Itp.WpfCamera 3.0.1

ITP WPF Camera API

Live preview and still capture from webcams in WPF applications. Uses WinRT MediaCapture for capture and presents preview frames to a D3DImage without copying them through the CPU.

Windows 10+ and WPF only. Unpackaged desktop apps are supported.

Capture dialog

CaptureWindow is a maximized dialog with a live preview, a camera switcher, and a Capture button (or F2). It returns one still, or throws OperationCanceledException if the user closes it.

try
{
    image.Source = await CaptureWindow.ShowDialogAsync(this);   // frozen, at capture resolution
}
catch (OperationCanceledException)
{
    // The user closed the dialog.
}
catch (Exception ex)
{
    // The camera could not be opened, failed while open, or could not capture.
    MessageBox.Show(this, ex.Message);
}

The dialog does not try to recover from failures. Any failure (including the camera being unplugged, taken by another application, or stopped by a session lock) closes the dialog and is rethrown from ShowDialogAsync.

Direct use

var cameras = await WinRtCameraDeviceEnumerator.EnumerateAsync();
using var camera = await WinRtCamera.OpenAsync(cameras[0],   // on the UI thread
    (_, e) => log.LogError((Exception)e.ExceptionObject, "Camera failed"));   // optional
previewImage.Source = camera.Preview;

BitmapSource still = await camera.CaptureAsync();

WinRtCamera must be opened, used, and disposed on a WPF dispatcher thread. Ownership is plain IDisposable: a camera that cannot be opened throws from OpenAsync, and an opened camera is released by Dispose whether or not it has failed.

The optional failure handler is notification only. It is called once, on the dispatcher thread, if an opened camera stops unexpectedly; afterwards CaptureAsync throws. It is never called for a camera that failed to open.

Cameras are opened for exclusive control, so only one WinRtCamera per device can be open at a time.

Settings

Settings are read with Esatto.Win32.Registry (HKCU/HKLM, with policy overrides) under SOFTWARE\In Touch Technologies\Esatto\Wpf.Camera:

Design

• Preview frames stay in GPU memory. Each MediaFrameReader frame's D3D11 surface is copied into a texture shared with a D3D9Ex device, whose surface is the D3DImage back buffer. Frames are dropped, not queued, while a present is pending.
• Stills use the low-lag photo pipeline, so they are not limited to the preview resolution. The photo's SoftwareBitmap is locked in place (LockBuffer) and copied once into a frozen BitmapSource.