在WPF中使用我编写的扩展方法很容易做到这一点。将项目滚动到视图中心所需要做的就是调用一个方法。
假设您有以下XAML：
<ListView x:Name="view" ItemsSource="{Binding Data}" />
<Combo@R_563_2419@ x:Name="@R_563_2419@" ItemsSource="{Binding Data}"
SelectionChanged="ScrollIntoView" />
您的ScrollIntoView方法将很简单：
private void ScrollIntoView(object sender, SelectionChangedEventArgs e)
{
view.ScrollToCenterOfView(@R_563_2419@.SelectedItem);
}
显然，这也可以使用viewmodel来完成，而不是显式地引用控件。
以下是实现。非常通用，可以处理所有IScrollInfo可能性。它可以与List@R_563_2419@或任何其他ItemsControl一起使用，并且可以与任何面板一起使用，包括StackPanel，VirtualizingStackPanel，WrapPanel，DockPanel，Canvas，Grid等。
只需将其放入项目中某个.cs文件中即可：
public static class ItemsControlExtensions
{
public static void ScrollToCenterOfView(this ItemsControl itemsControl, object item)
{
// Scroll immediately if possible
if(!itemsControl.TryScrollToCenterOfView(item))
{
// Otherwise wait until everything is loaded, then scroll
if(itemsControl is List@R_563_2419@) ((List@R_563_2419@)itemsControl).ScrollIntoView(item);
itemsControl.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(() =>
{
itemsControl.TryScrollToCenterOfView(item);
}));
}
}
private static bool TryScrollToCenterOfView(this ItemsControl itemsControl, object item)
{
// Find the container
var container = itemsControl.ItemContainerGenerator.ContainerFromItem(item) as UIElement;
if(container==null) return false;
// Find the ScrollContentPresenter
ScrollContentPresenter presenter = null;
for(Visual vis = container; vis!=null && vis!=itemsControl; vis = VisualTreeHelper.GetParent(vis) as Visual)
if((presenter = vis as ScrollContentPresenter)!=null)
break;
if(presenter==null) return false;
// Find the IScrollInfo
var scrollInfo =
!presenter.CanContentScroll ? presenter :
presenter.Content as IScrollInfo ??
FirstVisualChild(presenter.Content as ItemsPresenter) as IScrollInfo ??
presenter;
// Compute the center point of the container relative to the scrollInfo
Size size = container.RenderSize;
Point center = container.TransformToAncestor((Visual)scrollInfo).Transform(new Point(size.Width/2, size.Height/2));
center.Y += scrollInfo.VerticalOffset;
center.X += scrollInfo.HorizontalOffset;
// Adjust for logical scrolling
if(scrollInfo is StackPanel || scrollInfo is VirtualizingStackPanel)
{
double logicalCenter = itemsControl.ItemContainerGenerator.IndexFromContainer(container) + 0.5;
Orientation orientation = scrollInfo is StackPanel ? ((StackPanel)scrollInfo).Orientation : ((VirtualizingStackPanel)scrollInfo).Orientation;
if(orientation==Orientation.Horizontal)
center.X = logicalCenter;
else
center.Y = logicalCenter;
}
// Scroll the center of the container to the center of the viewport
if(scrollInfo.CanVerticallyScroll) scrollInfo.SetVerticalOffset(CenteringOffset(center.Y, scrollInfo.ViewportHeight, scrollInfo.ExtentHeight));
if(scrollInfo.CanHorizontallyScroll) scrollInfo.SetHorizontalOffset(CenteringOffset(center.X, scrollInfo.ViewportWidth, scrollInfo.ExtentWidth));
return true;
}
private static double CenteringOffset(double center, double viewport, double extent)
{
return Math.Min(extent - viewport, Math.Max(0, center - viewport/2));
}
private static DependencyObject FirstVisualChild(Visual visual)
{
if(visual==null) return null;
if(VisualTreeHelper.GetChildrenCount(visual)==0) return null;
return VisualTreeHelper.GetChild(visual, 0);
}
}
602392714
清零编程群