按钮#

Introduction#

The button class is derived from the controller base class and provides access to the EXP Controller’s buttons, allowing your robot to monitor presses to the controller’s buttons.

Access#

The controller class provides twelve button objects. Each object is an instance of the button class and can be accessed through a controller instance.

Object	Example Usage	描述
`ButtonA`	`Controller.ButtonA.pressing()`	A button
`ButtonB`	`Controller.ButtonB.pressing()`	B button
`ButtonDown`	`Controller.ButtonDown.pressing()`	Down button
`ButtonL1`	`Controller.ButtonL1.pressing()`	L1 button
`ButtonL2`	`Controller.ButtonL2.pressing()`	L2 button
`ButtonL3`	`Controller.ButtonL3.pressing()`	L3 button
`ButtonR1`	`Controller.ButtonR1.pressing()`	R1 button
`ButtonR2`	`Controller.ButtonR2.pressing()`	R2 button
`ButtonR3`	`Controller.ButtonR3.pressing()`	R3 button
`ButtonUp`	`Controller.ButtonUp.pressing()`	Up button

Notes#

The button object is provided by the controller. It is not constructed directly.

Member Functions#

The Button class includes the following member functions:

pressing — Returns whether or not the specified button is being pressed.
pressed — Registers a function to be called when the specified button is pressed.
released — Registers a function to be called when the specified button is released.

Before calling any button member functions, a controller instance must be created, as shown below:

// Create an EXP controller instance
controller Controller = controller();

pressing#

Returns whether a specific controller button is currently being pressed.

Available Functions

bool pressing() const;

Parameters

This function does not accept any parameters.

Return Values

Returns an integer indicating whether the specified button is being pressed:

1 — The button is being pressed.
0 — The button is not being pressed.

Examples

This function can be called on any controller button object, for example:

Controller.ButtonA
Controller.ButtonB
Controller.ButtonDown
Controller.ButtonL1
Controller.ButtonL2
Controller.ButtonL3
Controller.ButtonR1
Controller.ButtonR2
Controller.ButtonR3
Controller.ButtonUp

// Turn right while L1 is pressed
while (true) {
    if (Controller.ButtonL1.pressing()) {
        Drivetrain.turn(right);
    } else {
        Drivetrain.stop();
    }
    wait(5, msec);
}

pressed#

Registers a callback function that runs when a specific controller button is pressed.

Available Functions

void pressed( 
  void (* callback)(void) ) const;

Parameters

范围	Type	描述
`callback`	`void (*)(void)`	A function that is called when the specified button is pressed.

Return Values

This function does not return a value.

Examples

This function can be called on any controller button object, for example:

Controller.ButtonA
Controller.ButtonB
Controller.ButtonDown
Controller.ButtonL1
Controller.ButtonL2
Controller.ButtonL3
Controller.ButtonR1
Controller.ButtonR2
Controller.ButtonR3
Controller.ButtonUp

Define the callback function (outside of int main())

// Drive forward when A is pressed
void driveForward() {
    Drivetrain.driveFor(forward, 100, mm);
}

int main() {
  /* vexcodeInit() is only required when using VEXcode.
  Remove vexcodeInit() if compiling in VS Code. */
  vexcodeInit();

  // Call driveForward when the A button is pressed
  Controller.ButtonA.pressed(driveForward);
}

released#

Registers a callback function that runs when a specific controller button is released.

Available Functions

void released( 
  void (* callback)(void) ) const;

Parameters

范围	Type	描述
`callback`	`void (*)(void)`	A function that is called when the specified button is released.

Return Values

This function does not return a value.

Examples

This function can be called on any controller button object, for example:

Controller.ButtonA
Controller.ButtonB
Controller.ButtonDown
Controller.ButtonL1
Controller.ButtonL2
Controller.ButtonL3
Controller.ButtonR1
Controller.ButtonR2
Controller.ButtonR3
Controller.ButtonUp

Define the callback function (outside of int main())

// Drive backward when A is released
void backUp() {
    Drivetrain.driveFor(reverse, 100, mm);
}

int main() {
  /* vexcodeInit() is only required when using VEXcode.
  Remove vexcodeInit() if compiling in VS Code. */
  vexcodeInit();

  // Call backUp when the A button is released
  Controller.ButtonA.released(backUp);
}