArgs() { Page = topPage });
 272
 273                 return topPage;
 274             }
 275             var newTopPage = navigationPages[navigationPages.Count - 2];
 276
 277             //Invoke Page events
 278             newTopPage.InvokeAppearing();
 279             topPage.InvokeDisappearing();
 280
 281             transitionSet = CreateTransitions(topPage, newTopPage, false);
 282             transitionSet.Finished += (object sender, EventArgs e) =>
 283             {
 284                 Remove(topPage);
 285                 topPage.SetVisible(true);
 286
 287                 // Need to update Content of the new page
 288                 ShowContentOfPage(newTopPage);
 289
 290                 //Invoke Page events
 291                 newTopPage.InvokeAppeared();
 292                 topPage.InvokeDisappeared();
 293
 294                 //Invoke Popped event
 295                 Popped?.Invoke(this, new PoppedEventArgs() { Page = topPage });
 296             };
 297             transitionFinished = false;
 298
 299             return topPage;
 300         }
 301
 302         /// <summary>
 303         /// Pushes a page to Navigator.
 304         /// If the page is already in Navigator, then it is not pushed.
 305         /// </summary>
 306         /// <param name="page">The page to push to Navigator.</param>
 307         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 308         /// <since_tizen> 9 </since_tizen>
 309         public void Push(Page page)
 310         {
 311             if (!transitionFinished)
 312             {
 313                 Tizen.Log.Error("NUI", "Transition is still not finished.\n");
 314                 return;
 315             }
 316
 317             if (page == null)
 318             {
 319                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 320             }
 321
 322             //Duplicate page is not pushed.
 323             if (navigationPages.Contains(page)) return;
 324
 325             var curTop = Peek();
 326
 327             if (!curTop)
 328             {
 329                 Insert(0, page);
 330                 return;
 331             }
 332
 333             navigationPages.Add(page);
 334             Add(page);
 335             page.Navigator = this;
 336
 337             //Invoke Page events
 338             page.InvokeAppearing();
 339             curTop.InvokeDisappearing();
 340
 341             //TODO: The following transition codes will be replaced with view transition.
 342             InitializeAnimation();
 343
 344             if (page is DialogPage == false)
 345             {
 346                 curAnimation = new Animation(1000);
 347                 curAnimation.AnimateTo(curTop, "Opacity", 1.0f, 0, 1000);
 348                 curAnimation.EndAction = Animation.EndActions.StopFinal;
 349                 curAnimation.Finished += (object sender, EventArgs args) =>
 350                 {
 351                     curTop.SetVisible(false);
 352
 353                     //Invoke Page events
 354                     curTop.InvokeDisappeared();
 355                 };
 356                 curAnimation.Play();
 357
 358                 page.Opacity = 0.0f;
 359                 page.SetVisible(true);
 360                 newAnimation = new Animation(1000);
 361                 newAnimation.AnimateTo(page, "Opacity", 1.0f, 0, 1000);
 362                 newAnimation.EndAction = Animation.EndActions.StopFinal;
 363                 newAnimation.Finished += (object sender, EventArgs e) =>
 364                 {
 365                     // Need to update Content of the new page
 366                     ShowContentOfPage(page);
 367
 368                     //Invoke Page events
 369                     page.InvokeAppeared();
 370                     NotifyAccessibilityStatesChangeOfPages(curTop, page);
 371                 };
 372                 newAnimation.Play();
 373             }
 374             else
 375             {
 376                 ShowContentOfPage(page);
 377             }
 378         }
 379
 380         /// <summary>
 381         /// Pops the top page from Navigator.
 382         /// </summary>
 383         /// <returns>The popped page.</returns>
 384         /// <exception cref="InvalidOperationException">Thrown when there is no page in Navigator.</exception>
 385         /// <since_tizen> 9 </since_tizen>
 386         public Page Pop()
 387         {
 388             if (!transitionFinished)
 389             {
 390                 Tizen.Log.Error("NUI", "Transition is still not finished.\n");
 391                 return null;
 392             }
 393
 394             if (navigationPages.Count == 0)
 395             {
 396                 throw new InvalidOperationException("There is no page in Navigator.");
 397             }
 398
 399             var curTop = Peek();
 400
 401             if (navigationPages.Count == 1)
 402             {
 403                 Remove(curTop);
 404
 405                 //Invoke Popped event
 406                 Popped?.Invoke(this, new PoppedEventArgs() { Page = curTop });
 407
 408                 return curTop;
 409             }
 410
 411             var newTop = navigationPages[navigationPages.Count - 2];
 412
 413             //Invoke Page events
 414             newTop.InvokeAppearing();
 415             curTop.InvokeDisappearing();
 416
 417             //TODO: The following transition codes will be replaced with view transition.
 418             InitializeAnimation();
 419
 420             if (curTop is DialogPage == false)
 421             {
 422                 curAnimation = new Animation(1000);
 423                 curAnimation.AnimateTo(curTop, "Opacity", 0.0f, 0, 1000);
 424                 curAnimation.EndAction = Animation.EndActions.StopFinal;
 425                 curAnimation.Finished += (object sender, EventArgs e) =>
 426                 {
 427                     //Removes the current top page after transition is finished.
 428                     Remove(curTop);
 429                     curTop.Opacity = 1.0f;
 430
 431                     //Invoke Page events
 432                     curTop.InvokeDisappeared();
 433
 434                     //Invoke Popped event
 435                     Popped?.Invoke(this, new PoppedEventArgs() { Page = curTop });
 436                 };
 437                 curAnimation.Play();
 438
 439                 newTop.Opacity = 1.0f;
 440                 newTop.SetVisible(true);
 441                 newAnimation = new Animation(1000);
 442                 newAnimation.AnimateTo(newTop, "Opacity", 1.0f, 0, 1000);
 443                 newAnimation.EndAction = Animation.EndActions.StopFinal;
 444                 newAnimation.Finished += (object sender, EventArgs e) =>
 445                 {
 446                     // Need to update Content of the new page
 447                     ShowContentOfPage(newTop);
 448
 449                     //Invoke Page events
 450                     newTop.InvokeAppeared();
 451                 };
 452                 newAnimation.Play();
 453             }
 454             else
 455             {
 456                 Remove(curTop);
 457             }
 458
 459             return curTop;
 460         }
 461
 462         /// <summary>
 463         /// Returns the page of the given index in Navigator.
 464         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 465         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 466         /// </summary>
 467         /// <param name="index">The index of a page in Navigator.</param>
 468         /// <returns>The page of the given index in Navigator.</returns>
 469         /// <exception cref="ArgumentOutOfRangeException">Thrown when the argument index is less than 0, or greater than the number of pages.</exception>
 470         public Page GetPage(int index)
 471         {
 472             if ((index < 0) || (index > navigationPages.Count))
 473             {
 474                 throw new ArgumentOutOfRangeException(nameof(index), "index should be greater than or equal to 0, and less than or equal to the number of pages.");
 475             }
 476
 477             return navigationPages[index];
 478         }
 479
 480         /// <summary>
 481         /// Returns the current index of the given page in Navigator.
 482         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 483         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 484         /// </summary>
 485         /// <param name="page">The page in Navigator.</param>
 486         /// <returns>The index of the given page in Navigator. If the given page is not in the Navigator, then -1 is returned.</returns>
 487         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 488         /// <since_tizen> 9 </since_tizen>
 489         public int IndexOf(Page page)
 490         {
 491             if (page == null)
 492             {
 493                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 494             }
 495
 496             for (int i = 0; i < navigationPages.Count; i++)
 497             {
 498                 if (navigationPages[i] == page)
 499                 {
 500                     return i;
 501                 }
 502             }
 503
 504             return -1;
 505         }
 506
 507         /// <summary>
 508         /// Inserts a page at the specified index of Navigator.
 509         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 510         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 511         /// To find the current index of a page in Navigator, please use IndexOf(page).
 512         /// If the page is already in Navigator, then it is not inserted.
 513         /// </summary>
 514         /// <param name="index">The index of a page in Navigator where the page will be inserted.</param>
 515         /// <param name="page">The page to insert to Navigator.</param>
 516         /// <exception cref="ArgumentOutOfRangeException">Thrown when the argument index is less than 0, or greater than the number of pages.</exception>
 517         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 518         /// <since_tizen> 9 </since_tizen>
 519         public void Insert(int index, Page page)
 520         {
 521             if ((index < 0) || (index > navigationPages.Count))
 522             {
 523                 throw new ArgumentOutOfRangeException(nameof(index), "index should be greater than or equal to 0, and less than or equal to the number of pages.");
 524             }
 525
 526             if (page == null)
 527             {
 528                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 529             }
 530
 531             //Duplicate page is not pushed.
 532             if (navigationPages.Contains(page)) return;
 533
 534             //TODO: The following transition codes will be replaced with view transition.
 535             InitializeAnimation();
 536
 537             ShowContentOfPage(page);
 538
 539             if (index == PageCount)
 540             {
 541                 page.Opacity = 1.0f;
 542                 page.SetVisible(true);
 543             }
 544             else
 545             {
 546                 page.SetVisible(false);
 547                 page.Opacity = 0.0f;
 548             }
 549
 550             navigationPages.Insert(index, page);
 551             Add(page);
 552             page.Navigator = this;
 553             if (index == PageCount - 1)
 554             {
 555                 if (PageCount > 1)
 556                 {
 557                     NotifyAccessibilityStatesChangeOfPages(navigationPages[PageCount - 2], page);
 558                 }
 559                 else
 560                 {
 561                     NotifyAccessibilityStatesChangeOfPages(null, page);
 562                 }
 563             }
 564         }
 565
 566         /// <summary>
 567         /// Inserts a page to Navigator before an existing page.
 568         /// If the page is already in Navigator, then it is not inserted.
 569         /// </summary>
 570         /// <param name="before">The existing page, before which a page will be inserted.</param>
 571         /// <param name="page">The page to insert to Navigator.</param>
 572         /// <exception cref="ArgumentNullException">Thrown when the argument before is null.</exception>
 573         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 574         /// <exception cref="ArgumentException">Thrown when the argument before does not exist in Navigator.</exception>
 575         /// <since_tizen> 9 </since_tizen>
 576         public void InsertBefore(Page before, Page page)
 577         {
 578             if (before == null)
 579             {
 580                 throw new ArgumentNullException(nameof(before), "before should not be null.");
 581             }
 582
 583             if (page == null)
 584             {
 585                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 586             }
 587
 588             //Find the index of before page.
 589             int beforeIndex = navigationPages.FindIndex(x => x == before);
 590
 591             //before does not exist in Navigator.
 592             if (beforeIndex == -1)
 593             {
 594                 throw new ArgumentException("before does not exist in Navigator.", nameof(before));
 595             }
 596
 597             Insert(beforeIndex, page);
 598         }
 599
 600         /// <summary>
 601         /// Removes a page from Navigator.
 602         /// </summary>
 603         /// <param name="page">The page to remove from Navigator.</param>
 604         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 605         /// <since_tizen> 9 </since_tizen>
 606         public void Remove(Page page)
 607         {
 608             if (page == null)
 609             {
 610                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 611             }
 612
 613             //TODO: The following transition codes will be replaced with view transition.
 614             InitializeAnimation();
 615
 616             HideContentOfPage(page);
 617
 618             if (page == Peek())
 619             {
 620                 if (PageCount >= 2)
 621                 {
 622                     navigationPages[PageCount - 2].Opacity = 1.0f;
 623                     navigationPages[PageCount - 2].SetVisible(true);
 624                     NotifyAccessibilityStatesChangeOfPages(page, navigationPages[PageCount - 2]);
 625                 }
 626                 else if (PageCount == 1)
 627                 {
 628                     NotifyAccessibilityStatesChangeOfPages(page, null);
 629                 }
 630             }
 631             page.Navigator = null;
 632             navigationPages.Remove(page);
 633             base.Remove(page);
 634         }
 635
 636         /// <summary>
 637         /// Removes a page at the specified index of Navigator.
 638         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 639         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 640         /// To find the current index of a page in Navigator, please use IndexOf(page).
 641         /// </summary>
 642         /// <param name="index">The index of a page in Navigator where the page will be removed.</param>
 643         /// <exception cref="ArgumentOutOfRangeException">Thrown when the index is less than 0, or greater than or equal to the number of pages.</exception>
 644         /// <since_tizen> 9 </since_tizen>
 645         public void RemoveAt(int index)
 646         {
 647             if ((index < 0) || (index >= navigationPages.Count))
 648             {
 649                 throw new ArgumentOutOfRangeException(nameof(index), "index should be greater than or equal to 0, and less than the number of pages.");
 650             }
 651
 652             Remove(navigationPages[index]);
 653         }
 654
 655         /// <summary>
 656         /// Returns the page at the top of Navigator.
 657         /// </summary>
 658         /// <returns>The page at the top of Navigator.</returns>
 659         /// <since_tizen> 9 </since_tizen>
 660         public Page Peek()
 661         {
 662             if (navigationPages.Count == 0) return null;
 663
 664             return navigationPages[navigationPages.Count - 1];
 665         }
 666
 667         /// <summary>
 668         /// Disposes Navigator and all children on it.
 669         /// </summary>
 670         /// <param name="type">Dispose type.</param>
 671         [EditorBrowsable(EditorBrowsableState.Never)]
 672         protected override void Dispose(DisposeTypes type)
 673         {
 674             if (disposed)
 675             {
 676                 return;
 677             }
 678
 679             if (type == DisposeTypes.Explicit)
 680             {
 681                 foreach (Page page in navigationPages)
 682                 {
 683                     Utility.Dispose(page);
 684                 }
 685                 navigationPages.Clear();
 686
 687                 Window window;
 688
 689                 if (navigatorWindow.TryGetValue(this, out window) == true)
 690                 {
 691                     navigatorWindow.Remove(this);
 692                     windowNavigator.Remove(window);
 693                 }
 694             }
 695
 696             base.Dispose(type);
 697         }
 698
 699         /// <summary>
 700         /// Returns the default navigator of the given window.
 701         /// </summary>
 702         /// <returns>The default navigator of the given window.</returns>
 703         /// <exception cref="ArgumentNullException">Thrown when the argument window is null.</exception>
 704         /// <since_tizen> 9 </since_tizen>
 705         public static Navigator GetDefaultNavigator(Window window)
 706         {
 707             if (window == null)
 708             {
 709                 throw new ArgumentNullException(nameof(window), "window should not be null.");
 710             }
 711
 712             if (windowNavigator.ContainsKey(window) == true)
 713             {
 714                 return windowNavigator[window];
 715             }
 716
 717             var defaultNavigator = new Navigator();
 718             defaultNavigator.WidthResizePolicy = ResizePolicyType.FillToParent;
 719             defaultNavigator.HeightResizePolicy = ResizePolicyType.FillToParent;
 720             window.Add(defaultNavigator);
 721             windowNavigator.Add(window, defaultNavigator);
 722             navigatorWindow.Add(defaultNavigator, window);
 723
 724             return defaultNavigator;
 725         }
 726
 727         /// <summary>
 728         /// Create Transitions between currentTopPage and newTopPage
 729         /// </summary>
 730         /// <param name="currentTopPage">The top page of Navigator.</param>
 731         /// <param name="newTopPage">The new top page after transition.</param>
 732         /// <param name="pushTransition">True if this transition is for push new page</param>
 733         private TransitionSet CreateTransitions(Page currentTopPage, Page newTopPage, bool pushTransition)
 734         {
 735             currentTopPage.SetVisible(true);
 736             newTopPage.SetVisible(true);
 737
 738             List<View> taggedViewsInNewTopPage = new List<View>();
 739             RetrieveTaggedViews(taggedViewsInNewTopPage, newTopPage, true);
 740             List<View> taggedViewsInCurrentTopPage = new List<View>();
 741             RetrieveTaggedViews(taggedViewsInCurrentTopPage, currentTopPage, true);
 742
 743             List<KeyValuePair<View, View>> sameTaggedViewPair = new List<KeyValuePair<View, View>>();
 744             foreach(View currentTopPageView in taggedViewsInCurrentTopPage)
 745             {
 746                 bool findPair = false;
 747                 foreach(View newTopPageView in taggedViewsInNewTopPage)
 748                 {
 749                     if((currentTopPageView.TransitionOptions != null) && (newTopPageView.TransitionOptions != null) &&
 750                         currentTopPageView.TransitionOptions?.TransitionTag == newTopPageView.TransitionOptions?.TransitionTag)
 751                     {
 752                         sameTaggedViewPair.Add(new KeyValuePair<View, View>(currentTopPageView, newTopPageView));
 753                         findPair = true;
 754                         break;
 755                     }
 756                 }
 757                 if(findPair)
 758                 {
 759                     taggedViewsInNewTopPage.Remove(sameTaggedViewPair[sameTaggedViewPair.Count - 1].Value);
 760                 }
 761             }
 762             foreach(KeyValuePair<View, View> pair in sameTaggedViewPair)
 763             {
 764                 taggedViewsInCurrentTopPage.Remove(pair.Key);
 765             }
 766
 767             TransitionSet newTransitionSet = new TransitionSet();
 768             foreach(KeyValuePair<View, View> pair in sameTaggedViewPair)
 769             {
 770                 TransitionItem pairTransition = transition.CreateTransition(pair.Key, pair.Value, pushTransition);
 771                 if(pair.Value.TransitionOptions?.TransitionWithChild ?? false)
 772                 {
 773                     pairTransition.TransitionWithChild = true;
 774                 }
 775                 newTransitionSet.AddTransition(pairTransition);
 776             }
 777
 778             newTransitionSet.Finished += (object sender, EventArgs e) =>
 779             {
 780                 if(newTopPage.Layout != null)
 781                 {
 782                     newTopPage.Layout.RequestLayout();
 783                 }
 784                 if(currentTopPage.Layout != null)
 785                 {
 786                     currentTopPage.Layout.RequestLayout();
 787                 }
 788                 transitionFinished = true;
 789                 InvokeTransitionFinished();
 790                 transitionSet.Dispose();
 791                 currentTopPage.Opacity = 1.0f;
 792             };
 793
 794             if (!pushTransition || newTopPage is DialogPage == false)
 795             {
 796                 View transitionView = (currentTopPage is ContentPage) ? (currentTopPage as ContentPage).Content : (currentTopPage as DialogPage).Content;
 797                 if (currentTopPage.DisappearingTransition != null && transitionView != null)
 798                 {
 799                     TransitionItemBase disappearingTransition = currentTopPage.DisappearingTransition.CreateTransition(transitionView, false);
 800                     disappearingTransition.TransitionWithChild = true;
 801                     newTransitionSet.AddTransition(disappearingTransition);
 802                 }
 803                 else
 804                 {
 805                     currentTopPage.SetVisible(false);
 806                 }
 807             }
 808             if (pushTransition || currentTopPage is DialogPage == false)
 809             {
 810                 View transitionView = (newTopPage is ContentPage) ? (newTopPage as ContentPage).Content : (newTopPage as DialogPage).Content;
 811                 if (newTopPage.AppearingTransition != null && transitionView != null)
 812                 {
 813                     TransitionItemBase appearingTransition = newTopPage.AppearingTransition.CreateTransition(transitionView, true);
 814                     appearingTransition.TransitionWithChild = true;
 815                     newTransitionSet.AddTransition(appearingTransition);
 816                 }
 817             }
 818
 819             newTransitionSet.Play();
 820
 821             return newTransitionSet;
 822         }
 823
 824         /// <summary>
 825         /// Retrieve Tagged Views in the view tree.
 826         /// </summary>
 827         /// <param name="taggedViews">Returned tagged view list..</param>
 828         /// <param name="view">Root View to get tagged child View.</param>
 829         /// <param name="isRoot">Flag to check current View is page or not</param>
 830         private void RetrieveTaggedViews(List<View> taggedViews, View view, bool isRoot)
 831         {
 832             if (!isRoot && view.TransitionOptions != null)
 833             {
 834                 if (!string.IsNullOrEmpty(view.TransitionOptions?.TransitionTag))
 835                 {
 836                     taggedViews.Add((view as View));
 837                     if (view.TransitionOptions.TransitionWithChild)
 838                     {
 839                         return;
 840                     }
 841                 }
 842
 843             }
 844
 845             foreach (View child in view.Children)
 846             {
 847                 RetrieveTaggedViews(taggedViews, child, false);
 848             }
 849         }
 850
 851         /// <summary>
 852         /// Notify accessibility states change of pages.
 853         /// </summary>
 854         /// <param name="disappearedPage">Disappeared page</param>
 855         /// <param name="appearedPage">Appeared page</param>
 856         private void NotifyAccessibilityStatesChangeOfPages(Page disappearedPage, Page appearedPage)
 857         {
 858             if (disappearedPage != null)
 859             {
 860                 disappearedPage.UnregisterDefaultLabel();
 861                 //We can call disappearedPage.NotifyAccessibilityStatesChange
 862                 //To reduce accessibility events, we are using currently highlighted view instead
 863                 View curHighlightedView = Accessibility.Accessibility.GetCurrentlyHighlightedView();
 864                 if (curHighlightedView != null)
 865                 {
 866                     curHighlightedView.NotifyAccessibilityStatesChange(new AccessibilityStates(AccessibilityState.Visible, AccessibilityState.Showing), AccessibilityStatesNotifyMode.Single);
 867                 }
 868             }
 869
 870             if (appearedPage != null)
 871             {
 872                 appearedPage.RegisterDefaultLabel();
 873                 appearedPage.NotifyAccessibilityStatesChange(new AccessibilityStates(AccessibilityState.Visible, AccessibilityState.Showing), AccessibilityStatesNotifyMode.Single);
 874             }
 875         }
 876
 877         internal void InvokeTransitionFinished()
 878         {
 879             TransitionFinished?.Invoke(this, new EventArgs());
 880         }
 881
 882         //TODO: The following transition codes will be replaced with view transition.
 883         private void InitializeAnimation()
 884         {
 885             if (curAnimation != null)
 886             {
 887                 curAnimation.Stop();
 888                 curAnimation.Clear();
 889                 curAnimation = null;
 890             }
 891
 892             if (newAnimation != null)
 893             {
 894                 newAnimation.Stop();
 895                 newAnimation.Clear();
 896                 newAnimation = null;
 897             }
 898         }
 899
 900         // Show and Register Content of Page to Accessibility bridge
 901         private void ShowContentOfPage(Page page)
 902         {
 903             View content = (page is DialogPage) ? (page as DialogPage)?.Content : (page as ContentPage)?.Content;
 904             if (content != null)
 905             {
 906                 content.Show(); // Calls RegisterDefaultLabel()
 907             }
 908         }
 909
 910         // Hide and Remove Content of Page from Accessibility bridge
 911         private void HideContentOfPage(Page page)
 912         {
 913             View content = (page is DialogPage) ? (page as DialogPage)?.Content : (page as ContentPage)?.Content;
 914             if (content != null)
 915             {
 916                 content.Hide(); // Calls UnregisterDefaultLabel()
 917             }
 918         }
 919     }
 920 }