Change trace point value precision to be dynamic based on graph scale (#1148)

* Dynamic precision

* add comments

* feedback

* Update src/Calculator/Views/GraphingCalculator/GraphingCalculator.xaml.cpp

Co-Authored-By: Rudy Huyn <rudyhuyn@gmail.com>

* PR feedback

* Pr comment

Co-authored-by: Rudy Huyn <rudyhuyn@gmail.com>

src/Calculator/Views/GraphingCalculator/GraphingCalculator.xaml.cpp

@@ -207,12 +207,44 @@ void GraphingCalculator::OnEquationsVectorChanged(IObservableVector<EquationView
     GraphingControl->PlotGraph(false);
 }
 
+wstringstream GraphingCalculator::FormatTraceValue(double min, double max, float pointValue)
+{
+    wstringstream traceValueString;
+
+    // Extract precision we will round to 
+    auto precision = static_cast<int>(floor(log10(max - min)) - 3);
+
+    // Determine if we want to show scientific notation instead
+    if (precision <= -7 || precision  >= 7)
+    {
+        traceValueString << scientific;
+    }
+    else
+    {
+        traceValueString << fixed;
+    }
+
+    // If we are rounding to a decimal place, set the precision
+    if (precision < 0)
+    {
+        traceValueString << setprecision(::min(7, abs(precision))) << pointValue;
+    }
+    else
+    {
+        traceValueString << setprecision(0) << pointValue;
+    }
+
+    return traceValueString;
+}
+
 void GraphingCalculator::OnTracePointChanged(Point newPoint)
 {
     wstringstream traceValueString;
 
-    // TODO: The below precision should ideally be dynamic based on the current scale of the graph.
+    double xAxisMin, xAxisMax, yAxisMin, yAxisMax;
-    traceValueString << "(" << fixed << setprecision(1) << newPoint.X << ", " << fixed << setprecision(1) << newPoint.Y << ")";
+    GraphingControl->GetDisplayRanges(&xAxisMin, &xAxisMax, &yAxisMin, &yAxisMax);
+
+    traceValueString << "(" << FormatTraceValue(xAxisMin, xAxisMax, newPoint.X).str() << ", " << FormatTraceValue(yAxisMin, yAxisMax, newPoint.Y).str() << ")";
 
     TraceValue->Text = ref new String(traceValueString.str().c_str());
 

src/Calculator/Views/GraphingCalculator/GraphingCalculator.xaml.h

@@ -104,6 +104,7 @@ public ref class GraphingCalculator sealed : public Windows::UI::Xaml::Data::INo
         void OnEquationFormatRequested(Platform::Object ^ sender, CalculatorApp::Controls::MathRichEditBoxFormatRequest ^ e);
         void GraphMenuFlyoutItem_Click(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e);
         void OnVisualStateChanged(Platform::Object ^ sender, Windows::UI::Xaml::VisualStateChangedEventArgs ^ e);
+        std::wstringstream FormatTraceValue(double min, double max, float pointValue);
         void GraphViewButton_Click(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e);
     };
 

src/Calculator/pch.h

@@ -28,6 +28,8 @@
 #include <regex>
 #include <string>
 #include <tuple>
+#include <cmath>
+#include <algorithm>
 #include <iomanip>
 #include <WindowsNumerics.h>
 

src/GraphControl/Control/Grapher.h

@@ -232,10 +232,11 @@ public enum class GraphViewChangedReason
         {
             try
             {
-                if (m_graph != nullptr)
+                if (m_graph != nullptr && m_renderMain != nullptr)
                 {
                     if (auto render = m_graph->GetRenderer())
                     {
+                        Concurrency::critical_section::scoped_lock lock(m_renderMain->GetCriticalSection());
                         render->GetDisplayRanges(*xMin, *xMax, *yMin, *yMax);
                     }
                 }