Start implementation.

src/Frame.h

@@ -0,0 +1,83 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2016. 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 CAMERASERVER_FRAME_H_
+#define CAMERASERVER_FRAME_H_
+
+#include <atomic>
+#include <chrono>
+
+#include "llvm/SmallVector.h"
+
+#include "Image.h"
+
+namespace cs {
+
+class SourceImpl;
+
+class Frame {
+  friend class SourceImpl;
+
+  struct Data {
+    std::atomic_int refcount{0};
+    std::chrono::system_clock::time_point timestamp;
+    llvm::SmallVector<Image, 4> images;
+  };
+
+ public:
+  Frame(SourceImpl& source, Data* data) : m_source(&source), m_data(data) {
+    if (m_data) ++(m_data->refcount);
+  }
+
+  Frame(const Frame& frame) : m_source(frame.m_source), m_data(frame.m_data) {
+    if (m_data) ++(m_data->refcount);
+  }
+
+  Frame(Frame&& frame) : m_source(frame.m_source), m_data(frame.m_data) {
+    frame.m_data = nullptr;
+  }
+
+  ~Frame() { DecRef(); }
+
+  Frame& operator=(const Frame& frame) {
+    DecRef();
+    m_source = frame.m_source;
+    m_data = frame.m_data;
+    if (m_data) ++(m_data->refcount);
+    return *this;
+  }
+
+  explicit operator bool() const { return m_data; }
+
+  std::size_t size(std::size_t channel) const {
+    if (!m_data || channel >= m_data->images.size()) return 0;
+    return m_data->images[channel].size();
+  }
+
+  const char* data(std::size_t channel) const {
+    if (!m_data || channel >= m_data->images.size()) return nullptr;
+    return m_data->images[channel].data();
+  }
+
+  std::chrono::system_clock::time_point time() const {
+    if (!m_data) return std::chrono::system_clock::time_point{};
+    return m_data->timestamp;
+  }
+
+ private:
+  void DecRef() {
+    if (m_data && --(m_data->refcount) == 0) ReleaseFrame();
+  }
+  void ReleaseFrame();
+
+  SourceImpl* m_source;
+  Data* m_data;
+};
+
+}  // namespace cs
+
+#endif  // CAMERASERVER_FRAME_H_