Replace code with simpler but equivalent code

The if-branching is unnecessary because
  ceil(a-b) == -floor(b-a)

Also add comments to clarify subtle differences in seemingly
identical code snippets.

Change-Id: Idfd72e4aecf53805183f5b2741336d805fbfbb6a
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

1 files changed, 6 insertions, 10 deletions

diff --git a/src/charts/axis/chartaxiselement.cpp b/src/charts/axis/chartaxiselement.cpp
index b17f5cdb..d036041c 100644
--- a/src/charts/axis/chartaxiselement.cpp
+++ b/src/charts/axis/chartaxiselement.cpp
@@ -430,12 +430,10 @@ QStringList ChartAxisElement::createValueLabels(qreal min, qreal max, int ticks,
                 labels << presenter()->numberToString(value, 'f', n);
             }
         } else {
-            qreal value = tickAnchor;
-            if (value > min)
-                value = value - std::floor((value - min) / tickInterval) * tickInterval;
-            else
-                value = value + std::ceil((min - value) / tickInterval) * tickInterval;
+            const qreal ticksFromAnchor = (tickAnchor - min) / tickInterval;
+            const qreal firstMajorTick = tickAnchor - std::floor(ticksFromAnchor) * tickInterval;
 
+            qreal value = firstMajorTick;
             while (value <= max) {
                 labels << presenter()->numberToString(value, 'f', n);
                 value += tickInterval;
@@ -472,12 +470,10 @@ QStringList ChartAxisElement::createValueLabels(qreal min, qreal max, int ticks,
                 labels << formatLabel(formatSpec, array, value, precision, preStr, postStr);
             }
         } else {
-            qreal value = tickAnchor;
-            if (value > min)
-                value = value - std::floor((value - min) / tickInterval) * tickInterval;
-            else
-                value = value + std::ceil((min - value) / tickInterval) * tickInterval;
+            const qreal ticksFromAnchor = (tickAnchor - min) / tickInterval;
+            const qreal firstMajorTick = tickAnchor - std::floor(ticksFromAnchor) * tickInterval;
 
+            qreal value = firstMajorTick;
             while (value <= max) {
                 labels << formatLabel(formatSpec, array, value, precision, preStr, postStr);
                 value += tickInterval;