TASK 3 milestone 1: webcam capture (MediaCapture CPU-first, CameraManager refcount, picker, clip/mirror, schema v2, tests)
This commit is contained in:
@@ -0,0 +1,218 @@
|
||||
using System;
|
||||
using System.Collections.Generic;
|
||||
using System.Threading.Tasks;
|
||||
using System.Windows;
|
||||
using System.Windows.Media;
|
||||
using System.Windows.Media.Imaging;
|
||||
using System.Windows.Threading;
|
||||
using ytLive.Helpers;
|
||||
|
||||
namespace ytLive.Services;
|
||||
|
||||
/// <summary>
|
||||
/// Owns webcam capture sessions app-wide, refcounted by DeviceId. One device =
|
||||
/// at most one capture, one shared WriteableBitmap; the last release stops and
|
||||
/// disposes the source. Frames arrive on a worker thread and are coalesced onto
|
||||
/// the UI dispatcher (at most one pending copy per session, using the latest
|
||||
/// frame) so a 60fps device doesn't drown the render thread.
|
||||
/// </summary>
|
||||
public sealed class CameraManager : IDisposable
|
||||
{
|
||||
private sealed class CameraSession
|
||||
{
|
||||
public string DeviceId { get; }
|
||||
public ICameraFrameSource Source { get; }
|
||||
public Action<VideoFrame>? FrameHandler;
|
||||
public int RefCount;
|
||||
public bool Started;
|
||||
public WriteableBitmap? PreviewBitmap;
|
||||
public VideoFrame? LatestFrame;
|
||||
public bool FramePending;
|
||||
|
||||
public CameraSession(string deviceId, ICameraFrameSource source)
|
||||
{
|
||||
DeviceId = deviceId;
|
||||
Source = source;
|
||||
RefCount = 1;
|
||||
}
|
||||
}
|
||||
|
||||
private readonly ICameraEnumerator _enumerator;
|
||||
private readonly Func<string, ICameraFrameSource> _frameSourceFactory;
|
||||
private readonly Dispatcher? _uiDispatcher;
|
||||
private readonly Dictionary<string, CameraSession> _sessions = new();
|
||||
private readonly object _gate = new();
|
||||
|
||||
/// <summary>Raised on the UI thread when a camera's shared preview bitmap is first created.</summary>
|
||||
public event Action<string, WriteableBitmap>? PreviewBitmapChanged;
|
||||
|
||||
/// <summary>Raised when a capture fails to start (device in use, access denied, no preview source).</summary>
|
||||
public event Action<string, string>? CameraFailed;
|
||||
|
||||
public CameraManager(ICameraEnumerator enumerator, Func<string, ICameraFrameSource> frameSourceFactory,
|
||||
Dispatcher? uiDispatcher = null)
|
||||
{
|
||||
_enumerator = enumerator;
|
||||
_frameSourceFactory = frameSourceFactory;
|
||||
_uiDispatcher = uiDispatcher;
|
||||
}
|
||||
|
||||
public ICameraEnumerator Enumerator => _enumerator;
|
||||
|
||||
/// <summary>Increments the refcount for a device, starting capture the first time.</summary>
|
||||
public async Task<bool> AcquireAsync(string deviceId)
|
||||
{
|
||||
if (string.IsNullOrWhiteSpace(deviceId)) return false;
|
||||
|
||||
CameraSession session;
|
||||
bool shouldStart;
|
||||
lock (_gate)
|
||||
{
|
||||
if (_sessions.TryGetValue(deviceId, out var existing))
|
||||
{
|
||||
existing.RefCount++;
|
||||
shouldStart = false;
|
||||
session = existing;
|
||||
}
|
||||
else
|
||||
{
|
||||
session = new CameraSession(deviceId, _frameSourceFactory(deviceId));
|
||||
session.FrameHandler = frame => OnFrameAvailable(session, frame);
|
||||
session.Source.FrameAvailable += session.FrameHandler;
|
||||
_sessions[deviceId] = session;
|
||||
shouldStart = true;
|
||||
}
|
||||
}
|
||||
|
||||
if (!shouldStart) return session.Started;
|
||||
|
||||
try
|
||||
{
|
||||
await session.Source.StartAsync();
|
||||
session.Started = true;
|
||||
return true;
|
||||
}
|
||||
catch (Exception ex)
|
||||
{
|
||||
lock (_gate)
|
||||
_sessions.Remove(deviceId);
|
||||
session.Source.FrameAvailable -= session.FrameHandler;
|
||||
AppLog.Write($"CameraManager: failed to start camera '{deviceId}': {ex.Message}");
|
||||
CameraFailed?.Invoke(deviceId, ex.Message);
|
||||
await SafeStopAsync(session.Source);
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
/// <summary>Decrements the refcount; stops and disposes the source at zero.</summary>
|
||||
public async Task ReleaseAsync(string deviceId)
|
||||
{
|
||||
CameraSession? toStop = null;
|
||||
lock (_gate)
|
||||
{
|
||||
if (!_sessions.TryGetValue(deviceId, out var session)) return;
|
||||
if (--session.RefCount > 0) return;
|
||||
_sessions.Remove(deviceId);
|
||||
toStop = session;
|
||||
}
|
||||
|
||||
if (toStop == null) return;
|
||||
toStop.Source.FrameAvailable -= toStop.FrameHandler;
|
||||
await SafeStopAsync(toStop.Source);
|
||||
toStop.PreviewBitmap = null;
|
||||
}
|
||||
|
||||
public VideoFrame? GetLatestFrame(string deviceId)
|
||||
{
|
||||
lock (_gate)
|
||||
return _sessions.TryGetValue(deviceId, out var session) ? session.LatestFrame : null;
|
||||
}
|
||||
|
||||
public void Dispose()
|
||||
{
|
||||
List<CameraSession> sessions;
|
||||
lock (_gate)
|
||||
{
|
||||
sessions = new List<CameraSession>(_sessions.Values);
|
||||
_sessions.Clear();
|
||||
}
|
||||
|
||||
foreach (var session in sessions)
|
||||
{
|
||||
session.Source.FrameAvailable -= session.FrameHandler;
|
||||
_ = SafeStopAsync(session.Source);
|
||||
}
|
||||
}
|
||||
|
||||
private static async Task SafeStopAsync(ICameraFrameSource source)
|
||||
{
|
||||
try
|
||||
{
|
||||
await source.StopAsync();
|
||||
}
|
||||
catch (Exception ex)
|
||||
{
|
||||
AppLog.Write($"CameraManager: stopping camera failed: {ex.Message}");
|
||||
}
|
||||
}
|
||||
|
||||
private bool TryGetActiveSession(CameraSession session)
|
||||
{
|
||||
lock (_gate)
|
||||
return _sessions.TryGetValue(session.DeviceId, out var current) && ReferenceEquals(current, session);
|
||||
}
|
||||
|
||||
private void OnFrameAvailable(CameraSession session, VideoFrame frame)
|
||||
{
|
||||
if (!TryGetActiveSession(session)) return;
|
||||
session.LatestFrame = frame;
|
||||
|
||||
if (session.PreviewBitmap == null)
|
||||
{
|
||||
if (_uiDispatcher == null) return;
|
||||
if (_uiDispatcher.CheckAccess())
|
||||
EnsurePreviewBitmap(session);
|
||||
else
|
||||
_uiDispatcher.BeginInvoke(() =>
|
||||
{
|
||||
if (TryGetActiveSession(session))
|
||||
EnsurePreviewBitmap(session);
|
||||
}, DispatcherPriority.Render);
|
||||
return;
|
||||
}
|
||||
|
||||
if (_uiDispatcher == null || _uiDispatcher.CheckAccess())
|
||||
{
|
||||
CopyFrame(session);
|
||||
return;
|
||||
}
|
||||
|
||||
if (session.FramePending) return;
|
||||
session.FramePending = true;
|
||||
_uiDispatcher.BeginInvoke(() =>
|
||||
{
|
||||
session.FramePending = false;
|
||||
if (TryGetActiveSession(session) && session.PreviewBitmap != null)
|
||||
CopyFrame(session);
|
||||
}, DispatcherPriority.Render);
|
||||
}
|
||||
|
||||
private void EnsurePreviewBitmap(CameraSession session)
|
||||
{
|
||||
if (session.PreviewBitmap != null || session.LatestFrame == null) return;
|
||||
var frame = session.LatestFrame;
|
||||
var bitmap = new WriteableBitmap(frame.Width, frame.Height, 96, 96, PixelFormats.Bgra32, null);
|
||||
bitmap.WritePixels(new Int32Rect(0, 0, frame.Width, frame.Height), frame.BgraPixels, frame.Stride, 0);
|
||||
session.PreviewBitmap = bitmap;
|
||||
PreviewBitmapChanged?.Invoke(session.DeviceId, bitmap);
|
||||
}
|
||||
|
||||
private void CopyFrame(CameraSession session)
|
||||
{
|
||||
var bitmap = session.PreviewBitmap;
|
||||
var frame = session.LatestFrame;
|
||||
if (bitmap == null || frame == null) return;
|
||||
if (frame.Width != bitmap.PixelWidth || frame.Height != bitmap.PixelHeight) return;
|
||||
bitmap.WritePixels(new Int32Rect(0, 0, frame.Width, frame.Height), frame.BgraPixels, frame.Stride, 0);
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user