## libbtcore libbtcore — core library of the buzztard application framework |

## Synopsis

    #include <libbtcore/core.h>

    #define             BT_IS_STRING                        (a)
    #define             safe_string                         (a)
    #define             return_if_disposed                  ()
    #define             G_POINTER_ALIAS                     (type,var)
    #define             XML_CHAR_PTR                        (str)
    #define             g_object_try_ref                    (obj)
    #define             g_object_try_unref                  (obj)
    #define             g_object_try_weak_ref               (obj)
    #define             g_object_try_weak_unref             (obj)
    GList *             bt_gst_registry_get_element_names_matching_all_categories
                                                            (const gchar *class_filter);
    GList *             bt_gst_check_elements               (GList *list);
    GList *             bt_gst_check_core_elements          (void);
    gboolean            bt_gst_element_factory_can_sink_media_type
                                                            (GstElementFactory *factory,
                                                             const gchar *name);
    void                bt_gst_element_dbg_pads             (GstElement * const elem);
    GType               bt_g_type_get_base_type             (const GType type);
    guint               bt_cpu_load_get_current             (void);
    GOptionGroup *      bt_init_get_option_group            (void);
    void                bt_init_add_option_groups           (GOptionContext * const ctx);
    gboolean            bt_init_check                       (int *argc,
                                                             char **argv[],
                                                             GError **err);
    void                bt_init                             (int *argc,
                                                             char **argv[]);
    #define             BT_MAJOR_VERSION
    #define             BT_MINOR_VERSION
    #define             BT_MICRO_VERSION
    extern              const unsigned int bt_major_version;
    extern              const unsigned int bt_minor_version;
    extern              const unsigned int bt_micro_version;

## Description

The library offers base objects such as BtApplication and BtSong.

## Details

### BT_IS_STRING()

    #define BT_IS_STRING(a) (a && *a)

checks if the supplied string pointer is not `NULL` and contains not just '\0'

`a` : | string pointer

### safe_string()

    #define safe_string(a) ((gchar *)(a)?(gchar *)(a):"")

passed the supplied string through or return an empty string when it is NULL

`a` : | string pointer
Returns : | the given string or an empty string in the case of a NULL argument

### return_if_disposed()

    #define return_if_disposed() if(self->priv->dispose_has_run) return

checks `self->priv->dispose_has_run` and if true returns with the supplied arg. This macro is handy to use at the start of all class routines such as `_get_property()`, `_set_property()`, `_dispose()`.

`a` : | return value or nothing

### G_POINTER_ALIAS()

    #define             G_POINTER_ALIAS(type,var)

Defines a anonymous union to handle gcc-4.1s type punning warning that one gets when using e.g. `g_object_try_weak_ref()`

`type` : | the type
`var` : | the variable name

### XML_CHAR_PTR()

    #define XML_CHAR_PTR(str) ((xmlChar *)(str))

Cast to xmlChar*

`str` : | the string to cast

### g_object_try_ref()

    #define             g_object_try_ref(obj)

If the supplied object is not `NULL` then reference it via `g_object_ref()`.

`obj` : | the object to reference
Returns : | the referenced object or `NULL`

### g_object_try_unref()

    #define             g_object_try_unref(obj)

If the supplied object is not `NULL` then release the reference via `g_object_unref()`.

`obj` : | the object to release the reference

### g_object_try_weak_ref()

    #define             g_object_try_weak_ref(obj)

If the supplied object is not `NULL` then reference it via `g_object_add_weak_pointer()`.

`obj` : | the object to reference

### g_object_try_weak_unref()

    #define             g_object_try_weak_unref(obj)

If the supplied object is not `NULL` then release the reference via `g_object_remove_weak_pointer()`.

`obj` : | the object to release the reference

### bt_gst_registry_get_element_names_matching_all_categories ()

    GList *             bt_gst_registry_get_element_names_matching_all_categories
                                                            (const gchar *class_filter);

Iterates over all available plugins and filters by categories given in `class_filter`.

`class_filter` : | path for filtering (e.g. "Sink/Audio")
Returns : | list of element names, g_list_free after use.

### bt_gst_check_elements ()

    GList *             bt_gst_check_elements               (GList *list);

Check if the given elements exist.

`list` : | a GList with element names
Returns : | a list of elements that does not exist, `NULL` if all elements exist

### bt_gst_check_core_elements ()

    GList *             bt_gst_check_core_elements          (void);

Check if all core elements exist.

Returns : | a list of elements that does not exist, `NULL` if all elements exist

### bt_gst_element_factory_can_sink_media_type ()

    gboolean            bt_gst_element_factory_can_sink_media_type
                                                            (GstElementFactory *factory,
                                                             const gchar *name);

Check if a factories sink pads are compatible with the given `name`. The `name` can e.g. be "audio/x-raw-int".

`factory` : | element factory to check
`name` : | caps type name
Returns : | `TRUE` if the pads are compatible.

### bt_gst_element_dbg_pads ()

    void                bt_gst_element_dbg_pads             (GstElement * const elem);

Write out a list of pads for the given element

`elem` : | a GstElement

### bt_g_type_get_base_type ()

    GType               bt_g_type_get_base_type             (const GType type);

Call `g_type_parent()` as long as it returns a parent.

`type` : | a GType
Returns : | the super parent type, aka base type.

### bt_cpu_load_get_current ()

    guint               bt_cpu_load_get_current             (void);

Determines the current CPU load.

Returns : | CPU usage as integer ranging from 0% to 100%

### bt_init_get_option_group ()

    GOptionGroup *      bt_init_get_option_group            (void);

Returns a GOptionGroup with libbtcore's argument specifications. The group is set up to use standard GOption callbacks, so when using this group in combination with GOption parsing methods, all argument parsing and initialization is automated.

This function is useful if you want to integrate libbtcore with other libraries that use GOption (see `g_option_context_add_group()` ).

Returns : | a pointer to a GOption group. Should be dereferenced after use.

### bt_init_add_option_groups ()

    void                bt_init_add_option_groups           (GOptionContext * const ctx);

Adds all option groups to the main context the core library will pull in.

`ctx` : | main option context

### bt_init_check ()

    gboolean            bt_init_check                       (int *argc,
                                                             char **argv[],
                                                             GError **err);

Initializes the Buzztard core library.

This function will return `FALSE` if Buzztard core could not be initialized for some reason. If you want your program to fail fatally, use `bt_init()` instead.

`argc` : | pointer to application's argc. inout.
`argv` : | pointer to application's argv. array length=argc. inout length=argc.
`err` : | pointer to a GError to which a message will be posted on error
Returns : | `TRUE` if Buzztard core could be initialized.

### bt_init ()

    void                bt_init                             (int *argc,
                                                             char **argv[]);

Initializes the Buzztard Core library.

### Note

This function will terminate your program if it was unable to initialize the core for some reason. If you want your program to fall back, use `bt_init_check()` instead.

WARNING: This function does not work in the same way as corresponding functions in other glib-style libraries, such as `gtk_init()`. In particular, unknown command line options cause this function to abort program execution.

`argc` : | pointer to application's argc. inout.
`argv` : | pointer to application's argv. array length=argc. inout length=argc.

### BT_MAJOR_VERSION

    #define BT_MAJOR_VERSION 0

buzztard version stamp, major part; determined from configure.ac

### BT_MINOR_VERSION

    #define BT_MINOR_VERSION 5

buzztard version stamp, minor part; determined from configure.ac

### BT_MICRO_VERSION

    #define BT_MICRO_VERSION 0

buzztard version stamp, micro part; determined from configure.ac

### bt_major_version

    extern const unsigned int bt_major_version;

buzztard version stamp, major part; determined from BT_MAJOR_VERSION

### bt_minor_version

    extern const unsigned int bt_minor_version;

buzztard version stamp, minor part; determined from BT_MINOR_VERSION

### bt_micro_version

    extern const unsigned int bt_micro_version;

buzztard version stamp, micro part; determined from BT_MICRO_VERSION