Fix crash creating native image of size 0,0

[taublast]

Fixes bug appeared on iOS 17 crash creating native image of zero size when linear gradient is set for button at app startup

Description of Change

• iOS

Behavioral/Visual Changes

No crash

Before/After Screenshots

on iOS 17 crash creating native image of zero size when linear gradient is set for button at app startup

[SnowPowerCore]

+1 having this recent issue, would be really neat if this PR was merged

[taublast]

meanwhile you can use a use a custom renderer that would call the fixed extension. here is one for a Button for example:

using CoreGraphics;
using CRMMobileApp.iOS;
using Foundation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(Button), typeof(EnhancedButtonRenderer))]
namespace XXX.iOS
{
    public class EnhancedButtonRenderer : ButtonRenderer
    {
        //FIXED EXTENSION METHOD
        UIImage GetMyBackgroundImage(UIView control, Brush brush)
        {
            if (control == null || brush == null || brush.IsEmpty || control.Bounds == CGRect.Empty)
                return null;

            var backgroundLayer = control.GetBackgroundLayer(brush);

            if (backgroundLayer == null)
                return null;

            UIGraphics.BeginImageContextWithOptions(backgroundLayer.Bounds.Size, false, UIScreen.MainScreen.Scale);

            if (UIGraphics.GetCurrentContext() == null)
                return null;

            backgroundLayer.RenderInContext(UIGraphics.GetCurrentContext());
            UIImage gradientImage = UIGraphics.GetImageFromCurrentImageContext();
            UIGraphics.EndImageContext();

            return gradientImage;
        }

        protected override void SetBackground(Brush brush)
        {
            if (Control == null)
                return;

            try
            {
                UIColor backgroundColor = Element.BackgroundColor == Color.Default ? null : Element.BackgroundColor.ToUIColor();

                if (!Brush.IsNullOrEmpty(brush))
                {
                    if (brush is SolidColorBrush solidColorBrush)
                        backgroundColor = solidColorBrush.Color.ToUIColor();
                    else
                    {
                        //CALLING FIXED EXTENSION METHOD
                        var backgroundImage = GetMyBackgroundImage(this, brush);
                        backgroundColor = backgroundImage != null ? UIColor.FromPatternImage(backgroundImage) : UIColor.Clear;
                    }
                }

                Control.BackgroundColor = backgroundColor;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }
        }

    }
}

[jfversluis]

/azp run

[jfversluis]

Thanks so much for taking this up @taublast!

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[damiannestle]

Unfortunately this isn't the only control impacted by this issue - I'm getting the same error rendering a BoxView

[campersau]

@damiannestle you can simply copy the workaround for BoxView as well using the BoxRenderer instead.

[damiannestle]

@damiannestle you can simply copy the workaround for BoxView as well using the BoxRenderer instead.

Yes I've done that, although it is not quite so simple - the SetBackground method in BoxRenderer (which calls GetBackgroundImage which is the cause of the issue) accesses private members (_colorToRenderer) so I had to create a renderer that derived from VisualElementRenderer<BoxView> and copy the code from BoxRenderer, modified to call a local GetBackgroundImage per the above code.

If there is a simpler way I'd be happy to update my code.

It should really be fixed by Microsoft in Xamarin.Forms.Platform.iOS.BrushExtensions.GetBackgroundImage

[jfversluis]

@damiannestle do you have some code or reproduction that shows this bug? Could you maybe open a new issue for it so we can track that better separately?

[jfversluis]

Would anyone experiencing this be able to try the NuGets that result from this PR (see instructions here) and let me know if that fixes it for you?

[albilaga]

Would anyone experiencing this be able to try the NuGets that result from this PR (see instructions here) and let me know if that fixes it for you?

tried this and it working for my project. Is there will be another release for this @jfversluis ?