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using System;
using System.ComponentModel;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Media.Imaging;
using Xamarin.Forms.Internals;
#if WINDOWS_UWP
namespace Xamarin.Forms.Platform.UWP
#else
namespace Xamarin.Forms.Platform.WinRT
#endif
{
public class ImageRenderer : ViewRenderer<Image, Windows.UI.Xaml.Controls.Image>
{
bool _measured;
public override SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint)
{
if (Control.Source == null)
return new SizeRequest();
_measured = true;
var result = new Size { Width = ((BitmapImage)Control.Source).PixelWidth, Height = ((BitmapImage)Control.Source).PixelHeight };
return new SizeRequest(result);
}
protected override void Dispose(bool disposing)
{
if (Control != null)
{
Control.ImageOpened -= OnImageOpened;
}
base.Dispose(disposing);
}
protected override void OnElementChanged(ElementChangedEventArgs<Image> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
if (Control == null)
{
var image = new Windows.UI.Xaml.Controls.Image();
image.ImageOpened += OnImageOpened;
SetNativeControl(image);
}
UpdateSource();
UpdateAspect();
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == Image.SourceProperty.PropertyName)
UpdateSource();
else if (e.PropertyName == Image.AspectProperty.PropertyName)
UpdateAspect();
}
static Stretch GetStretch(Aspect aspect)
{
switch (aspect)
{
case Aspect.Fill:
return Stretch.Fill;
case Aspect.AspectFill:
return Stretch.UniformToFill;
default:
case Aspect.AspectFit:
return Stretch.Uniform;
}
}
void OnImageOpened(object sender, RoutedEventArgs routedEventArgs)
{
if (_measured)
{
RefreshImage();
}
}
void RefreshImage()
{
((IVisualElementController)Element)?.InvalidateMeasure(InvalidationTrigger.RendererReady);
}
void UpdateAspect()
{
Control.Stretch = GetStretch(Element.Aspect);
}
async void UpdateSource()
{
((IImageController)Element).SetIsLoading(true);
ImageSource source = Element.Source;
IImageSourceHandler handler;
if (source != null && (handler = Registrar.Registered.GetHandler<IImageSourceHandler>(source.GetType())) != null)
{
Windows.UI.Xaml.Media.ImageSource imagesource;
try
{
imagesource = await handler.LoadImageAsync(source);
}
catch (OperationCanceledException)
{
imagesource = null;
}
// In the time it takes to await the imagesource, some zippy little app
// might have disposed of this Image already.
if (Control != null)
Control.Source = imagesource;
RefreshImage();
}
else
Control.Source = null;
((IImageController)Element)?.SetIsLoading(false);
}
}
}
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