HandyControl/src/Shared/HandyControl_Shared/Controls/Image/ImageBlock.cs

using System;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
using HandyControl.Data;

namespace HandyControl.Controls
{
    public class ImageBlock : FrameworkElement
    {
        private readonly DispatcherTimer _dispatcherTimer;

        private BitmapSource _source;

        private int _indexMax;

        private int _indexMin;

        private int _currentIndex;

        private int _blockWidth;

        private int _blockHeight;

        private bool _isDisposed;

        public ImageBlock()
        {
            _dispatcherTimer = new DispatcherTimer(DispatcherPriority.Render)
            {
                Interval = Interval
            };

            IsVisibleChanged += ImageBlock_IsVisibleChanged;
        }

        ~ImageBlock() => Dispose();

        public void Dispose()
        {
            if (_isDisposed) return;

            IsVisibleChanged -= ImageBlock_IsVisibleChanged;
            _dispatcherTimer.Stop();
            _isDisposed = true;

            GC.SuppressFinalize(this);
        }

        private void ImageBlock_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            if(IsVisible)
            {
                _dispatcherTimer.Tick += DispatcherTimer_Tick;
                if (IsPlaying)
                {
                    _dispatcherTimer.Start();
                }
            }
            else
            {
                _dispatcherTimer.Stop();
                _dispatcherTimer.Tick -= DispatcherTimer_Tick;
            }
        }

        private void UpdateDatas()
        {
            if (_source == null) return;
            _indexMin = StartRow * Columns + StartColumn;
            _indexMax = EndRow * Columns + EndColumn;
            _currentIndex = _indexMin;
            _blockWidth = _source.PixelWidth / Columns;
            _blockHeight = _source.PixelHeight / Rows;
        }

        private static void OnPositionsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var ctl = (ImageBlock)d;
            ctl.UpdateDatas();
        }

        private void DispatcherTimer_Tick(object sender, EventArgs e) => InvalidateVisual();

        public static readonly DependencyProperty StartColumnProperty = DependencyProperty.Register(
            "StartColumn", typeof(int), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.Int0Box,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnPositionsChanged));

        public int StartColumn
        {
            get => (int) GetValue(StartColumnProperty);
            set => SetValue(StartColumnProperty, value);
        }

        public static readonly DependencyProperty StartRowProperty = DependencyProperty.Register(
            "StartRow", typeof(int), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.Int0Box,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnPositionsChanged));

        public int StartRow
        {
            get => (int) GetValue(StartRowProperty);
            set => SetValue(StartRowProperty, value);
        }

        public static readonly DependencyProperty EndColumnProperty = DependencyProperty.Register(
            "EndColumn", typeof(int), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.Int0Box,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnPositionsChanged));

        public int EndColumn
        {
            get => (int) GetValue(EndColumnProperty);
            set => SetValue(EndColumnProperty, value);
        }

        public static readonly DependencyProperty EndRowProperty = DependencyProperty.Register(
            "EndRow", typeof(int), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.Int0Box,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnPositionsChanged));

        public int EndRow
        {
            get => (int) GetValue(EndRowProperty);
            set => SetValue(EndRowProperty, value);
        }

        public static readonly DependencyProperty IsPlayingProperty = DependencyProperty.Register(
            "IsPlaying", typeof(bool), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.FalseBox,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnIsPlayingChanged));

        private static void OnIsPlayingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var ctl = (ImageBlock)d;
            if ((bool) e.NewValue)
            {
                ctl._dispatcherTimer.Start();
            }
            else
            {
                ctl._dispatcherTimer.Stop();
            }
        }

        public bool IsPlaying
        {
            get => (bool) GetValue(IsPlayingProperty);
            set => SetValue(IsPlayingProperty, ValueBoxes.BooleanBox(value));
        }

        public static readonly DependencyProperty ColumnsProperty = DependencyProperty.Register(
            "Columns", typeof(int), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.Int1Box,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnPositionsChanged), obj => (int)obj >= 1);

        public int Columns
        {
            get => (int) GetValue(ColumnsProperty);
            set => SetValue(ColumnsProperty, value);
        }

        public static readonly DependencyProperty RowsProperty = DependencyProperty.Register(
            "Rows", typeof(int), typeof(ImageBlock), new FrameworkPropertyMetadata(ValueBoxes.Int1Box,
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnPositionsChanged), obj => (int)obj >= 1);

        public int Rows
        {
            get => (int) GetValue(RowsProperty);
            set => SetValue(RowsProperty, value);
        }

        public static readonly DependencyProperty IntervalProperty = DependencyProperty.Register(
            "Interval", typeof(TimeSpan), typeof(ImageBlock), new PropertyMetadata(TimeSpan.FromSeconds(1), OnIntervalChanged));

        private static void OnIntervalChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var ctl = (ImageBlock) d;
            ctl._dispatcherTimer.Interval = (TimeSpan) e.NewValue;
        }

        public TimeSpan Interval
        {
            get => (TimeSpan) GetValue(IntervalProperty);
            set => SetValue(IntervalProperty, value);
        }

        public static readonly DependencyProperty SourceProperty = DependencyProperty.Register(
            "Source", typeof(ImageSource), typeof(ImageBlock), new FrameworkPropertyMetadata(default(ImageSource),
                FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, OnSourceChanged));

        private static void OnSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var ctl = (ImageBlock)d;
            ctl._source = e.NewValue as BitmapSource;
            ctl.UpdateDatas();
        }

        public ImageSource Source
        {
            get => (ImageSource)GetValue(SourceProperty);
            set => SetValue(SourceProperty, value);
        }

        protected override void OnRender(DrawingContext dc)
        {
            if (_source == null) return;
            var croppedBitmap = new CroppedBitmap(_source, CalDisplayRect());
            dc.DrawImage(croppedBitmap, new Rect(0, 0, RenderSize.Width, RenderSize.Height));
        }

        private Int32Rect CalDisplayRect()
        {
            if (_currentIndex > _indexMax)
            {
                _currentIndex = _indexMin;
            }

            var x = _currentIndex % Columns * _blockWidth;
            var y = _currentIndex / Columns * _blockHeight;

            var rect = new Int32Rect(x, y, _blockWidth, _blockHeight);
            _currentIndex++;
            return rect;
        }
    }
}