Retrieves an array of logical attributes for each character in the this.
| this |
a `PangoLayout` |
| attrs |
location to store a pointer to an array of logical attributes. This value must be freed with g_free. |
| n_attrs |
location to store the number of the attributes in the array. (The stored value will be one more than the total number of characters in the layout, since there need to be attributes corresponding to both the position before the first character and the position after the last character.) |