source: other-projects/nz-flag-design/trunk/render-3d/Flag_files/THREEx.KeyboardState.js@ 29721

// THREEx.KeyboardState.js keep the current state of the keyboard.
// It is possible to query it at any time. No need of an event.
// This is particularly convenient in loop driven case, like in
// 3D demos or games.
//
// # Usage
//
// **Step 1**: Create the object
//
// ```var keyboard  = new THREEx.KeyboardState();```
//
// **Step 2**: Query the keyboard state
//
// This will return true if shift and A are pressed, false otherwise
//
// ```keyboard.pressed("shift+A")```
//
// **Step 3**: Stop listening to the keyboard
//
// ```keyboard.destroy()```
//
// NOTE: this library may be nice as standaline. independant from three.js
// - rename it keyboardForGame
//
// # Code
//

/** @namespace */
var THREEx  = THREEx        || {};

/**
 * - NOTE: it would be quite easy to push event-driven too
 *   - microevent.js for events handling
 *   - in this._onkeyChange, generate a string from the DOM event
 *   - use this as event name
*/
THREEx.KeyboardState    = function()
{
    // to store the current state
    this.keyCodes   = {};
    this.modifiers  = {};
    
    // create callback to bind/unbind keyboard events
    var self    = this;
    this._onKeyDown = function(event){ self._onKeyChange(event, true); };
    this._onKeyUp   = function(event){ self._onKeyChange(event, false);};

    // bind keyEvents
    document.addEventListener("keydown", this._onKeyDown, false);
    document.addEventListener("keyup", this._onKeyUp, false);
}

/**
 * To stop listening of the keyboard events
*/
THREEx.KeyboardState.prototype.destroy  = function()
{
    // unbind keyEvents
    document.removeEventListener("keydown", this._onKeyDown, false);
    document.removeEventListener("keyup", this._onKeyUp, false);
}

THREEx.KeyboardState.MODIFIERS  = ['shift', 'ctrl', 'alt', 'meta'];
THREEx.KeyboardState.ALIAS  = {
    'left'      : 37,
    'up'        : 38,
    'right'     : 39,
    'down'      : 40,
    'space'     : 32,
    'pageup'    : 33,
    'pagedown'  : 34,
    'tab'       : 9
};

/**
 * to process the keyboard dom event
*/
THREEx.KeyboardState.prototype._onKeyChange = function(event, pressed)
{
    // log to debug
    //console.log("onKeyChange", event, pressed, event.keyCode, event.shiftKey, event.ctrlKey, event.altKey, event.metaKey)

    // update this.keyCodes
    var keyCode     = event.keyCode;
    this.keyCodes[keyCode]  = pressed;

    // update this.modifiers
    this.modifiers['shift']= event.shiftKey;
    this.modifiers['ctrl']  = event.ctrlKey;
    this.modifiers['alt']   = event.altKey;
    this.modifiers['meta']  = event.metaKey;
}

/**
 * query keyboard state to know if a key is pressed of not
 *
 * @param {String} keyDesc the description of the key. format : modifiers+key e.g shift+A
 * @returns {Boolean} true if the key is pressed, false otherwise
*/
THREEx.KeyboardState.prototype.pressed  = function(keyDesc)
{
    var keys    = keyDesc.split("+");
    for(var i = 0; i < keys.length; i++){
        var key     = keys[i];
        var pressed;
        if( THREEx.KeyboardState.MODIFIERS.indexOf( key ) !== -1 ){
            pressed = this.modifiers[key];
        }else if( Object.keys(THREEx.KeyboardState.ALIAS).indexOf( key ) != -1 ){
            pressed = this.keyCodes[ THREEx.KeyboardState.ALIAS[key] ];
        }else {
            pressed = this.keyCodes[key.toUpperCase().charCodeAt(0)]
        }
        if( !pressed)   return false;
    };
    return true;
}