Clocks

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Time control.

Functions

Clock*	clock_create (...)
void	clock_destroy (...)
bool_t	clock_frame (...)
void	clock_reset (...)
real64_t	clock_elapsed (...)

Simple objects that allow us, in a comfortable way, to measure the time span between two instants. They are also useful for launching events at regular time intervals (Listing 1).

Use clock_create to create a clock.
Use clock_reset to reset the clock.
Use clock_elapsed to measure elapsed time.

Listing 1: 25fps animation.

Clock *clock = clock_create(.04);
for (;;)
{
    ...
    if (clock_frame(clock) == TRUE)
        listener_event(transition, ekGUI_EVENT_ANIMATION, NULL, params, NULL, void, EvTransition, void);
    ...
}
clock_destroy(&clock);

clock_create ()

Create a clock.

Clock*
clock_create(const real64_t interval);

interval

Time interval for animation control (in seconds).

Return

The new clock.

clock_destroy ()

Destroy the clock.

void
clock_destroy(Clock **clk);

clk	Clock. Will be set to `NULL` after destruction.

clock_frame ()

Detect if a new sequence in an animation has expired.

bool_t
clock_frame(Clock *clk,
            real64_t *prev_frame,
            real64_t *curr_frame);

clk	Clock.
prev_frame	Time mark of the previous instant. Only relevant if returns `TRUE`.
curr_frame	Time mark of the current instant. Only relevant if returns `TRUE`.

Return

TRUE if the time has come to launch a new sequence. FALSE if we have to wait.

clock_reset ()

Set the clock to 0.0.

void
clock_reset(Clock *clk);

clk

Clock.

clock_elapsed ()

Gets the time elapsed since the object was created or since the last call to clock_reset.

real64_t
clock_elapsed(Clock *clk);

clk

Clock.

Return

The number of seconds (with precision of micro-seconds 0.000001).