src/Tizen.NUI.Components/Controls/ScrollableBase.cs

   1 /* Copyright (c) 2020 Samsung Electronics Co., Ltd.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at
   6  *
   7  * http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  *
  15  */
  16 using System;
  17 using Tizen.NUI.BaseComponents;
  18 using System.ComponentModel;
  19 using System.Diagnostics;
  20
  21 namespace Tizen.NUI.Components
  22 {
  23     /// <summary>
  24     /// [Draft] This class provides a View that can scroll a single View with a layout. This View can be a nest of Views.
  25     /// </summary>
  26     /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API.
  27     [EditorBrowsable(EditorBrowsableState.Never)]
  28     public class ScrollableBase : Control
  29     {
  30         static bool LayoutDebugScrollableBase = false; // Debug flag
  31         private Direction mScrollingDirection = Direction.Vertical;
  32         private bool mScrollEnabled = true;
  33         private int mPageWidth = 0;
  34
  35         private class ScrollableBaseCustomLayout : LayoutGroup
  36         {
  37             protected override void OnMeasure(MeasureSpecification widthMeasureSpec, MeasureSpecification heightMeasureSpec)
  38             {
  39                 Extents padding = Padding;
  40                 float totalHeight = padding.Top + padding.Bottom;
  41                 float totalWidth = padding.Start + padding.End;
  42
  43                 MeasuredSize.StateType childWidthState = MeasuredSize.StateType.MeasuredSizeOK;
  44                 MeasuredSize.StateType childHeightState = MeasuredSize.StateType.MeasuredSizeOK;
  45
  46                 Direction scrollingDirection = Direction.Vertical;
  47                 ScrollableBase scrollableBase = this.Owner as ScrollableBase;
  48                 if (scrollableBase)
  49                 {
  50                     scrollingDirection = scrollableBase.ScrollingDirection;
  51                 }
  52
  53                 // measure child, should be a single scrolling child
  54                 foreach (LayoutItem childLayout in LayoutChildren)
  55                 {
  56                     if (childLayout != null)
  57                     {
  58                         // Get size of child
  59                         // Use an Unspecified MeasureSpecification mode so scrolling child is not restricted to it's parents size in Height (for vertical scrolling)
  60                         // or Width for horizontal scrolling
  61                         MeasureSpecification unrestrictedMeasureSpec = new MeasureSpecification(heightMeasureSpec.Size, MeasureSpecification.ModeType.Unspecified);
  62
  63                         if (scrollingDirection == Direction.Vertical)
  64                         {
  65                             MeasureChildWithMargins(childLayout, widthMeasureSpec, new LayoutLength(0), unrestrictedMeasureSpec, new LayoutLength(0));  // Height unrestricted by parent
  66                         }
  67                         else
  68                         {
  69                             MeasureChildWithMargins(childLayout, unrestrictedMeasureSpec, new LayoutLength(0), heightMeasureSpec, new LayoutLength(0));  // Width unrestricted by parent
  70                         }
  71
  72                         float childWidth = childLayout.MeasuredWidth.Size.AsDecimal();
  73                         float childHeight = childLayout.MeasuredHeight.Size.AsDecimal();
  74
  75                         // Determine the width and height needed by the children using their given position and size.
  76                         // Children could overlap so find the left most and right most child.
  77                         Position2D childPosition = childLayout.Owner.Position2D;
  78                         float childLeft = childPosition.X;
  79                         float childTop = childPosition.Y;
  80
  81                         // Store current width and height needed to contain all children.
  82                         Extents childMargin = childLayout.Margin;
  83                         totalWidth = childWidth + childMargin.Start + childMargin.End;
  84                         totalHeight = childHeight + childMargin.Top + childMargin.Bottom;
  85
  86                         if (childLayout.MeasuredWidth.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  87                         {
  88                             childWidthState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  89                         }
  90                         if (childLayout.MeasuredWidth.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  91                         {
  92                             childHeightState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  93                         }
  94                     }
  95                 }
  96
  97
  98                 MeasuredSize widthSizeAndState = ResolveSizeAndState(new LayoutLength(totalWidth + Padding.Start + Padding.End), widthMeasureSpec, MeasuredSize.StateType.MeasuredSizeOK);
  99                 MeasuredSize heightSizeAndState = ResolveSizeAndState(new LayoutLength(totalHeight + Padding.Top + Padding.Bottom), heightMeasureSpec, MeasuredSize.StateType.MeasuredSizeOK);
 100                 totalWidth = widthSizeAndState.Size.AsDecimal();
 101                 totalHeight = heightSizeAndState.Size.AsDecimal();
 102
 103                 // Ensure layout respects it's given minimum size
 104                 totalWidth = Math.Max(totalWidth, SuggestedMinimumWidth.AsDecimal());
 105                 totalHeight = Math.Max(totalHeight, SuggestedMinimumHeight.AsDecimal());
 106
 107                 widthSizeAndState.State = childWidthState;
 108                 heightSizeAndState.State = childHeightState;
 109
 110                 SetMeasuredDimensions(ResolveSizeAndState(new LayoutLength(totalWidth + Padding.Start + Padding.End), widthMeasureSpec, childWidthState),
 111                                        ResolveSizeAndState(new LayoutLength(totalHeight + Padding.Top + Padding.Bottom), heightMeasureSpec, childHeightState));
 112
 113                 // Size of ScrollableBase is changed. Change Page width too.
 114                 scrollableBase.mPageWidth = (int)MeasuredWidth.Size.AsRoundedValue();
 115             }
 116
 117             protected override void OnLayout(bool changed, LayoutLength left, LayoutLength top, LayoutLength right, LayoutLength bottom)
 118             {
 119                 foreach (LayoutItem childLayout in LayoutChildren)
 120                 {
 121                     if (childLayout != null)
 122                     {
 123                         LayoutLength childWidth = childLayout.MeasuredWidth.Size;
 124                         LayoutLength childHeight = childLayout.MeasuredHeight.Size;
 125
 126                         Position2D childPosition = childLayout.Owner.Position2D;
 127                         Extents padding = Padding;
 128                         Extents childMargin = childLayout.Margin;
 129
 130                         LayoutLength childLeft = new LayoutLength(childPosition.X + childMargin.Start + padding.Start);
 131                         LayoutLength childTop = new LayoutLength(childPosition.Y + childMargin.Top + padding.Top);
 132
 133                         childLayout.Layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
 134                     }
 135                 }
 136             }
 137         } //  ScrollableBaseCustomLayout
 138
 139         /// <summary>
 140         /// The direction axis to scroll.
 141         /// </summary>
 142         /// <since_tizen> 6 </since_tizen>
 143         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API.
 144         [EditorBrowsable(EditorBrowsableState.Never)]
 145         public enum Direction
 146         {
 147             /// <summary>
 148             /// Horizontal axis.
 149             /// </summary>
 150             /// <since_tizen> 6 </since_tizen>
 151             Horizontal,
 152
 153             /// <summary>
 154             /// Vertical axis.
 155             /// </summary>
 156             /// <since_tizen> 6 </since_tizen>
 157             Vertical
 158         }
 159
 160         /// <summary>
 161         /// [Draft] Configurable speed threshold that register the gestures as a flick.
 162         /// If the flick speed less than the threshold then will not be considered a flick.
 163         /// </summary>
 164         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API.
 165         [EditorBrowsable(EditorBrowsableState.Never)]
 166         public float FlickThreshold { get; set; } = 0.2f;
 167
 168         /// <summary>
 169         /// [Draft] Configurable duration modifer for the flick animation.
 170         /// Determines the speed of the scroll, large value results in a longer flick animation. Range (0.1 - 1.0)
 171         /// </summary>
 172         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 173         [EditorBrowsable(EditorBrowsableState.Never)]
 174         public float FlickAnimationSpeed { get; set; } = 0.4f;
 175
 176         /// <summary>
 177         /// [Draft] Configurable modifer for the distance to be scrolled when flicked detected.
 178         /// It a ratio of the ScrollableBase's length. (not child's length).
 179         /// First value is the ratio of the distance to scroll with the weakest flick.
 180         /// Second value is the ratio of the distance to scroll with the strongest flick.
 181         /// Second > First.
 182         /// </summary>
 183         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 184         [EditorBrowsable(EditorBrowsableState.Never)]
 185         public Vector2 FlickDistanceMultiplierRange { get; set; } = new Vector2(0.6f, 1.8f);
 186
 187         /// <summary>
 188         /// [Draft] Scrolling direction mode.
 189         /// Default is Vertical scrolling.
 190         /// </summary>
 191         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 192         [EditorBrowsable(EditorBrowsableState.Never)]
 193         public Direction ScrollingDirection
 194         {
 195             get
 196             {
 197                 return mScrollingDirection;
 198             }
 199             set
 200             {
 201                 if (value != mScrollingDirection)
 202                 {
 203                     mScrollingDirection = value;
 204                     mPanGestureDetector.RemoveDirection(value == Direction.Horizontal ? PanGestureDetector.DirectionVertical : PanGestureDetector.DirectionHorizontal);
 205                     mPanGestureDetector.AddDirection(value == Direction.Horizontal ? PanGestureDetector.DirectionHorizontal : PanGestureDetector.DirectionVertical);
 206                 }
 207             }
 208         }
 209
 210         /// <summary>
 211         /// [Draft] Enable or disable scrolling.
 212         /// </summary>
 213         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 214         [EditorBrowsable(EditorBrowsableState.Never)]
 215         public bool ScrollEnabled
 216         {
 217             get
 218             {
 219                 return mScrollEnabled;
 220             }
 221             set
 222             {
 223                 if (value != mScrollEnabled)
 224                 {
 225                     mScrollEnabled = value;
 226                     if (mScrollEnabled)
 227                     {
 228                         mPanGestureDetector.Detected += OnPanGestureDetected;
 229                         mTapGestureDetector.Detected += OnTapGestureDetected;
 230                     }
 231                     else
 232                     {
 233                         mPanGestureDetector.Detected -= OnPanGestureDetected;
 234                         mTapGestureDetector.Detected -= OnTapGestureDetected;
 235                     }
 236                 }
 237             }
 238         }
 239
 240         /// <summary>
 241         /// [Draft] Pages mode, enables moving to the next or return to current page depending on pan displacement.
 242         /// Default is false.
 243         /// </summary>
 244         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 245         [EditorBrowsable(EditorBrowsableState.Never)]
 246         public bool SnapToPage { set; get; } = false;
 247
 248         /// <summary>
 249         /// [Draft] Get current page.
 250         /// Working propery with SnapToPage property.
 251         /// </summary>
 252         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 253         [EditorBrowsable(EditorBrowsableState.Never)]
 254         public int CurrentPage { get; private set; } = 0;
 255
 256         /// <summary>
 257         /// [Draft] Duration of scroll animation.
 258         /// </summary>
 259         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 260         [EditorBrowsable(EditorBrowsableState.Never)]
 261
 262         public int ScrollDuration { set; get; } = 125;
 263         /// <summary>
 264         /// [Draft] Scroll Available area.
 265         /// </summary>
 266         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 267         [EditorBrowsable(EditorBrowsableState.Never)]
 268         public Vector2 ScrollAvailableArea { set; get; }
 269
 270         /// <summary>
 271         /// ScrollEventArgs is a class to record scroll event arguments which will sent to user.
 272         /// </summary>
 273         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 274         [EditorBrowsable(EditorBrowsableState.Never)]
 275         public class ScrollEventArgs : EventArgs
 276         {
 277             Position position;
 278
 279             /// <summary>
 280             /// Default constructor.
 281             /// </summary>
 282             /// <param name="position">Current scroll position</param>
 283             /// <since_tizen> 6 </since_tizen>
 284             /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 285             public ScrollEventArgs(Position position)
 286             {
 287                 this.position = position;
 288             }
 289
 290             /// <summary>
 291             /// [Draft] Current scroll position.
 292             /// </summary>
 293             /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 294             [EditorBrowsable(EditorBrowsableState.Never)]
 295             public Position Position
 296             {
 297                 get
 298                 {
 299                     return position;
 300                 }
 301             }
 302         }
 303
 304         /// <summary>
 305         /// An event emitted when user starts dragging ScrollableBase, user can subscribe or unsubscribe to this event handler.<br />
 306         /// </summary>
 307         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 308         [EditorBrowsable(EditorBrowsableState.Never)]
 309         public event EventHandler<ScrollEventArgs> ScrollDragStartEvent;
 310
 311         /// <summary>
 312         /// An event emitted when user stops dragging ScrollableBase, user can subscribe or unsubscribe to this event handler.<br />
 313         /// </summary>
 314         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 315         [EditorBrowsable(EditorBrowsableState.Never)]
 316         public event EventHandler<ScrollEventArgs> ScrollDragEndEvent;
 317
 318
 319         /// <summary>
 320         /// An event emitted when the scrolling slide animation starts, user can subscribe or unsubscribe to this event handler.<br />
 321         /// </summary>
 322         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 323         [EditorBrowsable(EditorBrowsableState.Never)]
 324         public event EventHandler<ScrollEventArgs> ScrollAnimationStartEvent;
 325
 326         /// <summary>
 327         /// An event emitted when the scrolling slide animation ends, user can subscribe or unsubscribe to this event handler.<br />
 328         /// </summary>
 329         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 330         [EditorBrowsable(EditorBrowsableState.Never)]
 331         public event EventHandler<ScrollEventArgs> ScrollAnimationEndEvent;
 332
 333
 334         /// <summary>
 335         /// An event emitted when scrolling, user can subscribe or unsubscribe to this event handler.<br />
 336         /// </summary>
 337         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 338         [EditorBrowsable(EditorBrowsableState.Never)]
 339         public event EventHandler<ScrollEventArgs> ScrollEvent;
 340
 341
 342         /// <summary>
 343         /// Scrollbar for ScrollableBase.<br />
 344         /// </summary>
 345         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 346         [EditorBrowsable(EditorBrowsableState.Never)]
 347         public ScrollbarBase Scrollbar
 348         {
 349             get
 350             {
 351                 return scrollBar;
 352             }
 353             set
 354             {
 355                 if (scrollBar)
 356                 {
 357                     scrollBar.Unparent();
 358                 }
 359
 360                 scrollBar = value;
 361                 scrollBar.Name = "ScrollBar";
 362                 Add(scrollBar);
 363
 364                 if (hideScrollbar)
 365                 {
 366                     scrollBar.Hide();
 367                 }
 368                 else
 369                 {
 370                     scrollBar.Show();
 371                 }
 372
 373                 SetScrollbar();
 374             }
 375         }
 376
 377         /// <summary>
 378         /// [Draft] Always hide Scrollbar.
 379         /// </summary>
 380         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 381         [EditorBrowsable(EditorBrowsableState.Never)]
 382         public bool HideScrollBar
 383         {
 384             get
 385             {
 386                 return hideScrollbar;
 387             }
 388             set
 389             {
 390                 hideScrollbar = value;
 391
 392                 if (scrollBar)
 393                 {
 394                     if (value)
 395                     {
 396                         scrollBar.Hide();
 397                     }
 398                     else
 399                     {
 400                         scrollBar.Show();
 401                     }
 402                 }
 403             }
 404         }
 405
 406         private bool hideScrollbar = true;
 407         private Animation scrollAnimation;
 408         private float maxScrollDistance;
 409         private float childTargetPosition = 0.0f;
 410         private PanGestureDetector mPanGestureDetector;
 411         private TapGestureDetector mTapGestureDetector;
 412         private View mScrollingChild;
 413         private View mInterruptTouchingChild;
 414         private ScrollbarBase scrollBar;
 415         private float multiplier = 1.0f;
 416         private bool scrolling = false;
 417         private float ratioOfScreenWidthToCompleteScroll = 0.5f;
 418         private float totalDisplacementForPan = 0.0f;
 419         private Size previousContainerSize = new Size();
 420
 421         // If false then can only flick pages when the current animation/scroll as ended.
 422         private bool flickWhenAnimating = false;
 423         private PropertyNotification propertyNotification;
 424
 425         // Let's consider more whether this needs to be set as protected.
 426         private float finalTargetPosition;
 427
 428         /// <summary>
 429         /// [Draft] Constructor
 430         /// </summary>
 431         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 432         [EditorBrowsable(EditorBrowsableState.Never)]
 433         public ScrollableBase() : base()
 434         {
 435             mPanGestureDetector = new PanGestureDetector();
 436             mPanGestureDetector.Attach(this);
 437             mPanGestureDetector.AddDirection(PanGestureDetector.DirectionVertical);
 438             mPanGestureDetector.Detected += OnPanGestureDetected;
 439
 440             mTapGestureDetector = new TapGestureDetector();
 441             mTapGestureDetector.Attach(this);
 442             mTapGestureDetector.Detected += OnTapGestureDetected;
 443
 444             ClippingMode = ClippingModeType.ClipChildren;
 445
 446             mScrollingChild = new View();
 447             mScrollingChild.Name = "DefaultScrollingChild";
 448
 449             //Interrupt touching when panning is started;
 450             mInterruptTouchingChild = new View()
 451             {
 452                 Name = "InterruptTouchingChild",
 453                 Size = new Size(Window.Instance.WindowSize),
 454                 BackgroundColor = Color.Transparent,
 455             };
 456
 457             mInterruptTouchingChild.TouchEvent += OnIterruptTouchingChildTouched;
 458
 459             Layout = new ScrollableBaseCustomLayout();
 460
 461             Scrollbar = new Scrollbar();
 462         }
 463
 464         private bool OnIterruptTouchingChildTouched(object source, View.TouchEventArgs args)
 465         {
 466             return true;
 467         }
 468
 469         private void OnPropertyChanged(object source, PropertyNotification.NotifyEventArgs args)
 470         {
 471             OnScroll();
 472         }
 473
 474         /// <summary>
 475         /// Called after a child has been added to the owning view.
 476         /// </summary>
 477         /// <param name="view">The child which has been added.</param>
 478         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 479         [EditorBrowsable(EditorBrowsableState.Never)]
 480         public override void OnChildAdd(View view)
 481         {
 482             if (view.Name != "InterruptTouchingChild" && view.Name != "ScrollBar")
 483             {
 484                 if (mScrollingChild.Name != "DefaultScrollingChild")
 485                 {
 486                     propertyNotification.Notified -= OnPropertyChanged;
 487                     mScrollingChild.RemovePropertyNotification(propertyNotification);
 488                     mScrollingChild.Relayout -= OnScrollingChildRelayout;
 489                 }
 490
 491                 mScrollingChild = view;
 492                 mScrollingChild.Layout.SetPositionByLayout = false;
 493                 propertyNotification = mScrollingChild?.AddPropertyNotification("position", PropertyCondition.Step(1.0f));
 494                 propertyNotification.Notified += OnPropertyChanged;
 495                 mScrollingChild.Relayout += OnScrollingChildRelayout;
 496                 mScrollingChild.LowerToBottom();
 497             }
 498         }
 499
 500         /// <summary>
 501         /// Called after a child has been removed from the owning view.
 502         /// </summary>
 503         /// <param name="view">The child which has been removed.</param>
 504         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 505         [EditorBrowsable(EditorBrowsableState.Never)]
 506         public override void OnChildRemove(View view)
 507         {
 508             if (view.Name != "InterruptTouchingChild" && view.Name != "ScrollBar")
 509             {
 510                 propertyNotification.Notified -= OnPropertyChanged;
 511                 mScrollingChild.RemovePropertyNotification(propertyNotification);
 512                 mScrollingChild.Relayout -= OnScrollingChildRelayout;
 513
 514                 mScrollingChild.Layout.SetPositionByLayout = true;
 515                 mScrollingChild = new View();
 516             }
 517         }
 518
 519         private void OnScrollingChildRelayout(object source, EventArgs args)
 520         {
 521             // Size is changed. Calculate maxScrollDistance.
 522             bool isSizeChanged = previousContainerSize.Width != mScrollingChild.Size.Width || previousContainerSize.Height != mScrollingChild.Size.Height;
 523
 524             if (isSizeChanged)
 525             {
 526                 maxScrollDistance = CalculateMaximumScrollDistance();
 527                 SetScrollbar();
 528             }
 529
 530             previousContainerSize = mScrollingChild.Size;
 531         }
 532
 533         /// <summary>
 534         /// The composition of a Scrollbar can vary depending on how you use ScrollableBase.
 535         /// Set the composition that will go into the ScrollableBase according to your ScrollableBase.
 536         /// </summary>
 537         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 538         [EditorBrowsable(EditorBrowsableState.Never)]
 539         protected virtual void SetScrollbar()
 540         {
 541             if (Scrollbar)
 542             {
 543                 bool isHorizontal = ScrollingDirection == Direction.Horizontal;
 544                 float contentLength = isHorizontal ? mScrollingChild.Size.Width : mScrollingChild.Size.Height;
 545                 float viewportLength = isHorizontal ? Size.Width : Size.Height;
 546                 float currentPosition = isHorizontal ? mScrollingChild.CurrentPosition.X : mScrollingChild.CurrentPosition.Y;
 547                 Scrollbar.Initialize(contentLength, viewportLength, currentPosition, isHorizontal);
 548             }
 549         }
 550
 551         /// <summary>
 552         /// Scrolls to the item at the specified index.
 553         /// </summary>
 554         /// <param name="index">Index of item.</param>
 555         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 556         [EditorBrowsable(EditorBrowsableState.Never)]
 557         public void ScrollToIndex(int index)
 558         {
 559             if (mScrollingChild.ChildCount - 1 < index || index < 0)
 560             {
 561                 return;
 562             }
 563
 564             if (SnapToPage)
 565             {
 566                 CurrentPage = index;
 567             }
 568
 569             float targetPosition = Math.Min(ScrollingDirection == Direction.Vertical ? mScrollingChild.Children[index].Position.Y : mScrollingChild.Children[index].Position.X, maxScrollDistance);
 570             AnimateChildTo(ScrollDuration, -targetPosition);
 571         }
 572
 573         private void OnScrollDragStart()
 574         {
 575             ScrollEventArgs eventArgs = new ScrollEventArgs(mScrollingChild.CurrentPosition);
 576             ScrollDragStartEvent?.Invoke(this, eventArgs);
 577         }
 578
 579         private void OnScrollDragEnd()
 580         {
 581             ScrollEventArgs eventArgs = new ScrollEventArgs(mScrollingChild.CurrentPosition);
 582             ScrollDragEndEvent?.Invoke(this, eventArgs);
 583         }
 584
 585         private void OnScrollAnimationStart()
 586         {
 587             ScrollEventArgs eventArgs = new ScrollEventArgs(mScrollingChild.CurrentPosition);
 588             ScrollAnimationStartEvent?.Invoke(this, eventArgs);
 589         }
 590
 591         private void OnScrollAnimationEnd()
 592         {
 593             ScrollEventArgs eventArgs = new ScrollEventArgs(mScrollingChild.CurrentPosition);
 594             ScrollAnimationEndEvent?.Invoke(this, eventArgs);
 595         }
 596
 597         private bool readyToNotice = false;
 598
 599         private float noticeAnimationEndBeforePosition = 0.0f;
 600         // Let's consider more whether this needs to be set as protected.
 601         public float NoticeAnimationEndBeforePosition { get => noticeAnimationEndBeforePosition; set => noticeAnimationEndBeforePosition = value; }
 602
 603         private void OnScroll()
 604         {
 605             ScrollEventArgs eventArgs = new ScrollEventArgs(mScrollingChild.CurrentPosition);
 606             ScrollEvent?.Invoke(this, eventArgs);
 607
 608             bool isHorizontal = ScrollingDirection == Direction.Horizontal;
 609             float contentLength = isHorizontal ? mScrollingChild.Size.Width : mScrollingChild.Size.Height;
 610             float currentPosition = isHorizontal ? mScrollingChild.CurrentPosition.X : mScrollingChild.CurrentPosition.Y;
 611
 612             scrollBar.Update(contentLength, Math.Abs(currentPosition));
 613             CheckPreReachedTargetPosition();
 614         }
 615
 616         private void CheckPreReachedTargetPosition()
 617         {
 618             // Check whether we reached pre-reached target position
 619             if (readyToNotice &&
 620                 mScrollingChild.CurrentPosition.Y <= finalTargetPosition + NoticeAnimationEndBeforePosition &&
 621                 mScrollingChild.CurrentPosition.Y >= finalTargetPosition - NoticeAnimationEndBeforePosition)
 622             {
 623                 //Notice first
 624                 readyToNotice = false;
 625                 OnPreReachedTargetPosition(finalTargetPosition);
 626             }
 627         }
 628
 629         /// <summary>
 630         /// This helps developer who wants to know before scroll is reaching target position.
 631         /// </summary>
 632         /// <param name="targetPosition">Index of item.</param>
 633         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 634         [EditorBrowsable(EditorBrowsableState.Never)]
 635         protected virtual void OnPreReachedTargetPosition(float targetPosition)
 636         {
 637
 638         }
 639
 640         private void StopScroll()
 641         {
 642             if (scrollAnimation != null)
 643             {
 644                 if (scrollAnimation.State == Animation.States.Playing)
 645                 {
 646                     Debug.WriteLineIf(LayoutDebugScrollableBase, "StopScroll Animation Playing");
 647                     scrollAnimation.Stop(Animation.EndActions.Cancel);
 648                     OnScrollAnimationEnd();
 649                 }
 650                 scrollAnimation.Clear();
 651             }
 652         }
 653
 654         // static constructor registers the control type
 655         static ScrollableBase()
 656         {
 657             // ViewRegistry registers control type with DALi type registry
 658             // also uses introspection to find any properties that need to be registered with type registry
 659             CustomViewRegistry.Instance.Register(CreateInstance, typeof(ScrollableBase));
 660         }
 661
 662         internal static CustomView CreateInstance()
 663         {
 664             return new ScrollableBase();
 665         }
 666
 667         private void AnimateChildTo(int duration, float axisPosition)
 668         {
 669             Debug.WriteLineIf(LayoutDebugScrollableBase, "AnimationTo Animation Duration:" + duration + " Destination:" + axisPosition);
 670             finalTargetPosition = axisPosition;
 671
 672             StopScroll(); // Will replace previous animation so will stop existing one.
 673
 674             if (scrollAnimation == null)
 675             {
 676                 scrollAnimation = new Animation();
 677                 scrollAnimation.Finished += ScrollAnimationFinished;
 678             }
 679
 680             scrollAnimation.Duration = duration;
 681             scrollAnimation.DefaultAlphaFunction = new AlphaFunction(AlphaFunction.BuiltinFunctions.EaseOutSine);
 682             scrollAnimation.AnimateTo(mScrollingChild, (ScrollingDirection == Direction.Horizontal) ? "PositionX" : "PositionY", axisPosition);
 683             scrolling = true;
 684             OnScrollAnimationStart();
 685             scrollAnimation.Play();
 686         }
 687
 688         /// <summary>
 689         /// Scroll to specific position with or without animation.
 690         /// </summary>
 691         /// <param name="position">Destination.</param>
 692         /// <param name="animate">Scroll with or without animation</param>
 693         [EditorBrowsable(EditorBrowsableState.Never)]
 694         public void ScrollTo(float position, bool animate)
 695         {
 696             float currentPositionX = mScrollingChild.CurrentPosition.X != 0 ? mScrollingChild.CurrentPosition.X : mScrollingChild.Position.X;
 697             float currentPositionY = mScrollingChild.CurrentPosition.Y != 0 ? mScrollingChild.CurrentPosition.Y : mScrollingChild.Position.Y;
 698             float delta = ScrollingDirection == Direction.Horizontal ? currentPositionX : currentPositionY;
 699             // The argument position is the new pan position. So the new position of ScrollableBase becomes (-position).
 700             // To move ScrollableBase's position to (-position), it moves by (-position - currentPosition).
 701             delta = -position - delta;
 702
 703             ScrollBy(delta, animate);
 704         }
 705
 706         private float BoundScrollPosition(float targetPosition)
 707         {
 708             if (ScrollAvailableArea != null)
 709             {
 710                 float minScrollPosition = ScrollAvailableArea.X;
 711                 float maxScrollPosition = ScrollAvailableArea.Y;
 712
 713                 targetPosition = Math.Min(-minScrollPosition, targetPosition);
 714                 targetPosition = Math.Max(-maxScrollPosition, targetPosition);
 715             }
 716             else
 717             {
 718                 targetPosition = Math.Min(0, targetPosition);
 719                 targetPosition = Math.Max(-maxScrollDistance, targetPosition);
 720             }
 721
 722             return targetPosition;
 723         }
 724
 725         private void ScrollBy(float displacement, bool animate)
 726         {
 727             if (GetChildCount() == 0 || maxScrollDistance < 0)
 728             {
 729                 return;
 730             }
 731
 732             float childCurrentPosition = (ScrollingDirection == Direction.Horizontal) ? mScrollingChild.PositionX : mScrollingChild.PositionY;
 733
 734             Debug.WriteLineIf(LayoutDebugScrollableBase, "ScrollBy childCurrentPosition:" + childCurrentPosition +
 735                                                    " displacement:" + displacement,
 736                                                    " maxScrollDistance:" + maxScrollDistance);
 737
 738             childTargetPosition = childCurrentPosition + displacement; // child current position + gesture displacement
 739
 740
 741             Debug.WriteLineIf(LayoutDebugScrollableBase, "ScrollBy currentAxisPosition:" + childCurrentPosition + "childTargetPosition:" + childTargetPosition);
 742
 743             if (animate)
 744             {
 745                 // Calculate scroll animaton duration
 746                 float scrollDistance = Math.Abs(displacement);
 747                 int duration = (int)((320 * FlickAnimationSpeed) + (scrollDistance * FlickAnimationSpeed));
 748                 Debug.WriteLineIf(LayoutDebugScrollableBase, "Scroll Animation Duration:" + duration + " Distance:" + scrollDistance);
 749
 750                 readyToNotice = true;
 751
 752                 AnimateChildTo(duration, BoundScrollPosition(AdjustTargetPositionOfScrollAnimation(BoundScrollPosition(childTargetPosition))));
 753             }
 754             else
 755             {
 756                 finalTargetPosition = BoundScrollPosition(childTargetPosition);
 757
 758                 // Set position of scrolling child without an animation
 759                 if (ScrollingDirection == Direction.Horizontal)
 760                 {
 761                     mScrollingChild.PositionX = finalTargetPosition;
 762                 }
 763                 else
 764                 {
 765                     mScrollingChild.PositionY = finalTargetPosition;
 766                 }
 767
 768             }
 769         }
 770
 771         /// <summary>
 772         /// you can override it to clean-up your own resources.
 773         /// </summary>
 774         /// <param name="type">DisposeTypes</param>
 775         /// This will be public opened in tizen_5.5 after ACR done. Before ACR, need to be hidden as inhouse API.
 776         [EditorBrowsable(EditorBrowsableState.Never)]
 777         protected override void Dispose(DisposeTypes type)
 778         {
 779             if (disposed)
 780             {
 781                 return;
 782             }
 783
 784             if (type == DisposeTypes.Explicit)
 785             {
 786                 StopScroll();
 787
 788                 if (mPanGestureDetector != null)
 789                 {
 790                     mPanGestureDetector.Detected -= OnPanGestureDetected;
 791                     mPanGestureDetector.Dispose();
 792                     mPanGestureDetector = null;
 793                 }
 794
 795                 if (mTapGestureDetector != null)
 796                 {
 797                     mTapGestureDetector.Detected -= OnTapGestureDetected;
 798                     mTapGestureDetector.Dispose();
 799                     mTapGestureDetector = null;
 800                 }
 801             }
 802             base.Dispose(type);
 803         }
 804
 805         private float CalculateDisplacementFromVelocity(float axisVelocity)
 806         {
 807             // Map: flick speed of range (2.0 - 6.0) to flick multiplier of range (0.7 - 1.6)
 808             float speedMinimum = FlickThreshold;
 809             float speedMaximum = FlickThreshold + 6.0f;
 810             float multiplierMinimum = FlickDistanceMultiplierRange.X;
 811             float multiplierMaximum = FlickDistanceMultiplierRange.Y;
 812
 813             float flickDisplacement = 0.0f;
 814
 815             float speed = Math.Min(4.0f, Math.Abs(axisVelocity));
 816
 817             Debug.WriteLineIf(LayoutDebugScrollableBase, "ScrollableBase Candidate Flick speed:" + speed);
 818
 819             if (speed > FlickThreshold)
 820             {
 821                 // Flick length is the length of the ScrollableBase.
 822                 float flickLength = (ScrollingDirection == Direction.Horizontal) ? CurrentSize.Width : CurrentSize.Height;
 823
 824                 // Calculate multiplier by mapping speed between the multiplier minimum and maximum.
 825                 multiplier = ((speed - speedMinimum) / ((speedMaximum - speedMinimum) * (multiplierMaximum - multiplierMinimum))) + multiplierMinimum;
 826
 827                 // flick displacement is the product of the flick length and multiplier
 828                 flickDisplacement = ((flickLength * multiplier) * speed) / axisVelocity;  // *speed and /velocity to perserve sign.
 829
 830                 Debug.WriteLineIf(LayoutDebugScrollableBase, "Calculated FlickDisplacement[" + flickDisplacement + "] from speed[" + speed + "] multiplier:"
 831                                                         + multiplier);
 832             }
 833             return flickDisplacement;
 834         }
 835
 836         private float CalculateMaximumScrollDistance()
 837         {
 838             float scrollingChildLength = 0;
 839             float scrollerLength = 0;
 840             if (ScrollingDirection == Direction.Horizontal)
 841             {
 842                 Debug.WriteLineIf(LayoutDebugScrollableBase, "Horizontal");
 843
 844                 scrollingChildLength = mScrollingChild.Size.Width;
 845                 scrollerLength = Size.Width;
 846             }
 847             else
 848             {
 849                 Debug.WriteLineIf(LayoutDebugScrollableBase, "Vertical");
 850                 scrollingChildLength = mScrollingChild.Size.Height;
 851                 scrollerLength = Size.Height;
 852             }
 853
 854             Debug.WriteLineIf(LayoutDebugScrollableBase, "ScrollBy maxScrollDistance:" + (scrollingChildLength - scrollerLength) +
 855                                                    " parent length:" + scrollerLength +
 856                                                    " scrolling child length:" + scrollingChildLength);
 857
 858             return Math.Max(scrollingChildLength - scrollerLength, 0);
 859         }
 860
 861         private void PageSnap()
 862         {
 863             Debug.WriteLineIf(LayoutDebugScrollableBase, "PageSnap with pan candidate totalDisplacement:" + totalDisplacementForPan +
 864                                                                 " currentPage[" + CurrentPage + "]");
 865
 866             //Increment current page if total displacement enough to warrant a page change.
 867             if (Math.Abs(totalDisplacementForPan) > (mPageWidth * ratioOfScreenWidthToCompleteScroll))
 868             {
 869                 if (totalDisplacementForPan < 0)
 870                 {
 871                     CurrentPage = Math.Min(Math.Max(mScrollingChild.Children.Count - 1, 0), ++CurrentPage);
 872                 }
 873                 else
 874                 {
 875                     CurrentPage = Math.Max(0, --CurrentPage);
 876                 }
 877             }
 878
 879             // Animate to new page or reposition to current page
 880             float destinationX = -(mScrollingChild.Children[CurrentPage].Position.X + mScrollingChild.Children[CurrentPage].CurrentSize.Width / 2 - CurrentSize.Width / 2); // set to middle of current page
 881             Debug.WriteLineIf(LayoutDebugScrollableBase, "Snapping to page[" + CurrentPage + "] to:" + destinationX + " from:" + mScrollingChild.PositionX);
 882             AnimateChildTo(ScrollDuration, destinationX);
 883         }
 884
 885         private void Flick(float flickDisplacement)
 886         {
 887             if (SnapToPage)
 888             {
 889                 if ((flickWhenAnimating && scrolling == true) || (scrolling == false))
 890                 {
 891                     if (flickDisplacement < 0)
 892                     {
 893                         CurrentPage = Math.Min(Math.Max(mScrollingChild.Children.Count - 1, 0), CurrentPage + 1);
 894                         Debug.WriteLineIf(LayoutDebugScrollableBase, "Snap - to page:" + CurrentPage);
 895                     }
 896                     else
 897                     {
 898                         CurrentPage = Math.Max(0, CurrentPage - 1);
 899                         Debug.WriteLineIf(LayoutDebugScrollableBase, "Snap + to page:" + CurrentPage);
 900                     }
 901
 902                     float destinationX = -(mScrollingChild.Children[CurrentPage].Position.X + mScrollingChild.Children[CurrentPage].CurrentSize.Width / 2.0f - CurrentSize.Width / 2.0f); // set to middle of current page
 903                     Debug.WriteLineIf(LayoutDebugScrollableBase, "Snapping to :" + destinationX);
 904                     AnimateChildTo(ScrollDuration, destinationX);
 905                 }
 906             }
 907             else
 908             {
 909                 ScrollBy(flickDisplacement, true); // Animate flickDisplacement.
 910             }
 911         }
 912
 913         private void OnPanGestureDetected(object source, PanGestureDetector.DetectedEventArgs e)
 914         {
 915             if (e.PanGesture.State == Gesture.StateType.Started)
 916             {
 917                 Add(mInterruptTouchingChild);
 918                 Debug.WriteLineIf(LayoutDebugScrollableBase, "Gesture Start");
 919                 if (scrolling && !SnapToPage)
 920                 {
 921                     StopScroll();
 922                 }
 923                 totalDisplacementForPan = 0.0f;
 924                 OnScrollDragStart();
 925             }
 926             else if (e.PanGesture.State == Gesture.StateType.Continuing)
 927             {
 928                 if (ScrollingDirection == Direction.Horizontal)
 929                 {
 930                     ScrollBy(e.PanGesture.Displacement.X, false);
 931                     totalDisplacementForPan += e.PanGesture.Displacement.X;
 932                 }
 933                 else
 934                 {
 935                     ScrollBy(e.PanGesture.Displacement.Y, false);
 936                     totalDisplacementForPan += e.PanGesture.Displacement.Y;
 937                 }
 938                 Debug.WriteLineIf(LayoutDebugScrollableBase, "OnPanGestureDetected Continue totalDisplacementForPan:" + totalDisplacementForPan);
 939             }
 940             else if (e.PanGesture.State == Gesture.StateType.Finished)
 941             {
 942                 float axisVelocity = (ScrollingDirection == Direction.Horizontal) ? e.PanGesture.Velocity.X : e.PanGesture.Velocity.Y;
 943                 float flickDisplacement = CalculateDisplacementFromVelocity(axisVelocity);
 944
 945                 Debug.WriteLineIf(LayoutDebugScrollableBase, "FlickDisplacement:" + flickDisplacement + "TotalDisplacementForPan:" + totalDisplacementForPan);
 946                 OnScrollDragEnd();
 947
 948                 if (flickDisplacement > 0 | flickDisplacement < 0)// Flick detected
 949                 {
 950                     Flick(flickDisplacement);
 951                 }
 952                 else
 953                 {
 954                     // End of panning gesture but was not a flick
 955                     if (SnapToPage)
 956                     {
 957                         PageSnap();
 958                     }
 959                     else
 960                     {
 961                         ScrollBy(0, true);
 962                     }
 963                 }
 964                 totalDisplacementForPan = 0;
 965
 966                 Remove(mInterruptTouchingChild);
 967             }
 968         }
 969
 970         private new void OnTapGestureDetected(object source, TapGestureDetector.DetectedEventArgs e)
 971         {
 972             if (e.TapGesture.Type == Gesture.GestureType.Tap)
 973             {
 974                 // Stop scrolling if tap detected (press then relase).
 975                 // Unless in Pages mode, do not want a page change to stop part way.
 976                 if (scrolling && !SnapToPage)
 977                 {
 978                     StopScroll();
 979                 }
 980             }
 981         }
 982
 983         private void ScrollAnimationFinished(object sender, EventArgs e)
 984         {
 985             scrolling = false;
 986             CheckPreReachedTargetPosition();
 987             OnScrollAnimationEnd();
 988         }
 989
 990         /// <summary>
 991         /// Adjust scrolling position by own scrolling rules.
 992         /// Override this function when developer wants to change destination of flicking.(e.g. always snap to center of item)
 993         /// </summary>
 994         /// This may be public opened in tizen_6.0 after ACR done. Before ACR, need to be hidden as inhouse API
 995         [EditorBrowsable(EditorBrowsableState.Never)]
 996         protected virtual float AdjustTargetPositionOfScrollAnimation(float position)
 997         {
 998             return position;
 999         }
1000
1001     }
1002
1003 } // namespace