[glass] Add more widgets (#2947)

This adds the following widgets:
- Speed Controller
- Gyroscope
- Command
- Subsystem
- PIDController
- Scheduler

glass/src/libnt/native/cpp/NTSpeedController.cpp

@@ -0,0 +1,45 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "glass/networktables/NTSpeedController.h"
+
+using namespace glass;
+
+NTSpeedControllerModel::NTSpeedControllerModel(wpi::StringRef path)
+    : NTSpeedControllerModel(nt::GetDefaultInstance(), path) {}
+
+NTSpeedControllerModel::NTSpeedControllerModel(NT_Inst instance,
+                                               wpi::StringRef path)
+    : m_nt(instance),
+      m_value(m_nt.GetEntry(path + "/Value")),
+      m_name(m_nt.GetEntry(path + "/.name")),
+      m_valueData("NT_SpdCtrl:" + path),
+      m_nameValue(path.rsplit('/').second) {
+  m_nt.AddListener(m_value);
+  m_nt.AddListener(m_name);
+  Update();
+}
+
+void NTSpeedControllerModel::SetPercent(double value) {
+  nt::SetEntryValue(m_value, nt::NetworkTableValue::MakeDouble(value));
+}
+
+void NTSpeedControllerModel::Update() {
+  for (auto&& event : m_nt.PollListener()) {
+    if (event.entry == m_value) {
+      if (event.value && event.value->IsDouble())
+        m_valueData.SetValue(event.value->GetDouble());
+    } else if (event.entry == m_name) {
+      if (event.value && event.value->IsString())
+        m_nameValue = event.value->GetString();
+    }
+  }
+}
+
+bool NTSpeedControllerModel::Exists() {
+  return m_nt.IsConnected() && nt::GetEntryType(m_value) != NT_UNASSIGNED;
+}