键盘 ALT 修饰符不能被覆盖 [英] Keyboard ALT modifier cannot be overridden

问题描述

我正在编写一个 Javascript 类来处理击键和击键组合.例如，以下内容将为 SHIFT 键添加回调.

I'm writing a Javascript class to handle keystrokes as well as keystroke combinations. For example, the following would add a callback for the SHIFT key.

MYAPP.Keyboard.instance().observe(
    MYAPP.Keyboard.type.KEYDOWN,
    MYAPP.Keyboard.key.SHIFT,
    function() {
        $$('body').first().addClassName('keyboardHintShow');
    }
);

SHIFT+F 的示例是:

MYAPP.Keyboard.instance().observe(
    MYAPP.Keyboard.type.KEYUP,
    [MYAPP.Keyboard.key.F, MYAPP.Keyboard.key.SHIFT],
    function() {
        MYAPP.Broadcast.instance().signal('file');
    }
);  

到目前为止，这在 Firefox 中运行良好，但当我尝试使用 ALT 作为修饰符时则不然.出现两个问题.1) 事件传播没有停止，所以 Firefox 的文件菜单弹出.2)释放ALT和F后，只有F的onKeyUp触发，所以ALT的状态是错误的.ALT 与 SHIFT 有何不同?

This is working great in Firefox so far, but not when I attempt to use ALT as a modifier. Two problems arise. 1) Event propogation does not stop, so Firefox's File menu pops up. 2) After releasing ALT and F, only F's onKeyUp fires, so the state of ALT is wrong. What makes ALT so different from SHIFT?

完整代码如下:

MYAPP.Keyboard = Class.create({

/*******************************************************************************
PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUBLIC PUB
*******************************************************************************/

    /**
     * @return pointer
     */
    initialize: function() {
        this.downKeys = new Hash();
        this.observers = new Hash();

        document.observe(
            'keydown',
            this.onKeyDown.bind(this)
        );

        document.observe(
            'keyup',
            this.onKeyUp.bind(this)
        );
    },

    /**
     * @param MYAPP.Keyboard.type type
     * @param MYAPP.Keyboard.key | array of MYAPP.Keyboard.key keys
     * @param void function() callback
     * @return void
     */
    observe: function(type, keys, callback) {
        var main;
        var modifiers;

        if (typeof(keys) === 'number') {
            main = keys;
            modifiers = [];
        } else {
            main = keys.first();
            modifiers = keys.slice(1);
        }

        if (this.observers.get(type) === undefined) {
            this.observers.set(type, new Hash());
        }

        this.observers.get(type).set(
            main, {
                modifiers: modifiers,
                callback: callback
            }
        );
    },

    /**
     * @param MYAPP.Keyboard.type type
     * @param MYAPP.Keyboard.key
     * @return void
     */
    stopObserving: function(type, key) {
        this.observers.get(type).unset(key);
    },

/*******************************************************************************
PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE 
*******************************************************************************/

    /**
     * @param Event event
     * @return void
     */
    onKeyDown: function(event) {
        if (this.downKeys.get(event.keyCode) === true) {
            return;
        }

        this.downKeys.set(event.keyCode, true);

        var downObservers = this.observers.get(MYAPP.Keyboard.type.KEYDOWN);
        if (downObservers !== undefined) {
            this.runCallback(downObservers, event);
        }
        return false;
    },

    /**
     * @param Event event
     * @return void
     */
    onKeyUp: function(event) {
        this.downKeys.set(event.keyCode, false);

        var downObservers = this.observers.get(MYAPP.Keyboard.type.KEYUP);
        if (downObservers !== undefined) {
            this.runCallback(downObservers, event);
        }
        return false;
    },

    /**
     * @param Hash observers
     * @param Event event
     * @return void
     */
    runCallback: function(observers, event) {
        var overrideBrowser = false;
        var order = observers.get(event.keyCode);
        if (order !== undefined) {
            if (order.modifiers.size() === 0) {
                order.callback();
                Event.stop(event);
            } else {
                for (var i = 0; i < order.modifiers.size(); i++) {
                    var modifierStatus = this.downKeys.get(order.modifiers[i]);
                    if (modifierStatus === undefined || modifierStatus === false) {
                        return;
                    }
                    order.callback();
                    Event.stop(event);
                }
            }
        }
    }
});

/*******************************************************************************
STATIC STATIC STATIC STATIC STATIC STATIC STATIC STATIC STATIC STATIC STATIC STA
*******************************************************************************/

/**
 * @return Keyboard instance
 */
MYAPP.Keyboard.instance = function() {
    if (typeof(MYAPP.keyboard) === 'undefined') {
        MYAPP.keyboard = new MYAPP.Keyboard();
    }
    return MYAPP.keyboard;
};

/**
 * Event type
 */
MYAPP.Keyboard.type = {
    KEYUP: 0,
    KEYDOWN: 1 
};

/**
 * Keycodes for various keys.
 */
MYAPP.Keyboard.key = {
    SHIFT: 16,
    CTRL: 17,
    ALT: 18,
    A: 65,
    B: 66,
    C: 67,
    D: 68,
    E: 69,
    F: 70,
    G: 71,
    H: 72,
    I: 73,
    J: 74,
    K: 75,
    L: 76,
    M: 77,
    N: 78,
    O: 79,
    P: 80,
    Q: 81,
    R: 82,
    S: 83,
    T: 84,
    U: 85,
    V: 86,
    W: 87,
    X: 88,
    Y: 89,
    Z: 90
};

推荐答案

这个作为例子可能会有所帮助.在页面底部，作者声称他的脚本覆盖了所有修饰符 - Ctrl、Alt、Shift、Meta.希望这会有所帮助.

This may help as an example. At the bottom of the page the author claims that his script overrides all modifiers - Ctrl, Alt, Shift, Meta. Hope this help, somehow.

这篇关于键盘 ALT 修饰符不能被覆盖的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！