java - Scala/Swing - 响应同时发生的多个关键事件

Question

我试图弄清楚如何让 Scala Swing 对同时发生的多个关键事件使用react。我知道 Swing 如何检测按下的一个键，但例如它如何检测是否同时按下两个键？注意:没有 Java 经验

我知道第一个事件不起作用，但我尝试表示我试图用它完成的任务:

reactions += {
          //case KeyPressed(_, Key.Space && Key.Up, _, _)
              //label.text = "Space and Up are down"
            case KeyPressed(_, Key.Space, _, _) =>
                label.text = "Space is down"
            case KeyPressed(_, Key.Up, _, _) =>
                label.text = "Up is down"

        }

有什么想法可能有帮助吗？或者直接回答如何做？

Answer 1

创建一个缓冲区来保存所有按下的键

var pressedKeys = Buffer[Key.Value]()

当按下按键时，将按键添加到缓冲区并检查缓冲区是否包含一些想要的键值

 reactions += {
            case KeyPressed(_, key, _, _) =>
                pressedKeys += key
                if(pressedKeys contains Key.Space){ //Do if Space
                  label.text = "Space is down"
                  if(pressedKeys contains Key.Up) //Do if Space and Up
                    label.text = "Space and Up are down"
                }else if(pressedKeys contains Key.Up)//Do if Up
                  label.text = "Up is down"

释放按钮时清除缓冲区

            case KeyReleased(_, key, _, _) =>
                    pressedKeys = Buffer[Key.Value]()
                    /* I tried only to remove the last key with 
                     * pressedKeys -= key, but ended up working
                     *badly, because in many occasions the program
                     *did not remove the key*/