Windows 8 如何将 BitmapImage 作为流打开？

Posted 2023-04-12

【中文标题】Windows 8 如何将 BitmapImage 作为流打开？

【英文标题】：Windows 8 How to open a BitmapImage as a stream?

【发布时间】：2014-11-05 19:47:02

【问题描述】：

在 Windows 8 应用程序中，如何将 BitmapImage 转换为 Stream？我有一个 BitmapImages 列表，我将使用该列表将每个图像上传到服务器，我需要使用 Stream 来做到这一点。那么有没有办法将每个单独的 BitmapImage 转换为 Stream 呢？

【参考方案1】：

不，没有。您需要跟踪原始来源或改用WriteableBitmap。

【讨论】：

我已经玩了一点，我可以将图片保存为列表中的 StorageFile。我不相信我可以做 writeableBitmap。那么在这种情况下，有没有办法将 StorageFile 转换为 Stream？

OpenReadAsync 或类似的东西会产生一个流，不是吗？

我已经发布了与 Windows Phone 8.1 相关的答案。

【参考方案2】：

检索位图图像：

public async void ContinueFileOpenPicker(FileOpenPickerContinuationEventArgs args)

    if (args.Files.Count > 0)
    
        var imageFile = args.Files[0] as StorageFile;
        // Ensure the stream is disposed once the image is loaded
        using (IRandomAccessStream fileStream = await imageFile.OpenAsync(Windows.Storage.FileAccessMode.Read))
        
            // Set the image source to the selected bitmap
            BitmapImage bitmapImage = new BitmapImage();

            await bitmapImage.SetSourceAsync(fileStream);
            ImageControl.Source = bitmapImage;

            await _viewModel.Upload(imageFile);
                       
    

创建文件流：

internal async Task Upload(Windows.Storage.StorageFile file)

    var fileStream = await file.OpenAsync(FileAccessMode.Read);
    fileStream.Seek(0);

    var reader = new Windows.Storage.Streams.DataReader(fileStream.GetInputStreamAt(0));
    await reader.LoadAsync((uint)fileStream.Size);

    Globals.MemberId = ApplicationData.Current.LocalSettings.Values[Globals.PROFILE_KEY];
    var userName = "Rico";
    var sex = 1;
    var url = string.Format("01?memberid=2&name=3&sex=4", Globals.URL_PREFIX, "api/Images", Globals.MemberId, userName,sex);
    byte[] image = new byte[fileStream.Size];

    await UploadImage(image, url);

从图像创建内存流：

public async Task UploadImage(byte[] image, string url)

    Stream stream = new System.IO.MemoryStream(image);
    HttpStreamContent streamContent = new HttpStreamContent(stream.AsInputStream());

    Uri resourceAddress = null;
    Uri.TryCreate(url.Trim(), UriKind.Absolute, out resourceAddress);
    Windows.Web.Http.HttpRequestMessage request = new Windows.Web.Http.HttpRequestMessage(Windows.Web.Http.HttpMethod.Post, resourceAddress);
    request.Content = streamContent;

    var httpClient = new Windows.Web.Http.HttpClient();
    var cts = new CancellationTokenSource();
    Windows.Web.Http.HttpResponseMessage response = await httpClient.SendRequestAsync(request).AsTask(cts.Token);