“值不在预期范围内"打开 RandomAccessStream 时 [英] "Value does not fall within the expected range" when opening RandomAccessStream
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问题描述
我已经为这个问题苦苦挣扎了好几天.为什么在这种转换方法中会出现Value does not fall in the expected range
"异常?(它是 Windows Phone 8.1 应用)
I have been struggling with this problem for days. Why do I get "Value does not fall within the expected range
" exception in this conversion method? (it's windows phone 8.1 app)
public static async Task<string> ConvertToBase64(this BitmapImage bitmapImage)
{
RandomAccessStreamReference rasr = RandomAccessStreamReference.CreateFromUri(bitmapImage.UriSource);
var streamWithContent = await rasr.OpenReadAsync(); //raises an exception
byte[] buffer = new byte[streamWithContent.Size];
var result = await streamWithContent.ReadAsync(buffer.AsBuffer(), (uint)streamWithContent.Size, InputStreamOptions.None);
using (MemoryStream ms = new MemoryStream(result.ToArray()))
{
return Convert.ToBase64String(ms.ToArray());
}
}
我从资源中检索图像:
Photo = new BitmapImage(new Uri("ms-appx:///Assets/pies.jpg", UriKind.RelativeOrAbsolute));
newOffer.PhotoBase64 = await Photo.ConvertToBase64();
推荐答案
这似乎是 BitmapImage.UriSource
中的一个错误——它返回了一个无效的 URI:
This appears to be a bug in BitmapImage.UriSource
-- it returns an invalid URI:
var u1 = new Uri("ms-appx:///Assets/Logo.scale-240.png");
var u2 = new Uri("ms-appx:///Assets/Logo.scale-240.png");
// doesn't assert, because they are equal
Debug.Assert(u1 == u2, "URIs don't match");
BitmapImage bi = new BitmapImage(u1);
var u3 = bi.UriSource;
// asserts, because they are not equal
Debug.Assert(u1 == u3, "URIs don't match");
在这种情况下,u3
包含 ms-appx:/Assets/Logo.scale-240.png
—— 缺少额外的斜线.你可以这样修复:
In this case, u3
contains ms-appx:/Assets/Logo.scale-240.png
-- missing the extra slashes. You can fix like this:
var fixedUri = new Uri(u3.Scheme + "://" + u3.AbsolutePath);
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