public static void ScrollIntoViewSmoothly(this ListViewBase listViewBase, object item, ScrollIntoViewAlignment alignment)
{
if (listViewBase == null)
{
throw new ArgumentNullException(nameof(listViewBase));
}
var scrollViewer = listViewBase.GetDescendantsOfType<ScrollViewer>().First();
var originHorizontalOffset = scrollViewer.HorizontalOffset;
var originVerticalOffset = scrollViewer.VerticalOffset;
EventHandler<object> layoutUpdatedHandler = null;
layoutUpdatedHandler = delegate
{
listViewBase.LayoutUpdated -= layoutUpdatedHandler;
var targetHorizontalOffset = scrollViewer.HorizontalOffset;
var targetVerticalOffset = scrollViewer.VerticalOffset;
EventHandler<ScrollViewerViewChangedEventArgs> scrollHandler = null;
scrollHandler = (sender, e) =>
{
scrollViewer.ViewChanged -= scrollHandler;
scrollViewer.ChangeView(targetHorizontalOffset, targetVerticalOffset, null);
};
scrollViewer.ViewChanged += scrollHandler; ;
scrollViewer.ChangeView(originHorizontalOffset, originVerticalOffset, null, true);
};
listViewBase.LayoutUpdated += layoutUpdatedHandler;
listViewBase.ScrollIntoView(item, alignment);
}
public static async Task ScrollIntoViewAsync(this ListViewBase listViewBase, object item, ScrollIntoViewAlignment alignment = ScrollIntoViewAlignment.Leading)
{
var tcs = new TaskCompletionSource <object>();
var scrollViewer = listViewBase.GetScrollViewer();
EventHandler <object> layoutUpdated = (s1, e1) => tcs.TrySetResult(null);
EventHandler <ScrollViewerViewChangedEventArgs> viewChanged = (s, e) =>
{
scrollViewer.LayoutUpdated += layoutUpdated;
scrollViewer.UpdateLayout();
};
try
{
scrollViewer.ViewChanged += viewChanged;
listViewBase.ScrollIntoView(item, alignment);
await tcs.Task;
}
finally
{
scrollViewer.ViewChanged -= viewChanged;
scrollViewer.LayoutUpdated -= layoutUpdated;
}
}
public static void ScrollIntoViewSmoothly(this ListViewBase listViewBase, object item, ScrollIntoViewAlignment alignment)
{
if (listViewBase == null)
{
throw new ArgumentException(nameof(ListViewBase));
}
// GetFirstDescendantOfType 是 WinRTXamlToolkit 中的扩展方法，
// 寻找该控件在可视树上第一个符合类型的子元素。
ScrollViewer scrollViewer = XamlHelper.FindChildOfType <ScrollViewer>(listViewBase);
// 由于 ScrollViewer 肯定有，因此不做 null 检查判断了。
// 记录初始位置，用于 ScrollIntoView 检测目标位置后复原。
double originHorizontalOffset = scrollViewer.HorizontalOffset;
double originVerticalOffset = scrollViewer.VerticalOffset;
EventHandler <object> layoutUpdatedHandler = null;
layoutUpdatedHandler = delegate
{
listViewBase.LayoutUpdated -= layoutUpdatedHandler;
// 获取目标位置。
double targetHorizontalOffset = scrollViewer.HorizontalOffset;
double targetVerticalOffset = scrollViewer.VerticalOffset;
EventHandler <ScrollViewerViewChangedEventArgs> scrollHandler = null;
scrollHandler = delegate
{
scrollViewer.ViewChanged -= scrollHandler;
// 最终目的，带平滑滚动效果滚动到 item。
scrollViewer.ChangeView(targetHorizontalOffset, targetVerticalOffset, null);
};
scrollViewer.ViewChanged += scrollHandler;
// 复原位置，且不需要使用动画效果。
scrollViewer.ChangeView(originHorizontalOffset, originVerticalOffset, null, true);
};
listViewBase.LayoutUpdated += layoutUpdatedHandler;
// 跑腿。
listViewBase.ScrollIntoView(item, alignment);
}
public async Task GoToGroupAsync(int groupIndex, ScrollIntoViewAlignment scrollIntoViewAlignment = ScrollIntoViewAlignment.Leading)
{
if (groupCollection != null)
{
var gc = groupCollection;
if (groupIndex < gc.GroupHeaders.Count && groupIndex >= 0 && !isGotoGrouping)
{
isGotoGrouping = true;
//load more so that ScrollIntoViewAlignment.Leading can go to top
var loadcount = this.GetVisibleItemsCount() + 1;
progressRing.IsActive = true;
progressRing.Visibility = Visibility.Visible;
//make sure user don't do any other thing at the time.
this.IsHitTestVisible = false;
//await Task.Delay(3000);
while (gc.GroupHeaders[groupIndex].FirstIndex == -1)
{
if (gc.HasMoreItems)
{
await gc.LoadMoreItemsAsync(loadcount);
}
else
{
break;
}
}
if (gc.GroupHeaders[groupIndex].FirstIndex != -1)
{
//make sure there are enought items to go ScrollIntoViewAlignment.Leading
//this.count > (firstIndex + loadcount)
if (scrollIntoViewAlignment == ScrollIntoViewAlignment.Leading)
{
var more = this.Items.Count - (gc.GroupHeaders[groupIndex].FirstIndex + loadcount);
if (gc.HasMoreItems && more < 0)
{
await gc.LoadMoreItemsAsync((uint)Math.Abs(more));
}
}
progressRing.IsActive = false;
progressRing.Visibility = Visibility.Collapsed;
var groupFirstIndex = gc.GroupHeaders[groupIndex].FirstIndex;
ScrollIntoView(this.Items[groupFirstIndex], scrollIntoViewAlignment);
ListViewItem listViewItem = ContainerFromIndex(groupFirstIndex) as ListViewItem;
if (listViewItem != null)
{
GeneralTransform gt = listViewItem.TransformToVisual(this);
var rect = gt.TransformBounds(new Rect(0, 0, listViewItem.ActualWidth, listViewItem.ActualHeight));
//add delta,so that it does not look like suddenly
if (rect.Bottom < 0 || rect.Top > this.ActualHeight)
{
}
//already in viewport, maybe it will not change view
else
{
this.IsHitTestVisible = true;
isGotoGrouping = false;
}
}
}
else
{
this.IsHitTestVisible = true;
isGotoGrouping = false;
progressRing.IsActive = false;
progressRing.Visibility = Visibility.Collapsed;
}
}
}
}
public async Task GoToPreviousGroupAsync(ScrollIntoViewAlignment scrollIntoViewAlignment = ScrollIntoViewAlignment.Leading)
{
if (groupCollection != null)
{
var gc = groupCollection;
var currentGroupIndex = GetCurrentVisibleGroupIndex();
if (currentGroupIndex - 1 < 0)
{
currentGroupIndex = gc.GroupHeaders.Count - 1;
}
else
{
currentGroupIndex--;
}
await GoToGroupAsync(currentGroupIndex, scrollIntoViewAlignment);
}
}
public static async Task ScrollIntoViewAsync(this ListViewBase listViewBase, object item, ScrollIntoViewAlignment alignment, bool updateLayout)
{
var tcs = new TaskCompletionSource <object>();
var scrollViewer = listViewBase.GetScrollViewer();
void layoutUpdated(object s1, object e1)
{
tcs.TrySetResult(null);
}
void viewChanged(object s, ScrollViewerViewChangedEventArgs e)
{
scrollViewer.LayoutUpdated += layoutUpdated;
if (updateLayout)
{
scrollViewer.UpdateLayout();
}
}
try
{
scrollViewer.ViewChanged += viewChanged;
listViewBase.ScrollIntoView(item, alignment);
await tcs.Task;
}
finally
{
scrollViewer.ViewChanged -= viewChanged;
scrollViewer.LayoutUpdated -= layoutUpdated;
}
}
public async Task GoToGroupAsync(int groupIndex, ScrollIntoViewAlignment scrollIntoViewAlignment = ScrollIntoViewAlignment.Leading)
{
if (groupCollection != null)
{
var gc = groupCollection;
if (groupIndex < gc.GroupHeaders.Count && groupIndex >= 0 && !isGotoGrouping)
{
isGotoGrouping = true;
//load more so that ScrollIntoViewAlignment.Leading can go to top
var loadcount = this.GetVisibleItemsCount() + 1;
progressRing.IsActive = true;
progressRing.Visibility = Visibility.Visible;
//make sure user don't do any other thing at the time.
this.IsHitTestVisible = false;
//await Task.Delay(3000);
while (gc.GroupHeaders[groupIndex].FirstIndex == -1)
{
if (gc.HasMoreItems)
{
await gc.LoadMoreItemsAsync(loadcount);
}
else
{
break;
}
}
if (gc.GroupHeaders[groupIndex].FirstIndex != -1)
{
//make sure there are enought items to go ScrollIntoViewAlignment.Leading
//this.count > (firstIndex + loadcount)
if (scrollIntoViewAlignment == ScrollIntoViewAlignment.Leading)
{
var more = this.Items.Count - (gc.GroupHeaders[groupIndex].FirstIndex + loadcount);
if (gc.HasMoreItems && more < 0)
{
await gc.LoadMoreItemsAsync((uint)Math.Abs(more));
}
}
progressRing.IsActive = false;
progressRing.Visibility = Visibility.Collapsed;
var groupFirstIndex = gc.GroupHeaders[groupIndex].FirstIndex;
ScrollIntoView(this.Items[groupFirstIndex], scrollIntoViewAlignment);
//already in viewport, maybe it will not change view
if (groupDic.ContainsKey(gc.GroupHeaders[groupIndex]) && groupDic[gc.GroupHeaders[groupIndex]].Visibility == Visibility.Visible)
{
this.IsHitTestVisible = true;
isGotoGrouping = false;
}
}
else
{
this.IsHitTestVisible = true;
isGotoGrouping = false;
progressRing.IsActive = false;
progressRing.Visibility = Visibility.Collapsed;
}
}
}
}
public async ValueTask ScrollIntoViewAsync(ElementReference element, ScrollIntoViewAlignment block, ScrollIntoViewAlignment inline, bool smooth = false)
{
var module = await _jsRuntime
.ImportOrGetModuleAsync(ModulePath, ModuleKey, _jsRefStore);
await module.InvokeVoidAsync(
"scrollIntoView",
element,
MapScrollIntoViewAlignment(block),
MapScrollIntoViewAlignment(inline),
smooth);
}
public void ScrollIntoView(ElementReference element, ScrollIntoViewAlignment block, ScrollIntoViewAlignment inline, bool smooth = false)
{
_jsInProcessObjectRef !.InvokeVoid(
"scrollIntoView",
element,
MapScrollIntoViewAlignment(block),
MapScrollIntoViewAlignment(inline),
smooth);
}
public async Task ScrollToItem(object item, VerticalAlignment alignment, bool highlight, double?pixel = null, ScrollIntoViewAlignment direction = ScrollIntoViewAlignment.Leading, bool?disableAnimation = null)
{
var scrollViewer = ScrollingHost;
if (scrollViewer == null)
{
Logs.Logger.Debug(Logs.Target.Chat, "ScrollingHost == null");
return;
}
// We are going to try two times, as the first one seem to fail sometimes
// leading the chat to the wrong scrolling position
var iter = 2;
var selectorItem = ContainerFromItem(item) as SelectorItem;
while (selectorItem == null && iter > 0)
{
Logs.Logger.Debug(Logs.Target.Chat, string.Format("selectorItem == null, {0} try", iter + 1));
// call task-based ScrollIntoViewAsync to realize the item
await this.ScrollIntoViewAsync(item, direction);
// this time the item shouldn't be null again
selectorItem = ContainerFromItem(item) as SelectorItem;
iter--;
}
if (selectorItem == null)
{
Logs.Logger.Debug(Logs.Target.Chat, "selectorItem == null, abort");
return;
}
// calculate the position object in order to know how much to scroll to
var transform = selectorItem.TransformToVisual((UIElement)scrollViewer.Content);
var position = transform.TransformPoint(new Point(0, 0));
// If position is negative layout should still happen,
// Lets wait for it.
if (position.Y < 0)
{
Logs.Logger.Debug(Logs.Target.Chat, "position.Y is negative, let's wait for layout");
// call task-based ScrollIntoViewAsync to realize the item
await this.ScrollIntoViewAsync(item, direction);
// this time the item shouldn't be null again
selectorItem = ContainerFromItem(item) as SelectorItem;
if (selectorItem == null)
{
Logs.Logger.Debug(Logs.Target.Chat, "selectorItem == null after layout, abort");
return;
}
transform = selectorItem.TransformToVisual((UIElement)scrollViewer.Content);
position = transform.TransformPoint(new Point(0, 0));
}
if (alignment == VerticalAlignment.Top)
{
if (pixel is double adjust)
{
position.Y -= adjust;
}
}
else if (alignment == VerticalAlignment.Center)
{
if (selectorItem.ActualHeight < ActualHeight - 48)
{
position.Y -= (ActualHeight - selectorItem.ActualHeight) / 2d;
}
else
{
position.Y -= 48 + 4;
}
}
else if (alignment == VerticalAlignment.Bottom)
{
position.Y -= ActualHeight - selectorItem.ActualHeight;
if (pixel is double adjust)
{
position.Y += adjust;
}
}
if (highlight)
{
var bubble = selectorItem.Descendants <MessageBubble>().FirstOrDefault() as MessageBubble;
if (bubble != null)
{
bubble.Highlight();
}
}
// scroll to desired position with animation!
await scrollViewer.ChangeViewAsync(null, position.Y, disableAnimation ?? alignment != VerticalAlignment.Center);
//scrollViewer.ChangeView(null, position.Y, null, disableAnimation ?? alignment != VerticalAlignment.Center);
}
public async Task GoToGroupAsync(int groupIndex, ScrollIntoViewAlignment scrollIntoViewAlignment = ScrollIntoViewAlignment.Leading)
{
if (groupCollection != null)
{
var gc = groupCollection;
if (groupIndex < gc.GroupHeaders.Count && groupIndex >= 0 && !isGotoGrouping)
{
isGotoGrouping = true;
//load more so that ScrollIntoViewAlignment.Leading can go to top
var loadcount = this.GetVisibleItemsCount() + 1;
progressRing.IsActive = true;
progressRing.Visibility = Visibility.Visible;
//make sure user don't do any other thing at the time.
this.IsHitTestVisible = false;
//await Task.Delay(3000);
while (gc.GroupHeaders[groupIndex].FirstIndex == -1)
{
if (gc.HasMoreItems)
{
await gc.LoadMoreItemsAsync(loadcount);
}
else
{
break;
}
}
if (gc.GroupHeaders[groupIndex].FirstIndex != -1)
{
//make sure there are enought items to go ScrollIntoViewAlignment.Leading
//this.count > (firstIndex + loadcount)
if (scrollIntoViewAlignment == ScrollIntoViewAlignment.Leading)
{
var more = this.Items.Count - (gc.GroupHeaders[groupIndex].FirstIndex + loadcount);
if (gc.HasMoreItems && more < 0)
{
await gc.LoadMoreItemsAsync((uint)Math.Abs(more));
}
}
progressRing.IsActive = false;
progressRing.Visibility = Visibility.Collapsed;
var groupFirstIndex = gc.GroupHeaders[groupIndex].FirstIndex;
ScrollIntoView(this.Items[groupFirstIndex], scrollIntoViewAlignment);
//already in viewport, maybe it will not change view
if (groupDic.ContainsKey(gc.GroupHeaders[groupIndex]) && groupDic[gc.GroupHeaders[groupIndex]].Visibility == Visibility.Visible)
{
this.IsHitTestVisible = true;
isGotoGrouping = false;
}
}
else
{
this.IsHitTestVisible = true;
isGotoGrouping = false;
progressRing.IsActive = false;
progressRing.Visibility = Visibility.Collapsed;
}
}
}
}