rpi-rgb-led-matrix/include/led-matrix.h

// -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
// Copyright (C) 2013 Henner Zeller <h.zeller@acm.org>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation version 2.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://gnu.org/licenses/gpl-2.0.txt>

// Controlling 16x32 or 32x32 RGB matrixes via GPIO. It allows daisy chaining
// of a string of these, and also connecting a parallel string on newer
// Raspberry Pis with more GPIO pins available.

#ifndef RPI_RGBMATRIX_H
#define RPI_RGBMATRIX_H

#include <stdint.h>
#include <string>
#include <vector>

#include "gpio.h"
#include "canvas.h"
#include "thread.h"
#include "transformer.h"

namespace rgb_matrix {
class RGBMatrix;
class FrameCanvas;   // Canvas for Double- and Multibuffering
namespace internal { class Framebuffer; }

// The RGB matrix provides the framebuffer and the facilities to constantly
// update the LED matrix.
//
// This implement the Canvas interface that represents the display with
// (32 * chained_displays)x(rows * parallel_displays) pixels.
//
// If can do multi-buffering using the CreateFrameCanvas() and SwapOnVSync()
// methods. This is useful for animations and to prevent tearing.
//
// If you arrange the panels in a different way in the physical space, write
// a CanvasTransformer that does coordinate remapping and which should be added
// to the transformers, like with LargeSquare64x64Transformer in demo-main.cc.
class RGBMatrix : public Canvas {
public:
  // Options to initialize the RGBMatrix.
  struct Options {
    Options();   // Creates a default option set.

    // Validate the options and possibly output a message to string.
    bool Validate(std::string *err);

    // The "rows" are the number
    // of rows supported by the display, so 32 or 16. Default: 32.
    int rows;

    // The chain_length is the number of displays daisy-chained together
    // (output of one connected to input of next). Default: 1
    int chain_length;

    // The number of parallel chains connected to the Pi; in old Pis with 26
    // GPIO pins, that is 1, in newer Pis with 40 interfaces pins, that can
    // also be 2 or 3. The effective number of pixels in vertical direction is
    // then thus rows * parallel. Default: 1
    int parallel;

    // Set PWM bits used for output. Default is 11, but if you only deal with
    // limited comic-colors, 1 might be sufficient. Lower require less CPU and
    // increases refresh-rate.
    int pwm_bits;

    // This allows to change the base time-unit for the on-time in the lowest
    // significant bit in nanoseconds.
    // Higher numbers provide better quality (more accurate color, less
    // ghosting), but have a negative impact on the frame rate.
    //
    // For the same frame-rate, displays with higher multiplexing (e.g. 1:16
    // vs. 1:8) require lower values.
    //
    // Good values for full-color display (PWM=11) are somewhere between
    // 100 and 300.
    //
    // If you you use reduced bit color (e.g. PWM=1 for 8 colors like for text),
    // then higher values might be good to minimize ghosting (and you can afford
    // that, because lower PWM values result in higher frame-rates).
    //
    // How to decide ? Just leave the default if things are fine. If you see
    // ghosting in high-contrast applications (e.g. text), increase the value.
    // If you want to tweak, watch the framerate (--led-show-refresh) while
    // playing with this number and the PWM values.
    int pwm_lsb_nanoseconds;

    // The initial brightness of the panel in percent. Valid range is 1..100
    // Default: 100
    int brightness;

    // Scan mode: 0=progressive, 1=interlaced
    int scan_mode;

    bool show_refresh_rate;
    bool swap_green_blue;
    bool inverse_colors;
  };

  // Create an RGBMatrix.
  //
  // If "io" is not NULL, initializes GPIO pins and starts refreshing the
  // screen immediately. If you need finer control, pass NULL here and see
  // SetGPIO() method.
  //
  // The resulting canvas is (options.rows * options.parallel) high and
  // (32 * options.chain_length) wide.
  RGBMatrix(GPIO *io, const Options &options);

  // Convenience constructor if you don't need the fine-control with the
  // Options object.
  RGBMatrix(GPIO *io, int rows = 32, int chained_displays = 1,
            int parallel_displays = 1);

  virtual ~RGBMatrix();

  // Set GPIO output if it was not set already in constructor (otherwise: NoOp).
  // If "start_thread" is true, starts the refresh thread.
  //
  // When would you start the thread separately from setting the GPIO ?
  // If you are becoming a daemon, you must start the thread _after_ that,
  // because all threads are stopped after daemon.
  // However, you need to set the GPIO before dropping privileges (which you
  // usually do when running as daemon).
  //
  // So if you write a daemon with dropping privileges, this is the pseudocode
  // of what you need to do:
  // ------------
  //   RGBMatrix::Options opts;
  //   RGBMatrix *matrix = new RGBMatrix(NULL, opts);  // No init with gpio yet.
  //   GPIO gpio;
  //   gpio.Init();
  //   matrix->SetGPIO(&gpio, false);   // First init GPIO use..
  //   drop_privileges();               // .. then drop privileges.
  //   daemon(0, 0);                    // .. start daemon before threads.
  //   matrix->StartRefresh();          // Now start thread.
  // -------------
  void SetGPIO(GPIO *io, bool start_thread = true);

  // Start thread. Typically, you don't need this, see SetGPIO() description
  // when you might want it.
  // It doesn't harm to call if the thread is already started.
  // Returns 'false' if it couldn't start because GPIO was not set yet.
  bool StartRefresh();

  // Set PWM bits used for output. Default is 11, but if you only deal with
  // limited comic-colors, 1 might be sufficient. Lower require less CPU and
  // increases refresh-rate.
  //
  // Returns boolean to signify if value was within range.
  //
  // This sets the PWM bits for the current active FrameCanvas and future
  // ones that are created with CreateFrameCanvas().
  bool SetPWMBits(uint8_t value);
  uint8_t pwmbits();   // return the pwm-bits of the currently active buffer.

  // Map brightness of output linearly to input with CIE1931 profile.
  void set_luminance_correct(bool on);
  bool luminance_correct() const;

  // Set brightness in percent. 1%..100%.
  // This will only affect newly set pixels.
  void SetBrightness(uint8_t brightness);
  uint8_t brightness();

  //-- Double- and Multibuffering.

  // Create a new buffer to be used for multi-buffering. The returned new
  // Buffer implements a Canvas with the same size of thie RGBMatrix.
  // You can use it to draw off-screen on it, then swap it with the active
  // buffer using SwapOnVSync(). That would be classic double-buffering.
  //
  // You can also create as many FrameCanvas as you like and for instance use
  // them to pre-fill scenes of an animation for fast playback later.
  //
  // The ownership of the created Canvases remains with the RGBMatrix, so you
  // don't have to worry about deleting them.
  FrameCanvas *CreateFrameCanvas();

  // This method waits to the next VSync and swaps the active buffer with the
  // supplied buffer. The formerly active buffer is returned.
  //
  // If you pass in NULL, the active buffer is returned, but it won't be
  // replaced with NULL. You can use the NULL-behavior to just wait on
  // VSync or to retrieve the initial buffer when preparing a multi-buffer
  // animation.
  //
  // The optional "framerate_fraction" parameter allows to choose which
  // multiple of the global frame-count to use. So it slows down your animation
  // to an exact fraction of the refresh rate.
  // Default is 1, so immediately next available frame.
  // (Say you have 140Hz refresh rate, then a value of 5 would give you an
  // 28Hz animation, nicely locked to the frame-rate).
  FrameCanvas *SwapOnVSync(FrameCanvas *other, unsigned framerate_fraction = 1);

  // Set image transformer that maps the logical canvas we provide to the
  // physical canvas (e.g. panel mapping, rotation ...).
  // Does _not_ take ownership of the transformer.
  void SetTransformer(CanvasTransformer *transformer);
  inline CanvasTransformer *transformer() { return transformer_; }

  // -- Canvas interface. These write to the active FrameCanvas
  // (see documentation in canvas.h)
  virtual int width() const;
  virtual int height() const;
  virtual void SetPixel(int x, int y,
                        uint8_t red, uint8_t green, uint8_t blue);
  virtual void Clear();
  virtual void Fill(uint8_t red, uint8_t green, uint8_t blue);

private:
  class UpdateThread;
  friend class UpdateThread;

  Options params_;
  bool do_luminance_correct_;

  FrameCanvas *active_;

  GPIO *io_;
  Mutex active_frame_sync_;
  UpdateThread *updater_;
  std::vector<FrameCanvas*> created_frames_;
  CanvasTransformer *transformer_;
};

class FrameCanvas : public Canvas {
public:
  // Set PWM bits used for this Frame.
  // Simple comic-colors, 1 might be sufficient (111 RGB, i.e. 8 colors).
  // Lower require less CPU.
  // Returns boolean to signify if value was within range.
  bool SetPWMBits(uint8_t value);
  uint8_t pwmbits();

  // Map brightness of output linearly to input with CIE1931 profile.
  void set_luminance_correct(bool on);
  bool luminance_correct() const;

  void SetBrightness(uint8_t brightness);
  uint8_t brightness();

  // -- Canvas interface.
  virtual int width() const;
  virtual int height() const;
  virtual void SetPixel(int x, int y,
                        uint8_t red, uint8_t green, uint8_t blue);
  virtual void Clear();
  virtual void Fill(uint8_t red, uint8_t green, uint8_t blue);

private:
  friend class RGBMatrix;

  FrameCanvas(internal::Framebuffer *frame) : frame_(frame){}
  virtual ~FrameCanvas();
  internal::Framebuffer *framebuffer() { return frame_; }

  internal::Framebuffer *const frame_;
};

// Convenience utility to create a Matrix and extract relevant values from the
// command line. Commandline flags are something like --led-rows, --led-chain,
// --led-parallel. See output of PrintMatrixFlags() for all available options.
//
// You call it with the address of 'argc' and 'argv' that you get from main();
// The function will extract the options and remove these from argv, so that
// your own flag processing does not have to deal with unknown options.
//
// The optional parameter is RGBMatrix::Option which allows you to
// pre-set options, such as your chain and parallel settings. It is also an
// out-parameter, so its values are changed according to what the user
// set on the command line.
//
// Example use:
/*
using rgb_matrix::RGBMatrix;
int main(int argc, char **argv) {
  // Set some defaults
  RGBMatrix::Options my_defaults;
  my_defaults.chain_length = 3;
  my_defaults.show_refresh_rate = true;
  rgb_matrix::RuntimeOptions runtime;
  runtime.drop_privileges = 1;
  RGBMatrix *matrix = rgb_matrix::CreateMatrixFromFlags(&argc, &argv,
                                                        &my_defaults, &runtime);
  if (matrix == NULL) {
    PrintMatrixFlags(stderr, my_defaults);
    return 1;
  }

  // Do your own command line handling with the remaining options.

  //  .. now use matrix

  delete matrix;   // Make sure to delete it in the end.
}
*/
struct RuntimeOptions {
  RuntimeOptions();

  int gpio_slowdown;    // 0 = no slowdown.
  int daemon;           // -1 disabled. 0=off, 1=on.
  int drop_privileges;  // -1 disabled. 0=off, 1=on.
};

RGBMatrix *CreateMatrixFromFlags(
  int *argc, char ***argv,
  RGBMatrix::Options *default_options = NULL,
  RuntimeOptions *runtime_options = NULL);

// Show all the available options for CreateMatrixFromFlags(). If
// show_daemon_option is set to false, the --led-daemon option is not shown.
void PrintMatrixFlags(FILE *out,
                      const RGBMatrix::Options &defaults = RGBMatrix::Options(),
                      const RuntimeOptions &rt_opt = RuntimeOptions());

}  // end namespace rgb_matrix
#endif  // RPI_RGBMATRIX_H