问题描述

当用户按下组合键时，我需要获取键的代码以及哪些修饰键(Ctrl、Alt、Shift 等)当前被按下，并据此选择适当的反应.有比以下更清洁的方法吗?(使用 InputProcessor#keyDown):

When a user presses a key combination, I need to get key's code and which modifier keys (Ctrl, Alt, Shift etc) are currently pressed, and choose an appropriate reaction based on that. Is there a cleaner way to do this than the following? (using InputProcessor#keyDown):

public boolean keyDown(int keycode) {
      boolean ctrl, alt, shift, ...;
      if (Gdx.input.isKeyPressed(Input.Keys.LEFT_SHIFT) || Gdx.input.isKeyPressed(Input.Keys.RIGHT_SHIFT)) {
            shift = true;
      } else if (/* same for ctrl */) {
          ctrl = true;
      } else  /* same for other modifiers */ {
          //...
      }
      // Finally, choose an action based on the key combination pressed
      if (shift && keycode == Input.Keys.A) {
          // What to do if Shift+A is pressed
      } else if (/* and so on */) {
          //...     
      }
}

我看到有 Input.Keys.META_* 位掩码，这可能是我需要的，但我没有找到任何关于如何使用这些位掩码的示例.

I see there are Input.Keys.META_* bitmasks, which are probably what I need, but I haven't found any example on how to use those.

推荐答案

您可以使用 keyDown() 方法来检测是否按下了 shift(或任何其他修饰键)以及 keyUp() 方法是否再次释放:

You could use the keyDown() method to detect whether the shift (or any other modifier key) is pressed and the keyUp() method whether it is released again:

class MyInputProcesses extends InputProcesses {
  boolean shift = false;
  // etc...

  public boolean keyDown(int keycode) {
    switch(keycode) {
      case Input.Keys.LEFT_SHIFT :
      case Input.Keys.RIGHT_SHIFT:
        shift = true;
        break;
      case Input.Keys.A:
        if(shift) {
          // Do something if Shift+A is pressed
        }
        break;
    }
    // etc...
  }

  public boolean keyUp(int keycode) {
    switch(keycode) {
      case Input.Keys.LEFT_SHIFT :
      case Input.Keys.RIGHT_SHIFT:
        shift = false;
        break;
      // etc...
    }
  }
}

该方法可以防止您询问修饰键的状态，并且更容易修改这些键的触发器(例如，只接受左移).

The approach prevents you asking the states of the modifier keys and it is easier to modify the triggers for these keys (e.g. only accept the left shift).

我猜这个解决方案是否更好/更好是个人喜好.我怀疑这会更快(明显).

Whether this solution is better/nicer is of personal preference I guess. I doubt it that this will be any (noticeable) faster.

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