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/ConfigurableSourceImpl.h

@@ -0,0 +1,56 @@
+/*----------------------------------------------------------------------------*/
+/* 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_CONFIGURABLESOURCEIMPL_H_
+#define CSCORE_CONFIGURABLESOURCEIMPL_H_
+
+#include <atomic>
+#include <functional>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <wpi/ArrayRef.h>
+#include <wpi/Twine.h>
+
+#include "SourceImpl.h"
+
+namespace cs {
+
+class ConfigurableSourceImpl : public SourceImpl {
+ protected:
+  ConfigurableSourceImpl(const wpi::Twine& name, wpi::Logger& logger,
+                         Notifier& notifier, Telemetry& telemetry,
+                         const VideoMode& mode);
+
+ public:
+  ~ConfigurableSourceImpl() override;
+
+  void Start() override;
+
+  bool SetVideoMode(const VideoMode& mode, CS_Status* status) override;
+
+  void NumSinksChanged() override;
+  void NumSinksEnabledChanged() override;
+
+  // OpenCV-specific functions
+  void NotifyError(const wpi::Twine& msg);
+  int CreateProperty(const wpi::Twine& name, CS_PropertyKind kind, int minimum,
+                     int maximum, int step, int defaultValue, int value);
+  int CreateProperty(const wpi::Twine& name, CS_PropertyKind kind, int minimum,
+                     int maximum, int step, int defaultValue, int value,
+                     std::function<void(CS_Property property)> onChange);
+  void SetEnumPropertyChoices(int property, wpi::ArrayRef<std::string> choices,
+                              CS_Status* status);
+
+ private:
+  std::atomic_bool m_connected{true};
+};
+
+}  // namespace cs
+
+#endif  // CSCORE_CONFIGURABLESOURCEIMPL_H_