doc: 增加下载示例

Author: ArgoZhang

src/BootstrapBlazor.Server/Components/Samples/VideoDevices.razor

@@ -18,6 +18,7 @@ private IVideoDevice? VideoDeviceService { get; set; }</Pre>
                 <Button Text="@Localizer["VideoDeviceOpenText"]" Icon="fa-solid fa-play" OnClick="OnOpenVideo" IsDisabled="_isOpen || string.IsNullOrEmpty(_deviceId)"></Button>
                 <Button Text="@Localizer["VideoDeviceCloseText"]" Icon="fa-solid fa-stop" OnClick="OnCloseVideo" IsDisabled="!_isOpen"></Button>
                 <Button Text="@Localizer["VideoDeviceCaptureText"]" Icon="fa-solid fa-camera" OnClick="OnCapture" IsDisabled="!_isOpen"></Button>
+                <Button Text="@Localizer["VideoDeviceDownloadText"]" Icon="fa-solid fa-download" OnClick="OnDownload" IsDisabled="!_isOpen"></Button>
                 <Button Text="QVGA" IsDisabled="!_isOpen" OnClickWithoutRender="() => OnApply(320, 240)"></Button>
                 <Button Text="VGA" IsDisabled="!_isOpen" OnClickWithoutRender="() => OnApply(640, 480)"></Button>
                 <Button Text="HD" IsDisabled="!_isOpen" OnClickWithoutRender="() => OnApply(1280, 960)"></Button>

src/BootstrapBlazor.Server/Components/Samples/VideoDevices.razor.cs

@@ -13,6 +13,9 @@ public partial class VideoDevices : IAsyncDisposable
     [Inject, NotNull]
     private IVideoDevice? VideoDeviceService { get; set; }
 
+    [Inject, NotNull]
+    private DownloadService? DownloadService { get; set; }
+
     private readonly List<IMediaDeviceInfo> _devices = [];
 
     private List<SelectedItem> _items = [];
@@ -61,6 +64,15 @@ private async Task OnCapture()
         _previewUrl = await VideoDeviceService.GetPreviewUrl();
     }
 
+    private async Task OnDownload()
+    {
+        var stream = await VideoDeviceService.GetPreviewData();
+        if (stream != null)
+        {
+            await DownloadService.DownloadFromStreamAsync("preview.png", stream);
+        }
+    }
+
     private async Task OnApply(int width, int height) => await VideoDeviceService.Apply(new MediaTrackConstraints() { Width = width, Height = height });
 
     private async Task DisposeAsync(bool disposing)