Graph meter dynamic scaling

Signed-off-by: Kang-Che Sung <[email protected]>

Meter.c

@@ -206,12 +206,36 @@ static const char* const GraphMeterMode_dotsAscii[] = {
    /*20*/":", /*21*/":", /*22*/":"
 };
 
+static void GraphMeterMode_printScale(int exponent) {
+   if (exponent < 10) {
+      // "1" to "512"; the (exponent < 0) case is not implemented.
+      assert(exponent >= 0);
+      printw("%3u", 1U << exponent);
+   } else if (exponent > (int)ARRAYSIZE(unitPrefixes) * 10 + 6) {
+      addstr("inf");
+   } else if (exponent % 10 < 7) {
+      // "1K" to "64K", "1M" to "64M", "1G" to "64G", etc.
+      printw("%2u%c", 1U << (exponent % 10), unitPrefixes[exponent / 10 - 1]);
+   } else {
+      // "M/8" (=128K), "M/4" (=256K), "M/2" (=512K), "G/8" (=128M), etc.
+      printw("%c/%u", unitPrefixes[exponent / 10], 1U << (10 - exponent % 10));
+   }
+}
+
 static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
    // Draw the caption
    const char* caption = Meter_getCaption(this);
    attrset(CRT_colors[METER_TEXT]);
    const int captionLen = 3;
    mvaddnstr(y, x, caption, captionLen);
+
+   // Prepare parameters for drawing
+   uint8_t maxItems = Meter_maxItems(this);
+   bool isPercentChart = Meter_isPercentChart(this);
+   bool needsScaleDisplay = maxItems > 0 && GRAPH_HEIGHT >= 2;
+   if (needsScaleDisplay) {
+      move(y + 1, x); // Cursor position for printing the scale
+   }
    x += captionLen;
    w -= captionLen;
 
@@ -243,8 +267,10 @@ 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;
+         }
       }
    }
 
@@ -272,10 +298,38 @@ static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
    }
    size_t i = nValues - (size_t)w * 2;
 
+   // Determine and print the graph scale
+   double total = 1.0;
+   int scaleExp = 0;
+   if (maxItems > 0 && !isPercentChart) {
+      total = 0.0;
+      for (size_t j = i; j < nValues; j++) {
+         if (total < data->values[j]) {
+            total = data->values[j];
+	 }
+      }
+      assert(total <= DBL_MAX);
+      (void)frexp(total, &scaleExp);
+      if (scaleExp < 0) {
+         scaleExp = 0;
+      }
+      total = ldexp(1.0, scaleExp);
+      if (total > DBL_MAX) {
+         total = DBL_MAX;
+      }
+   }
+   assert(total >= 1.0);
+   if (needsScaleDisplay) {
+      if (isPercentChart) {
+         addstr("  %");
+      } else {
+         GraphMeterMode_printScale(scaleExp);
+      }
+   }
+
    // Draw the actual graph
    for (int col = 0; i < nValues - 1; i += 2, col++) {
       int pix = GraphMeterMode_pixPerRow * GRAPH_HEIGHT;
-      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));