update

matrix/include/content-streamer.h

@@ -0,0 +1,108 @@
+// -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
+//
+// Abstractions to read and write FrameCanvas objects to streams. This allows
+// you to create canned streams of content with minimal overhead at runtime
+// to play with extreme pixel-throughput which also minimizes overheads in
+// the Pi to avoid stuttering or brightness glitches.
+//
+// The disadvantage is, that this represents the full expanded internal
+// representation of a frame, so is very large memory wise.
+//
+// These abstractions are used in util/led-image-viewer.cc to read and
+// write such animations to disk. It is also used in util/video-viewer.cc
+// to write a version to disk that then can be played with the led-image-viewer.
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/types.h>
+
+#include <string>
+
+namespace rgb_matrix {
+class FrameCanvas;
+
+// An abstraction of a data stream.
+class StreamIO {
+public:
+  virtual ~StreamIO() {}
+
+  // Rewind stream.
+  virtual void Rewind() = 0;
+
+  // Read bytes into buffer. Similar to Posix behavior that allows short reads.
+  virtual ssize_t Read(void *buf, size_t count) = 0;
+
+  // Write bytes from buffer. Similar to Posix behavior that allows short
+  // writes.
+  virtual ssize_t Append(const void *buf, size_t count) = 0;
+};
+
+class FileStreamIO : public StreamIO {
+public:
+  explicit FileStreamIO(int fd);
+  ~FileStreamIO();
+
+  virtual void Rewind();
+  virtual ssize_t Read(void *buf, size_t count);
+  virtual ssize_t Append(const void *buf, size_t count);
+
+private:
+  const int fd_;
+};
+
+class MemStreamIO : public StreamIO {
+public:
+  virtual void Rewind();
+  virtual ssize_t Read(void *buf, size_t count);
+  virtual ssize_t Append(const void *buf, size_t count);
+
+private:
+  std::string buffer_;  // super simplistic.
+  size_t pos_;
+};
+
+class StreamWriter {
+public:
+  // Does not take ownership of StreamIO
+  StreamWriter(StreamIO *io);
+
+  // Stream out given canvas at the given time. "hold_time_us" indicates
+  // for how long this frame is to be shown in microseconds.
+  bool Stream(const FrameCanvas &frame, uint32_t hold_time_us);
+
+private:
+  void WriteFileHeader(const FrameCanvas &frame, size_t len);
+
+  StreamIO *const io_;
+  bool header_written_;
+};
+
+class StreamReader {
+public:
+  // Does not take ownership of StreamIO
+  StreamReader(StreamIO *io);
+  ~StreamReader();
+
+  // Go back to the beginning.
+  void Rewind();
+
+  // Get next frame and its timestamp. Returns 'false' if there is an error
+  // or end of stream reached..
+  bool GetNext(FrameCanvas *frame, uint32_t* hold_time_us);
+
+private:
+  enum State {
+    STREAM_AT_BEGIN,
+    STREAM_READING,
+    STREAM_ERROR,
+  };
+  bool ReadFileHeader(const FrameCanvas &frame);
+
+  StreamIO *io_;
+  size_t frame_buf_size_;
+  State state_;
+
+  char *header_frame_buffer_;
+};
+}