[C#/WINUI3/.NET6] ItemsRepeater 엘리먼트 : Layout 속성에서 VirtualizingLayout 상속 객체를 만들어 가상화/스크롤 가능한 커스텀 레이아웃 사용하기
■ ItemsRepeater 엘리먼트의 Layout 속성에서 VirtualizingLayout 상속 객체를 만들어 가상화/스크롤 가능한 커스텀 레이아웃을 사용하는 방법을 보여준다. ▶ ActivityFeedLayoutState.cs
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using System.Collections.Generic; using Windows.Foundation; namespace TestProject { /// <summary> /// 활동 피드 레이아웃 상태 /// </summary> public class ActivityFeedLayoutState { //////////////////////////////////////////////////////////////////////////////////////////////////// Field ////////////////////////////////////////////////////////////////////////////////////////// Private #region Field /// <summary> /// 레이아웃 사각형 리스트 /// </summary> private List<Rect> layoutRectList; #endregion //////////////////////////////////////////////////////////////////////////////////////////////////// Property ////////////////////////////////////////////////////////////////////////////////////////// Publoc #region 첫번째 실현 인덱스 - FirstRealizedIndex /// <summary> /// 첫번째 실현 인덱스 /// </summary> public int FirstRealizedIndex { get; set; } #endregion #region 레이아웃 사각형 리스트 - LayoutRectList /// <summary> /// 레이아웃 사각형 리스트 /// </summary> public List<Rect> LayoutRectList { get { if(this.layoutRectList == null) { this.layoutRectList = new List<Rect>(); } return this.layoutRectList; } } #endregion } } |
▶ ActivityFeedLayout.cs
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using System; using Windows.Foundation; using Microsoft.UI.Xaml.Controls; using Microsoft.UI.Xaml; namespace TestProject { /// <summary> /// 활동 피드 레이아웃 /// </summary> public class ActivityFeedLayout : VirtualizingLayout { //////////////////////////////////////////////////////////////////////////////////////////////////// Dependency Property ////////////////////////////////////////////////////////////////////////////////////////// Static //////////////////////////////////////////////////////////////////////////////// Public #region 행 간격 속성 - RowSpacingProperty /// <summary> /// 행 간격 속성 /// </summary> public static readonly DependencyProperty RowSpacingProperty = DependencyProperty.Register ( "RowSpacing", typeof(double), typeof(ActivityFeedLayout), new PropertyMetadata(0, PropertyChangedCallback) ); #endregion #region 열 간격 속성 - ColumnSpacingProperty /// <summary> /// 열 간격 속성 /// </summary> public static readonly DependencyProperty ColumnSpacingProperty = DependencyProperty.Register ( "ColumnSpacing", typeof(double), typeof(ActivityFeedLayout), new PropertyMetadata(0, PropertyChangedCallback) ); #endregion #region 최소 항목 크기 속성 - MinimumItemSizeProperty /// <summary> /// 최소 항목 크기 속성 /// </summary> public static readonly DependencyProperty MinimumItemSizeProperty = DependencyProperty.Register ( "MinimumItemSize", typeof(Size), typeof(ActivityFeedLayout), new PropertyMetadata(Size.Empty, PropertyChangedCallback) ); #endregion //////////////////////////////////////////////////////////////////////////////////////////////////// Field ////////////////////////////////////////////////////////////////////////////////////////// Private #region Field /// <summary> /// 행 간격 /// </summary> private double rowSpacing; /// <summary> /// 열 간격 /// </summary> private double columnSpacing; /// <summary> /// 최소 항목 크기 /// </summary> private Size minimumItemSize = Size.Empty; #endregion //////////////////////////////////////////////////////////////////////////////////////////////////// Property ////////////////////////////////////////////////////////////////////////////////////////// Public #region 행 간격 - RowSpacing /// <summary> /// 행 간격 /// </summary> public double RowSpacing { get { return this.rowSpacing; } set { SetValue(RowSpacingProperty, value); } } #endregion #region 열 간격 - ColumnSpacing /// <summary> /// 열 간격 /// </summary> public double ColumnSpacing { get { return this.columnSpacing; } set { SetValue(ColumnSpacingProperty, value); } } #endregion #region 최소 항목 크기 - MinimumItemSize /// <summary> /// 최소 항목 크기 /// </summary> public Size MinimumItemSize { get { return this.minimumItemSize; } set { SetValue(MinimumItemSizeProperty, value); } } #endregion //////////////////////////////////////////////////////////////////////////////////////////////////// Method ////////////////////////////////////////////////////////////////////////////////////////// Static //////////////////////////////////////////////////////////////////////////////// Private #region 속성 변경시 콜백 처리하기 - PropertyChangedCallback(d, e) /// <summary> /// 속성 변경시 콜백 처리하기 /// </summary> /// <param name="d">의존 객체</param> /// <param name="e">이벤트 인자</param> private static void PropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e) { ActivityFeedLayout layout = d as ActivityFeedLayout; if(e.Property == RowSpacingProperty) { layout.rowSpacing = (double)e.NewValue; } else if(e.Property == ColumnSpacingProperty) { layout.columnSpacing = (double)e.NewValue; } else if(e.Property == MinimumItemSizeProperty) { layout.minimumItemSize = (Size)e.NewValue; } else { throw new InvalidOperationException("Don't know what you are talking about!"); } layout.InvalidateMeasure(); } #endregion ////////////////////////////////////////////////////////////////////////////////////////// Instance //////////////////////////////////////////////////////////////////////////////// Protected #region 컨텍스트용 초기화하기 (코어) - InitializeForContextCore(context) /// <summary> /// 컨텍스트용 초기화하기 (코어) /// </summary> /// <param name="context">가상화 레이아웃 컨텍스트</param> protected override void InitializeForContextCore(VirtualizingLayoutContext context) { base.InitializeForContextCore(context); if(!(context.LayoutState is ActivityFeedLayoutState)) { context.LayoutState = new ActivityFeedLayoutState(); } } #endregion #region 컨텍스트용 초기화 취소하기 (코어) - UninitializeForContextCore(context) /// <summary> /// 컨텍스트용 초기화 취소하기 (코어) /// </summary> /// <param name="context">가상화 레이아웃 컨텍스트</param> protected override void UninitializeForContextCore(VirtualizingLayoutContext context) { base.UninitializeForContextCore(context); context.LayoutState = null; } #endregion #region 측정하기 (오버라이드) - MeasureOverride(context, availableSize) /// <summary> /// 측정하기 (오버라이드) /// </summary> /// <param name="context">가상화 레이아웃 컨텍스트</param> /// <param name="availableSize">이용 가능한 크기</param> /// <returns>측정 크기</returns> protected override Size MeasureOverride(VirtualizingLayoutContext context, Size availableSize) { if(MinimumItemSize == Size.Empty) { UIElement firstElement = context.GetOrCreateElementAt(0); firstElement.Measure(new Size(float.PositiveInfinity, float.PositiveInfinity)); this.minimumItemSize = firstElement.DesiredSize; } int firstRowIndex = Math.Max ( (int)(context.RealizationRect.Y / (MinimumItemSize.Height + RowSpacing)) - 1, 0 ); int lastRowIndex = Math.Min ( (int)(context.RealizationRect.Bottom / (this.MinimumItemSize.Height + this.RowSpacing)) + 1, (int)(context.ItemCount / 3) ); ActivityFeedLayoutState state = context.LayoutState as ActivityFeedLayoutState; state.LayoutRectList.Clear(); state.FirstRealizedIndex = firstRowIndex * 3; double desiredItemWidth = Math.Max ( this.MinimumItemSize.Width, (availableSize.Width - ColumnSpacing * 3) / 4 ); for(int rowIndex = firstRowIndex; rowIndex < lastRowIndex; rowIndex++) { int firstItemIndex = rowIndex * 3; Rect[] boundRectangleArrayForCurrentRow = CalculateLayoutBoundRectangleArrayForRow(rowIndex, desiredItemWidth); for(int columnIndex = 0; columnIndex < 3; columnIndex++) { int index = firstItemIndex + columnIndex; UIElement containerElement = context.GetOrCreateElementAt(index); containerElement.Measure ( new Size ( boundRectangleArrayForCurrentRow[columnIndex].Width, boundRectangleArrayForCurrentRow[columnIndex].Height ) ); state.LayoutRectList.Add(boundRectangleArrayForCurrentRow[columnIndex]); } } double extentHeight; if(context.ItemCount == 0) { extentHeight = 0; } else { extentHeight = ((int)(context.ItemCount / 3) - 1) * (MinimumItemSize.Height + RowSpacing) + MinimumItemSize.Height; } return new Size(desiredItemWidth * 4 + this.ColumnSpacing * 2, extentHeight); } #endregion #region 배치하기 (오버라이드) - ArrangeOverride(context, finalSize) /// <summary> /// 배치하기 (오버라이드) /// </summary> /// <param name="context">가상화 레이아웃 컨텍스트</param> /// <param name="finalSize">최종 크기</param> /// <returns>배치 크기</returns> protected override Size ArrangeOverride(VirtualizingLayoutContext context, Size finalSize) { ActivityFeedLayoutState state = context.LayoutState as ActivityFeedLayoutState; VirtualizingLayoutContext virtualContext = context as VirtualizingLayoutContext; int currentIndex = state.FirstRealizedIndex; foreach(Rect arrangeRect in state.LayoutRectList) { UIElement containerElement = virtualContext.GetOrCreateElementAt(currentIndex); containerElement.Arrange(arrangeRect); currentIndex++; } return finalSize; } #endregion //////////////////////////////////////////////////////////////////////////////// Private #region 행을 위한 레이아웃 경계 사각형 배열 계산하기 - CalculateLayoutBoundRectangleArrayForRow(rowIndex, desiredItemWidth) /// <summary> /// 행을 위한 레이아웃 경계 사각형 배열 계산하기 /// </summary> /// <param name="rowIndex">행 인덱스</param> /// <param name="desiredItemWidth">희망 항목 너비</param> /// <returns>레이아웃 경계 사각형 배열</returns> private Rect[] CalculateLayoutBoundRectangleArrayForRow(int rowIndex, double desiredItemWidth) { Rect[] boundRectangeArrayForRow = new Rect[3]; double yoffset = rowIndex * (MinimumItemSize.Height + RowSpacing); boundRectangeArrayForRow[0].Y = boundRectangeArrayForRow[1].Y = boundRectangeArrayForRow[2].Y = yoffset; boundRectangeArrayForRow[0].Height = boundRectangeArrayForRow[1].Height = boundRectangeArrayForRow[2].Height = MinimumItemSize.Height; if(rowIndex % 2 == 0) { boundRectangeArrayForRow[0].X = 0; boundRectangeArrayForRow[0].Width = desiredItemWidth; boundRectangeArrayForRow[1].X = boundRectangeArrayForRow[0].Right + ColumnSpacing; boundRectangeArrayForRow[1].Width = desiredItemWidth; boundRectangeArrayForRow[2].X = boundRectangeArrayForRow[1].Right + ColumnSpacing; boundRectangeArrayForRow[2].Width = desiredItemWidth * 2 + ColumnSpacing; } else { boundRectangeArrayForRow[0].X = 0; boundRectangeArrayForRow[0].Width = (desiredItemWidth * 2 + ColumnSpacing); boundRectangeArrayForRow[1].X = boundRectangeArrayForRow[0].Right + ColumnSpacing; boundRectangeArrayForRow[1].Width = desiredItemWidth; boundRectangeArrayForRow[2].X = boundRectangeArrayForRow[1].Right + ColumnSpacing; boundRectangeArrayForRow[2].Width = desiredItemWidth; } return boundRectangeArrayForRow; } #endregion } } |