[glass] Add glass: an application for display of robot data

This reuses many pieces of the current simulation GUI.  The common pieces have
been refactored into the libglass library.

The libglass library is designed to be usable for other standalone data
visualization applications (e.g. viewing data logs).

The name "glass" comes from "glass cockpit", as the application features
several multi-function displays that can be adjusted to display robot
information as needed.

glass/src/lib/native/cpp/hardware/PCM.cpp

@@ -0,0 +1,150 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019-2020 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/hardware/PCM.h"
+
+#include <cstdio>
+#include <cstring>
+
+#include <imgui.h>
+#include <wpi/SmallVector.h>
+
+#include "glass/Context.h"
+#include "glass/DataSource.h"
+#include "glass/other/DeviceTree.h"
+#include "glass/support/ExtraGuiWidgets.h"
+#include "glass/support/IniSaverInfo.h"
+
+using namespace glass;
+
+bool glass::DisplayPCMSolenoids(PCMModel* model, int index,
+                                bool outputsEnabled) {
+  wpi::SmallVector<int, 16> channels;
+  model->ForEachSolenoid([&](SolenoidModel& solenoid, int j) {
+    if (auto data = solenoid.GetOutputData()) {
+      if (j >= static_cast<int>(channels.size())) channels.resize(j + 1);
+      channels[j] = (outputsEnabled && data->GetValue()) ? 1 : -1;
+    }
+  });
+
+  if (channels.empty()) return false;
+
+  // show nonexistent channels as empty
+  for (auto&& ch : channels) {
+    if (ch == 0) ch = -2;
+  }
+
+  // build header label
+  std::string* name = GetStorage().GetStringRef("name");
+  char label[128];
+  if (!name->empty()) {
+    std::snprintf(label, sizeof(label), "%s [%d]###name", name->c_str(), index);
+  } else {
+    std::snprintf(label, sizeof(label), "PCM[%d]###name", index);
+  }
+
+  // header
+  bool open = CollapsingHeader(label);
+
+  PopupEditName("name", name);
+
+  ImGui::SetItemAllowOverlap();
+  ImGui::SameLine();
+
+  // show channels as LED indicators
+  static const ImU32 colors[] = {IM_COL32(255, 255, 102, 255),
+                                 IM_COL32(128, 128, 128, 255)};
+  DrawLEDs(channels.data(), channels.size(), channels.size(), colors);
+
+  if (open) {
+    ImGui::PushItemWidth(ImGui::GetFontSize() * 4);
+    model->ForEachSolenoid([&](SolenoidModel& solenoid, int j) {
+      if (auto data = solenoid.GetOutputData()) {
+        PushID(j);
+        char solenoidName[64];
+        auto& info = data->GetNameInfo();
+        info.GetLabel(solenoidName, sizeof(solenoidName), "Solenoid", j);
+        data->LabelText(solenoidName, "%s", channels[j] == 1 ? "On" : "Off");
+        info.PopupEditName(j);
+        PopID();
+      }
+    });
+    ImGui::PopItemWidth();
+  }
+
+  return true;
+}
+
+void glass::DisplayPCMsSolenoids(PCMsModel* model, bool outputsEnabled,
+                                 wpi::StringRef noneMsg) {
+  bool hasAny = false;
+  model->ForEachPCM([&](PCMModel& pcm, int i) {
+    PushID(i);
+    if (DisplayPCMSolenoids(&pcm, i, outputsEnabled)) hasAny = true;
+    PopID();
+  });
+  if (!hasAny && !noneMsg.empty())
+    ImGui::TextUnformatted(noneMsg.begin(), noneMsg.end());
+}
+
+void glass::DisplayCompressorDevice(PCMModel* model, int index,
+                                    bool outputsEnabled) {
+  auto compressor = model->GetCompressor();
+  if (!compressor || !compressor->Exists()) return;
+  DisplayCompressorDevice(compressor, index, outputsEnabled);
+}
+
+void glass::DisplayCompressorDevice(CompressorModel* model, int index,
+                                    bool outputsEnabled) {
+  char name[32];
+  std::snprintf(name, sizeof(name), "Compressor[%d]", index);
+  if (BeginDevice(name)) {
+    // output enabled
+    if (auto runningData = model->GetRunningData()) {
+      bool value = outputsEnabled && runningData->GetValue();
+      if (DeviceBoolean("Running", false, &value, runningData)) {
+        model->SetRunning(value);
+      }
+    }
+
+    // closed loop enabled
+    if (auto enabledData = model->GetEnabledData()) {
+      int value = enabledData->GetValue() ? 1 : 0;
+      static const char* enabledOptions[] = {"disabled", "enabled"};
+      if (DeviceEnum("Closed Loop", true, &value, enabledOptions, 2,
+                     enabledData)) {
+        model->SetEnabled(value != 0);
+      }
+    }
+
+    // pressure switch
+    if (auto pressureSwitchData = model->GetPressureSwitchData()) {
+      int value = pressureSwitchData->GetValue() ? 1 : 0;
+      static const char* switchOptions[] = {"full", "low"};
+      if (DeviceEnum("Pressure", false, &value, switchOptions, 2,
+                     pressureSwitchData)) {
+        model->SetPressureSwitch(value != 0);
+      }
+    }
+
+    // compressor current
+    if (auto currentData = model->GetCurrentData()) {
+      double value = currentData->GetValue();
+      if (DeviceDouble("Current (A)", false, &value, currentData)) {
+        model->SetCurrent(value);
+      }
+    }
+
+    EndDevice();
+  }
+}
+
+void glass::DisplayCompressorsDevice(PCMsModel* model, bool outputsEnabled) {
+  model->ForEachPCM([&](PCMModel& pcm, int i) {
+    DisplayCompressorDevice(&pcm, i, outputsEnabled);
+  });
+}