Filter graph

Connecting processing blocks

Generate usage scenario:

Filter* source;
Filter* sink;
// connect source's output to sink's input
source->GetPort("output")->Connect(sink->GetPort("input"));
// main loop
while (true) {
  // data output from source will be sent to sink for processing automatically
  source->Process();
}

A more "practical" example, in which a block's output port can be connected to 2 other input blocks:

#include "filter_graph.h"

// A block that generates random integers.
class IntegerGenerator : public filter_graph::Filter {
 public:
  IntegerGenerator() : rand_out_("rand_out") {
    AddOutput(&rand_out_);
  }

 protected:
  void OnProcess() {
    int number = rand();
    rand_out_.Write(number, sizeof(int));
  }

 private:
  Port rand_out;
};

// A block that consumes an integer and print out to standard output.
class IntegerPrinter : public filter_graph::Filter {
 public:
  IntegerPrinter() : integer_in_("integer_in") {
    AddInput(&integer_in_);
  }

 protected:
  void OnProcess() {
    int* number;
    integer_in_.Read(&number);
    cout << *number << endl;
  }

 private:
  Port integer_in_;
};

// A block that consumes an integer and write to log file.
class IntegerLogger : public filter_graph::Filter {
 public:
  IntegerLogger() : integer_in_("integer_in") {
    AddInput(&integer_in_);
  }

 protected:
  void OnProcess() {
    int* number;
    integer_in_.Read(&number);
    fwrite(number, sizeof(int), 1, log_file_);
  }

 private:
  Port integer_in_;
};

// set up of the filter graph
IntegerGenerator generator;
IntegerPrinter printer;
IntegerLogger logger;
generator["rand_out"]->Connect(printer["integer_in"]);
generator["rand_out"]->Connect(logger["integer_in"]);
// run the graph 50 iterations
for (int i=0; i<50; ++i)
  generator.Process();  // random integers generated by the generator block
                        // will be printed to the screen and written to log
                        // file at the same time.