summaryrefslogtreecommitdiff
path: root/Xamarin.Forms.Platform.iOS
diff options
context:
space:
mode:
authorSamantha Houts <samhouts@users.noreply.github.com>2017-06-23 10:37:00 (GMT)
committerRui Marinho <me@ruimarinho.net>2017-06-23 10:37:00 (GMT)
commita9f6acb87013e9da87340a41fe4571216144cf8c (patch)
tree66dc28a370b9528777ca6f2ad213d8a948e11aee /Xamarin.Forms.Platform.iOS
parent80b72ceda3ed017f62af45c5591a11c29f3fdd3d (diff)
downloadxamarin-forms-a9f6acb87013e9da87340a41fe4571216144cf8c.zip
xamarin-forms-a9f6acb87013e9da87340a41fe4571216144cf8c.tar.gz
xamarin-forms-a9f6acb87013e9da87340a41fe4571216144cf8c.tar.bz2
[iOS] ListView with UnevenRows and Cell Heights will no longer be slow to load (#994)
* Add repro for 56896 * [iOS] Cached defined row heights for estimation * [iOS] Null check source
Diffstat (limited to 'Xamarin.Forms.Platform.iOS')
-rw-r--r--Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs59
1 files changed, 51 insertions, 8 deletions
diff --git a/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs
index 84c0daa..e52f6cc 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs
@@ -1,9 +1,11 @@
´╗┐using System;
using System.Collections;
+using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
+using System.Threading.Tasks;
using Foundation;
using UIKit;
using Xamarin.Forms.Internals;
@@ -364,14 +366,16 @@ namespace Xamarin.Forms.Platform.iOS
void UpdateEstimatedRowHeight()
{
- if (_estimatedRowHeight)
- return;
-
var rowHeight = Element.RowHeight;
if (Element.HasUnevenRows && rowHeight == -1)
{
var source = _dataSource as UnevenListViewDataSource;
- if (_shouldEstimateRowHeight)
+
+ // We want to make sure we reset the cached defined row heights whenever this is called.
+ // Failing to do this will regress Bugzilla 43313 (strange animation when adding rows with uneven heights)
+ source?.CacheDefinedRowHeights();
+
+ if (_shouldEstimateRowHeight && !_estimatedRowHeight)
{
if (source != null)
{
@@ -386,7 +390,7 @@ namespace Xamarin.Forms.Platform.iOS
}
}
}
- else
+ else if (!_estimatedRowHeight)
{
Control.EstimatedRowHeight = 0;
_estimatedRowHeight = true;
@@ -623,6 +627,9 @@ namespace Xamarin.Forms.Platform.iOS
{
IVisualElementRenderer _prototype;
bool _disposed;
+ bool _useEstimatedRowHeight;
+
+ ConcurrentDictionary<NSIndexPath, nfloat> _rowHeights = new ConcurrentDictionary<NSIndexPath, nfloat>();
public UnevenListViewDataSource(ListView list, FormsUITableViewController uiTableViewController) : base(list, uiTableViewController)
{
@@ -632,6 +639,24 @@ namespace Xamarin.Forms.Platform.iOS
{
}
+ internal void CacheDefinedRowHeights()
+ {
+ Task.Run(() =>
+ {
+ var templatedItems = TemplatedItemsView.TemplatedItems;
+
+ foreach (var cell in templatedItems)
+ {
+ if (_disposed)
+ return;
+
+ double? cellRenderHeight = cell?.RenderHeight;
+ if (cellRenderHeight > 0)
+ _rowHeights[cell.GetIndexPath()] = (nfloat)cellRenderHeight;
+ }
+ });
+ }
+
internal nfloat GetEstimatedRowHeight(UITableView table)
{
if (List.RowHeight != -1)
@@ -656,21 +681,36 @@ namespace Xamarin.Forms.Platform.iOS
if (firstCell.Height > 0 && !List.IsGroupingEnabled)
{
// Seems like we've got cells which already specify their height; since the heights are known,
- // we don't need to use estimatedRowHeight at all; zero will disable it and use the known heights
+ // we don't need to use estimatedRowHeight at all; zero will disable it and use the known heights.
+ // However, not setting the EstimatedRowHeight will drastically degrade performance with large lists.
+ // In this case, we will cache the specified cell heights asynchronously, which will be returned one time on
+ // table load by EstimatedHeight.
+
return 0;
}
return CalculateHeightForCell(table, firstCell);
}
+ public override nfloat EstimatedHeight(UITableView tableView, NSIndexPath indexPath)
+ {
+ if (_useEstimatedRowHeight)
+ return tableView.EstimatedRowHeight;
+
+ // Note: It is *not* an optimization to first check if the array has any values.
+ nfloat specifiedRowHeight;
+ if (_rowHeights.TryGetValue(indexPath, out specifiedRowHeight) && specifiedRowHeight > 0)
+ return specifiedRowHeight;
+
+ return UITableView.AutomaticDimension;
+ }
+
public override nfloat GetHeightForRow(UITableView tableView, NSIndexPath indexPath)
{
var cell = GetCellForPath(indexPath);
if (List.RowHeight == -1 && cell.Height == -1 && cell is ViewCell)
- {
return UITableView.AutomaticDimension;
- }
var renderHeight = cell.RenderHeight;
return renderHeight > 0 ? (nfloat)renderHeight : DefaultRowHeight;
@@ -709,6 +749,9 @@ namespace Xamarin.Forms.Platform.iOS
}
}
+ // Let the EstimatedHeight method know to use this value.
+ // Much more efficient than checking the value each time.
+ _useEstimatedRowHeight = true;
return (nfloat)req.Request.Height;
}