包装ImageSource以进行Base64图像序列化 [英] Wrap ImageSource for Base64 image serialization

问题描述

我有一个WPF控件，其中包含带有图像的面板.我正在尝试对其进行序列化，以便可以独立加载它，而不必在本地文件夹中包含图像.

I have a WPF control that contains panels with images. I'm trying to serialize this so that it can be loaded standalone without having to have images in a local folder.

我知道我可以将图像存储为Base64字符串，然后可以将其备份，但是我想做的是包装ImageSource类以接受Base64字符串作为源.

I know that I can store the images as a Base64 string and then possibly load that back up, but what I would like to do is wrap the ImageSource class to accept a Base64 string as the source.

我稍微看了一下ImageSource类，我相信我对它的工作原理并不了解.当我在自定义包装类中实现ImageSource时，会得到2种我不清楚的方法:

I looked into the ImageSource class a bit, and I believe I just don't know enough about how it works. When I implement ImageSource in my custom wrapper class I get 2 methods that I'm unclear on:

1. 元数据

1. Metadata

CreateInstanceCore

CreateInstanceCore

我想知道是否有人可以阐明这些方法，或者指出我的方向不会导致我回到MSDN文档中.

I was wondering if anyone could shed some light on these methods, or point me in a direction that doesn't lead me back to MSDN documentation.

推荐答案

此类包装了一个bitmapImage，它是从base64字符串属性初始化的:

This class wraps a BitmapImage which is initialized from a base64 string property:

public class Base64BitmapImage : BitmapSource
{
    private BitmapImage bitmap;
    private string base64Source;

    public string Base64Source
    {
        get { return base64Source; }
        set
        {
            base64Source = value;
            bitmap = new BitmapImage();

            if (DecodeFailed != null)
            {
                bitmap.DecodeFailed += DecodeFailed;
            }

            using (var stream = new MemoryStream(Convert.FromBase64String(base64Source)))
            {
                bitmap.BeginInit();
                bitmap.CacheOption = BitmapCacheOption.OnLoad;
                bitmap.StreamSource = stream;
                bitmap.EndInit();
            }

            if (DecodeFailed != null)
            {
                bitmap.DecodeFailed -= DecodeFailed;
            }

            bitmap.Freeze();
        }
    }

    public override event EventHandler<ExceptionEventArgs> DecodeFailed;

    public override bool IsDownloading
    {
        get { return false; }
    }

    public override PixelFormat Format
    {
        get { return bitmap != null ? bitmap.Format : base.Format; }
    }

    public override double DpiX
    {
        get { return bitmap != null ? bitmap.DpiX : base.DpiX; }
    }

    public override double DpiY
    {
        get { return bitmap != null ? bitmap.DpiY : base.DpiY; }
    }

    public override double Width
    {
        get { return bitmap != null ? bitmap.Width : base.Width; }
    }

    public override double Height
    {
        get { return bitmap != null ? bitmap.Height : base.Height; }
    }

    public override int PixelWidth
    {
        get { return bitmap != null ? bitmap.PixelWidth : base.PixelWidth; }
    }

    public override int PixelHeight
    {
        get { return bitmap != null ? bitmap.PixelHeight : base.PixelHeight; }
    }

    public override ImageMetadata Metadata
    {
        get { return bitmap != null ? bitmap.Metadata : base.Metadata; }
    }

    public override void CopyPixels(Array pixels, int stride, int offset)
    {
        if (bitmap != null)
        {
            bitmap.CopyPixels(pixels, stride, offset);
        }
    }

    public override void CopyPixels(Int32Rect sourceRect, Array pixels, int stride, int offset)
    {
        if (bitmap != null)
        {
            bitmap.CopyPixels(sourceRect, pixels, stride, offset);
        }
    }

    public override void CopyPixels(Int32Rect sourceRect, IntPtr buffer, int bufferSize, int stride)
    {
        if (bitmap != null)
        {
            bitmap.CopyPixels(sourceRect, buffer, bufferSize, stride);
        }
    }

    protected override Freezable CreateInstanceCore()
    {
        var instance = new Base64BitmapImage();
        instance.bitmap = bitmap;
        instance.base64Source = base64Source;
        return instance;
    }
}

它可以这样使用:

<Image>
    <Image.Source>
        <local:Base64BitmapImage Base64Source="..."/>
    </Image.Source>
</Image>

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