Xamarin表单：不显示创建的图像

Question

我已经从https://github.com/MitchMilam/Drawit为Android和UWP（未在iOS中测试）创建了一个工作示例。

我在stackoverflow上一遍又一遍地看着，但无论给出什么建议，我都找不到答案。

我正在创建画布，我想在下一个屏幕中显示图像。 我的主屏幕代码是：

using System;
using System.Collections.Generic;
using System.Linq;
using Xamarin.Forms;

namespace XamarinGame
{
    class MainPage : ContentPage
    {
        private const int PalleteSpacing = 3;
        public ImageWithTouch DrawingImage;
        private Dictionary<string, Color> ColorPallete;

        public MainPage()
        {
            NavigationPage.SetHasNavigationBar(this, false);
            Content = BuildGrid();

            // Accomodate iPhone status bar.
            Padding = new Thickness(10, Device.OnPlatform(20, 0, 0), 10, 10);
        }

        private Grid BuildGrid()
        {
            return new Grid
            {
                VerticalOptions = LayoutOptions.FillAndExpand,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                RowDefinitions = {
                    new RowDefinition {
                        Height = GridLength.Auto
                    },
                    new RowDefinition {
                        Height = new GridLength (1, GridUnitType.Star)
                    },
                },
                ColumnDefinitions = {
                    new ColumnDefinition {
                        Width = new GridLength (100, GridUnitType.Absolute)
                    },
                    new ColumnDefinition {
                        Width = new GridLength (1, GridUnitType.Star)
                    },
                },
                Children =
                {
                    {new Label {
                        Text = "Draw It",
                        Font = Font.BoldSystemFontOfSize (50),
                        HorizontalOptions = LayoutOptions.CenterAndExpand,
                        VerticalOptions = LayoutOptions.FillAndExpand
                    }, 0, 2, 0, 1},
                    {BuildPalletFrame(), 0, 1},
                    {new ContentView {
                        Content = BuildDrawingFrame(),
                        Padding = new Thickness(10, 0, 0, 0),
                        HorizontalOptions = LayoutOptions.FillAndExpand,
                        VerticalOptions = LayoutOptions.FillAndExpand
                    }, 1, 1}
                }
            };
        }

        private StackLayout CreatePalletStack()
        {
            BuildColorPallete();

            var stack = new StackLayout
            {
                Spacing = PalleteSpacing,
                Orientation = StackOrientation.Vertical,
                VerticalOptions = LayoutOptions.FillAndExpand
            };

            stack.SizeChanged += OnStackSizeChanged;

            foreach (var button in ColorPallete.Select(color => new Button
            {
                Text = color.Key,
                TextColor = GetTextColor(color.Value),
                BackgroundColor = color.Value,
                Font = Font.BoldSystemFontOfSize(NamedSize.Medium),
            }))
            {
                button.Clicked += OnButtonClicked;

                stack.Children.Add(button);
            }

            var saveButton = new Button
            {
                Text = "Save",

            };
            saveButton.Clicked += OnSaveButtonClicked;
            stack.Children.Add(saveButton);

            return stack;
        }

        private void OnSaveButtonClicked(object sender, EventArgs e)
        {
            Navigation.PushModalAsync(new ShowImage(DrawingImage, "Test"));
        }

        // Formula for computing Luminance out of R G B, which is something close to luminance = (red * 0.3) + (green * 0.6) + (blue * 0.1).
        // Original Source: http://stackoverflow.com/questions/20978198/how-to-match-uilabels-textcolor-to-its-background
        private static Color GetTextColor(Color backgroundColor)
        {
            var backgroundColorDelta = ((backgroundColor.R * 0.3) + (backgroundColor.G * 0.6) + (backgroundColor.B * 0.1));

            return (backgroundColorDelta > 0.4f) ? Color.Black : Color.White;
        }

        private Frame BuildPalletFrame()
        {
            var palleteFrame = new Frame
            {
                BackgroundColor = Color.White,
                Padding = 5,
                Content = CreatePalletStack()
            };

            return palleteFrame;
        }

        private Frame BuildDrawingFrame()
        {
            DrawingImage = new ImageWithTouch
            {
                VerticalOptions = LayoutOptions.FillAndExpand,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                BackgroundColor = Color.White,
                CurrentLineColor = Color.Black
            };

            DrawingImage.SetBinding(ImageWithTouch.CurrentLineColorProperty, "CurrentLineColor");

            var palleteFrame = new Frame
            {
                BackgroundColor = Color.White,
                Padding = 5,
                HasShadow = false,
                OutlineColor = Color.Black,
                Content = DrawingImage
            };

            return palleteFrame;
        }

        private void BuildColorPallete()
        {
            ColorPallete = new Dictionary<string, Color>
            {
                { "White", Color.White },
                { "Silver", Color.Silver },
                { "Gray", Color.Gray },
                { "Yellow", Color.Yellow },
                { "Aqua", Color.Aqua },
                { "Blue", Color.Blue },
                { "Navy", Color.Navy },
                { "Lime", Color.Lime },
                { "Green", Color.Green },
                { "Teal", Color.Teal },
                { "Olive", Color.Olive },
                { "Fuschia", Color.Fuschia },
                { "Red", Color.Red },
                { "Purple", Color.Purple },
                { "Maroon", Color.Maroon },
                { "Black", Color.Black },
            };
        }

        #region Event Handlers

        private void OnButtonClicked(object sender, EventArgs e)
        {
            var button = (Button)sender;

            DrawingImage.CurrentLineColor = button.BackgroundColor;
        }

        private void OnStackSizeChanged(object sender, EventArgs args)
        {
            var stackLayout = (StackLayout)sender;

            var width = stackLayout.Width;
            var height = stackLayout.Height;

            if (width <= 0 || height <= 0)
            {
                return;
            }

            var stackChildSize = height / stackLayout.Children.Count;
            var font = Font.BoldSystemFontOfSize(0.4 * stackChildSize);

            foreach (var button in stackLayout.Children.Cast<Button>())
            {
                button.Font = font;

                button.HeightRequest = stackChildSize - PalleteSpacing;
            }
        }

        #endregion

    }
}

我要加载的下一个屏幕的代码是：

    [XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ShowImage : ContentPage
{
    public ShowImage (Image image, string message)
    {
        InitializeComponent ();
        NewText.Text = "This is a long test "  + message;
        CreatedImage.Source = image.Source;

    }
}
}

ShowImage中的图像源始终为空，并且未显示绘制的图像。它显示我发送的消息。

如何在下一个屏幕中显示图像？ 我可以将其转换为bytearray或其他什么？仅供参考：我想将其发送到（C＃）网络服务。 我已经在UWP和Android上对此进行了测试。