public bool RemoveVisualElement(SurfacePair pair)
{
// we don't allow the root element to be removed.
if (pair.UIWidget.Parent == null)
{
return(false);
}
var parentId = pair.UIWidget.Parent.Id;
var parentPair = this[parentId];
if (parentPair == null)
{
return(false);
}
// this is the only child of the content page
if (parentId == Root.Id)
{
var page = parentPair.VisualElement as ContentPage;
if (page != null)
{
page.Content = null;
return(true);
}
}
// this maybe a layout control
var viewContainer = parentPair.VisualElement as IViewContainer <View>;
var childView = pair.VisualElement as View;
var parentView = parentPair.VisualElement;
// we can only remove view types; this shouldn't happen.
if (childView == null)
{
return(false);
}
// is this a content property?
if (viewContainer == null && ElementHelper.HasContentProperty(parentView))
{
ElementHelper.ClearContentProperty(parentView);
return(true);
}
// is it a layout control? i.e. stacklayout, grid..
if (viewContainer == null)
{
return(false);
}
// made it this far, it's a layout control.
viewContainer.Children.Remove(childView);
return(true);
}
protected override UIWidget BuildTree(Element childView, UIWidget parentWidget)
{
/*
* 1. Return parent widget if child view is null.
* Since, We won't be able to create a UIWidget out of the view.
*/
if (childView == null)
{
return(parentWidget);
}
/*
* 2. Create a UIWidget for the child view.
*/
var childWidget = CreateUIWidget(childView, parentWidget);
parentWidget.Children.Add(childWidget);
if (ElementHelper.HasContentProperty(childView))
{
childWidget.AllowsManyChildren = ElementHelper.ContentPropertyAllowsManyChildren(childView);
childWidget.IsContentPropertyViewType = ElementHelper.IsContentPropertyView(childView);
childWidget.ContentPropertyTypeName = ElementHelper.GetContentPropertyTypeName(childView);
childWidget.HasContentProperty = true;
childWidget.IsLayout = false;
}
else
{
childWidget.HasContentProperty = false;
}
/*
* 3. Determine if the child view has children of it's own.
*/
var isParentView = childView as ILayoutController;
if (isParentView != null)
{
childWidget.IsLayout = true;
}
// ListView check
IReadOnlyList <Element> grandChildren;
var isListView = childView as ITemplatedItemsView <Cell>;
if (isListView == null)
{
grandChildren = isParentView?.Children;
}
else
{
grandChildren = isListView.TemplatedItems;
}
// TableView check
if (grandChildren == null && childView is TableView)
{
var tableView = childView as TableView;
var cells = new List <Element>();
foreach (var section in tableView.Root)
{
foreach (var cell in section)
{
cells.Add(cell);
}
}
grandChildren = cells.ToArray();
}
// no children
if (grandChildren == null || grandChildren.Count == 0)
{
return(parentWidget);
}
/*
* 4. The child does have it's own children.
*/
foreach (var grandChild in grandChildren)
{
if (grandChild != null)
{
if (grandChild is ILayoutController)
{
BuildTree(grandChild, childWidget);
}
else if (grandChild is ListView)
{
BuildTree(grandChild, childWidget);
}
else if (grandChild is TableView)
{
var grandTable = grandChild as TableView;
var tableWidget = CreateUIWidget(grandChild, childWidget);
childWidget.Children.Add(tableWidget);
foreach (var section in grandTable.Root)
{
foreach (var cell in section)
{
BuildTree(cell, tableWidget);
}
}
}
else if (grandChild is ViewCell)
{
var grandViewCell = grandChild as ViewCell;
var grandViewCellWidget = CreateUIWidget(grandChild, childWidget);
childWidget.Children.Add(grandViewCellWidget);
if (grandViewCell.View != null)
{
BuildTree(grandViewCell.View, grandViewCellWidget);
}
}
else
{
var grandChildWidget = CreateUIWidget(grandChild, childWidget);
if (ElementHelper.HasContentProperty(grandChild))
{
grandChildWidget.IsLayout = true;
}
childWidget.Children.Add(grandChildWidget);
}
}
}
return(parentWidget);
}
