lqr_carver_set_alpha_channel — sets the alpha channel index in a LqrCarver object
#include <lqr.h>
| LqrRetVal lqr_carver_set_alpha_channel( | LqrCarver * carver, | 
| gint channel_index ); | 
                        The function lqr_carver_set_alpha_channel sets the alpha channel index of
                        the image stored in the LqrCarver pointed to by carver to
                        channel_index (between 0 and channels -
                        1, where channels is the number of colour channels of the
                        carver).
                    
                        Use a negative value for cahnnel_index to specify that no alpha channel
                        is present.
                    
If the specified channel coincides with the current value of the black channel, the black channel is unset.
                        Calling this function sets the image time of the carver to
                        LQR_CUSTOM_IMAGE.