public static async Task ApplyDrawableAsync(this IVisualElementRenderer renderer,
BindableObject bindable,
BindableProperty imageSourceProperty,
Context context,
Action <Drawable> onSet,
Action <bool> onLoading = null,
CancellationToken cancellationToken = default(CancellationToken))
{
_ = context ?? throw new ArgumentNullException(nameof(context));
_ = imageSourceProperty ?? throw new ArgumentNullException(nameof(imageSourceProperty));
_ = onSet ?? throw new ArgumentNullException(nameof(onSet));
// make sure things are good before we start
BindableObject element = null;
if (!renderer.IsDrawableSourceValid(bindable, out element))
{
return;
}
onLoading?.Invoke(true);
if (element.GetValue(imageSourceProperty) is ImageSource initialSource && !initialSource.IsEmpty)
{
try
{
string cacheKey = String.Empty;
// Todo improve for other sources
// volley the requests better up front so that if the same request comes in it isn't requeued
if (initialSource is UriImageSource uri && uri.CachingEnabled)
{
cacheKey = Device.PlatformServices.GetMD5Hash(uri.Uri.ToString());
var cacheObject = await GetCache().GetAsync(cacheKey, uri.CacheValidity, async() =>
{
var drawable = await context.GetFormsDrawableAsync(initialSource, cancellationToken);
return(drawable);
});
Drawable returnValue = null;
if (cacheObject is Bitmap bitmap)
{
returnValue = new BitmapDrawable(context.Resources, bitmap);
}
else
{
returnValue = cacheObject as Drawable;
}
if (!renderer.IsDrawableSourceValid(bindable, out element))
{
return;
}
// only set if we are still on the same image
if (element.GetValue(imageSourceProperty) == initialSource)
{
using (returnValue)
onSet(returnValue);
}
}
else
{
using (var drawable = await context.GetFormsDrawableAsync(initialSource, cancellationToken))
{
if (!renderer.IsDrawableSourceValid(bindable, out element))
{
return;
}
// only set if we are still on the same image
if (element.GetValue(imageSourceProperty) == initialSource)
{
onSet(drawable);
}
}
}
}