如何从 StorageFile 获取 IRandomAccessStream

Question

首先我声明

private MediaCapture _mediaCapture;
StorageFile capturedPhoto;
IRandomAccessStream imageStream;

第二次捕捉

var lowLagCapture = await _mediaCapture.PrepareLowLagPhotoCaptureAsync(ImageEncodingProperties.CreateUncompressed(MediaPixelFormat.Bgra8));

var capturedPhoto = await lowLagCapture.CaptureAsync();


await lowLagCapture.FinishAsync();

第三个我在设置图片来源：

var softwareBitmap = capturedPhoto.Frame.SoftwareBitmap;
SoftwareBitmap softwareBitmapBGRB = SoftwareBitmap.Convert(softwareBitmap, BitmapPixelFormat.Bgra8, BitmapAlphaMode.Premultiplied);
SoftwareBitmapSource bitmapSource = new SoftwareBitmapSource();
await bitmapSource.SetBitmapAsync(softwareBitmapBGRB);

image.Source = bitmapSource;

如何获取 imageStream？我在 xaml 中使用了 CaptureElement 工具。

Answer 1

这很简单，问题是你想用那个IRandomAccessStreem 做什么。以下是我认为您需要的一些代码：

public void HandleImageFileOperations(StorageFile file)
{
    if (file != null)
    {
         //converts the StorageFile to IRandomAccessStream
         var stream = await file.OpenAsync(FileAccessMode.Read);
         //creates the stream to an Image just in-case you want to show it
         var image = new Windows.UI.Xaml.Media.Imaging.BitmapImage();
         image.SetSource(stream);

         //creates the image into byte array just in-case you need it to store the image
         byte[] bitmapImageBytes = null;
         var reader = new Windows.Storage.Streams.DataReader(stream.GetInputStreamAt(0));
         bitmapImageBytes = new byte[stream.Size];
         await reader.LoadAsync((uint)stream.Size);
         reader.ReadBytes(bitmapImageBytes);
    }
}