charts: stub out marker API

This introduces the concept of border markers intended to serve
as timeline references/milestones.

Here only the minimal API for setting their distance is added,
nothing is actually implemented yet.

2 files changed, 11 insertions, 0 deletions

diff --git a/src/charts.c b/src/charts.c
index 8001526..9d31603 100644
--- a/src/charts.c
+++ b/src/charts.c
@@ -65,6 +65,7 @@ typedef struct _vwm_charts_t {
 	vmon_t					vmon;
 	float					prev_sampling_interval_secs, sampling_interval_secs;
 	int					sampling_paused, contiguous_drops, primed;
+	unsigned				marker_distance;
 	float					inv_ticks_per_sec, inv_total_delta;
 	unsigned				defer_maintenance:1;
 } vwm_charts_t;
@@ -1300,6 +1301,15 @@ void vwm_charts_rate_set(vwm_charts_t *charts, unsigned hertz)
 }
 
 
+/* set an arbitrary marker spacing in pixels, 0 disables markers (default) */
+void vwm_charts_marker_distance_set(vwm_charts_t *charts, unsigned distance)
+{
+	assert(charts);
+
+	charts->marker_distance = distance;
+}
+
+
 /* convenience function for returning the time delta as a seconds.fraction float */
 static float delta(struct timespec *cur, struct timespec *prev)
 {
diff --git a/src/charts.h b/src/charts.h
index e175d18..888fc9d 100644
--- a/src/charts.h
+++ b/src/charts.h
@@ -18,6 +18,7 @@ void vwm_charts_destroy(vwm_charts_t *charts);
 void vwm_charts_rate_increase(vwm_charts_t *charts);
 void vwm_charts_rate_decrease(vwm_charts_t *charts);
 void vwm_charts_rate_set(vwm_charts_t *charts, unsigned hertz);
+void vwm_charts_marker_distance_set(vwm_charts_t *charts, unsigned distance);
 int vwm_charts_update(vwm_charts_t *charts, int *desired_delay_us);
 
 vwm_chart_t * vwm_chart_create(vwm_charts_t *charts, int pid, int width, int height, const char *name);