[wpilib] Add hex string constructor to Color and Color8Bit

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

@@ -4,8 +4,6 @@
 
 #include "frc/util/Color.h"
 
-#include <fmt/format.h>
-
 using namespace frc;
 
 std::string Color::HexString() const {

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

@@ -4,8 +4,6 @@
 
 #include "frc/util/Color8Bit.h"
 
-#include <fmt/format.h>
-
 using namespace frc;
 
 std::string Color8Bit::HexString() const {

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

@@ -5,7 +5,12 @@
 #pragma once
 
 #include <algorithm>
+#include <stdexcept>
 #include <string>
+#include <string_view>
+
+#include <fmt/core.h>
+#include <wpi/StringExtras.h>
 
 namespace frc {
 
@@ -739,6 +744,9 @@ class Color {
    */
   static const Color kYellowGreen;
 
+  /**
+   * Constructs a default color (black).
+   */
   constexpr Color() = default;
 
   /**
@@ -763,6 +771,33 @@ class Color {
   constexpr Color(int r, int g, int b)
       : Color(r / 255.0, g / 255.0, b / 255.0) {}
 
+  /**
+   * Constructs a Color from a hex string.
+   *
+   * @param hexString a string of the format <tt>\#RRGGBB</tt>
+   * @throws std::invalid_argument if the hex string is invalid.
+   */
+  explicit constexpr Color(std::string_view hexString) {
+    if (hexString.length() != 7 || !hexString.starts_with("#") ||
+        !wpi::isHexDigit(hexString[1]) || !wpi::isHexDigit(hexString[2]) ||
+        !wpi::isHexDigit(hexString[3]) || !wpi::isHexDigit(hexString[4]) ||
+        !wpi::isHexDigit(hexString[5]) || !wpi::isHexDigit(hexString[6])) {
+      throw std::invalid_argument(
+          fmt::format("Invalid hex string for Color \"{}\"", hexString));
+    }
+
+    int r = wpi::hexDigitValue(hexString[1]) * 16 +
+            wpi::hexDigitValue(hexString[2]);
+    int g = wpi::hexDigitValue(hexString[3]) * 16 +
+            wpi::hexDigitValue(hexString[4]);
+    int b = wpi::hexDigitValue(hexString[5]) * 16 +
+            wpi::hexDigitValue(hexString[6]);
+
+    red = r / 255.0;
+    green = g / 255.0;
+    blue = b / 255.0;
+  }
+
   constexpr bool operator==(const Color&) const = default;
 
   /**

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

@@ -5,7 +5,12 @@
 #pragma once
 
 #include <algorithm>
+#include <stdexcept>
 #include <string>
+#include <string_view>
+
+#include <fmt/core.h>
+#include <wpi/StringExtras.h>
 
 #include "Color.h"
 
@@ -16,6 +21,9 @@ namespace frc {
  */
 class Color8Bit {
  public:
+  /**
+   * Constructs a default color (black).
+   */
   constexpr Color8Bit() = default;
 
   /**
@@ -40,11 +48,59 @@ class Color8Bit {
         green(color.green * 255),
         blue(color.blue * 255) {}
 
+  /**
+   * Constructs a Color8Bit from a hex string.
+   *
+   * @param hexString a string of the format <tt>\#RRGGBB</tt>
+   * @throws std::invalid_argument if the hex string is invalid.
+   */
+  explicit constexpr Color8Bit(std::string_view hexString) {
+    if (hexString.length() != 7 || !hexString.starts_with("#") ||
+        !wpi::isHexDigit(hexString[1]) || !wpi::isHexDigit(hexString[2]) ||
+        !wpi::isHexDigit(hexString[3]) || !wpi::isHexDigit(hexString[4]) ||
+        !wpi::isHexDigit(hexString[5]) || !wpi::isHexDigit(hexString[6])) {
+      throw std::invalid_argument(
+          fmt::format("Invalid hex string for Color \"{}\"", hexString));
+    }
+
+    red = wpi::hexDigitValue(hexString[1]) * 16 +
+          wpi::hexDigitValue(hexString[2]);
+    green = wpi::hexDigitValue(hexString[3]) * 16 +
+            wpi::hexDigitValue(hexString[4]);
+    blue = wpi::hexDigitValue(hexString[5]) * 16 +
+           wpi::hexDigitValue(hexString[6]);
+  }
+
+  constexpr bool operator==(const Color8Bit&) const = default;
+
   constexpr operator Color() const {  // NOLINT
     return Color(red / 255.0, green / 255.0, blue / 255.0);
   }
 
-  constexpr bool operator==(const Color8Bit&) const = default;
+  /**
+   * Create a Color8Bit from a hex string.
+   *
+   * @param hexString a string of the format <tt>\#RRGGBB</tt>
+   * @return Color8Bit object from hex string.
+   * @throws std::invalid_argument if the hex string is invalid.
+   */
+  static constexpr Color8Bit FromHexString(std::string_view hexString) {
+    if (hexString.length() != 7 || !hexString.starts_with("#") ||
+        !wpi::isHexDigit(hexString[1]) || !wpi::isHexDigit(hexString[2]) ||
+        !wpi::isHexDigit(hexString[3]) || !wpi::isHexDigit(hexString[4]) ||
+        !wpi::isHexDigit(hexString[5]) || !wpi::isHexDigit(hexString[6])) {
+      throw std::invalid_argument(
+          fmt::format("Invalid hex string for Color \"{}\"", hexString));
+    }
+
+    int r = wpi::hexDigitValue(hexString[0]) * 16 +
+            wpi::hexDigitValue(hexString[1]);
+    int g = wpi::hexDigitValue(hexString[2]) * 16 +
+            wpi::hexDigitValue(hexString[3]);
+    int b = wpi::hexDigitValue(hexString[4]) * 16 +
+            wpi::hexDigitValue(hexString[5]);
+    return Color8Bit{r, g, b};
+  }
 
   /**
    * Return this color represented as a hex string.

wpilibc/src/test/native/cpp/util/Color8BitTest.cpp

@@ -0,0 +1,62 @@
+// 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 <gtest/gtest.h>
+
+#include "frc/util/Color8Bit.h"
+
+TEST(Color8BitTest, ConstructDefault) {
+  constexpr frc::Color8Bit color;
+
+  EXPECT_EQ(0, color.red);
+  EXPECT_EQ(0, color.green);
+  EXPECT_EQ(0, color.blue);
+}
+
+TEST(Color8BitTest, ConstructFromInts) {
+  constexpr frc::Color8Bit color{255, 128, 64};
+
+  EXPECT_EQ(255, color.red);
+  EXPECT_EQ(128, color.green);
+  EXPECT_EQ(64, color.blue);
+}
+
+TEST(Color8BitTest, ConstructFromColor) {
+  constexpr frc::Color8Bit color{frc::Color{255, 128, 64}};
+
+  EXPECT_EQ(255, color.red);
+  EXPECT_EQ(128, color.green);
+  EXPECT_EQ(64, color.blue);
+}
+
+TEST(Color8BitTest, ConstructFromHexString) {
+  constexpr frc::Color8Bit color{"#FF8040"};
+
+  EXPECT_EQ(255, color.red);
+  EXPECT_EQ(128, color.green);
+  EXPECT_EQ(64, color.blue);
+
+  // No leading #
+  EXPECT_THROW(frc::Color8Bit{"112233"}, std::invalid_argument);
+
+  // Too long
+  EXPECT_THROW(frc::Color8Bit{"#11223344"}, std::invalid_argument);
+
+  // Invalid hex characters
+  EXPECT_THROW(frc::Color8Bit{"#$$$$$$"}, std::invalid_argument);
+}
+
+TEST(Color8BitTest, ImplicitConversionToColor) {
+  frc::Color color = frc::Color8Bit{255, 128, 64};
+
+  EXPECT_NEAR(1.0, color.red, 1e-2);
+  EXPECT_NEAR(0.5, color.green, 1e-2);
+  EXPECT_NEAR(0.25, color.blue, 1e-2);
+}
+
+TEST(Color8BitTest, ToHexString) {
+  constexpr frc::Color8Bit color{255, 128, 64};
+
+  EXPECT_EQ("#FF8040", color.HexString());
+}

wpilibc/src/test/native/cpp/util/ColorTest.cpp

@@ -0,0 +1,62 @@
+// 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 <gtest/gtest.h>
+
+#include "frc/util/Color.h"
+
+TEST(ColorTest, ConstructDefault) {
+  constexpr frc::Color color;
+
+  EXPECT_DOUBLE_EQ(0.0, color.red);
+  EXPECT_DOUBLE_EQ(0.0, color.green);
+  EXPECT_DOUBLE_EQ(0.0, color.blue);
+}
+
+TEST(ColorTest, ConstructFromDoubles) {
+  constexpr frc::Color color{1.0, 0.5, 0.25};
+
+  EXPECT_NEAR(1.0, color.red, 1e-2);
+  EXPECT_NEAR(0.5, color.green, 1e-2);
+  EXPECT_NEAR(0.25, color.blue, 1e-2);
+}
+
+TEST(ColorTest, ConstructFromInts) {
+  constexpr frc::Color color{255, 128, 64};
+
+  EXPECT_NEAR(1.0, color.red, 1e-2);
+  EXPECT_NEAR(0.5, color.green, 1e-2);
+  EXPECT_NEAR(0.25, color.blue, 1e-2);
+}
+
+TEST(ColorTest, ConstructFromHexString) {
+  constexpr frc::Color color{"#FF8040"};
+
+  EXPECT_NEAR(1.0, color.red, 1e-2);
+  EXPECT_NEAR(0.5, color.green, 1e-2);
+  EXPECT_NEAR(0.25, color.blue, 1e-2);
+
+  // No leading #
+  EXPECT_THROW(frc::Color{"112233"}, std::invalid_argument);
+
+  // Too long
+  EXPECT_THROW(frc::Color{"#11223344"}, std::invalid_argument);
+
+  // Invalid hex characters
+  EXPECT_THROW(frc::Color{"#$$$$$$"}, std::invalid_argument);
+}
+
+TEST(ColorTest, FromHSV) {
+  constexpr frc::Color color = frc::Color::FromHSV(90, 128, 64);
+
+  EXPECT_DOUBLE_EQ(0.1256103515625, color.red);
+  EXPECT_DOUBLE_EQ(0.2510986328125, color.green);
+  EXPECT_DOUBLE_EQ(0.2510986328125, color.blue);
+}
+
+TEST(ColorTest, ToHexString) {
+  constexpr frc::Color color{255, 128, 64};
+
+  EXPECT_EQ("#FF8040", color.HexString());
+}

wpilibj/src/main/java/edu/wpi/first/wpilibj/util/Color.java

@@ -21,6 +21,13 @@ public class Color {
   public final double blue;
   private String m_name;
 
+  /** Constructs a default color (black). */
+  public Color() {
+    red = 0.0;
+    green = 0.0;
+    blue = 0.0;
+  }
+
   /**
    * Constructs a Color from doubles.
    *
@@ -69,6 +76,22 @@ private Color(double red, double green, double blue, String name) {
     this.m_name = name;
   }
 
+  /**
+   * Constructs a Color from a hex string.
+   *
+   * @param hexString a string of the format <code>#RRGGBB</code>
+   * @throws IllegalArgumentException if the hex string is invalid.
+   */
+  public Color(String hexString) {
+    if (hexString.length() != 7 || !hexString.startsWith("#")) {
+      throw new IllegalArgumentException("Invalid hex string \"" + hexString + "\"");
+    }
+
+    this.red = Integer.valueOf(hexString.substring(1, 3), 16) / 255.0;
+    this.green = Integer.valueOf(hexString.substring(3, 5), 16) / 255.0;
+    this.blue = Integer.valueOf(hexString.substring(5, 7), 16) / 255.0;
+  }
+
   /**
    * Creates a Color from HSV values.
    *

wpilibj/src/main/java/edu/wpi/first/wpilibj/util/Color8Bit.java

@@ -14,6 +14,13 @@ public class Color8Bit {
   public final int green;
   public final int blue;
 
+  /** Constructs a default color (black). */
+  public Color8Bit() {
+    red = 0;
+    green = 0;
+    blue = 0;
+  }
+
   /**
    * Constructs a Color8Bit.
    *
@@ -36,6 +43,22 @@ public Color8Bit(Color color) {
     this((int) (color.red * 255), (int) (color.green * 255), (int) (color.blue * 255));
   }
 
+  /**
+   * Constructs a Color8Bit from a hex string.
+   *
+   * @param hexString a string of the format <code>#RRGGBB</code>
+   * @throws IllegalArgumentException if the hex string is invalid.
+   */
+  public Color8Bit(String hexString) {
+    if (hexString.length() != 7 || !hexString.startsWith("#")) {
+      throw new IllegalArgumentException("Invalid hex string \"" + hexString + "\"");
+    }
+
+    this.red = Integer.valueOf(hexString.substring(1, 3), 16);
+    this.green = Integer.valueOf(hexString.substring(3, 5), 16);
+    this.blue = Integer.valueOf(hexString.substring(5, 7), 16);
+  }
+
   @Override
   public boolean equals(Object other) {
     if (this == other) {