在 UWP 中将 WriteableBitmap 图像转换为 Array
Converting a WriteableBitmap image ToArray in UWP
我正在从我的 Azure 服务上的 Blob 存储访问图像。我返回图像的 uri
,然后使用 HttpClient 尝试下载它。 uri
经验证无误。
using (HttpClient client = new HttpClient())
{
try
{
HttpResponseMessage response = await client.GetAsync(new Uri(((App)Application.Current).results.statsInformation.ImageBlob.ImageUri, UriKind.RelativeOrAbsolute));
if (response != null && response.StatusCode == HttpStatusCode.OK)
{
using (var stream = await response.Content.ReadAsStreamAsync())
{
using (var memStream = new MemoryStream())
{
await stream.CopyToAsync(memStream);
memStream.Position = 0;
memStream.Seek(0, SeekOrigin.Begin);
myOnlineImage.SetSource(memStream.AsRandomAccessStream());
}
}
}
}
catch (Exception)
{
throw;
}
}
来自服务器的图像存储在变量myOnlineImage
中。然后我想使用 myOnlineImage.PixelBuffer.ToArray();
提取像素信息。这是因为图像没有正确下载吗?谁能帮我解决这个问题?
我收到的异常是:
异常
Message "Value cannot be null.\r\nParameter name: source"
StackTrace " at System.Runtime.InteropServices.Marshal.CopyToManaged(IntPtr source, Object destination, Int32 startIndex, Int32 length)\r\n at System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions.CopyTo(IBuffer source, UInt32 sourceIndex, Byte[] destination, Int32 destinationIndex, Int32 count)\r\n at System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions.ToArray(IBuffer source, UInt32 sourceIndex, Int32 count)\r\n at System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions.ToArray(IBuffer source)\r\n at Stonegaard_endless_runner.MainPage.d__7.MoveNext()"
额外
我已经检查过我有线程访问图像。
在某些情况下,您不能使用 System.Runtime.InteropServices
。
指针 myOnlineImage.PixelBuffer
为空。
您可以使用 BitmapImage
但不能使用 WriteableBitmap
并转换为 byte[]
BitmapDecoder
, BitmapFrame
, PixelDataProvider
喜欢msdn的例子:
byte[] image_array = null;
int image_array_width = 0;
int image_array_height = 0;
using (HttpClient client = new HttpClient())
{
try
{
HttpResponseMessage response = await client.GetAsync(new Uri("http://www.example.com/logo.png", UriKind.RelativeOrAbsolute));
if (response != null && response.StatusCode == HttpStatusCode.OK)
{
using (Stream stream = await (response.Content.ReadAsStreamAsync()))
{
using (IRandomAccessStream strm = stream.AsRandomAccessStream())
{
strm.Seek(0);
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(strm);
BitmapFrame bitmapFrame = await decoder.GetFrameAsync(0);
// Get the pixels
var transform = new BitmapTransform { ScaledWidth = decoder.PixelWidth, ScaledHeight = decoder.PixelHeight };
PixelDataProvider dataProvider =
await bitmapFrame.GetPixelDataAsync(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Straight,
transform,
ExifOrientationMode.RespectExifOrientation,
ColorManagementMode.ColorManageToSRgb);
await strm.FlushAsync();
image_array = dataProvider.DetachPixelData();
image_array_width = (int)decoder.PixelWidth;
image_array_height = (int)decoder.PixelHeight;
}
}
}
}
catch (Exception)
{
throw;
}
}
我正在从我的 Azure 服务上的 Blob 存储访问图像。我返回图像的 uri
,然后使用 HttpClient 尝试下载它。 uri
经验证无误。
using (HttpClient client = new HttpClient())
{
try
{
HttpResponseMessage response = await client.GetAsync(new Uri(((App)Application.Current).results.statsInformation.ImageBlob.ImageUri, UriKind.RelativeOrAbsolute));
if (response != null && response.StatusCode == HttpStatusCode.OK)
{
using (var stream = await response.Content.ReadAsStreamAsync())
{
using (var memStream = new MemoryStream())
{
await stream.CopyToAsync(memStream);
memStream.Position = 0;
memStream.Seek(0, SeekOrigin.Begin);
myOnlineImage.SetSource(memStream.AsRandomAccessStream());
}
}
}
}
catch (Exception)
{
throw;
}
}
来自服务器的图像存储在变量myOnlineImage
中。然后我想使用 myOnlineImage.PixelBuffer.ToArray();
提取像素信息。这是因为图像没有正确下载吗?谁能帮我解决这个问题?
我收到的异常是:
异常
Message "Value cannot be null.\r\nParameter name: source"
StackTrace " at System.Runtime.InteropServices.Marshal.CopyToManaged(IntPtr source, Object destination, Int32 startIndex, Int32 length)\r\n at System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions.CopyTo(IBuffer source, UInt32 sourceIndex, Byte[] destination, Int32 destinationIndex, Int32 count)\r\n at System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions.ToArray(IBuffer source, UInt32 sourceIndex, Int32 count)\r\n at System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions.ToArray(IBuffer source)\r\n at Stonegaard_endless_runner.MainPage.d__7.MoveNext()"
额外
我已经检查过我有线程访问图像。
在某些情况下,您不能使用 System.Runtime.InteropServices
。
指针 myOnlineImage.PixelBuffer
为空。
您可以使用 BitmapImage
但不能使用 WriteableBitmap
并转换为 byte[]
BitmapDecoder
, BitmapFrame
, PixelDataProvider
喜欢msdn的例子:
byte[] image_array = null;
int image_array_width = 0;
int image_array_height = 0;
using (HttpClient client = new HttpClient())
{
try
{
HttpResponseMessage response = await client.GetAsync(new Uri("http://www.example.com/logo.png", UriKind.RelativeOrAbsolute));
if (response != null && response.StatusCode == HttpStatusCode.OK)
{
using (Stream stream = await (response.Content.ReadAsStreamAsync()))
{
using (IRandomAccessStream strm = stream.AsRandomAccessStream())
{
strm.Seek(0);
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(strm);
BitmapFrame bitmapFrame = await decoder.GetFrameAsync(0);
// Get the pixels
var transform = new BitmapTransform { ScaledWidth = decoder.PixelWidth, ScaledHeight = decoder.PixelHeight };
PixelDataProvider dataProvider =
await bitmapFrame.GetPixelDataAsync(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Straight,
transform,
ExifOrientationMode.RespectExifOrientation,
ColorManagementMode.ColorManageToSRgb);
await strm.FlushAsync();
image_array = dataProvider.DetachPixelData();
image_array_width = (int)decoder.PixelWidth;
image_array_height = (int)decoder.PixelHeight;
}
}
}
}
catch (Exception)
{
throw;
}
}