C#•2y ago

❔ MAUI custom content view only loads content correctly once

Hey I have created a MAUI custom control using handlers that uses MapContent to render content in a HorizontalScrollView (on android at least). The first time I set the content property through code or xaml, everything renders fine. The second time however, nothing is shown.

2 Replies

tom_gentOP•2y ago

the content is mapped like this

public static void MapContent(CarouselScrollViewHandler handler, CarouselScrollView carouselScrollView)
        {
            _ = handler.PlatformView ?? throw new InvalidOperationException($"{nameof(PlatformView)} should have been set by base class.");
            _ = handler.VirtualView ?? throw new InvalidOperationException($"{nameof(VirtualView)} should have been set by base class.");
            _ = handler.MauiContext ?? throw new InvalidOperationException($"{nameof(MauiContext)} should have been set by base class.");

            if (handler._mauiCarouselScrollView != null)
            {
                handler._mauiCarouselScrollView.RemoveAllViews();

                if (carouselScrollView.Content != null)
                {
                    View virtualContentView = (View)carouselScrollView.PresentedContent;
                    var contentView = virtualContentView.ToPlatform(handler.MauiContext);
                    handler._mauiCarouselScrollView.AddView(contentView);

                    contentView.Measure((int)virtualContentView.WidthRequest, (int)virtualContentView.HeightRequest);

                    contentView.RequestLayout();
                    contentView.Invalidate();

                    handler._mauiCarouselScrollView.RequestLayout();
                    handler._mauiCarouselScrollView.Invalidate();
                }
            }
        }

public static void MapContent(CarouselScrollViewHandler handler, CarouselScrollView carouselScrollView)
        {
            _ = handler.PlatformView ?? throw new InvalidOperationException($"{nameof(PlatformView)} should have been set by base class.");
            _ = handler.VirtualView ?? throw new InvalidOperationException($"{nameof(VirtualView)} should have been set by base class.");
            _ = handler.MauiContext ?? throw new InvalidOperationException($"{nameof(MauiContext)} should have been set by base class.");

            if (handler._mauiCarouselScrollView != null)
            {
                handler._mauiCarouselScrollView.RemoveAllViews();

                if (carouselScrollView.Content != null)
                {
                    View virtualContentView = (View)carouselScrollView.PresentedContent;
                    var contentView = virtualContentView.ToPlatform(handler.MauiContext);
                    handler._mauiCarouselScrollView.AddView(contentView);

                    contentView.Measure((int)virtualContentView.WidthRequest, (int)virtualContentView.HeightRequest);

                    contentView.RequestLayout();
                    contentView.Invalidate();

                    handler._mauiCarouselScrollView.RequestLayout();
                    handler._mauiCarouselScrollView.Invalidate();
                }
            }
        }

Accord•2y ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

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❔ MAUI custom content view only loads content correctly once