[Bug] Aspect settings not working on MacOS (4.3-pre)

[DennisWelu]

Description

Only 1 of the 3 aspect settings works on XF Mac.

Steps to Reproduce

1. Create a Xamarin Forms project from template
2. Add the Mac project to it as per document: https://docs.microsoft.com/en-us/xamarin/xamarin-forms/platform/other/mac
3. Add image controls to the main page with each aspect setting being used.
4. Run the app.

Expected Behavior

The expected behavior is demonstrated on iOS:

Actual Behavior

The actual behavior in a MacOS window:

Basic Information

• Version with issue: 4.3-pre3
• Last known good version: ?, but this appears to be a recent major refactor that would be my guess at when it broke: ce148bf#diff-59032a35e10fb51bc88a456719271ac1R1-R12. I think it may have lost some things (see my comment at the end of that link).
• IDE: VS on Mac

Reproduction Link

ImageAspect.zip

[jfversluis]

Hi @DennisWelu thanks for reporting this. I am kind of confused though.

The title states Mac OS, but you are showing iOS screenshots?

That was to show the expected output, gotcha! :)

[DennisWelu]

👍 @jfversluis Yup! I should have captioned them, but the first image (expected) is actually the iOS simulator running the same code. The 2nd image (actual) is a MacOS window just shaped roughly the same aspect so it's a closer apple to apples comparison.

[jfversluis]

I'm wondering if this ever worked, even before the refactor you're mentioning.

In any case, I got the 80% solution here: 723d10d

But as it turns out there is no built-in AspectFill for an NSImage... So just need to add that and this should be good again.

[DennisWelu]

Super work. I believe it did work previously - I have a Mac app that uses AspectFill and the behavior changed after updating. From what I've seen in a couple places the layer has to be captured for the NSImage at the right time then the gravity of the layer can be made to fulfill the AspectFill behavior: https://stackoverflow.com/questions/23002653/nsimageview-image-aspect-fill/38752428#38752428

[jfversluis]

Thanks @DennisWelu, I've seen that. The weird thing about that code is: the Layer.Content wants a CGImage not an NSImage

[DennisWelu]

I'm just lofting out observations from casual review of the changes, but I do see it grabbing the CGImage from the NSImage here ce148bf#diff-d1473c83345d2991d27d0b7cb03cf161L112 to set the layer Contents. With the updated structure of the renderer I'm not sure how to best make it adjust between the different aspect values. Would have to study that further.

[jfversluis]

Wow it must've been Friday afternoon... It simply has a CGImage property 😅.

Implemented it like this and now they all work again. Thanks for the second pair of eyes! I'll open the PR right after this.

[DennisWelu]

Awesome! Thanks @jfversluis!

[DennisWelu]

I am sad that 2 of 3 aspect settings for Image will continue to not work until vNext+1.
:-(

[jfversluis]

+1 @DennisWelu sorry about that :( You're more than welcome to take my PR and try to fix that last piece

[DennisWelu]

@jfversluis LOL, appreciate the sympathy! I did make one comment on the PR as I started to look through the changes a bit. Haven't gotten to the point of ACTUALLY trying to make it work. If I can peel off a couple hours from other projects I might, but can't promise!

[Suplanus]

I have a crazy workaround for scale to full size of the parent control (like window).
Call this on Resizing the parent or setting the image to new size.
You also have to set it to a min value. This could not be null because of #8981

private void ScaleImageToWindowSize(bool visible)
{
    // Have to scale down and then up that macOs is recognize the change 🤦‍♂️
    if (Device.Idiom == TargetIdiom.Desktop)
    {
        this.Dispatcher.BeginInvokeOnMainThread(() =>
        {
            if (visible)
            {
                // Calc needed fullscreen size                    
                double windowMax = Math.Max(this.Width, this.Height);
                double imageMax = Math.Max(ImageBlurred.Width, ImageBlurred.Height);
                double scale = windowMax / imageMax;
                if (scale < 1 || double.IsInfinity(scale))
                {
                    ImageBlurred.Scale = 1;
                }
                else
                {
                    ImageBlurred.Scale = scale + 0.2; // Little offset because there is a black border
                }
            }
            else
            {
                // Have to set this to get original size
                ImageBlurred.HorizontalOptions = LayoutOptions.Center;
                ImageBlurred.VerticalOptions = LayoutOptions.Center;
                ImageBlurred.Scale = 0.0001;
            }
        });
    }
}