Use a recursive (instead of iterative) minmax depth finder

This is a bit more natural, and makes it much easier to do scale
independence.  In particular, I want to make it possible to grow and
shrink the graph, and this should make it particularly simple to react
by giving more or fewer minmax points.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/profile.c b/profile.c
index 9c2f4ed126567ef16ae5dc6f036f2dd53f611ba4..7c72d0b8c2b8be4aa50670f328127dbdb2cacda2 100644 (file)
--- a/profile.c
+++ b/profile.c
@@ -67,7 +67,7 @@ static void plot_text(cairo_t *cr, text_render_options_t *tro,
  * We exit early if we hit "enough" of a depth reversal,
  * which is roughly 10 feet.
  */
-static struct sample *next_minmax(struct dive *dive, struct sample *sample, struct sample *end, int minmax)
+static struct sample *next_minmax(struct sample *sample, struct sample *end, int minmax)
 {
        const int enough = 3000;
        struct sample *result;
@@ -116,6 +116,50 @@ static struct sample *next_minmax(struct dive *dive, struct sample *sample, stru
 /* Scale to 0,0 -> maxx,maxy */
 #define SCALE(x,y) (x)*maxx/scalex,(y)*maxy/scaley
 
+void plot_text_samples(struct dive *dive, cairo_t *cr,
+                       double maxx, double maxy,
+                       double scalex, double scaley,
+                       struct sample *a, struct sample *b)
+{
+       struct sample *max, *min;
+
+       if (b < a)
+               return;
+       if (b->time.seconds - a->time.seconds < 3*60)
+               return;
+
+       max = next_minmax(a, b, 1);
+       if (max) {
+               text_render_options_t tro = {1.0, 0.2, 0.2, CENTER};
+               int sec = max->time.seconds;
+               depth_t depth = max->depth;
+               const char *fmt;
+               double d;
+
+               min = next_minmax(max, b, 0);
+               plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, a, max);
+               if (min) {
+                       plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, max, min);
+                       plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, min, b);
+               } else
+                       plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, max, b);
+
+               switch (output_units.length) {
+               case METERS:
+                       d = depth.mm / 1000.0;
+                       fmt = "%.1f";
+                       break;
+               case FEET:
+                       d = to_feet(depth);
+                       fmt = "%.0f";
+                       break;
+               }
+
+               plot_text(cr, &tro, SCALE(sec, depth.mm), fmt, d);
+               return;
+       }
+}
+
 static void plot_depth_text(struct dive *dive, cairo_t *cr,
        double maxx, double maxy)
 {
@@ -141,29 +185,7 @@ static void plot_depth_text(struct dive *dive, cairo_t *cr,
        sample = dive->sample;
        end = dive->sample + dive->samples - 1;
 
-       while ((sample = next_minmax(dive, sample, end, 1)) != NULL) {
-               text_render_options_t tro = {1.0, 0.2, 0.2, CENTER};
-               int sec = sample->time.seconds;
-               depth_t depth = sample->depth;
-               const char *fmt;
-               double d;
-
-               switch (output_units.length) {
-               case METERS:
-                       d = depth.mm / 1000.0;
-                       fmt = "%.1f";
-                       break;
-               case FEET:
-                       d = to_feet(depth);
-                       fmt = "%.0f";
-                       break;
-               }
-
-               plot_text(cr, &tro, SCALE(sec, depth.mm), fmt, d);
-               sample = next_minmax(dive, sample, end, 0);
-               if (!sample)
-                       break;
-       }
+       plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, sample, end);
 }
 
 static void plot_depth_profile(struct dive *dive, cairo_t *cr,