101 lines
3.6 KiB
C#
101 lines
3.6 KiB
C#
using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Controls.Primitives;
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using System.Windows.Media;
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using System.Windows.Threading;
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namespace Main.Test;
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public partial class StyledDataGrid
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{
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private DispatcherTimer? imageResumeTimer;
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private bool draggingScrollThumb;
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private void InitializeImageLoadingPause()
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{
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imageResumeTimer = new DispatcherTimer(DispatcherPriority.Background, Dispatcher)
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{
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Interval = TimeSpan.FromMilliseconds(500)
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};
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imageResumeTimer.Tick += (_, _) =>
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{
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imageResumeTimer.Stop();
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if (!draggingScrollThumb && IsLoaded) SetImageLoadingSuspended(false);
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};
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AddHandler(Thumb.DragStartedEvent, new DragStartedEventHandler(ScrollThumbDragStarted), true);
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AddHandler(Thumb.DragCompletedEvent, new DragCompletedEventHandler(ScrollThumbDragCompleted), true);
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AddHandler(ScrollViewer.ScrollChangedEvent, new ScrollChangedEventHandler(ImageScrollChanged), true);
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Unloaded += (_, _) =>
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{
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imageResumeTimer.Stop(); draggingScrollThumb = false;
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SetImageLoadingSuspended(true);
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};
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Loaded += (_, _) => { ApplyImageLoadingOptions(); SetImageLoadingSuspended(false); };
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ApplyImageLoadingOptions();
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}
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private void SetImageLoadingSuspended(bool suspended)
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{
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SetValue(IsImageLoadingSuspendedPropertyKey, suspended);
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NetworkThumbnail.SetIsLoadingSuspended(this, suspended);
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}
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private void ApplyImageLoadingOptions()
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{
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NetworkThumbnail.SetCacheEnabled(this, EnableImageCache);
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if (imageResumeTimer == null) return;
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if (!PauseImageLoadingWhileDragging)
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{
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imageResumeTimer.Stop(); draggingScrollThumb = false; SetImageLoadingSuspended(false);
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}
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}
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private bool IsOwnScrollBar(DependencyObject? source)
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{
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var foundScrollBar = false;
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for (var parent = source; parent != null; parent = VisualTreeHelper.GetParent(parent))
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{
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if (parent is ScrollBar) foundScrollBar = true;
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if (parent is DataGrid) return ReferenceEquals(parent, this) && foundScrollBar;
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}
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return false;
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}
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private void ScrollThumbDragStarted(object sender, DragStartedEventArgs e)
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{
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if (!PauseImageLoadingWhileDragging || !IsOwnScrollBar(e.OriginalSource as DependencyObject)) return;
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draggingScrollThumb = true;
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imageResumeTimer!.Stop();
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// 继承到可见图片及随后回收生成的新行，立即取消请求并清空图片。
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SetImageLoadingSuspended(true);
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}
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private void ScrollThumbDragCompleted(object sender, DragCompletedEventArgs e)
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{
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if (!PauseImageLoadingWhileDragging || !IsOwnScrollBar(e.OriginalSource as DependencyObject)) return;
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draggingScrollThumb = false;
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RestartImageResumeTimer();
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}
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private void ImageScrollChanged(object sender, ScrollChangedEventArgs e)
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{
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if (!NetworkThumbnail.GetIsLoadingSuspended(this) || draggingScrollThumb ||
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(e.VerticalChange == 0 && e.HorizontalChange == 0) ||
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!IsOwnScrollViewer(e.OriginalSource as DependencyObject)) return;
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RestartImageResumeTimer();
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}
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private bool IsOwnScrollViewer(DependencyObject? source)
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{
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for (var parent = source; parent != null; parent = VisualTreeHelper.GetParent(parent))
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if (parent is DataGrid) return ReferenceEquals(parent, this);
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return false;
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}
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private void RestartImageResumeTimer()
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{
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imageResumeTimer!.Stop();
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imageResumeTimer.Start();
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}
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}
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