73 typedef struct preview_stream_ops {  struct
74     int (*dequeue_buffer)(struct preview_stream_ops* w,  argument
76     int (*enqueue_buffer)(struct preview_stream_ops* w,  argument
78     int (*cancel_buffer)(struct preview_stream_ops* w,  argument
80     int (*set_buffer_count)(struct preview_stream_ops* w, int count);  argument
81     int (*set_buffers_geometry)(struct preview_stream_ops* pw,  argument
83     int (*set_crop)(struct preview_stream_ops *w,  argument
85     int (*set_usage)(struct preview_stream_ops* w, int usage);  argument
86     int (*set_swap_interval)(struct preview_stream_ops *w, int interval);  argument
87     int (*get_min_undequeued_buffer_count)(const struct preview_stream_ops *w,  argument
89     int (*lock_buffer)(struct preview_stream_ops* w,  argument
95     int (*set_timestamp)(struct preview_stream_ops *w, int64_t timestamp);  argument