Graph meter dynamic scaling and percent graph drawing

Implement dynamic scaling for Graph meter mode, and separate it from
"100% graph" drawing. This is controlled by the "isPercentChart"
property of a MeterClass.

If "isPercentChart" is true, the meter would be drawn as a
"100% graph". Graph meters now expect the "total" value may change, and
the newly changed "total" value no longer affects the percent graph
drawings of earlier meter values.

If "isPercentChart" is false, the meter would be drawn with a dynamic
scale.

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

Author: Explorer09

Meter.c

@@ -230,9 +230,12 @@ static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
    }
    w -= captionLen;
 
+   // Prepare parameters for drawing
    assert(this->h >= 1);
    int h = this->h;
 
+   bool isPercentChart = Meter_isPercentChart(this);
+
    GraphData* data = &this->drawData;
 
    // Expand the graph data buffer if necessary
@@ -261,8 +264,10 @@ static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
 
       data->values[nValues - 1] = 0.0;
       if (this->curItems > 0) {
-         assert(this->values);
-         data->values[nValues - 1] = sumPositiveValues(this->values, this->curItems);
+         data->values[nValues - 1] = Meter_computeSum(this);
+         if (isPercentChart && this->total > 0.0) {
+            data->values[nValues - 1] /= this->total;
+         }
       }
    }
 
@@ -292,10 +297,19 @@ static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
    }
    size_t i = nValues - (size_t)w * 2;
 
+   // Determine the graph scale
+   double total = 1.0;
+   if (!isPercentChart) {
+      for (size_t j = i; j < nValues; j++) {
+         total = MAXIMUM(data->values[j], total);
+      }
+      assert(total <= DBL_MAX);
+   }
+   assert(total >= 1.0);
+
    // Draw the actual graph
    for (int col = 0; i < nValues - 1; i += 2, col++) {
       int pix = GraphMeterMode_pixPerRow * h;
-      double total = MAXIMUM(this->total, 1);
       int v1 = (int) lround(CLAMP(data->values[i] / total * pix, 1.0, pix));
       int v2 = (int) lround(CLAMP(data->values[i + 1] / total * pix, 1.0, pix));