Update "total" value for non-percent bar meters

If "isPercentChart" of a meter is false, update its "total" value
automatically in the bar meter mode. The "total" value is capped to
DBL_MAX in order to ensure the division never produces NaN.

The newly introduced Meter_computeSum() function will be reused by the
feature "Graph meter dynamic scaling and percent graph drawing".

Signed-off-by: Kang-Che Sung <explorer09@gmail.com>

Author: Explorer09

Meter.c

@@ -10,6 +10,7 @@ in the source distribution for its full text.
 #include "Meter.h"
 
 #include <assert.h>
+#include <float.h>
 #include <limits.h> // IWYU pragma: keep
 #include <math.h>
 #include <stdlib.h>
@@ -47,6 +48,14 @@ static inline void Meter_displayBuffer(const Meter* this, RichString* out) {
    }
 }
 
+static double Meter_computeSum(const Meter* this) {
+   assert(this->curItems > 0);
+   assert(this->values);
+   double sum = sumPositiveValues(this->values, this->curItems);
+   // Prevent rounding to infinity in IEEE 754
+   return MINIMUM(DBL_MAX, sum);
+}
+
 /* ---------- TextMeterMode ---------- */
 
 static void TextMeterMode_draw(Meter* this, int x, int y, int w) {
@@ -100,6 +109,12 @@ static void BarMeterMode_draw(Meter* this, int x, int y, int w) {
       w--;
    }
 
+   // Update the "total" if necessary
+   if (!Meter_isPercentChart(this) && this->curItems > 0) {
+      double sum = Meter_computeSum(this);
+      this->total = MAXIMUM(sum, this->total);
+   }
+
    if (w < 1) {
       goto end;
    }