[apps] Graph: create a RootGraphController

apps/graph/graph/root_graph_controller.cpp

@@ -0,0 +1,22 @@
+#include "root_graph_controller.h"
+#include "../app.h"
+
+using namespace Shared;
+using namespace Poincare;
+
+namespace Graph {
+
+RootGraphController::RootGraphController(Responder * parentResponder, GraphView * graphView, BannerView * bannerView, Shared::InteractiveCurveViewRange * curveViewRange, CurveViewCursor * cursor) :
+  CalculationGraphController(parentResponder, graphView, bannerView, curveViewRange, cursor, I18n::Message::NoZeroFound)
+{
+}
+
+const char * RootGraphController::title() {
+  return I18n::translate(I18n::Message::Zeros);
+}
+
+CartesianFunction::Point RootGraphController::computeNewPointOfInterest(double start, double step, double max, Context * context) {
+  return {.abscissa = m_function->nextRootFrom(start, step, max, context), .value = 0.0};
+}
+
+}