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

   1 /*
   2  * Copyright(c) 2020 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 using System;
  18 using System.ComponentModel;
  19 using Tizen.NUI.BaseComponents;
  20 using Tizen.NUI.Binding;
  21
  22 namespace Tizen.NUI.Components
  23 {
  24     /// <summary>
  25     /// The Scrollbar is a component that contains track and thumb to indicate the current scrolled position of a scrollable object.
  26     /// </summary>
  27     [EditorBrowsable(EditorBrowsableState.Never)]
  28     public class Scrollbar : ScrollbarBase
  29     {
  30         #region Fields
  31
  32         /// <summary>Bindable property of TrackThickness</summary>
  33         [EditorBrowsable(EditorBrowsableState.Never)]
  34         public static readonly BindableProperty TrackThicknessProperty = BindableProperty.Create(nameof(TrackThickness), typeof(float), typeof(Scrollbar), default(float), propertyChanged: (bindable, oldValue, newValue) =>
  35         {
  36             var instance = ((Scrollbar)bindable);
  37             var thickness = (float?)newValue;
  38
  39             instance.scrollbarStyle.TrackThickness = thickness;
  40             instance.UpdateTrackThickness(thickness ?? 0);
  41         },
  42         defaultValueCreator: (bindable) =>
  43         {
  44             return ((Scrollbar)bindable).scrollbarStyle.TrackThickness ?? 0;
  45         });
  46
  47         /// <summary>Bindable property of ThumbThickness</summary>
  48         [EditorBrowsable(EditorBrowsableState.Never)]
  49         public static readonly BindableProperty ThumbThicknessProperty = BindableProperty.Create(nameof(ThumbThickness), typeof(float), typeof(Scrollbar), default(float), propertyChanged: (bindable, oldValue, newValue) =>
  50         {
  51             var instance = ((Scrollbar)bindable);
  52             var thickness = (float?)newValue;
  53
  54             instance.scrollbarStyle.ThumbThickness = thickness;
  55             instance.UpdateThumbThickness(thickness ?? 0);
  56         },
  57         defaultValueCreator: (bindable) =>
  58         {
  59             return ((Scrollbar)bindable).scrollbarStyle.ThumbThickness ?? 0;
  60         });
  61
  62         /// <summary>Bindable property of TrackColor</summary>
  63         [EditorBrowsable(EditorBrowsableState.Never)]
  64         public static readonly BindableProperty TrackColorProperty = BindableProperty.Create(nameof(TrackColor), typeof(Color), typeof(Scrollbar), null, propertyChanged: (bindable, oldValue, newValue) =>
  65         {
  66             var instance = ((Scrollbar)bindable);
  67             var color = (Color)newValue;
  68
  69             instance.scrollbarStyle.TrackColor = color;
  70             instance.UpdateTrackColor(color);
  71         },
  72         defaultValueCreator: (bindable) =>
  73         {
  74             return ((Scrollbar)bindable).scrollbarStyle.TrackColor;
  75         });
  76
  77         /// <summary>Bindable property of ThumbColor</summary>
  78         [EditorBrowsable(EditorBrowsableState.Never)]
  79         public static readonly BindableProperty ThumbColorProperty = BindableProperty.Create(nameof(ThumbColor), typeof(Color), typeof(Scrollbar), null, propertyChanged: (bindable, oldValue, newValue) =>
  80         {
  81             var instance = ((Scrollbar)bindable);
  82             var color = (Color)newValue;
  83
  84             instance.scrollbarStyle.ThumbColor = color;
  85             instance.UpdateThumbColor(color);
  86         },
  87         defaultValueCreator: (bindable) =>
  88         {
  89             return ((Scrollbar)bindable).scrollbarStyle.ThumbColor;
  90         });
  91
  92         /// <summary>Bindable property of TrackPadding</summary>
  93         [EditorBrowsable(EditorBrowsableState.Never)]
  94         public static readonly BindableProperty TrackPaddingProperty = BindableProperty.Create(nameof(TrackPadding), typeof(Extents), typeof(Scrollbar), null, propertyChanged: (bindable, oldValue, newValue) =>
  95         {
  96             var instance = ((Scrollbar)bindable);
  97             var trackPadding = (Extents)newValue;
  98
  99             instance.scrollbarStyle.TrackPadding = trackPadding;
 100             instance.UpdateTrackPadding(trackPadding);
 101         },
 102         defaultValueCreator: (bindable) =>
 103         {
 104             return ((Scrollbar)bindable).scrollbarStyle.TrackPadding;
 105         });
 106
 107         private ColorVisual trackVisual;
 108         private ColorVisual thumbVisual;
 109         private Animation thumbPositionAnimation;
 110         private Animation thumbSizeAnimation;
 111         private Calculator calculator;
 112         private Size containerSize = new Size(0, 0);
 113         private ScrollbarStyle scrollbarStyle => ViewStyle as ScrollbarStyle;
 114         private bool mScrollEnabled = true;
 115         private float previousPosition;
 116
 117         #endregion Fields
 118
 119
 120         #region Constructors
 121
 122         /// <summary>
 123         /// Create an empty Scrollbar.
 124         /// </summary>
 125         public Scrollbar() : base()
 126         {
 127         }
 128
 129         /// <summary>
 130         /// Create a Scrollbar and initialize with properties.
 131         /// </summary>
 132         /// <param name="contentLength">The length of the scrollable content area.</param>
 133         /// <param name="viewportLength">The length of the viewport representing the amount of visible content.</param>
 134         /// <param name="currentPosition">The current position of the viewport in scrollable content area. This is the viewport's top position if the scroller is vertical, otherwise, left.</param>
 135         /// <param name="isHorizontal">Whether the direction of scrolling is horizontal or not. It is vertical by default.</param>
 136         [EditorBrowsable(EditorBrowsableState.Never)]
 137         public Scrollbar(float contentLength, float viewportLength, float currentPosition, bool isHorizontal = false) : this()
 138         {
 139             Initialize(contentLength, viewportLength, currentPosition, isHorizontal);
 140         }
 141
 142         /// <summary>
 143         /// Create an empty Scrollbar with a ScrollbarStyle instance to set style properties.
 144         /// </summary>
 145         [EditorBrowsable(EditorBrowsableState.Never)]
 146         public Scrollbar(ScrollbarStyle style) : base(style)
 147         {
 148         }
 149
 150         /// <summary>
 151         /// Static constructor to initialize bindable properties when loading.
 152         /// </summary>
 153         static Scrollbar()
 154         {
 155         }
 156
 157         #endregion Constructors
 158
 159
 160         #region Properties
 161
 162         /// <summary>
 163         /// Return a copied Style instance of Scrollbar
 164         /// </summary>
 165         /// <remarks>
 166         /// It returns copied Style instance and changing it does not effect to the Scrollbar.
 167         /// Style setting is possible by using constructor or the function of ApplyStyle(ViewStyle viewStyle)
 168         /// </remarks>
 169         [EditorBrowsable(EditorBrowsableState.Never)]
 170         public new ScrollbarStyle Style
 171         {
 172             get
 173             {
 174                 var result = new ScrollbarStyle(scrollbarStyle);
 175                 result.CopyPropertiesFromView(this);
 176                 return result;
 177             }
 178         }
 179
 180         /// <summary>
 181         /// The thickness of the track.
 182         /// </summary>
 183         [EditorBrowsable(EditorBrowsableState.Never)]
 184         public float TrackThickness
 185         {
 186             get => (float)GetValue(TrackThicknessProperty);
 187             set => SetValue(TrackThicknessProperty, value);
 188         }
 189
 190         /// <summary>
 191         /// The thickness of the thumb.
 192         /// </summary>
 193         [EditorBrowsable(EditorBrowsableState.Never)]
 194         public float ThumbThickness
 195         {
 196             get => (float)GetValue(ThumbThicknessProperty);
 197             set => SetValue(ThumbThicknessProperty, value);
 198         }
 199
 200         /// <summary>
 201         /// The color of the track part.
 202         /// </summary>
 203         [EditorBrowsable(EditorBrowsableState.Never)]
 204         public Color TrackColor
 205         {
 206             get => (Color)GetValue(TrackColorProperty);
 207             set => SetValue(TrackColorProperty, value);
 208         }
 209
 210         /// <summary>
 211         /// The color of the thumb part.
 212         /// </summary>
 213         [EditorBrowsable(EditorBrowsableState.Never)]
 214         public Color ThumbColor
 215         {
 216             get => (Color)GetValue(ThumbColorProperty);
 217             set => SetValue(ThumbColorProperty, value);
 218         }
 219
 220         /// <summary>
 221         /// The padding value of the track.
 222         /// </summary>
 223         [EditorBrowsable(EditorBrowsableState.Never)]
 224         public Extents TrackPadding
 225         {
 226             get => (Extents)GetValue(TrackPaddingProperty);
 227             set => SetValue(TrackPaddingProperty, value);
 228         }
 229
 230         #endregion Properties
 231
 232
 233         #region Methods
 234
 235         /// <inheritdoc/>
 236         [EditorBrowsable(EditorBrowsableState.Never)]
 237         public override void Initialize(float contentLength, float viewportLength, float currentPosition, bool isHorizontal = false)
 238         {
 239             if (isHorizontal)
 240             {
 241                 calculator = new HorizontalCalculator(contentLength > 0.0f ? contentLength : 0.0f, viewportLength, currentPosition);
 242             }
 243             else
 244             {
 245                 calculator = new VerticalCalculator(contentLength > 0.0f ? contentLength : 0.0f, viewportLength, currentPosition);
 246             }
 247
 248             thumbPositionAnimation?.Stop();
 249             thumbPositionAnimation = null;
 250
 251             thumbSizeAnimation?.Stop();
 252             thumbSizeAnimation = null;
 253
 254             Size trackSize = calculator.CalculateTrackSize(TrackThickness, containerSize, TrackPadding);
 255             Vector2 trackPosition = calculator.CalculateTrackPosition(TrackPadding);
 256             Size thumbSize = calculator.CalculateThumbSize(ThumbThickness, trackSize);
 257             Vector2 thumbPosition = calculator.CalculateThumbPosition(trackSize, thumbSize, TrackPadding);
 258
 259             if (trackVisual == null)
 260             {
 261                 trackVisual = new ColorVisual
 262                 {
 263                     SuppressUpdateVisual = true,
 264                     Color = TrackColor,
 265                     SizePolicy = VisualTransformPolicyType.Absolute,
 266                     Origin = calculator.CalculatorTrackAlign(),
 267                     AnchorPoint = calculator.CalculatorTrackAlign(),
 268                     Size = trackSize,
 269                     Position = trackPosition,
 270                 };
 271
 272                 AddVisual("Track", trackVisual);
 273             }
 274             else
 275             {
 276                 trackVisual.Size = trackSize;
 277                 trackVisual.Position = trackPosition;
 278                 trackVisual.UpdateVisual(true);
 279             }
 280
 281             if (thumbVisual == null)
 282             {
 283                 thumbVisual = new ColorVisual
 284                 {
 285                     SuppressUpdateVisual = true,
 286                     MixColor = ThumbColor,
 287                     SizePolicy = VisualTransformPolicyType.Absolute,
 288                     Origin = calculator.CalculatorThumbAlign(),
 289                     AnchorPoint = calculator.CalculatorThumbAlign(),
 290                     Opacity = calculator.CalculateThumbVisibility() ? 1.0f : 0.0f,
 291                     Size = thumbSize,
 292                     Position = thumbPosition,
 293                 };
 294
 295                 AddVisual("Thumb", thumbVisual);
 296             }
 297             else
 298             {
 299                 thumbVisual.Size = thumbSize;
 300                 thumbVisual.Position = thumbPosition;
 301                 thumbVisual.UpdateVisual(true);
 302             }
 303         }
 304
 305         /// <inheritdoc/>
 306         /// <remarks>Please note that, for now, only alpha functions created with BuiltinFunctions are valid when animating. Otherwise, it will be treated as a linear alpha function. </remarks>
 307         [EditorBrowsable(EditorBrowsableState.Never)]
 308         public override void Update(float contentLength, float position, uint durationMs = 0, AlphaFunction alphaFunction = null)
 309         {
 310             if (calculator == null)
 311             {
 312                 return;
 313             }
 314
 315             calculator.contentLength = contentLength > 0.0f ? contentLength : 0.0f;
 316             previousPosition = calculator.currentPosition;
 317             calculator.currentPosition = position;
 318
 319             thumbVisual.Size = calculator.CalculateThumbSize(ThumbThickness, trackVisual.Size);
 320             thumbVisual.Position = calculator.CalculateThumbScrollPosition(trackVisual.Size, thumbVisual.Position, TrackPadding);
 321             thumbVisual.Opacity = calculator.CalculateThumbVisibility() ? 1.0f : 0.0f;
 322
 323             if (durationMs == 0)
 324             {
 325                 thumbVisual.UpdateVisual(true);
 326
 327                 return;
 328             }
 329
 330             // TODO Support non built-in alpha function for visual trainsition in DALi.
 331             AlphaFunction.BuiltinFunctions builtinAlphaFunction = alphaFunction?.GetBuiltinFunction() ?? AlphaFunction.BuiltinFunctions.Default;
 332
 333             thumbPositionAnimation?.Stop();
 334             thumbPositionAnimation = AnimateVisual(thumbVisual, "position", thumbVisual.Position, 0, (int)durationMs, builtinAlphaFunction);
 335             thumbPositionAnimation.Play();
 336
 337             thumbSizeAnimation?.Stop();
 338             thumbSizeAnimation = AnimateVisual(thumbVisual, "size", thumbVisual.Size, 0, (int)durationMs, builtinAlphaFunction);
 339             thumbSizeAnimation.Play();
 340         }
 341
 342         /// <inheritdoc/>
 343         /// <remarks>Please note that, for now, only alpha functions created with BuiltinFunctions are valid when animating. Otherwise, it will be treated as a linear alpha function. </remarks>
 344         [EditorBrowsable(EditorBrowsableState.Never)]
 345         public override void ScrollTo(float position, uint durationMs = 0, AlphaFunction alphaFunction = null)
 346         {
 347             if (mScrollEnabled == false)
 348             {
 349                 return;
 350             }
 351
 352             if (calculator == null)
 353             {
 354                 return;
 355             }
 356
 357             previousPosition = calculator.currentPosition;
 358             calculator.currentPosition = position;
 359             thumbVisual.Position = calculator.CalculateThumbScrollPosition(trackVisual.Size, thumbVisual.Position, TrackPadding);
 360
 361             if (durationMs == 0)
 362             {
 363                 thumbVisual.UpdateVisual(true);
 364
 365                 return;
 366             }
 367
 368             // TODO Support non built-in alpha function for visual trainsition in DALi.
 369             AlphaFunction.BuiltinFunctions builtinAlphaFunction = alphaFunction?.GetBuiltinFunction() ?? AlphaFunction.BuiltinFunctions.Default;
 370
 371             thumbPositionAnimation?.Stop();
 372             thumbPositionAnimation = AnimateVisual(thumbVisual, "position", thumbVisual.Position, 0, (int)durationMs, builtinAlphaFunction);
 373             thumbPositionAnimation.Play();
 374         }
 375
 376         /// <inheritdoc/>
 377         [EditorBrowsable(EditorBrowsableState.Never)]
 378         public override void OnRelayout(Vector2 size, RelayoutContainer container)
 379         {
 380             base.OnRelayout(size, container);
 381
 382             if (size.Width == containerSize.Width && size.Height == containerSize.Height)
 383             {
 384                 return;
 385             }
 386
 387             containerSize = new Size(size.Width, size.Height);
 388
 389             if (calculator == null)
 390             {
 391                 return;
 392             }
 393
 394             trackVisual.Size = calculator.CalculateTrackSize(TrackThickness, containerSize, TrackPadding);
 395             trackVisual.Position = calculator.CalculateTrackPosition(TrackPadding);
 396             thumbVisual.Size = calculator.CalculateThumbSize(ThumbThickness, trackVisual.Size);
 397             thumbVisual.Position = calculator.CalculateThumbPosition(trackVisual.Size, thumbVisual.Size, TrackPadding);
 398
 399             trackVisual.UpdateVisual(true);
 400             thumbVisual.UpdateVisual(true);
 401         }
 402
 403         /// <inheritdoc/>
 404         [EditorBrowsable(EditorBrowsableState.Never)]
 405         public override void ApplyStyle(ViewStyle viewStyle)
 406         {
 407             base.ApplyStyle(viewStyle);
 408
 409             if (viewStyle is ScrollbarStyle scrollbarStyle)
 410             {
 411                 // Apply essential look.
 412                 if (scrollbarStyle.TrackThickness == null) scrollbarStyle.TrackThickness = 6.0f;
 413                 if (scrollbarStyle.ThumbThickness == null) scrollbarStyle.ThumbThickness = 6.0f;
 414                 if (scrollbarStyle.TrackColor == null) scrollbarStyle.TrackColor = new Color(1.0f, 1.0f, 1.0f, 0.15f);
 415                 if (scrollbarStyle.ThumbColor == null) scrollbarStyle.ThumbColor = new Color(0.6f, 0.6f, 0.6f, 1.0f);
 416                 if (scrollbarStyle.TrackPadding == null) scrollbarStyle.TrackPadding = 4;
 417                 if (scrollbarStyle.WidthResizePolicy == null) scrollbarStyle.WidthResizePolicy = ResizePolicyType.FillToParent;
 418                 if (scrollbarStyle.HeightResizePolicy == null) scrollbarStyle.HeightResizePolicy = ResizePolicyType.FillToParent;
 419             }
 420         }
 421
 422         /// <inheritdoc/>
 423         [EditorBrowsable(EditorBrowsableState.Never)]
 424         protected override ViewStyle CreateViewStyle()
 425         {
 426             return new ScrollbarStyle();
 427         }
 428
 429         /// <summary>
 430         /// Update TrackThickness property of the scrollbar.
 431         /// </summary>
 432         /// <param name="thickness">The width of the track.</param>
 433         [EditorBrowsable(EditorBrowsableState.Never)]
 434         protected virtual void UpdateTrackThickness(float thickness)
 435         {
 436             if (trackVisual == null)
 437             {
 438                 return;
 439             }
 440
 441             trackVisual.Size = calculator.CalculateTrackSize(thickness, containerSize, TrackPadding);
 442             trackVisual.UpdateVisual(true);
 443         }
 444
 445         /// <summary>
 446         /// Update ThumbThickness property of the scrollbar.
 447         /// </summary>
 448         /// <param name="thickness">The width of the track.</param>
 449         [EditorBrowsable(EditorBrowsableState.Never)]
 450         protected virtual void UpdateThumbThickness(float thickness)
 451         {
 452             if (thumbVisual == null)
 453             {
 454                 return;
 455             }
 456
 457             thumbVisual.Size = calculator.CalculateThumbSize(thickness, trackVisual.Size);
 458             thumbVisual.UpdateVisual(true);
 459         }
 460
 461         /// <summary>
 462         /// Update TrackColor property of the scrollbar.
 463         /// </summary>
 464         /// <param name="color">The color of the track.</param>
 465         [EditorBrowsable(EditorBrowsableState.Never)]
 466         protected virtual void UpdateTrackColor(Color color)
 467         {
 468             if (trackVisual == null)
 469             {
 470                 return;
 471             }
 472
 473             trackVisual.MixColor = color;
 474             trackVisual.UpdateVisual(true);
 475         }
 476
 477         /// <summary>
 478         /// Update ThumbColor property of the scrollbar.
 479         /// </summary>
 480         /// <param name="color">The color of the thumb.</param>
 481         [EditorBrowsable(EditorBrowsableState.Never)]
 482         protected virtual void UpdateThumbColor(Color color)
 483         {
 484             if (thumbVisual == null)
 485             {
 486                 return;
 487             }
 488
 489             thumbVisual.MixColor = color;
 490             thumbVisual.UpdateVisual(true);
 491         }
 492
 493         /// <summary>
 494         /// Update TrackPadding property of the scrollbar.
 495         /// </summary>
 496         /// <param name="trackPadding">The padding of the track.</param>
 497         protected virtual void UpdateTrackPadding(Extents trackPadding)
 498         {
 499             if (calculator == null)
 500             {
 501                 return;
 502             }
 503
 504             trackVisual.Size = calculator.CalculateTrackSize(TrackThickness, containerSize, trackPadding);
 505             trackVisual.Position = calculator.CalculateTrackPosition(trackPadding);
 506             thumbVisual.Size = calculator.CalculateThumbSize(ThumbThickness, trackVisual.Size);
 507             thumbVisual.Position = calculator.CalculateThumbPaddingPosition(trackVisual.Size, thumbVisual.Size, thumbVisual.Position, trackPadding);
 508
 509             trackVisual.UpdateVisual(true);
 510             thumbVisual.UpdateVisual(true);
 511         }
 512
 513         /// <inheritdoc/>
 514         [EditorBrowsable(EditorBrowsableState.Never)]
 515         public override bool ScrollEnabled
 516         {
 517             get
 518             {
 519                 return mScrollEnabled;
 520             }
 521             set
 522             {
 523                 if (value != mScrollEnabled)
 524                 {
 525                     mScrollEnabled = value;
 526                 }
 527             }
 528         }
 529
 530         /// <inheritdoc/>
 531         [EditorBrowsable(EditorBrowsableState.Never)]
 532         public override Position ScrollPosition
 533         {
 534             get
 535             {
 536                 if (calculator == null)
 537                 {
 538                     return new Position(0.0f, 0.0f);
 539                 }
 540
 541                 float length = Math.Min(Math.Max(calculator.currentPosition, 0.0f), calculator.contentLength - calculator.visibleLength);
 542
 543                 if (calculator is HorizontalCalculator)
 544                 {
 545                     return new Position(length, 0.0f);
 546                 }
 547                 else
 548                 {
 549                     return new Position(0.0f, length);
 550                 }
 551             }
 552         }
 553
 554         /// <inheritdoc/>
 555         [EditorBrowsable(EditorBrowsableState.Never)]
 556         public override Position ScrollCurrentPosition
 557         {
 558             get
 559             {
 560                 if (calculator == null)
 561                 {
 562                     return new Position(0.0f, 0.0f);
 563                 }
 564
 565                 float length = Math.Min(Math.Max(calculator.currentPosition, 0.0f), calculator.contentLength - calculator.visibleLength);
 566
 567                 if (thumbPositionAnimation != null)
 568                 {
 569                     float progress = thumbPositionAnimation.CurrentProgress;
 570                     float previousLength = Math.Min(Math.Max(previousPosition, 0.0f), calculator.contentLength - calculator.visibleLength);
 571
 572                     length = ((1.0f - progress) * previousLength) + (progress * length);
 573                 }
 574
 575                 if (calculator is HorizontalCalculator)
 576                 {
 577                     return new Position(length, 0.0f);
 578                 }
 579                 else
 580                 {
 581                     return new Position(0.0f, length);
 582                 }
 583             }
 584         }
 585
 586         #endregion Methods
 587
 588
 589         #region Classes
 590
 591         private abstract class Calculator
 592         {
 593             public float contentLength;
 594             public float visibleLength;
 595             public float currentPosition;
 596
 597             public Calculator(float contentLength, float visibleLength, float currentPosition)
 598             {
 599                 this.contentLength = contentLength;
 600                 this.visibleLength = visibleLength;
 601                 this.currentPosition = currentPosition;
 602             }
 603
 604             public bool CalculateThumbVisibility()
 605             {
 606                 return contentLength > visibleLength;
 607             }
 608
 609             public abstract Visual.AlignType CalculatorTrackAlign();
 610             public abstract Visual.AlignType CalculatorThumbAlign();
 611             public abstract Size CalculateTrackSize(float thickness, Size containerSize, Extents trackPadding);
 612             public abstract Vector2 CalculateTrackPosition(Extents trackPadding);
 613             public abstract Size CalculateThumbSize(float thickness, Size trackSize);
 614             public abstract Vector2 CalculateThumbPosition(Size trackSize, Size thumbSize, Extents trackPadding);
 615             public abstract Vector2 CalculateThumbPaddingPosition(Size trackSize, Size thumbSize, Vector2 thumbCurrentPosition, Extents trackPadding);
 616             public abstract Vector2 CalculateThumbScrollPosition(Size trackSize, Vector2 thumbCurrentPosition, Extents trackPadding);
 617         }
 618
 619         private class HorizontalCalculator : Calculator
 620         {
 621             public HorizontalCalculator(float contentLength, float visibleLength, float currentPosition) : base(contentLength, visibleLength, currentPosition)
 622             {
 623             }
 624
 625             public override Visual.AlignType CalculatorTrackAlign()
 626             {
 627                 return Visual.AlignType.BottomCenter;
 628             }
 629
 630             public override Visual.AlignType CalculatorThumbAlign()
 631             {
 632                 return Visual.AlignType.BottomBegin;
 633             }
 634
 635             public override Size CalculateTrackSize(float thickness, Size containerSize, Extents trackPadding)
 636             {
 637                 return new Size(containerSize.Width - trackPadding?.Start??0 - trackPadding?.End??0, thickness);
 638             }
 639
 640             public override Vector2 CalculateTrackPosition(Extents trackPadding)
 641             {
 642                 return new Vector2(0, -trackPadding?.Bottom??0);
 643             }
 644
 645             public override Size CalculateThumbSize(float thickness, Size trackSize)
 646             {
 647                 return new Size(trackSize.Width * visibleLength / contentLength, thickness);
 648             }
 649
 650             public override Vector2 CalculateThumbPosition(Size trackSize, Size thumbSize, Extents trackPadding)
 651             {
 652                 float padding = ((trackSize.Height - thumbSize.Height) / 2.0f) + trackPadding?.Bottom??0;
 653                 float pos = Math.Min(Math.Max(currentPosition, 0.0f), contentLength - visibleLength);
 654                 return new Vector2(trackPadding?.Start??0 + trackSize.Width * pos / contentLength, -padding);
 655             }
 656
 657             public override Vector2 CalculateThumbPaddingPosition(Size trackSize, Size thumbSize, Vector2 thumbCurrentPosition, Extents trackPadding)
 658             {
 659                 float padding = ((trackSize.Height - thumbSize.Height) / 2.0f) + trackPadding?.Bottom??0;
 660                 return new Vector2(thumbCurrentPosition.X, -padding);
 661             }
 662
 663             public override Vector2 CalculateThumbScrollPosition(Size trackSize, Vector2 thumbCurrentPosition, Extents trackPadding)
 664             {
 665                 float pos = Math.Min(Math.Max(currentPosition, 0.0f), contentLength - visibleLength);
 666                 return new Vector2(trackPadding?.Start??0 + trackSize.Width * pos / contentLength, thumbCurrentPosition.Y);
 667             }
 668         }
 669
 670         private class VerticalCalculator : Calculator
 671         {
 672             public VerticalCalculator(float contentLength, float visibleLength, float currentPosition) : base(contentLength, visibleLength, currentPosition)
 673             {
 674             }
 675
 676             public override Visual.AlignType CalculatorTrackAlign()
 677             {
 678                 return Visual.AlignType.CenterEnd;
 679             }
 680
 681             public override Visual.AlignType CalculatorThumbAlign()
 682             {
 683                 return Visual.AlignType.TopEnd;
 684             }
 685
 686             public override Size CalculateTrackSize(float thickness, Size containerSize, Extents trackPadding)
 687             {
 688                 return new Size(thickness, containerSize.Height - trackPadding?.Top??0 - trackPadding?.Bottom??0);
 689             }
 690
 691             public override Vector2 CalculateTrackPosition(Extents trackPadding)
 692             {
 693                 return new Vector2(-trackPadding?.End??0, 0);
 694             }
 695
 696             public override Size CalculateThumbSize(float thickness, Size trackSize)
 697             {
 698                 return new Size(thickness, trackSize.Height * visibleLength / contentLength);
 699             }
 700
 701             public override Vector2 CalculateThumbPosition(Size trackSize, Size thumbSize, Extents trackPadding)
 702             {
 703                 float padding = ((trackSize.Width - thumbSize.Width) / 2.0f) + trackPadding?.End??0;
 704                 float pos = Math.Min(Math.Max(currentPosition, 0.0f), contentLength - visibleLength);
 705                 return new Vector2(-padding, trackPadding?.Top??0 + trackSize.Height * pos / contentLength);
 706             }
 707
 708             public override Vector2 CalculateThumbPaddingPosition(Size trackSize, Size thumbSize, Vector2 thumbCurrentPosition, Extents trackPadding)
 709             {
 710                 float padding = ((trackSize.Width - thumbSize.Width) / 2.0f) + trackPadding?.End??0;
 711                 return new Vector2(-padding, thumbCurrentPosition.Y);
 712             }
 713
 714             public override Vector2 CalculateThumbScrollPosition(Size trackSize, Vector2 thumbPosition, Extents trackPadding)
 715             {
 716                 float pos = Math.Min(Math.Max(currentPosition, 0.0f), contentLength - visibleLength);
 717                 return new Vector2(thumbPosition.X, trackPadding?.Top??0 + trackSize.Height * pos / contentLength);
 718             }
 719         }
 720
 721         #endregion Classes
 722     }
 723 }