public static (UIView NativeView, VisualElement FormsElement) RealizeView(object view, DataTemplate viewTemplate, ItemsView itemsView)
{
if (viewTemplate != null)
{
// Run this through the extension method in case it's really a DataTemplateSelector
viewTemplate = viewTemplate.SelectDataTemplate(view, itemsView);
// We have a template; turn it into a Forms view
var templateElement = viewTemplate.CreateContent() as View;
// Make sure the Visual property is available when the renderer is created
PropertyPropagationExtensions.PropagatePropertyChanged(null, templateElement, itemsView);
var renderer = GetHandler(templateElement, itemsView.FindMauiContext());
var element = renderer.VirtualView as VisualElement;
// and set the view as its BindingContext
element.BindingContext = view;
return((UIView)renderer.NativeView, element);
}
if (view is View formsView)
{
// Make sure the Visual property is available when the renderer is created
PropertyPropagationExtensions.PropagatePropertyChanged(null, formsView, itemsView);
// No template, and the EmptyView is a Forms view; use that
var renderer = GetHandler(formsView, itemsView.FindMauiContext());
var element = renderer.VirtualView as VisualElement;
return((UIView)renderer.NativeView, element);
}
return(new UILabel {
TextAlignment = UITextAlignment.Center, Text = $"{view}"
}, null);
}
public void Bind(DataTemplate template, object bindingContext, ItemsView itemsView)
{
var oldElement = PlatformHandler?.VirtualView as View;
// Run this through the extension method in case it's really a DataTemplateSelector
var itemTemplate = template.SelectDataTemplate(bindingContext, itemsView);
if (itemTemplate != CurrentTemplate)
{
// Remove the old view, if it exists
if (oldElement != null)
{
oldElement.MeasureInvalidated -= MeasureInvalidated;
oldElement.BindingContext = null;
itemsView.RemoveLogicalChild(oldElement);
ClearSubviews();
_size = Size.Zero;
}
// Create the content and renderer for the view
var view = itemTemplate.CreateContent() as View;
// Set the binding context _before_ we create the renderer; that way, it's available during OnElementChanged
view.BindingContext = bindingContext;
var renderer = TemplateHelpers.GetHandler(view, itemsView.FindMauiContext());
SetRenderer(renderer);
// And make the new Element a "child" of the ItemsView
// We deliberately do this _after_ setting the binding context for the new element;
// if we do it before, the element briefly inherits the ItemsView's bindingcontext and we
// emit a bunch of needless binding errors
itemsView.AddLogicalChild(view);
// Prevents the use of default color when there are VisualStateManager with Selected state setting the background color
// First we check whether the cell has the default selected background color; if it does, then we should check
// to see if the cell content is the VSM to set a selected color
if (SelectedBackgroundView.BackgroundColor == Maui.Platform.ColorExtensions.Gray && IsUsingVSMForSelectionColor(view))
{
SelectedBackgroundView = new UIView
{
BackgroundColor = UIColor.Clear
};
}
}
else
{
// Same template
if (oldElement != null)
{
if (oldElement.BindingContext == null || !(oldElement.BindingContext.Equals(bindingContext)))
{
// If the data is different, update it
// Unhook the MeasureInvalidated handler, otherwise it'll fire for every invalidation during the
// BindingContext change
oldElement.MeasureInvalidated -= MeasureInvalidated;
oldElement.BindingContext = bindingContext;
oldElement.MeasureInvalidated += MeasureInvalidated;
UpdateCellSize();
}
}
}
CurrentTemplate = itemTemplate;
}
static INativeViewHandler CreateHandler(View view, ItemsView itemsView) => TemplateHelpers.GetHandler(view, itemsView.FindMauiContext());
