Equation button updates: Enable/Disable on click, button content f1, f2, f3..., visibility icon on hover (#804)

* Added enable/disable line functionality

* Update EquationTextBox to change the opacity of functions have are not visible. Update the function label for the EquationTextBox to increment the label to show f1, f2, f3, etc

* rebase key-graph-features and fix issue where removing an equation box and adding a new one repopulates the previous equation

* Added visibility icon for the equation button hover

* updated EquationButton to be a toggle button to better handle the LineHidden state and other PR comment fixes.

* Updated EquationButton style to use a toggle button and to have placeholder icons for the show/hide states

* Updated equation button after pulling the refactor work into the branch. Fixed the Equation Button in KGF UI

* Fixed Pepe's bugs

* Uncomment temporary.pfx in calculator.vcxproj

src/CalcViewModel/CalcViewModel.vcxproj

@@ -448,4 +448,4 @@
     </PropertyGroup>
     <Error Condition="!Exists('..\..\packages\Microsoft.UI.Xaml.2.0.181018003.1\build\native\Microsoft.UI.Xaml.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.UI.Xaml.2.0.181018003.1\build\native\Microsoft.UI.Xaml.targets'))" />
   </Target>
-</Project>
+</Project>

src/CalcViewModel/GraphingCalculator/EquationViewModel.cpp

@@ -34,6 +34,7 @@ namespace CalculatorApp::ViewModel
 
     EquationViewModel::EquationViewModel(GraphControl::Equation ^ equation)
         : m_AnalysisErrorVisible{ false }
+        , m_FunctionLabelIndex{ 0 }
         , m_KeyGraphFeaturesItems{ ref new Vector<KeyGraphFeaturesItem ^>() }
         , m_resourceLoader{ Windows::ApplicationModel::Resources::ResourceLoader::GetForCurrentView() }
     {

src/CalcViewModel/GraphingCalculator/EquationViewModel.h

@@ -40,6 +40,7 @@ public
 
         OBSERVABLE_OBJECT();
         OBSERVABLE_PROPERTY_R(GraphControl::Equation ^, GraphEquation);
+        OBSERVABLE_PROPERTY_RW(int, FunctionLabelIndex);
 
         property Platform::String ^ Expression
         {
@@ -73,6 +74,22 @@ public
             }
         }
 
+        property bool IsLineEnabled
+        {
+            bool get()
+            {
+                return GraphEquation->IsLineEnabled;
+            }
+            void set(bool value)
+            {
+                if (GraphEquation->IsLineEnabled != value)
+                {
+                    GraphEquation->IsLineEnabled = value;
+                    RaisePropertyChanged("IsLineEnabled");
+                }
+            }
+        }
+
         // Key Graph Features
         OBSERVABLE_PROPERTY_R(Platform::String ^, AnalysisErrorString);
         OBSERVABLE_PROPERTY_R(bool, AnalysisErrorVisible);