Module.h File Reference

Detailed Description

Information required to use the StreamingClient as a plugin.

Sometimes it's useful for client applications to avoid linking against libola, say for instance if they install separately from OLA. By deferring the linking and using libola as a plugin, clients can use OLA if it's installed on the system or if not, take some other action like displaing a message or using another output mechanism.

This file provides plugin interfaces so that a client code can load a small subset of libola at runtime. For each function we #define the symbol name and then provide the function type signature and the actual function itself.

http://www.tldp.org/HOWTO/html_single/C++-dlopen provides some good background.

#include <dlfcn.h>
#include <ola/client/StreamingClient.h>
#include <ola/DmxBuffer.h>
#include <ola/client/Module.h>

#include <iostream>

using std::cout;
using std::endl;

template <typename FunctionType>
FunctionType LoadSymbol(void *module, const char *symbol) {
  FunctionType ptr = reinterpret_cast<FunctionType>(dlsym(module, symbol));
  if (!ptr) {
    cout << "Failed to find " << symbol << " " << dlerror() << endl;
  }
  return ptr;
}

int main() {
  ola::client::StreamingClientInterface *client = NULL;

  // Adjust to suit.
  void *module = dlopen("/usr/local/lib/libola.dylib", RTLD_NOW);
  // void *module = dlopen("/usr/local/lib/libola.so", RTLD_NOW);
  if (!module) {
    cout << "Failed to load" << dlerror() << endl;
    return -1;
  }

  ola_new_streaming_client_t *new_client_ptr =
      LoadSymbol<ola_new_streaming_client_t*>(module, OLA_NEW_STREAMING_CLIENT);
  ola_delete_streaming_client_t *delete_client_ptr =
      LoadSymbol<ola_delete_streaming_client_t*>(
         module, OLA_DELETE_STREAMING_CLIENT);
  ola_new_dmxbuffer_t *new_buffer_ptr =
      LoadSymbol<ola_new_dmxbuffer_t*>(module, OLA_NEW_DMXBUFFER);
  ola_delete_dmxbuffer_t *delete_buffer_ptr =
      LoadSymbol<ola_delete_dmxbuffer_t*>(module, OLA_DELETE_DMXBUFFER);
  ola_set_dmxbuffer_t *set_buffer_ptr =
      LoadSymbol<ola_set_dmxbuffer_t*>(module, OLA_SET_DMXBUFFER);

  if (!(new_client_ptr && delete_client_ptr && new_buffer_ptr &&
        delete_buffer_ptr && set_buffer_ptr)) {
    return -1;
  }

  ola::client::StreamingClient::Options options;
  client = new_client_ptr(options);
  cout << "Setup() returned: " << client->Setup() << endl;

  ola::DmxBuffer *buffer = new_buffer_ptr();

  // Now actually send the DMX
  uint8_t data[] = {1, 2, 3};
  set_buffer_ptr(buffer, data, sizeof(data));
  const unsigned int universe = 1;
  client->SendDMX(universe, *buffer, ola::client::StreamingClient::SendArgs());

  client->Stop();

  delete_buffer_ptr(buffer);
  delete_client_ptr(client);

  if (module) {
    dlclose(module);
  }
}

Go to the source code of this file.

Namespaces
namespace	ola
	The namespace containing all OLA symbols.
namespace	ola::client
	OLA C++ API.

Macros
#define	OLA_NEW_STREAMING_CLIENT   "ola_new_streaming_client"
	The symbol for the function to create a new StreamingClient.
#define	OLA_DELETE_STREAMING_CLIENT   "ola_delete_streaming_client"
	The symbol for the function to delete a StreamingClient.
#define	OLA_NEW_DMXBUFFER   "ola_new_dmxbuffer"
	The symbol for the function to create a new DmxBuffer.
#define	OLA_DELETE_DMXBUFFER   "ola_delete_dmxbuffer"
	The symbol for the function to delete a DmxBuffer.
#define	OLA_SET_DMXBUFFER   "ola_set_dmxbuffer"
	The symbol for the function to set the contents of a DmxBuffer.

Typedefs
typedef ola::client::StreamingClientInterface *	ola_new_streaming_client_t (const ola::client::StreamingClient::Options &options)
	A function pointer to create a new StreamingClient.
typedef void	ola_delete_streaming_client_t (ola::client::StreamingClientInterface *client)
	A function pointer to delete a StreamingClient.
typedef ola::DmxBuffer *	ola_new_dmxbuffer_t ()
	A function pointer to create a new DmxBuffer.
typedef void	ola_delete_dmxbuffer_t (ola::DmxBuffer *buffer)
	A function pointer to delete a DmxBuffer.
typedef void	ola_set_dmxbuffer_t (ola::DmxBuffer *buffer, const uint8_t *data, unsigned int size)
	A function pointer to set the contents of a DmxBuffer.

Functions
ola::client::StreamingClientInterface *	ola_new_streaming_client (const ola::client::StreamingClient::Options &options)
void	ola_delete_streaming_client (ola::client::StreamingClientInterface *client)
ola::DmxBuffer *	ola_new_dmxbuffer ()
void	ola_delete_dmxbuffer (ola::DmxBuffer *buffer)
void	ola_set_dmxbuffer (ola::DmxBuffer *buffer, const uint8_t *data, unsigned int size)

Typedef Documentation

typedef void ola_set_dmxbuffer_t(ola::DmxBuffer *buffer, const uint8_t *data, unsigned int size)

A function pointer to set the contents of a DmxBuffer.

To avoid the vtable penalty with DmxBuffer we expose a function to call Set(). If you want to access other methods in DmxBuffer please send a patch.