Add raw sources and sinks to cscore (#1670)

In some cases, we don't want the cv requirement to get an image, for instance interop with other versions of opencv

This enables getting a raw image, and handling conversions from the user side.

cscore/src/main/native/cpp/RawSinkImpl.h

@@ -0,0 +1,52 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2016-2019 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#ifndef CSCORE_RAWSINKIMPL_H_
+#define CSCORE_RAWSINKIMPL_H_
+
+#include <stdint.h>
+
+#include <atomic>
+#include <functional>
+#include <thread>
+
+#include <wpi/Twine.h>
+#include <wpi/condition_variable.h>
+
+#include "Frame.h"
+#include "SinkImpl.h"
+#include "cscore_raw.h"
+
+namespace cs {
+class SourceImpl;
+
+class RawSinkImpl : public SinkImpl {
+ public:
+  RawSinkImpl(const wpi::Twine& name, wpi::Logger& logger, Notifier& notifier,
+              Telemetry& telemetry);
+  RawSinkImpl(const wpi::Twine& name, wpi::Logger& logger, Notifier& notifier,
+              Telemetry& telemetry,
+              std::function<void(uint64_t time)> processFrame);
+  ~RawSinkImpl() override;
+
+  void Stop();
+
+  uint64_t GrabFrame(CS_RawFrame& frame);
+  uint64_t GrabFrame(CS_RawFrame& frame, double timeout);
+
+ private:
+  void ThreadMain();
+
+  uint64_t GrabFrameImpl(CS_RawFrame& rawFrame, Frame& incomingFrame);
+
+  std::atomic_bool m_active;  // set to false to terminate threads
+  std::thread m_thread;
+  std::function<void(uint64_t time)> m_processFrame;
+};
+}  // namespace cs
+
+#endif  // CSCORE_RAWSINKIMPL_H_