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using CoreGraphics;
using UIKit;
using Xamarin.Forms.Internals;
namespace Xamarin.Forms.Platform.iOS
{
public class NativeViewWrapperRenderer : ViewRenderer<NativeViewWrapper, UIView>
{
public override SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint)
{
if (Element?.GetDesiredSizeDelegate == null)
return base.GetDesiredSize(widthConstraint, heightConstraint);
// The user has specified a different implementation of GetDesiredSize
var result = Element.GetDesiredSizeDelegate(this, widthConstraint, heightConstraint);
// If the GetDesiredSize delegate returns a SizeRequest, we use it; if it returns null,
// fall back to the default implementation
return result ?? base.GetDesiredSize(widthConstraint, heightConstraint);
}
public override void LayoutSubviews()
{
if (Element?.LayoutSubViews == null)
{
((IVisualElementController)Element)?.InvalidateMeasure(InvalidationTrigger.MeasureChanged);
base.LayoutSubviews();
return;
}
// The user has specified a different implementation of LayoutSubviews
var handled = Element.LayoutSubViews();
if (!handled)
{
// If the delegate wasn't able to handle the request, fall back to the default implementation
base.LayoutSubviews();
}
}
public override CGSize SizeThatFits(CGSize size)
{
if (Element?.SizeThatFitsDelegate == null)
return base.SizeThatFits(size);
// The user has specified a different implementation of SizeThatFits
var result = Element.SizeThatFitsDelegate(size);
// If the delegate returns a value, we use it;
// if it returns null, fall back to the default implementation
return result ?? base.SizeThatFits(size);
}
protected override void OnElementChanged(ElementChangedEventArgs<NativeViewWrapper> e)
{
base.OnElementChanged(e);
if (e.OldElement == null)
SetNativeControl(Element.NativeView);
}
/// <summary>
/// The native control we're wrapping isn't ours to dispose of
/// </summary>
protected override bool ManageNativeControlLifetime => false;
}
}
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