Ooui-tws-port/Ooui.Forms/Renderers/ListViewRenderer.cs

326 lines
11 KiB
C#
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using Ooui.Forms.Extensions;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Timers;
using Xamarin.Forms;
using Xamarin.Forms.Internals;
using Ooui.Forms.Cells;
namespace Ooui.Forms.Renderers
{
public class ListViewRenderer : ViewRenderer<ListView, List>
{
const int DefaultRowHeight = 44;
private bool _disposed;
IVisualElementRenderer _prototype;
Timer _timer;
int _rowHeight;
public int RowHeight
{
get => _rowHeight;
set => _rowHeight = value;
}
public ListViewRenderer ()
{
}
ITemplatedItemsView<Cell> TemplatedItemsView => Element;
protected override void OnElementChanged (ElementChangedEventArgs<ListView> e)
{
if (e.OldElement != null) {
var templatedItems = TemplatedItemsView.TemplatedItems;
templatedItems.CollectionChanged -= OnCollectionChanged;
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e.OldElement.ScrollToRequested -= ListView_ScrollToRequested;
}
if (e.NewElement != null) {
if (Control == null) {
var list = new List ();
list.Style.Overflow = "scroll";
list.Style.Padding = "0";
// Make the list element positioned so child elements will
// be positioned relative to it. This will allow the list
// to scroll properly.
list.Style.Position = "relative";
SetNativeControl (list);
}
var templatedItems = TemplatedItemsView.TemplatedItems;
templatedItems.CollectionChanged += OnCollectionChanged;
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e.NewElement.ScrollToRequested += ListView_ScrollToRequested;
UpdateRowHeight();
UpdateItems ();
UpdateSeparator ();
UpdateBackgroundColor ();
}
base.OnElementChanged (e);
}
protected override void OnElementPropertyChanged (object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged (sender, e);
if (e.PropertyName == ItemsView<Cell>.ItemsSourceProperty.PropertyName)
UpdateItems();
else if (e.PropertyName == Xamarin.Forms.ListView.RowHeightProperty.PropertyName)
{
UpdateRowHeight();
UpdateItems();
}
else if (e.PropertyName == VisualElement.WidthProperty.PropertyName)
{
if (_timer != null)
{
_timer.Stop();
}
else
{
_timer = new Timer();
_timer.Interval = 250;
_timer.Elapsed += delegate {
UpdateItems();
};
_timer.Enabled = true;
_timer.AutoReset = false;
}
_timer.Start();
}
else if (e.PropertyName == Xamarin.Forms.ListView.SeparatorColorProperty.PropertyName)
UpdateSeparator ();
else if (e.PropertyName == Xamarin.Forms.ListView.SeparatorVisibilityProperty.PropertyName)
UpdateSeparator ();
}
protected override void Dispose (bool disposing)
{
UnsubscribeCellClicks ();
base.Dispose (disposing);
if (disposing && !_disposed) {
ClearPrototype();
if (Element != null) {
var templatedItems = TemplatedItemsView.TemplatedItems;
templatedItems.CollectionChanged -= OnCollectionChanged;
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Element.ScrollToRequested -= ListView_ScrollToRequested;
}
_disposed = true;
}
}
void ClearPrototype()
{
if (_prototype != null)
{
var element = _prototype.Element;
element?.ClearValue(Platform.RendererProperty);
_prototype?.Dispose();
_prototype = null;
}
}
private void OnCollectionChanged (object sender, NotifyCollectionChangedEventArgs e)
{
UpdateItems ();
UpdateSeparator ();
}
private void UnsubscribeCellClicks ()
{
if (Control == null)
return;
foreach (var c in Control.Children) {
if (c is Element e)
e.Click -= ListItem_Click;
}
}
private void UpdateItems ()
{
if (Control == null)
return;
var listItems = Control.Children.OfType<ListItem> ().ToList ();
var items = TemplatedItemsView.TemplatedItems;
if (listItems.Count > items.Count) {
for (var i = items.Count; i < listItems.Count; i++) {
listItems[i].Click -= ListItem_Click;
Control.RemoveChild (listItems[i]);
}
listItems.RemoveRange (items.Count, listItems.Count - items.Count);
}
if (listItems.Count < items.Count) {
for (var i = listItems.Count; i < items.Count; i++) {
var li = new ListItem ();
li.Style["list-style-type"] = "none";
li.Click += ListItem_Click;
Control.AppendChild (li);
listItems.Add (li);
}
}
bool grouping = Element.IsGroupingEnabled;
if (grouping) {
// Not Implemented
}
else {
var i = 0;
double offset = 0;
foreach (var item in items) {
var li = listItems[i];
var nativeCell = items[i];
var children = li.Children;
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var rv = children.Count > 0 ? children[0] as CellElement : null;
var cell = GetCell (item, rv);
var height = CalculateHeightForCell(nativeCell);
li.Style.Height = height;
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var viewCell = cell.Cell as ViewCell;
if (viewCell != null && viewCell.View != null)
{
var rect = new Rectangle(0, offset, Element.Width, height);
Layout.LayoutChildIntoBoundingRegion(viewCell.View, rect);
}
offset += height;
if (rv == null) {
li.AppendChild (cell);
}
i++;
}
}
}
private void UpdateSeparator()
{
if (Control == null)
return;
var listItems = Control.Children.OfType<ListItem>().ToList();
foreach (var li in listItems)
{
if (Element.SeparatorVisibility == SeparatorVisibility.Default)
{
var color = Element.SeparatorColor.ToOouiColor(Color.FromStyleValue("#999"));
li.Style["border-bottom"] = string.Format("{0}px {1} {2}", 1, "solid", color.ToString());
}
else
{
li.Style["border-bottom"] = null;
}
}
}
void ListItem_Click (object sender, TargetEventArgs e)
{
if (Control == null)
return;
var it = (ListItem)sender;
var ndx = Control.Children.IndexOf (it);
Element.NotifyRowTapped (ndx, null);
}
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void ListView_ScrollToRequested (object sender, ScrollToRequestedEventArgs e)
{
if (Control == null)
return;
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var oe = (ITemplatedItemsListScrollToRequestedEventArgs)e;
var item = oe.Item;
var group = oe.Group;
switch (e.Position) {
case ScrollToPosition.Start:
Control.Send (Ooui.Message.Set (Control.Id, "scrollTop", 0));
break;
case ScrollToPosition.End:
Control.Send (Ooui.Message.Set (Control.Id, "scrollTop", new Ooui.Message.PropertyReference { TargetId = Control.Id, Key = "scrollHeight" }));
break;
}
}
void UpdateRowHeight()
{
var rowHeight = Element.RowHeight;
if (Element.HasUnevenRows && rowHeight == -1)
RowHeight = -1;
else
RowHeight = rowHeight <= 0 ? DefaultRowHeight : rowHeight;
}
internal double CalculateHeightForCell(Cell cell)
{
if (!Element.HasUnevenRows)
{
return RowHeight;
}
else
{
var viewCell = cell as ViewCell;
if (viewCell != null && viewCell.View != null)
{
var target = viewCell.View;
if (_prototype == null)
_prototype = Platform.CreateRenderer(target);
else
_prototype.SetElement(target);
Platform.SetRenderer(target, _prototype);
var req = target.Measure(Element.Width, double.PositiveInfinity, MeasureFlags.IncludeMargins);
target.ClearValue(Platform.RendererProperty);
foreach (Xamarin.Forms.Element descendant in target.Descendants())
{
IVisualElementRenderer renderer = Platform.GetRenderer(descendant as VisualElement);
// Clear renderer from descendent; this will not happen in Dispose as normal because we need to
// unhook the Element from the renderer before disposing it.
descendant.ClearValue(Platform.RendererProperty);
renderer?.Dispose();
renderer = null;
}
var height = req.Request.Height;
return height > 1 ? height : DefaultRowHeight;
}
var renderHeight = cell.RenderHeight;
return renderHeight > 0 ? renderHeight : DefaultRowHeight;
}
}
void UpdateBackgroundColor ()
{
if (Control == null)
return;
var backgroundColor = Element.BackgroundColor.ToOouiColor (Xamarin.Forms.Color.White);
Control.Style.BackgroundColor = backgroundColor;
}
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CellElement GetCell (Cell cell, CellElement reusableView)
{
var renderer = (Cells.CellRenderer)Registrar.Registered.GetHandlerForObject<IRegisterable> (cell);
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var realCell = renderer.GetCellElement (cell, reusableView, Control);
return realCell;
}
}
}