Store itemNum in GraphColorCell

Meter.c

@@ -315,13 +315,6 @@ static void GraphMeterMode_reallocateGraphBuffer(Meter* this, const GraphDrawCon
 
    // Fill new spaces with blank records
    memset(data->buffer, 0, moveOffset * sizeof(*data->buffer));
-   if (context->maxItems > 1) {
-      for (size_t i = 0; i < moveOffset; i++) {
-         if (context->isPercentChart || i % nCellsPerValue > 0) {
-            data->buffer[i].c.itemIndex = UINT8_MAX;
-         }
-      }
-   }
 
 bufferInitialized:
    data->nValues = nValues;
@@ -572,7 +565,7 @@ static uint16_t GraphMeterMode_makeDetailsMask(const GraphColorComputeState* pre
 static void GraphMeterMode_paintCellsForItem(GraphColorCell* cellsStart, unsigned int increment, uint8_t itemIndex, unsigned int nCells, uint16_t mask) {
    GraphColorCell* cell = cellsStart;
    while (nCells > 0) {
-      cell->c.itemIndex = itemIndex;
+      cell->c.itemNum = itemIndex + 1;
       if (nCells == 1) {
          cell->c.details = (uint8_t)mask;
       } else if (cell == cellsStart) {
@@ -896,9 +889,9 @@ static void GraphMeterMode_recordNewValue(Meter* this, const GraphDrawContext* c
    // Clear cells
    unsigned int i = ((unsigned int)numDots + 8 - 1) / 8; // Round up
    i = GraphMeterMode_valueCellIndex(graphHeight, isPercentChart, 0, i, NULL, NULL);
-   for (; i < nCellsPerValue; i++) {
-      valueStart[i].c.itemIndex = UINT8_MAX;
-      valueStart[i].c.details = 0x00;
+   if (i != (unsigned int)-1) {
+      assert(i < nCellsPerValue);
+      memset(&valueStart[i], 0, (nCellsPerValue - i) * sizeof(*valueStart));
    }
 
    if (sum <= 0.0)
@@ -982,7 +975,7 @@ static int GraphMeterMode_lookupCell(const Meter* this, const GraphDrawContext*
    assert(y < graphHeight);
    y = graphHeight - 1 - y;
 
-   uint8_t itemIndex = UINT8_MAX;
+   uint8_t itemIndex = (uint8_t)-1;
    *details = 0x00; // Empty the cell
 
    if (maxItems < 1)
@@ -1040,7 +1033,7 @@ static int GraphMeterMode_lookupCell(const Meter* this, const GraphDrawContext*
       }
 
       const GraphColorCell* cell = &valueStart[i];
-      itemIndex = cell->c.itemIndex;
+      itemIndex = cell->c.itemNum - 1;
       *details = GraphMeterMode_scaleCellDetails(cell->c.details, scaleFactor);
    }
    /* fallthrough */
@@ -1049,7 +1042,7 @@ static int GraphMeterMode_lookupCell(const Meter* this, const GraphDrawContext*
    if (y == 0)
       *details |= 0xC0;
 
-   if (itemIndex == UINT8_MAX)
+   if (itemIndex == (uint8_t)-1)
       return BAR_SHADOW;
 
    assert(itemIndex < maxItems);

Meter.h

@@ -102,7 +102,7 @@ typedef union GraphColorCell_ {
    int16_t scaleExp;
    uint16_t numDots;
    struct GraphColorCellCell_ {
-      uint8_t itemIndex;
+      uint8_t itemNum;
       uint8_t details;
    } c;
 } GraphColorCell;