[wpilib] Add IsJoystickConnected method (#2847)

wpilibc/src/main/native/cpp/DriverStation.cpp

@@ -331,6 +331,11 @@ int DriverStation::GetJoystickAxisType(int stick, int axis) const {
   return static_cast<bool>(descriptor.axisTypes);
 }
 
+bool DriverStation::IsJoystickConnected(int stick) const {
+  return GetStickAxisCount(stick) > 0 || GetStickButtonCount(stick) > 0 ||
+         GetStickPOVCount(stick) > 0;
+}
+
 bool DriverStation::IsEnabled() const {
   HAL_ControlWord controlWord;
   HAL_GetControlWord(&controlWord);

wpilibc/src/main/native/cpp/GenericHID.cpp

@@ -47,6 +47,10 @@ int GenericHID::GetButtonCount() const {
   return m_ds->GetStickButtonCount(m_port);
 }
 
+bool GenericHID::IsConnected() const {
+  return m_ds->IsJoystickConnected(m_port);
+}
+
 GenericHID::HIDType GenericHID::GetType() const {
   return static_cast<HIDType>(m_ds->GetJoystickType(m_port));
 }

wpilibc/src/main/native/include/frc/DriverStation.h

@@ -181,6 +181,17 @@ class DriverStation : public ErrorBase {
    */
   int GetJoystickAxisType(int stick, int axis) const;
 
+  /**
+   * Returns if a joystick is connected to the Driver Station.
+   *
+   * This makes a best effort guess by looking at the reported number of axis,
+   * buttons, and POVs attached.
+   *
+   * @param stick The joystick port number
+   * @return true if a joystick is connected
+   */
+  bool IsJoystickConnected(int stick) const;
+
   /**
    * Check if the DS has enabled the robot.
    *

wpilibc/src/main/native/include/frc/GenericHID.h

@@ -136,6 +136,13 @@ class GenericHID : public ErrorBase {
    */
   int GetButtonCount() const;
 
+  /**
+   * Get if the HID is connected.
+   *
+   * @return true if the HID is connected
+   */
+  bool IsConnected() const;
+
   /**
    * Get the type of the HID.
    *