makeDetailsMask() use prevTopPoint

Meter.c

@@ -477,7 +477,7 @@ static void GraphMeterMode_addItemAdjStack(GraphColorAdjStack* stack, double sca
    stack->nItems++;
 }
 
-static uint16_t GraphMeterMode_makeDetailsMask(const GraphColorComputeState* prev, const GraphColorComputeState* new, double rem, int blanksAtTopCell) {
+static uint16_t GraphMeterMode_makeDetailsMask(const GraphColorComputeState* prev, const GraphColorComputeState* new, double prevTopPoint, double rem, int blanksAtTopCell) {
    assert(new->nCellsPainted > prev->nCellsPainted);
    assert(rem >= 0.0);
    assert(rem < 1.0);
@@ -487,39 +487,39 @@ static uint16_t GraphMeterMode_makeDetailsMask(const GraphColorComputeState* pre
    if (isItemOnEdge && rem > 0.0 && rem < (0.125 * dotAlignment))
       rem = (0.125 * dotAlignment);
 
+   double maxBlanks = (1.0 - rem) * 8.0;
+
    uint8_t blanksAtEnd;
    bool roundsUpInAscii = false;
    bool roundsDownInAscii = false;
    if (blanksAtTopCell >= 0) {
       assert(blanksAtTopCell < 8);
       blanksAtEnd = (uint8_t)blanksAtTopCell;
       roundsUpInAscii = true;
-   } else if (prev->nCellsPainted == 0 || prev->topPoint <= (double)(int)prev->nCellsPainted) {
-      blanksAtEnd = (uint8_t)((1.0 - rem) * 8.0) % 8;
-   } else if ((double)(int)new->nCellsPainted > new->topPoint) {
-      assert((int)new->nCellsPainted - new->topPoint < 1.0);
+   } else if (prev->nCellsPainted == 0 || (double)(int)prev->nCellsPainted >= prevTopPoint) {
+      blanksAtEnd = (uint8_t)maxBlanks % 8;
+   } else {
       // Unlike other conditions, this one rounds to nearest for visual reason.
       // In case of a tie, display the dot at lower position of the graph,
       // i.e. MSB of the "details" data.
-      double fraction = (1.0 - rem) * 8.0;
-      fraction -= (int)fraction;
-      double distance = ((double)(int)new->nCellsPainted - new->topPoint) * 8.0 + (1.0 - fraction) * 0.5;
+      double fraction = maxBlanks - (int)maxBlanks;
+      double distance = maxBlanks + ((double)(int)prev->nCellsPainted - prevTopPoint) * 8.0 + (1.0 - fraction) * 0.5;
+      if (distance <= 0.0)
+         distance = 0.0;
+
       blanksAtEnd = (uint8_t)distance;
 
       // Tiebreaking direction that may be needed in the ASCII display mode.
       distance = distance - (int)distance;
-      assert(distance >= 0.0);
       assert(distance < 1.0);
       roundsUpInAscii = distance < 0.5;
       roundsDownInAscii = distance > 0.5;
-   } else {
-      blanksAtEnd = 0;
    }
    assert(blanksAtEnd < 8);
 
    uint8_t blanksAtStart;
    if (prev->nCellsPainted > 0) {
-      blanksAtStart = (uint8_t)((int)((1.0 - rem) * 8.0) - blanksAtEnd) % 8;
+      blanksAtStart = (uint8_t)((int)maxBlanks - blanksAtEnd) % 8;
    } else {
       // Always zero blanks for the first cell.
       // When an item would be painted with all cells (from the first cell to
@@ -551,11 +551,11 @@ static uint16_t GraphMeterMode_makeDetailsMask(const GraphColorComputeState* pre
       }
    } else if ((mask & 0xBFFD) == 0x1FFC) {
       // 5 dots at start, 6 or 7 dots at end
-      assert((mask & 0xFFFD) == 0x1FFC);
+      assert(mask == 0x1FFC || mask == 0x1FFE);
       mask &= 0xF7FF;
    } else if ((mask & 0xBFFD) == 0x3FF8) {
       // 6 or 7 dots at start, 5 dots at end
-      assert((mask & 0xBFFF) == 0x3FF8);
+      assert(mask == 0x3FF8 || mask == 0x7FF8);
       mask &= 0xFFEF;
    }
 
@@ -613,7 +613,6 @@ static void GraphMeterMode_computeColors(Meter* this, const GraphDrawContext* co
 
    GraphColorComputeState restart = {
       .valueSum = 0.0,
-      .topPoint = 0.0,
       .nCellsPainted = 0,
       .nItemsPainted = 0
    };
@@ -668,7 +667,6 @@ static void GraphMeterMode_computeColors(Meter* this, const GraphDrawContext* co
             assert(new.valueSum < DBL_MAX || prev.valueSum + value >= DBL_MAX);
          }
 
-         new.topPoint = (new.valueSum / scaledTotal) * (double)(int)graphHeight;
          double area = (value / scaledTotal) * (double)(int)graphHeight;
          double rem = area;
 
@@ -708,7 +706,8 @@ static void GraphMeterMode_computeColors(Meter* this, const GraphDrawContext* co
             assert(restart.nItemsPainted == prev.nItemsPainted);
 
             if (!rItemIsDetermined) {
-               stack.startPoint = new.topPoint;
+               double newTopPoint = (new.valueSum / scaledTotal) * (double)(int)graphHeight;
+               stack.startPoint = newTopPoint;
                rItemMinCells = nCells;
                rem = 0.0;
             } else if (rItemHasExtraCell) {
@@ -782,8 +781,9 @@ static void GraphMeterMode_computeColors(Meter* this, const GraphDrawContext* co
          }
 
          if (nCells > 0 && new.nCellsPainted <= nCellsToPaint) {
+            double prevTopPoint = (prev.valueSum / scaledTotal) * (double)(int)graphHeight;
             int blanksAtTopCellArg = (new.nCellsPainted == nCellsToPaint) ? (int)blanksAtTopCell : -1;
-            uint16_t mask = GraphMeterMode_makeDetailsMask(&prev, &new, rem, blanksAtTopCellArg);
+            uint16_t mask = GraphMeterMode_makeDetailsMask(&prev, &new, prevTopPoint, rem, blanksAtTopCellArg);
 
             GraphColorCell* cellsStart = &valueStart[firstCellIndex + (size_t)increment * prev.nCellsPainted];
             GraphMeterMode_paintCellsForItem(cellsStart, increment, prev.nItemsPainted, nCells, mask);

Meter.h

@@ -145,7 +145,6 @@ typedef struct GraphDrawContext_ {
    This structure is intended to be used only as local variables. */
 typedef struct GraphColorComputeState_ {
    double valueSum;
-   double topPoint;
    unsigned int nCellsPainted;
    uint8_t nItemsPainted;
 } GraphColorComputeState;