## Types Types — Generic data types |

## Synopsis

    typedef             cairo_bool_t;
                        cairo_user_data_key_t;
    void                (*cairo_destroy_func_t)             (void *data);

## Description

Generic data types used in the cairo API

## Details

### cairo_bool_t

    typedef int cairo_bool_t;

cairo_bool_t is used for boolean values. Returns of type cairo_bool_t will always be either 0 or 1, but testing against these values explicitly is not encouraged; just use the value as a boolean condition.

     if (cairo_in_stroke (cr, x, y)) {
         /* do something */
     }

### cairo_user_data_key_t

    typedef struct {
        int unused;
    } cairo_user_data_key_t;

cairo_user_data_key_t is used for attaching user data to cairo data structures. The actual contents of the struct is never used, and there is no need to initialize the object; only the unique address of a cairo_data_key_t object is used. Typically, you would just use the address of a static cairo_data_key_t object.

int `unused`; | not used; ignore.

### cairo_destroy_func_t ()

    void                (*cairo_destroy_func_t)             (void *data);

cairo_destroy_func_t the type of function which is called when a data element is destroyed. It is passed the pointer to the data element and should free any memory and resources allocated for it.

`data` : | The data element being destroyed.