Windows Phone-字节数组到BitmapImage转换器引发异常 [英] Windows Phone - byte array to BitmapImage converter throws exception

问题描述

我有一个BitmapImage转换器的字节数组，它工作正常。为了在我的应用程序中支持图块，我从图像创建了图块（调整大小和裁剪）并将其作为字节数组保存到我的数据库中。现在，如果要在转换器中显示此图块，则会引发异常：

I have a byte array to a BitmapImage converter and it works fine. For tile support within my app, I create a tile from an image (resize and crop it) and save it into my database as byte array. Now, if I want to display this tile with my converter, it throws an exception:

找不到组件。 （来自HRESULT的异常：0x88982F50）

我创建图块的方法：

            WriteableBitmap bmp = new WriteableBitmap(img);

            int height = bmp.PixelHeight;
            int newHeight = 0;

            int width = bmp.PixelWidth;
            int newWidth = 0;

            // calculate new height and new width...

            bmp = bmp.Resize(newWidth, newHeight, WriteableBitmapExtensions.Interpolation.Bilinear);
            bmp = bmp.Crop(0, 0, 336, 336);
            byte[] byteArray = bmp.ToByteArray();

            item.Tile = byteArray;

我在实体中的图块的财产：

My property for the tile within my entity:

    private byte[] _tile;

    [Column(DbType = "IMAGE")]
    public byte[] Tile
    {
        get { return _tile; }
        set { SetProperty(ref _tile, value); }
    }

我的字节数组到BitmapImage转换器方法：

My byte array to BitmapImage converter method:

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value != null && value is byte[])
        {
            using (var stream = new MemoryStream((byte[])value))
            {
                stream.Seek(0, SeekOrigin.Begin);

                BitmapImage image = new BitmapImage();
                image.SetSource(stream);

                return image;
            }
        }

        return null;
    }

我认为问题在于字节数组被保存为Base64编码的字符串数据库，解码回字节数组时出现错误，但是我不知道如何解决。

I think the problem is that the byte array is saved as Base64 encoded string in the database and there's an error while decoding back to byte array, but I don't know how to solve it.

推荐答案

I我担心您创建字节数组的方法。是否由于某些原因您不使用 SaveJpeg 扩展名？我无法识别您正在执行的WritableBitmap.ToByteArray调用。请改用以下代码：

I'm concerned about your methodology for creating a byte array. Is there some reason you're not using the SaveJpeg extension? I don't recognize the WritableBitmap.ToByteArray call you're making. Try instead the following code:

int quality = 90;

using (var ms = new System.IO.MemoryStream()) {
    bmp.SaveJpeg(ms, bmp.PixelWidth, bmp.PixelHeight, 0, quality);
    item.Tile = ms.ToArray();
}

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