Add a DownsampleMode properties for Forms / Native

[YZahringer]

Hello,

How to use InterpolationMode.None / NearestNeighbor in Xamarin Forms to have pixelized resized image? I use FFImage.DownsampleMode="None" with UWP, but I can not find any way in Xamarin XAML Forms.

I use this to enlarge a small QrCode image, that's why I need to disable "anti-aliasing". In CSS i use:

@mixin pixelated {
-ms-interpolation-mode: nearest-neighbor; // IE 7+ (non-standard property)
image-rendering: -webkit-optimize-contrast; // Safari 6, UC Browser 9.9
image-rendering: -webkit-crisp-edges; // Safari 7+
image-rendering: -moz-crisp-edges; // Firefox 3.6+
image-rendering: -o-crisp-edges; // Opera 12
image-rendering: pixelated; // Chrome 41+ and Opera 26+
}

Is there any way to do this with FFImageLoading?

[daniel-luberda]

Here's the current implementation, I hope it would help:

https://github.com/luberda-molinet/FFImageLoading/blob/master/source/FFImageLoading.Windows/Extensions/ImageExtensions.cs#L182-L191

Currently in Forms, it's a global configuration setting (you provide it with a custom configuration). I forgot to add a property for CachedImage instance, so I'll mark it as a feature to add.

[JTOne123]

What was changed in the latest release(2.2.13) with DownsampleToViewSize in forms for UWP?

Issue is: into big CachedImage loads too small sized images

but if set a height and width everything is ok

Is it something was broken or fixed?

[daniel-luberda]

@JTOne123 Read this: https://github.com/luberda-molinet/FFImageLoading/wiki/Xamarin.Forms-API#downsampletoviewsize-bool-default-false

I was a bit tired of explaining the same thing multiple times (people were experiencing poor performance), so I put a fixed value (which is very low) when view doesn't have a size defined (is expandable). If you experience this, it means than DownsampleToViewSize didn't work at all for that view and you should use DownsampleWidth / DownsampleHeight as described in wiki. I just released 2.2.14 which will additionally warn about this in logs. :)

[JTOne123]

yep, definitely it is my case, thank for an answer

[daniel-luberda]

2.2.14 just released. It will also log an error with explanation. 46e021b

[YZahringer]

The DownsampleMode property has been added to the CachedImage instance?

[daniel-luberda]

Sorry, wrong issue.

[daniel-luberda]

#859