Constructing the boilerplate

The first thing to do when making a new element is to specify some basic details about it: what its name is, who wrote it, what version number it is, etc. We also need to define an object to represent the element and to store the data the element needs. I shall refer to these details collectively as the boilerplate.

Doing it the hard way with GstObject

The standard way of defining the boilerplate is simply to write some code, and fill in some structures. The easiest way to do this is to copy an example and modify according to your needs.

First we will examine the code you would be likely to place in a header file (although since the interface to the code is entirely defined by the pluging system, and doesn't depend on reading a header file, this is not crucial.) The code here can be found in examples/plugins/example.h

  /* Definition of structure storing data for this element. */
  typedef struct _GstExample GstExample;
  struct _GstExample {
    GstElement element;

    GstPad *sinkpad,*srcpad;

    gint8 active;
  };

  /* Standard definition defining a class for this element. */
  typedef struct _GstExampleClass GstExampleClass;
  struct _GstExampleClass {
    GstElementClass parent_class;
  };

  /* Standard macros for defining types for this element.  */
  #define GST_TYPE_EXAMPLE \
    (gst_example_get_type())
  #define GST_EXAMPLE(obj) \
    (GTK_CHECK_CAST((obj),GST_TYPE_EXAMPLE,GstExample))
  #define GST_EXAMPLE_CLASS(klass) \
    (GTK_CHECK_CLASS_CAST((klass),GST_TYPE_EXAMPLE,GstExample))
  #define GST_IS_EXAMPLE(obj) \
    (GTK_CHECK_TYPE((obj),GST_TYPE_EXAMPLE))
  #define GST_IS_EXAMPLE_CLASS(obj) \
    (GTK_CHECK_CLASS_TYPE((klass),GST_TYPE_EXAMPLE))

  /* Standard function returning type information. */
  GtkType gst_example_get_type(void);