Tweak temperature plot to look better for small fluctuations

If the temperature is in a very narrow range the existing code visually
exaggerated the fluctuations. This tries to dampen that effect a bit.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

diff --git a/profile.c b/profile.c
index 35a1366bffd90dc42e95edd14fe00f9cd6af951a..7cad699ceaae7a868d3126f1c8072cf1ebf97845 100644 (file)
--- a/profile.c
+++ b/profile.c
@@ -300,7 +300,7 @@ static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi
 
 static int setup_temperature_limits(struct graphics_context *gc, struct plot_info *pi)
 {
-       int maxtime, mintemp, maxtemp;
+       int maxtime, mintemp, maxtemp, delta;
 
        /* Get plot scaling limits */
        maxtime = get_maxtime(pi);
@@ -308,9 +308,16 @@ static int setup_temperature_limits(struct graphics_context *gc, struct plot_inf
        maxtemp = pi->maxtemp;
 
        gc->leftx = 0; gc->rightx = maxtime;
-       /* Show temperatures in roughly the lower third */
-       gc->topy = maxtemp + (maxtemp - mintemp)*2;
-       gc->bottomy = mintemp - (maxtemp - mintemp)/2;
+       /* Show temperatures in roughly the lower third, but make sure the scale
+          is at least somewhat reasonable */
+       delta = maxtemp - mintemp;
+       if (delta > 3000) { /* more than 3K in fluctuation */
+               gc->topy = maxtemp + delta*2;
+               gc->bottomy = mintemp - delta/2;
+       } else {
+               gc->topy = maxtemp + 1500 + delta*2;
+               gc->bottomy = mintemp - delta/2;
+       }
 
        return maxtemp > mintemp;
 }