Gamepad

package com.seattlesolvers.solverslib.gamepad

SolversLib provides enhanced Gamepad features. These classes are essentially extensions of the stock FTC SDK Gamepad features but with easier implementation methods.

GamepadKeys

Provides enum representations of the buttons, D-Pad, bumpers, and triggers. Buttons, D-Pad, and bumpers are stored in GamepadKeys.Button and triggers are stored in GamepadKeys.Trigger. SolversLib has updated support for PS4 / PS5 controllers as well.

Buttons
Y
X
A
B
TRIANGLE
CIRCLE
SQUARE
CROSS
LEFT_BUMPER
RIGHT_BUMPER
BACK
START
DPAD_UP
DPAD_DOWN
DPAD_LEFT
DPAD_RIGHT
LEFT_STICK_BUTTON
RIGHT_STICK_BUTTON
PS
SHARE
TOUCHPAD
TOUCHPAD_FINGER_1
TOUCHPAD_FINGER_2

Trigger
LEFT_TRIGGER
RIGHT_TRIGGER

// these are from the GamepadButton class that is used
// for command-based frameworks
GamepadButton grabButton = new GamepadButton(
    gamepad1, GamepadKeys.Button.A
);
GamepadButton releaseButton = new GamepadButton(
    gamepad2, GamepadKeys.Button.B
);

GamepadEx gamepadEx = new GamepadEx(gamepad1);

GamepadEx

An extension of the stock FTC SDK Gamepad class. Constructed simply from a Gamepad. Provides six intuitive value-getting methods:

• getButton(): Given a GamepadKeys.Button, this method will check if that Button is pressed, returning a boolean of whether that Button is pressed.

gamepadEx.getButton(GamepadKeys.Button.A);

• getTrigger(): Given a GamepadKeys.Trigger, this method will return the value of the Trigger (0 if unpressed, 1 if fully depressed).

gamepadEx.getTrigger(GamepadKeys.Trigger.RIGHT_TRIGGER);

• getLeftY(): Returns the value of the y-axis of the left joystick (note that the value returned is the opposite of what would be returned from the standard gamepad object).

gamepadEx.getLeftY();

• getRightY(): Returns the value of the y-axis of the right joystick

gamepadEx.getRightY();

• getLeftX(): Returns the value of the x-axis of the left joystick

gamepadEx.getLeftX();

• getRightX(): Returns the value of the x-axis of the right joystick

gamepadEx.getRightX();

KeyReader

The KeyReader interface is the base for objects that monitor an individual button or trigger on a gamepad. All Reader classes must implement these functions:

• readValue(): Reads the current value of the key, true or false, and updates the values used by the reader. Returns nothing. This must be called once every loop.

• isDown() : Checks if key is currently down. Will return a boolean of whether that key is pressed.

• wasJustPressed() : Returns boolean whether the key is pressed, but only if it was previously not pressed.

• wasJustReleased() : Returns boolean indicating whether the key is not pressed, but only if it was previously pressed.

• stateJustChanged : Returns boolean indicating that the key's value has switched.

TriggerReader

The TriggerReader class implements the KeyReader interface. Because GamepadEx Triggers return a double , the TriggerReader class interprets a value of greater than 0.5 as a trigger press.

The following constructs a new Trigger Reader with a GamepadEx gamepad and GamepadKeys.Trigger trigger.

TriggerReader triggerReader = new TriggerReader(
    gamepadEx, GamepadKeys.Trigger.RIGHT_TRIGGER
);

Below are the different methods you can use with the trigger reader.

triggerReader.isDown();
triggerReader.readValue();
triggerReader.stateJustChanged();
triggerReader.wasJustPressed();
triggerReader.wasJustReleased();

ButtonReader

The ButtonReaderclass implements the KeyReader interface. It checks if a button is pressed, released, or is down.

ButtonReader reader = new ButtonReader(
    gamepadEx, GamepadKeys.Button.A
);

• ButtonReader(GamepadEx gamepad, GamepadKeys.Button button): Constructs a new Button Reader with a GamepadEx gamepad and a GamepadKeys.Button button.

• ButtonReader(BooleanSupplier supplier): Constructs a new Button Reader using the value of a boolean supplier instead of a gamepad, which allows reading value states easily without a gamepad.

reader.readValue();
reader.wasJustPressed();
reader.stateJustChanged();
reader.isDown();
reader.wasJustReleased();

The GamepadEx objects actually contain ButtonReaders. For every GamepadKeys.Button, there is a matching ButtonReader entry in the map. It is stored internally as a Map<GamepadKeys.Button, ButtonReader>. This allows you to use these features just with the GamepadEx class.

// create the gamepad
GamepadEx myGamepad = new GamepadEx(gamepad1);

/** The methods for using the ButtonReaders **/
myGamepad.wasJustPressed(GamepadKeys.Button.A);
myGamepad.stateJustChanged(GamepadKeys.Button.A);
myGamepad.isDown(GamepadKeys.Button.A);
myGamepad.wasJustReleased(GamepadKeys.Button.A);

// pass the GamepadKeys.Button that you want to read
// into the method argument

// to read all buttons at once, perform a single call
myGamepad.readButtons();
/*
this is the equivalent of calling readValue() once
for all your readers
*/

ToggleButtonReader

ToggleButtonReader toggleButtonReader = new ToggleButtonReader(
    gamepadEx, GamepadKeys.Button.A
);

The ToggleButtonReader class extends ButtonReader and adds the ability to get the status of a toggle. readValue() needs to be run in a loop to get the state of the toggle.

getState() : Gets the toggle value of a button or boolean supplier.

toggleButtonReader.getState();

Usage

GamepadEx toolOp = new GamepadEx(gamepad2);
ToggleButtonReader aReader = new ToggleButtonReader(
  toolOp, GamepadKeys.Button.A
);

while (...) {
  if (aReader.getState()) {
    // if toggle state true
  } else {
    // if toggle state false
  }
  aReader.readValue();
}

Slew Rate Limiters

The SlewRateLimiter class caps how fast a joystick value is allowed to change. Instead of the output jumping instantly from 0 to 1 when you slam the stick, it ramps toward the target at a maximum rate you choose, smoothing out acceleration. This reduces wheel slip and tipping on drivetrains, and is especially popular for swerve drives, where sudden input changes can fight against module rotation.

Credit to FTC 16379 Kookybotz for this code.

SlewRateLimiter API

Rate limits are in units per second. A joystick axis ranges from -1 to 1, so a rate limit of 2.0 lets the output go from 0 to full deflection in half a second.

• SlewRateLimiter(double positiveRateLimit, double negativeRateLimit, double initialValue): Constructs a limiter with separate limits for increasing and decreasing output (the negative rate limit should be a negative number) and a starting output value.

• SlewRateLimiter(double rateLimit, double initialValue): Constructs a limiter with a symmetric limit of ±rateLimit and a starting output value.

• SlewRateLimiter(double rateLimit): Constructs a limiter with a symmetric limit of ±rateLimit and a starting output value of 0.

• calculate(double input): Returns the input, limited so it changes no faster than the rate limits allow since the previous call. Call this once per loop with the raw value.

• updateRateLimit(double rateLimit): Changes the rate limit on the fly, setting the positive limit to rateLimit and the negative limit to -rateLimit.

SlewRateLimiter limiter = new SlewRateLimiter(4.0);

// in your loop
double smoothed = limiter.calculate(gamepad1.left_stick_x);

A SlewRateLimiter is stateful — it remembers its previous output and an internal timer. Construct it once (e.g. in init) and reuse it every loop. Creating a new limiter each loop resets that state, so the output stays pinned near the initial value and the stick will barely respond.

Enabling through GamepadEx

GamepadEx can apply slew rate limiting for you. Attach a limiter to each joystick axis with setJoystickSlewRateLimiters(SlewRateLimiter LX, SlewRateLimiter LY, SlewRateLimiter RX, SlewRateLimiter RY), where L/R is the left/right joystick and X/Y is the axis. Pass null for any axis you do not want limited. The method returns the GamepadEx object for chaining.

Once set, getLeftX(), getLeftY(), getRightX(), and getRightY() automatically return the rate-limited values — no extra calls needed in your loop. Note that limiting only applies through these GamepadEx getters, not when reading the stock gamepad fields directly.

GamepadEx driverOp = new GamepadEx(gamepad1)
    .setJoystickSlewRateLimiters(
        new SlewRateLimiter(4.0), // left stick x
        new SlewRateLimiter(4.0), // left stick y
        new SlewRateLimiter(6.0), // right stick x (turning can respond faster)
        null                      // right stick y (not limited)
    );

Usage

GamepadEx driverOp = new GamepadEx(gamepad1)
    .setJoystickSlewRateLimiters(
        new SlewRateLimiter(4.0),
        new SlewRateLimiter(4.0),
        new SlewRateLimiter(6.0),
        null
    );

waitForStart();

while (opModeIsActive()) {
    double strafe = driverOp.getLeftX();
    double forward = driverOp.getLeftY();
    double turn = driverOp.getRightX();

    drive.driveRobotCentric(strafe, forward, turn);
}