是的，我找到了解决方案。代码要遵循。但在此之前，让我解释一下我所做的一切。

Yes, I found a solution. Code to follow. But before that, let me explain a bit what I have done.

因此，我们需要自己动手处理图像及其底层资源（位图或可绘制，但你想调用它）。基本上，它归结为处置原生的'ImageRenderer'对象。

So, there's definitely a need to take maters in our own hands to dispose the image and its underlying resources (bitmap or drawable, however you want to call it). Basically, it comes down to dispose the native 'ImageRenderer' object.

现在，无法从任何地方获取对该ImageRenderer的引用，因为为了这样做，需要能够调用Platform.GetRenderer（... ）。无法访问平台类，因为它的范围被声明为内部。

Now, there's no way to obtain a reference to that ImageRenderer from anywhere because in order to do so, one need to be able to call Platform.GetRenderer(...). Access to the 'Platform' class is inaccessible since its scope is declared as 'internal'.

所以，除了分类以外，我别无选择Image类及其（Android）Renderer并从内部销毁此Renderer本身（将'true'作为参数传递。不要尝试使用'false'）。在渲染器内部，我挂钩到页面消失（如果是TabbedPage）。在大多数情况下，Page Disappear事件不能很好地发挥作用，例如当页面仍在屏幕堆栈中但由于另一页面正在顶部上绘制而消失。如果丢弃图像，则当页面再次被揭开（显示）时，它将不会显示图像。在这种情况下，我们必须挂钩主导航页面的'Popped'事件。

So, I have been left with no choice other than to sub-class the Image class and its (Android) Renderer and destroy this Renderer itself from inside (passing 'true' as argument. Don't try with 'false'). Inside the Renderer I hook on to page disappear (In case of a TabbedPage). In most situations the Page Disappear event will not serve the purpose well, such as when the page is still in the screen stack but disappears due to a another page is being drawn on Top of it. If you dispose the Image(s) than, when the page gets uncovered (shown) again, it will not display the images. In such case we have to hook on the the main Navigation Page's 'Popped' event.

我试图尽我所能解释。其余的 - 我希望 - 你将能够从代码中获得：

I have tried to explain to the best I could. The rest - I hope - you will be able to get from the code:

这是PCL项目中的图像子类。

This is the Image Sub-Class in the PCL Project.

using System;

using Xamarin.Forms;

namespace ApplicationClient.CustomControls
{
    public class LSImage : Image
    {
    }
}

以下代码位于Droid项目中。

The following code is in the Droid project.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Views.InputMethods;
using Android.Widget;
using Android.Util;
using Application.Droid.CustomControls;
using ApplicationClient.CustomControls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

    [assembly: ExportRenderer(typeof(ApplicationClient.CustomControls.LSImage), typeof(LSImageRenderer))]

    namespace Application.Droid.CustomControls
    {
        public class LSImageRenderer : ImageRenderer
        {
            Page page;
            NavigationPage navigPage;

            protected override void OnElementChanged(ElementChangedEventArgs<Image> e)
            {
                base.OnElementChanged(e);
                if (e.OldElement == null)
                {
                    if (GetContainingViewCell(e.NewElement) != null)
                    {
                        page = GetContainingPage(e.NewElement);
                        if (page.Parent is TabbedPage)
                        {
                            page.Disappearing += PageContainedInTabbedPageDisapearing;
                            return;
                        }

                        navigPage = GetContainingNavigationPage(page);
                        if (navigPage != null)
                            navigPage.Popped += OnPagePopped;
                    }
                    else if ((page = GetContainingTabbedPage(e.NewElement)) != null)
                    {
                        page.Disappearing += PageContainedInTabbedPageDisapearing;
                    }
                }
            }

            void PageContainedInTabbedPageDisapearing (object sender, EventArgs e)
            {
                this.Dispose(true);
                page.Disappearing -= PageContainedInTabbedPageDisapearing;
            }

            protected override void Dispose(bool disposing)
            {
                Log.Info("**** LSImageRenderer *****", "Image got disposed");
                base.Dispose(disposing);
            }

            private void OnPagePopped(object s, NavigationEventArgs e)
            {
                if (e.Page == page)
                {
                    this.Dispose(true);
                    navigPage.Popped -= OnPagePopped;
                }
            }

            private Page GetContainingPage(Xamarin.Forms.Element element)
            {
                Element parentElement = element.ParentView;

                if (typeof(Page).IsAssignableFrom(parentElement.GetType()))
                    return (Page)parentElement;
                else
                    return GetContainingPage(parentElement);
            }

            private ViewCell GetContainingViewCell(Xamarin.Forms.Element element)
            {
                Element parentElement = element.Parent;

                if (parentElement == null)
                    return null;

                if (typeof(ViewCell).IsAssignableFrom(parentElement.GetType()))
                    return (ViewCell)parentElement;
                else
                    return GetContainingViewCell(parentElement);
            }

            private TabbedPage GetContainingTabbedPage(Element element)
            {
                Element parentElement = element.Parent;

                if (parentElement == null)
                    return null;

                if (typeof(TabbedPage).IsAssignableFrom(parentElement.GetType()))
                    return (TabbedPage)parentElement;
                else
                    return GetContainingTabbedPage(parentElement);
            }

            private NavigationPage GetContainingNavigationPage(Element element)
            {
                Element parentElement = element.Parent;

                if (parentElement == null)
                    return null;

                if (typeof(NavigationPage).IsAssignableFrom(parentElement.GetType()))
                    return (NavigationPage)parentElement;
                else
                    return GetContainingNavigationPage(parentElement);
            }
        }
    }

最后，我更改了PCL项目中ApplicationClient命名空间中的应用程序名称和Droid项目中的Application.Droid。您应该将其更改为您的应用名称。

Finally, I have changed the Name of the Application in the namespace to 'ApplicationClient' in the PCL project and to 'Application.Droid' in Droid project. You should change it to your app name.

此外，在Renderer类末尾的几个递归方法，我知道我可以将它组合成一个Generic方法。问题是，当需要出现时，我一次建立一个。所以，这就是我离开它的方式。

Also, the few recursive methods at the end of the Renderer class, I know that I could combine it into one Generic method. The thing is, that I have build one at a time as the need arose. So, this is how I left it.

快乐编码，

Avrohom