From 901cce9e67a504cfe99023306ee6ae74ce7cd4c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Mon, 9 Sep 2019 10:44:30 +0200
Subject: [PATCH] [apps/graph] Move nextRootFrom from the controller to the
 model CartesianFunction and take into account function domain

---
 apps/graph/graph/root_graph_controller.cpp |  6 +-----
 apps/shared/cartesian_function.cpp         | 17 +++++++++++++++++
 apps/shared/cartesian_function.h           |  3 +++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/apps/graph/graph/root_graph_controller.cpp b/apps/graph/graph/root_graph_controller.cpp
index dd41713d4..413a5155c 100644
--- a/apps/graph/graph/root_graph_controller.cpp
+++ b/apps/graph/graph/root_graph_controller.cpp
@@ -17,11 +17,7 @@ const char * RootGraphController::title() {
 }
 
 Coordinate2D<double> RootGraphController::computeNewPointOfInterest(double start, double step, double max, Context * context) {
-  // TODO The following three lines should be factored.
-  constexpr int bufferSize = CodePoint::MaxCodePointCharLength + 1;
-  char unknownX[bufferSize];
-  Poincare::SerializationHelper::CodePoint(unknownX, bufferSize, UCodePointUnknownX);
-  return Coordinate2D<double>(Shared::PoincareHelpers::NextRoot(functionStore()->modelForRecord(m_record)->expressionReduced(context), unknownX, start, step, max, context), 0.0);
+  return functionStore()->modelForRecord(m_record)->nextRootFrom(start, step, max, context);
 }
 
 }
diff --git a/apps/shared/cartesian_function.cpp b/apps/shared/cartesian_function.cpp
index e4b3beca0..bf3ebcf54 100644
--- a/apps/shared/cartesian_function.cpp
+++ b/apps/shared/cartesian_function.cpp
@@ -274,6 +274,10 @@ Coordinate2D<T> CartesianFunction::templatedApproximateAtParameter(T t, Poincare
       PoincareHelpers::ApproximateWithValueForSymbol(e.childAtIndex(1), unknown, t, context));
 }
 
+Coordinate2D<double> CartesianFunction::nextRootFrom(double start, double step, double max, Context * context) const {
+  return nextPointOfInterestFrom(start, step, max, context, [](Expression e, char * symbol, double start, double step, double max, Context * context) { return Coordinate2D<double>(PoincareHelpers::NextRoot(e, symbol, start, step, max, context), 0.0); });
+}
+
 Coordinate2D<double> CartesianFunction::nextIntersectionFrom(double start, double step, double max, Poincare::Context * context, CartesianFunction * f) const {
   assert(plotType() == PlotType::Cartesian);
   constexpr int bufferSize = CodePoint::MaxCodePointCharLength + 1;
@@ -291,6 +295,19 @@ Coordinate2D<double> CartesianFunction::nextIntersectionFrom(double start, doubl
   return PoincareHelpers::NextIntersection(expressionReduced(context), unknownX, start, step, max, context, f->expressionReduced(context));
 }
 
+Coordinate2D<double> CartesianFunction::nextPointOfInterestFrom(double start, double step, double max, Context * context, ComputePointOfInterest compute) const {
+  constexpr int bufferSize = CodePoint::MaxCodePointCharLength + 1;
+  char unknownX[bufferSize];
+  SerializationHelper::CodePoint(unknownX, bufferSize, UCodePointUnknownX);
+  if (step > 0.0f) {
+    start = maxDouble(start, tMin());
+    max = minDouble(max, tMax());
+  } else {
+    start = minDouble(start, tMax());
+    max = maxDouble(max, tMin());
+  }
+  return compute(expressionReduced(context), unknownX, start, step, max, context);
+}
 
 template Coordinate2D<float> CartesianFunction::templatedApproximateAtParameter<float>(float, Poincare::Context *) const;
 template Coordinate2D<double> CartesianFunction::templatedApproximateAtParameter<double>(double, Poincare::Context *) const;
diff --git a/apps/shared/cartesian_function.h b/apps/shared/cartesian_function.h
index 6f8b90a6e..2b3e36b50 100644
--- a/apps/shared/cartesian_function.h
+++ b/apps/shared/cartesian_function.h
@@ -59,8 +59,11 @@ public:
 
   // Cartesian calculation
   Poincare::Coordinate2D<double> nextIntersectionFrom(double start, double step, double max, Poincare::Context * context, CartesianFunction * f) const;
+  Poincare::Coordinate2D<double> nextRootFrom(double start, double step, double max, Poincare::Context * context) const;
 private:
   constexpr static float k_polarParamRangeSearchNumberOfPoints = 100.0f; // This is ad hoc, no special justification
+  typedef Poincare::Coordinate2D<double> (*ComputePointOfInterest)(Poincare::Expression e, char * symbol, double start, double step, double max, Poincare::Context * context);
+  Poincare::Coordinate2D<double> nextPointOfInterestFrom(double start, double step, double max, Poincare::Context * context, ComputePointOfInterest compute) const;
   template <typename T> Poincare::Coordinate2D<T> privateEvaluateXYAtParameter(T t, Poincare::Context * context) const;
   /* CartesianFunctionRecordDataBuffer is the layout of the data buffer of Record
    * representing a CartesianFunction. See comment on