cerlib

Keyboard

Query key states

Querying key states is done using cer::isKeyDown() and cer::isKeyUp().

// Gets a value indicating whether a specific key is currently pressed.
auto isKeyDown(Key key) -> bool;

// Gets a value indicating whether a specific key is currently released.
auto isKeyUp(Key key) -> bool;
Example 
auto time     = game.time();
auto dt       = float(time.elapsed);
auto movement = dt * 200.0f;

if (isKeyDown(Key::Up)) {
  spritePosition.y -= movement;
}

if (isKeyDown(Key::Down)) {
  spritePosition.y += movement;
}

cerlib provides further convenience functions that allow you to detect changes in a key’s state.

auto wasKeyJustPressed(Key key) -> bool;

auto wasKeyJustReleased(Key key) -> bool;

wasKeyJustPressed is true when a key was released in the previous frame, but is pressed in the current frame. wasKeyReleased is the opposite, meaning that it detects when a key was released in the current frame.

Example 
if (wasKeyJustPressed(Key::Space)) {
  shoot();
}

Keyboard events

Note

This assumes that you’ve read Events.

The following events are related to the keyboard:

  • KeyPressEvent: Raised when a key was pressed.
  • KeyReleaseEvent: Raised when a key was released.
Example 
// ...

while (game.tick()) {
  game.handleEvents(
    [](KeyPressEvent e) {
      logInfo("Key {} was pressed, with modifiers {}.",
              e.key, e.modifiers);
    },
    [](KeyReleaseEvent e) {
      logInfo("Key {} was released, with modifiers {}.",
              e.key, e.modifiers);
    },
    cerIgnoreEvent,
  );

  // ...
}
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