[commands] Add functions to HID classes to allow use of axes as BooleanEvents/Triggers (#4762)

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

@@ -89,6 +89,20 @@ BooleanEvent GenericHID::POVCenter(EventLoop* loop) const {
   return POV(360, loop);
 }
 
+BooleanEvent GenericHID::AxisLessThan(int axis, double threshold,
+                                      EventLoop* loop) const {
+  return BooleanEvent(loop, [this, axis, threshold]() {
+    return this->GetRawAxis(axis) < threshold;
+  });
+}
+
+BooleanEvent GenericHID::AxisGreaterThan(int axis, double threshold,
+                                         EventLoop* loop) const {
+  return BooleanEvent(loop, [this, axis, threshold]() {
+    return this->GetRawAxis(axis) > threshold;
+  });
+}
+
 int GenericHID::GetAxisCount() const {
   return DriverStation::GetStickAxisCount(m_port);
 }

wpilibc/src/main/native/cpp/XboxController.cpp

@@ -197,3 +197,25 @@ bool XboxController::GetStartButtonReleased() {
 BooleanEvent XboxController::Start(EventLoop* loop) const {
   return BooleanEvent(loop, [this]() { return this->GetStartButton(); });
 }
+
+BooleanEvent XboxController::LeftTrigger(double threshold,
+                                         EventLoop* loop) const {
+  return BooleanEvent(loop, [this, threshold]() {
+    return this->GetLeftTriggerAxis() > threshold;
+  });
+}
+
+BooleanEvent XboxController::LeftTrigger(EventLoop* loop) const {
+  return this->LeftTrigger(0.5, loop);
+}
+
+BooleanEvent XboxController::RightTrigger(double threshold,
+                                          EventLoop* loop) const {
+  return BooleanEvent(loop, [this, threshold]() {
+    return this->GetRightTriggerAxis() > threshold;
+  });
+}
+
+BooleanEvent XboxController::RightTrigger(EventLoop* loop) const {
+  return this->RightTrigger(0.5, loop);
+}

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

@@ -231,6 +231,31 @@ class GenericHID {
    */
   BooleanEvent POVCenter(EventLoop* loop) const;
 
+  /**
+   * Constructs an event instance that is true when the axis value is less than
+   * threshold
+   *
+   * @param axis The axis to read, starting at 0.
+   * @param threshold The value below which this trigger should return true.
+   * @param loop the event loop instance to attach the event to.
+   * @return an event instance that is true when the axis value is less than the
+   * provided threshold.
+   */
+  BooleanEvent AxisLessThan(int axis, double threshold, EventLoop* loop) const;
+
+  /**
+   * Constructs an event instance that is true when the axis value is greater
+   * than threshold
+   *
+   * @param axis The axis to read, starting at 0.
+   * @param threshold The value above which this trigger should return true.
+   * @param loop the event loop instance to attach the event to.
+   * @return an event instance that is true when the axis value is greater than
+   * the provided threshold.
+   */
+  BooleanEvent AxisGreaterThan(int axis, double threshold,
+                               EventLoop* loop) const;
+
   /**
    * Get the number of axes for the HID.
    *

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

@@ -342,6 +342,50 @@ class XboxController : public GenericHID {
    */
   BooleanEvent Start(EventLoop* loop) const;
 
+  /**
+   * Constructs an event instance around the axis value of the left trigger. The
+   * returned trigger will be true when the axis value is greater than {@code
+   * threshold}.
+   * @param threshold the minimum axis value for the returned event to be true.
+   * This value should be in the range [0, 1] where 0 is the unpressed state of
+   * the axis.
+   * @param loop the event loop instance to attach the event to.
+   * @return an event instance that is true when the left trigger's axis exceeds
+   * the provided threshold, attached to the given event loop
+   */
+  BooleanEvent LeftTrigger(double threshold, EventLoop* loop) const;
+
+  /**
+   * Constructs an event instance around the axis value of the left trigger.
+   * The returned trigger will be true when the axis value is greater than 0.5.
+   * @param loop the event loop instance to attach the event to.
+   * @return an event instance that is true when the right trigger's axis
+   * exceeds 0.5, attached to the given event loop
+   */
+  BooleanEvent LeftTrigger(EventLoop* loop) const;
+
+  /**
+   * Constructs an event instance around the axis value of the right trigger.
+   * The returned trigger will be true when the axis value is greater than
+   * {@code threshold}.
+   * @param threshold the minimum axis value for the returned event to be true.
+   * This value should be in the range [0, 1] where 0 is the unpressed state of
+   * the axis.
+   * @param loop the event loop instance to attach the event to.
+   * @return an event instance that is true when the right trigger's axis
+   * exceeds the provided threshold, attached to the given event loop
+   */
+  BooleanEvent RightTrigger(double threshold, EventLoop* loop) const;
+
+  /**
+   * Constructs an event instance around the axis value of the right trigger.
+   * The returned trigger will be true when the axis value is greater than 0.5.
+   * @param loop the event loop instance to attach the event to.
+   * @return an event instance that is true when the right trigger's axis
+   * exceeds 0.5, attached to the given event loop
+   */
+  BooleanEvent RightTrigger(EventLoop* loop) const;
+
   struct Button {
     static constexpr int kLeftBumper = 5;
     static constexpr int kRightBumper = 6;