[wpilib] Improve Color.toString (#4450)

wpilibc/src/main/native/cpp/smartdashboard/Mechanism2d.cpp

@@ -34,8 +34,7 @@ MechanismRoot2d* Mechanism2d::GetRoot(std::string_view name, double x,
 }
 
 void Mechanism2d::SetBackgroundColor(const Color8Bit& color) {
-  std::snprintf(m_color, sizeof(m_color), "#%02X%02X%02X", color.red,
-                color.green, color.blue);
+  m_color = color.HexString();
   if (m_table) {
     m_table->GetEntry(kBackgroundColor).SetString(m_color);
   }

wpilibc/src/main/native/cpp/util/Color.cpp

@@ -0,0 +1,15 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "frc/util/Color.h"
+
+#include <fmt/format.h>
+
+using namespace frc;
+
+std::string Color::HexString() const {
+  return fmt::format("#{:02X}{:02X}{:02X}", static_cast<int>(255.0 * red),
+                     static_cast<int>(255.0 * green),
+                     static_cast<int>(255.0 * blue));
+}

wpilibc/src/main/native/cpp/util/Color8Bit.cpp

@@ -0,0 +1,13 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "frc/util/Color8Bit.h"
+
+#include <fmt/format.h>
+
+using namespace frc;
+
+std::string Color8Bit::HexString() const {
+  return fmt::format("#{:02X}{:02X}{:02X}", red, green, blue);
+}

wpilibc/src/main/native/include/frc/smartdashboard/Mechanism2d.h

@@ -79,7 +79,7 @@ class Mechanism2d : public nt::NTSendable,
  private:
   double m_width;
   double m_height;
-  char m_color[10];
+  std::string m_color;
   mutable wpi::mutex m_mutex;
   std::shared_ptr<nt::NetworkTable> m_table;
   wpi::StringMap<std::unique_ptr<MechanismRoot2d>> m_roots;

wpilibc/src/main/native/include/frc/util/Color.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <algorithm>
+#include <string>
 
 namespace frc {
 
@@ -808,6 +809,13 @@ class Color {
     }
   }
 
+  /**
+   * Return this color represented as a hex string.
+   *
+   * @return a string of the format <tt>\#RRGGBB</tt>
+   */
+  std::string HexString() const;
+
   double red = 0.0;
   double green = 0.0;
   double blue = 0.0;

wpilibc/src/main/native/include/frc/util/Color8Bit.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <algorithm>
+#include <string>
 
 #include "Color.h"
 
@@ -43,6 +44,13 @@ class Color8Bit {
     return Color(red / 255.0, green / 255.0, blue / 255.0);
   }
 
+  /**
+   * Return this color represented as a hex string.
+   *
+   * @return a string of the format <tt>\#RRGGBB</tt>
+   */
+  std::string HexString() const;
+
   int red = 0;
   int green = 0;
   int blue = 0;