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             curTop.SaveKeyFocus();
 342
 343             //TODO: The following transition codes will be replaced with view transition.
 344             InitializeAnimation();
 345
 346             if (page is DialogPage == false)
 347             {
 348                 curAnimation = new Animation(1000);
 349                 curAnimation.AnimateTo(curTop, "Opacity", 1.0f, 0, 1000);
 350                 curAnimation.EndAction = Animation.EndActions.StopFinal;
 351                 curAnimation.Finished += (object sender, EventArgs args) =>
 352                 {
 353                     curTop.SetVisible(false);
 354
 355                     //Invoke Page events
 356                     curTop.InvokeDisappeared();
 357                 };
 358                 curAnimation.Play();
 359
 360                 page.Opacity = 0.0f;
 361                 page.SetVisible(true);
 362                 newAnimation = new Animation(1000);
 363                 newAnimation.AnimateTo(page, "Opacity", 1.0f, 0, 1000);
 364                 newAnimation.EndAction = Animation.EndActions.StopFinal;
 365                 newAnimation.Finished += (object sender, EventArgs e) =>
 366                 {
 367                     // Need to update Content of the new page
 368                     ShowContentOfPage(page);
 369
 370                     //Invoke Page events
 371                     page.InvokeAppeared();
 372                     NotifyAccessibilityStatesChangeOfPages(curTop, page);
 373
 374                     page.RestoreKeyFocus();
 375                 };
 376                 newAnimation.Play();
 377             }
 378             else
 379             {
 380                 ShowContentOfPage(page);
 381                 page.RestoreKeyFocus();
 382             }
 383         }
 384
 385         /// <summary>
 386         /// Pops the top page from Navigator.
 387         /// </summary>
 388         /// <returns>The popped page.</returns>
 389         /// <exception cref="InvalidOperationException">Thrown when there is no page in Navigator.</exception>
 390         /// <since_tizen> 9 </since_tizen>
 391         public Page Pop()
 392         {
 393             if (!transitionFinished)
 394             {
 395                 Tizen.Log.Error("NUI", "Transition is still not finished.\n");
 396                 return null;
 397             }
 398
 399             if (navigationPages.Count == 0)
 400             {
 401                 throw new InvalidOperationException("There is no page in Navigator.");
 402             }
 403
 404             var curTop = Peek();
 405
 406             if (navigationPages.Count == 1)
 407             {
 408                 Remove(curTop);
 409
 410                 //Invoke Popped event
 411                 Popped?.Invoke(this, new PoppedEventArgs() { Page = curTop });
 412
 413                 return curTop;
 414             }
 415
 416             var newTop = navigationPages[navigationPages.Count - 2];
 417
 418             //Invoke Page events
 419             newTop.InvokeAppearing();
 420             curTop.InvokeDisappearing();
 421             curTop.SaveKeyFocus();
 422
 423             //TODO: The following transition codes will be replaced with view transition.
 424             InitializeAnimation();
 425
 426             if (curTop is DialogPage == false)
 427             {
 428                 curAnimation = new Animation(1000);
 429                 curAnimation.AnimateTo(curTop, "Opacity", 0.0f, 0, 1000);
 430                 curAnimation.EndAction = Animation.EndActions.StopFinal;
 431                 curAnimation.Finished += (object sender, EventArgs e) =>
 432                 {
 433                     //Removes the current top page after transition is finished.
 434                     Remove(curTop);
 435                     curTop.Opacity = 1.0f;
 436
 437                     //Invoke Page events
 438                     curTop.InvokeDisappeared();
 439
 440                     //Invoke Popped event
 441                     Popped?.Invoke(this, new PoppedEventArgs() { Page = curTop });
 442                 };
 443                 curAnimation.Play();
 444
 445                 newTop.Opacity = 1.0f;
 446                 newTop.SetVisible(true);
 447                 newAnimation = new Animation(1000);
 448                 newAnimation.AnimateTo(newTop, "Opacity", 1.0f, 0, 1000);
 449                 newAnimation.EndAction = Animation.EndActions.StopFinal;
 450                 newAnimation.Finished += (object sender, EventArgs e) =>
 451                 {
 452                     // Need to update Content of the new page
 453                     ShowContentOfPage(newTop);
 454
 455                     //Invoke Page events
 456                     newTop.InvokeAppeared();
 457
 458                     newTop.RestoreKeyFocus();
 459                 };
 460                 newAnimation.Play();
 461             }
 462             else
 463             {
 464                 Remove(curTop);
 465             }
 466
 467             return curTop;
 468         }
 469
 470         /// <summary>
 471         /// Returns the page of the given index in Navigator.
 472         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 473         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 474         /// </summary>
 475         /// <param name="index">The index of a page in Navigator.</param>
 476         /// <returns>The page of the given index in Navigator.</returns>
 477         /// <exception cref="ArgumentOutOfRangeException">Thrown when the argument index is less than 0, or greater than the number of pages.</exception>
 478         public Page GetPage(int index)
 479         {
 480             if ((index < 0) || (index > navigationPages.Count))
 481             {
 482                 throw new ArgumentOutOfRangeException(nameof(index), "index should be greater than or equal to 0, and less than or equal to the number of pages.");
 483             }
 484
 485             return navigationPages[index];
 486         }
 487
 488         /// <summary>
 489         /// Returns the current index of the given page in Navigator.
 490         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 491         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 492         /// </summary>
 493         /// <param name="page">The page in Navigator.</param>
 494         /// <returns>The index of the given page in Navigator. If the given page is not in the Navigator, then -1 is returned.</returns>
 495         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 496         /// <since_tizen> 9 </since_tizen>
 497         public int IndexOf(Page page)
 498         {
 499             if (page == null)
 500             {
 501                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 502             }
 503
 504             for (int i = 0; i < navigationPages.Count; i++)
 505             {
 506                 if (navigationPages[i] == page)
 507                 {
 508                     return i;
 509                 }
 510             }
 511
 512             return -1;
 513         }
 514
 515         /// <summary>
 516         /// Inserts a page at the specified index of Navigator.
 517         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 518         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 519         /// To find the current index of a page in Navigator, please use IndexOf(page).
 520         /// If the page is already in Navigator, then it is not inserted.
 521         /// </summary>
 522         /// <param name="index">The index of a page in Navigator where the page will be inserted.</param>
 523         /// <param name="page">The page to insert to Navigator.</param>
 524         /// <exception cref="ArgumentOutOfRangeException">Thrown when the argument index is less than 0, or greater than the number of pages.</exception>
 525         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 526         /// <since_tizen> 9 </since_tizen>
 527         public void Insert(int index, Page page)
 528         {
 529             if ((index < 0) || (index > navigationPages.Count))
 530             {
 531                 throw new ArgumentOutOfRangeException(nameof(index), "index should be greater than or equal to 0, and less than or equal to the number of pages.");
 532             }
 533
 534             if (page == null)
 535             {
 536                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 537             }
 538
 539             //Duplicate page is not pushed.
 540             if (navigationPages.Contains(page)) return;
 541
 542             //TODO: The following transition codes will be replaced with view transition.
 543             InitializeAnimation();
 544
 545             ShowContentOfPage(page);
 546
 547             if (index == PageCount)
 548             {
 549                 page.Opacity = 1.0f;
 550                 page.SetVisible(true);
 551             }
 552             else
 553             {
 554                 page.SetVisible(false);
 555                 page.Opacity = 0.0f;
 556             }
 557
 558             navigationPages.Insert(index, page);
 559             Add(page);
 560             page.Navigator = this;
 561             if (index == PageCount - 1)
 562             {
 563                 if (PageCount > 1)
 564                 {
 565                     NotifyAccessibilityStatesChangeOfPages(navigationPages[PageCount - 2], page);
 566                 }
 567                 else
 568                 {
 569                     NotifyAccessibilityStatesChangeOfPages(null, page);
 570                 }
 571             }
 572         }
 573
 574         /// <summary>
 575         /// Inserts a page to Navigator before an existing page.
 576         /// If the page is already in Navigator, then it is not inserted.
 577         /// </summary>
 578         /// <param name="before">The existing page, before which a page will be inserted.</param>
 579         /// <param name="page">The page to insert to Navigator.</param>
 580         /// <exception cref="ArgumentNullException">Thrown when the argument before is null.</exception>
 581         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 582         /// <exception cref="ArgumentException">Thrown when the argument before does not exist in Navigator.</exception>
 583         /// <since_tizen> 9 </since_tizen>
 584         public void InsertBefore(Page before, Page page)
 585         {
 586             if (before == null)
 587             {
 588                 throw new ArgumentNullException(nameof(before), "before should not be null.");
 589             }
 590
 591             if (page == null)
 592             {
 593                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 594             }
 595
 596             //Find the index of before page.
 597             int beforeIndex = navigationPages.FindIndex(x => x == before);
 598
 599             //before does not exist in Navigator.
 600             if (beforeIndex == -1)
 601             {
 602                 throw new ArgumentException("before does not exist in Navigator.", nameof(before));
 603             }
 604
 605             Insert(beforeIndex, page);
 606         }
 607
 608         /// <summary>
 609         /// Removes a page from Navigator.
 610         /// </summary>
 611         /// <param name="page">The page to remove from Navigator.</param>
 612         /// <exception cref="ArgumentNullException">Thrown when the argument page is null.</exception>
 613         /// <since_tizen> 9 </since_tizen>
 614         public void Remove(Page page)
 615         {
 616             if (page == null)
 617             {
 618                 throw new ArgumentNullException(nameof(page), "page should not be null.");
 619             }
 620
 621             //TODO: The following transition codes will be replaced with view transition.
 622             InitializeAnimation();
 623
 624             HideContentOfPage(page);
 625
 626             if (page == Peek())
 627             {
 628                 if (PageCount >= 2)
 629                 {
 630                     navigationPages[PageCount - 2].Opacity = 1.0f;
 631                     navigationPages[PageCount - 2].SetVisible(true);
 632                     NotifyAccessibilityStatesChangeOfPages(page, navigationPages[PageCount - 2]);
 633                 }
 634                 else if (PageCount == 1)
 635                 {
 636                     NotifyAccessibilityStatesChangeOfPages(page, null);
 637                 }
 638             }
 639             page.Navigator = null;
 640             navigationPages.Remove(page);
 641             base.Remove(page);
 642         }
 643
 644         /// <summary>
 645         /// Removes a page at the specified index of Navigator.
 646         /// The indices of pages in Navigator are basically the order of pushing or inserting to Navigator.
 647         /// So a page's index in Navigator can be changed whenever push/insert or pop/remove occurs.
 648         /// To find the current index of a page in Navigator, please use IndexOf(page).
 649         /// </summary>
 650         /// <param name="index">The index of a page in Navigator where the page will be removed.</param>
 651         /// <exception cref="ArgumentOutOfRangeException">Thrown when the index is less than 0, or greater than or equal to the number of pages.</exception>
 652         /// <since_tizen> 9 </since_tizen>
 653         public void RemoveAt(int index)
 654         {
 655             if ((index < 0) || (index >= navigationPages.Count))
 656             {
 657                 throw new ArgumentOutOfRangeException(nameof(index), "index should be greater than or equal to 0, and less than the number of pages.");
 658             }
 659
 660             Remove(navigationPages[index]);
 661         }
 662
 663         /// <summary>
 664         /// Returns the page at the top of Navigator.
 665         /// </summary>
 666         /// <returns>The page at the top of Navigator.</returns>
 667         /// <since_tizen> 9 </since_tizen>
 668         public Page Peek()
 669         {
 670             if (navigationPages.Count == 0) return null;
 671
 672             return navigationPages[navigationPages.Count - 1];
 673         }
 674
 675         /// <summary>
 676         /// Disposes Navigator and all children on it.
 677         /// </summary>
 678         /// <param name="type">Dispose type.</param>
 679         [EditorBrowsable(EditorBrowsableState.Never)]
 680         protected override void Dispose(DisposeTypes type)
 681         {
 682             if (disposed)
 683             {
 684                 return;
 685             }
 686
 687             if (type == DisposeTypes.Explicit)
 688             {
 689                 foreach (Page page in navigationPages)
 690                 {
 691                     Utility.Dispose(page);
 692                 }
 693                 navigationPages.Clear();
 694
 695                 Window window;
 696
 697                 if (navigatorWindow.TryGetValue(this, out window) == true)
 698                 {
 699                     navigatorWindow.Remove(this);
 700                     windowNavigator.Remove(window);
 701                 }
 702             }
 703
 704             base.Dispose(type);
 705         }
 706
 707         /// <summary>
 708         /// Returns the default navigator of the given window.
 709         /// </summary>
 710         /// <returns>The default navigator of the given window.</returns>
 711         /// <exception cref="ArgumentNullException">Thrown when the argument window is null.</exception>
 712         /// <since_tizen> 9 </since_tizen>
 713         public static Navigator GetDefaultNavigator(Window window)
 714         {
 715             if (window == null)
 716             {
 717                 throw new ArgumentNullException(nameof(window), "window should not be null.");
 718             }
 719
 720             if (windowNavigator.ContainsKey(window) == true)
 721             {
 722                 return windowNavigator[window];
 723             }
 724
 725             var defaultNavigator = new Navigator();
 726             defaultNavigator.WidthResizePolicy = ResizePolicyType.FillToParent;
 727             defaultNavigator.HeightResizePolicy = ResizePolicyType.FillToParent;
 728             window.Add(defaultNavigator);
 729             windowNavigator.Add(window, defaultNavigator);
 730             navigatorWindow.Add(defaultNavigator, window);
 731
 732             return defaultNavigator;
 733         }
 734
 735         /// <summary>
 736         /// Create Transitions between currentTopPage and newTopPage
 737         /// </summary>
 738         /// <param name="currentTopPage">The top page of Navigator.</param>
 739         /// <param name="newTopPage">The new top page after transition.</param>
 740         /// <param name="pushTransition">True if this transition is for push new page</param>
 741         private TransitionSet CreateTransitions(Page currentTopPage, Page newTopPage, bool pushTransition)
 742         {
 743             currentTopPage.SetVisible(true);
 744             newTopPage.SetVisible(true);
 745
 746             List<View> taggedViewsInNewTopPage = new List<View>();
 747             RetrieveTaggedViews(taggedViewsInNewTopPage, newTopPage, true);
 748             List<View> taggedViewsInCurrentTopPage = new List<View>();
 749             RetrieveTaggedViews(taggedViewsInCurrentTopPage, currentTopPage, true);
 750
 751             List<KeyValuePair<View, View>> sameTaggedViewPair = new List<KeyValuePair<View, View>>();
 752             foreach (View currentTopPageView in taggedViewsInCurrentTopPage)
 753             {
 754                 bool findPair = false;
 755                 foreach (View newTopPageView in taggedViewsInNewTopPage)
 756                 {
 757                     if ((currentTopPageView.TransitionOptions != null) && (newTopPageView.TransitionOptions != null) &&
 758                         currentTopPageView.TransitionOptions?.TransitionTag == newTopPageView.TransitionOptions?.TransitionTag)
 759                     {
 760                         sameTaggedViewPair.Add(new KeyValuePair<View, View>(currentTopPageView, newTopPageView));
 761                         findPair = true;
 762                         break;
 763                     }
 764                 }
 765                 if (findPair)
 766                 {
 767                     taggedViewsInNewTopPage.Remove(sameTaggedViewPair[sameTaggedViewPair.Count - 1].Value);
 768                 }
 769             }
 770             foreach (KeyValuePair<View, View> pair in sameTaggedViewPair)
 771             {
 772                 taggedViewsInCurrentTopPage.Remove(pair.Key);
 773             }
 774
 775             TransitionSet newTransitionSet = new TransitionSet();
 776             foreach (KeyValuePair<View, View> pair in sameTaggedViewPair)
 777             {
 778                 TransitionItem pairTransition = transition.CreateTransition(pair.Key, pair.Value, pushTransition);
 779                 if (pair.Value.TransitionOptions?.TransitionWithChild ?? false)
 780                 {
 781                     pairTransition.TransitionWithChild = true;
 782                 }
 783                 newTransitionSet.AddTransition(pairTransition);
 784             }
 785
 786             newTransitionSet.Finished += (object sender, EventArgs e) =>
 787             {
 788                 if (newTopPage.Layout != null)
 789                 {
 790                     newTopPage.Layout.RequestLayout();
 791                 }
 792                 if (currentTopPage.Layout != null)
 793                 {
 794                     currentTopPage.Layout.RequestLayout();
 795                 }
 796                 transitionFinished = true;
 797                 InvokeTransitionFinished();
 798                 transitionSet.Dispose();
 799                 currentTopPage.Opacity = 1.0f;
 800             };
 801
 802             if (!pushTransition || newTopPage is DialogPage == false)
 803             {
 804                 View transitionView = (currentTopPage is ContentPage) ? (currentTopPage as ContentPage).Content : (currentTopPage as DialogPage).Content;
 805                 if (currentTopPage.DisappearingTransition != null && transitionView != null)
 806                 {
 807                     TransitionItemBase disappearingTransition = currentTopPage.DisappearingTransition.CreateTransition(transitionView, false);
 808                     disappearingTransition.TransitionWithChild = true;
 809                     newTransitionSet.AddTransition(disappearingTransition);
 810                 }
 811                 else
 812                 {
 813                     currentTopPage.SetVisible(false);
 814                 }
 815             }
 816             if (pushTransition || currentTopPage is DialogPage == false)
 817             {
 818                 View transitionView = (newTopPage is ContentPage) ? (newTopPage as ContentPage).Content : (newTopPage as DialogPage).Content;
 819                 if (newTopPage.AppearingTransition != null && transitionView != null)
 820                 {
 821                     TransitionItemBase appearingTransition = newTopPage.AppearingTransition.CreateTransition(transitionView, true);
 822                     appearingTransition.TransitionWithChild = true;
 823                     newTransitionSet.AddTransition(appearingTransition);
 824                 }
 825             }
 826
 827             newTransitionSet.Play();
 828
 829             return newTransitionSet;
 830         }
 831
 832         /// <summary>
 833         /// Retrieve Tagged Views in the view tree.
 834         /// </summary>
 835         /// <param name="taggedViews">Returned tagged view list..</param>
 836         /// <param name="view">Root View to get tagged child View.</param>
 837         /// <param name="isRoot">Flag to check current View is page or not</param>
 838         private void RetrieveTaggedViews(List<View> taggedViews, View view, bool isRoot)
 839         {
 840             if (!isRoot && view.TransitionOptions != null)
 841             {
 842                 if (!string.IsNullOrEmpty(view.TransitionOptions?.TransitionTag))
 843                 {
 844                     taggedViews.Add((view as View));
 845                     if (view.TransitionOptions.TransitionWithChild)
 846                     {
 847                         return;
 848                     }
 849                 }
 850
 851             }
 852
 853             foreach (View child in view.Children)
 854             {
 855                 RetrieveTaggedViews(taggedViews, child, false);
 856             }
 857         }
 858
 859         /// <summary>
 860         /// Notify accessibility states change of pages.
 861         /// </summary>
 862         /// <param name="disappearedPage">Disappeared page</param>
 863         /// <param name="appearedPage">Appeared page</param>
 864         private void NotifyAccessibilityStatesChangeOfPages(Page disappearedPage, Page appearedPage)
 865         {
 866             if (disappearedPage != null)
 867             {
 868                 disappearedPage.UnregisterDefaultLabel();
 869                 //We can call disappearedPage.NotifyAccessibilityStatesChange
 870                 //To reduce accessibility events, we are using currently highlighted view instead
 871                 View curHighlightedView = Accessibility.Accessibility.GetCurrentlyHighlightedView();
 872                 if (curHighlightedView != null)
 873                 {
 874                     curHighlightedView.NotifyAccessibilityStatesChange(new AccessibilityStates(AccessibilityState.Visible, AccessibilityState.Showing), AccessibilityStatesNotifyMode.Single);
 875                 }
 876             }
 877
 878             if (appearedPage != null)
 879             {
 880                 appearedPage.RegisterDefaultLabel();
 881                 appearedPage.NotifyAccessibilityStatesChange(new AccessibilityStates(AccessibilityState.Visible, AccessibilityState.Showing), AccessibilityStatesNotifyMode.Single);
 882             }
 883         }
 884
 885         internal void InvokeTransitionFinished()
 886         {
 887             TransitionFinished?.Invoke(this, new EventArgs());
 888         }
 889
 890         //TODO: The following transition codes will be replaced with view transition.
 891         private void InitializeAnimation()
 892         {
 893             if (curAnimation != null)
 894             {
 895                 curAnimation.Stop();
 896                 curAnimation.Clear();
 897                 curAnimation = null;
 898             }
 899
 900             if (newAnimation != null)
 901             {
 902                 newAnimation.Stop();
 903                 newAnimation.Clear();
 904                 newAnimation = null;
 905             }
 906         }
 907
 908         // Show and Register Content of Page to Accessibility bridge
 909         private void ShowContentOfPage(Page page)
 910         {
 911             View content = (page is DialogPage) ? (page as DialogPage)?.Content : (page as ContentPage)?.Content;
 912             if (content != null)
 913             {
 914                 content.Show(); // Calls RegisterDefaultLabel()
 915             }
 916         }
 917
 918         // Hide and Remove Content of Page from Accessibility bridge
 919         private void HideContentOfPage(Page page)
 920         {
 921             View content = (page is DialogPage) ? (page as DialogPage)?.Content : (page as ContentPage)?.Content;
 922             if (content != null)
 923             {
 924                 content.Hide(); // Calls UnregisterDefaultLabel()
 925             }
 926         }
 927     }
 928 }