fix "empty" channel split, clang-tidy, fix tests

Author: schaumb

src/base/alg/merge.h

@@ -1,6 +1,7 @@
 #ifndef ALG_MERGE_H
 #define ALG_MERGE_H
 
+#include <algorithm>
 #include <cstdint>
 #include <functional>
 #include <ranges>

src/chart/generator/axis.cpp

@@ -295,6 +295,10 @@ DimensionAxis interpolate(const DimensionAxis &op0,
 	DimensionAxis res;
 
 	res.factor = factor;
+	res.hasMarker = !Math::Floating::is_zero(
+	    Math::Niebloid::interpolate(op0.hasMarker,
+	        op1.hasMarker,
+	        factor));
 	using Val = DimensionAxis::Values::value_type;
 
 	const Val *latest1{};
@@ -387,7 +391,7 @@ interpolate(const SplitAxis &op0, const SplitAxis &op1, double factor)
 			if (needMerge) {
 				if (firstSpecial) {
 					firstSpecial = false;
-					return merger(val, {{}, {1.0}});
+					return merger(val, {});
 				}
 
 				Math::Range<> range{0.0, 1.0};
@@ -410,15 +414,15 @@ interpolate(const SplitAxis &op0, const SplitAxis &op1, double factor)
 	    res.parts,
 	    Alg::merge_args{.projection = &PartPair::first,
 	        .transformer_1 =
-	            one_side(merger(factor), op1.parts.empty()),
+	            one_side(merger(factor), op1.parts.size() <= 1),
 	        .transformer_2 =
-	            one_side(merger(1 - factor), op0.parts.empty()),
+	            one_side(merger(1 - factor), op0.parts.size() <= 1),
 	        .need_merge = {needMerge},
 	        .merger = merger(factor)});
 
 	if (!needMerge && op0.parts.empty() != op1.parts.empty()
-	    && (!op0.dimension.empty() || op0.measure.enabled.get())
-	    && (!op1.dimension.empty() || op1.measure.enabled.get()))
+	    && (op0.dimension.hasMarker || op0.measure.enabled.get())
+	    && (op1.dimension.hasMarker || op1.measure.enabled.get()))
 		res.parts.insert({std::nullopt,
 		    {.weight = op0.parts.empty() ? 1 - factor : factor}});
 

src/chart/generator/axis.h

@@ -129,6 +129,7 @@ struct DimensionAxis
 	using Values = std::multimap<Data::SliceIndex, Item>;
 
 	double factor{};
+	bool hasMarker{};
 
 	DimensionAxis() = default;
 	bool add(const Data::SliceIndex &index,

src/chart/generator/plotbuilder.cpp

@@ -426,6 +426,7 @@ void PlotBuilder::calcLegendAndLabel(const Data::DataTable &dataTable)
 					        true,
 					        merge))
 						++count;
+					calcLegend.dimension.hasMarker = true;
 				}
 
 			if (auto &&series = plot->getOptions()->labelSeries(type);
@@ -448,7 +449,6 @@ void PlotBuilder::calcAxis(const Data::DataTable &dataTable,
     AxisId type)
 {
 	const auto &scale = plot->getOptions()->getChannels().at(type);
-	if (scale.isEmpty()) return;
 
 	auto &axisProps =
 	    plot->getOptions()->getChannels().axisPropsAt(type);
@@ -495,6 +495,8 @@ void PlotBuilder::calcAxis(const Data::DataTable &dataTable,
 				    {},
 				    false,
 				    merge);
+
+			axis.dimension.hasMarker = true;
 		}
 		if (auto &&series = plot->getOptions()->labelSeries(type);
 		    !axis.dimension.setLabels(axisProps.step.getValue(1.0))

src/chart/rendering/markers/connectingmarker.cpp

@@ -55,8 +55,8 @@ ConnectingMarker::ConnectingMarker(const DrawingContext &ctx,
 	linear = !polar || horizontal
 	      || Math::FuzzyBool::And(
 	          !isHorizontal
-	              && !ctx.plot->axises.at(Gen::AxisId::x)
-	                      .dimension.empty(),
+	              && ctx.plot->axises.at(Gen::AxisId::x)
+	                     .dimension.hasMarker,
 	          ctx.plot->axises.at(Gen::AxisId::x)
 	              .measure.enabled.factor(false),
 	          !horizontal);