src/browser/keyboard.js

"use strict";

/**
 * @constructor
 */
function KeyboardAdapter()
{
    var 
        /**
         * @type {!Object.<boolean>}
         */
        keys_pressed = {},

        keyboard = this,

        // callback to call on a keypress
        send_code;

    this.enabled = true;

    /** 
     * Format:
     * Javascript event.keyCode -> make code
     * @const 
     */
    var charmap = new Uint16Array([
        0, 0, 0, 0, 0, 0, 0, 0,
        // 0x08: backspace, tab, enter
        0x0E, 0x0F, 0, 0, 0, 0x1C, 0, 0,

        // 0x10: shift, ctrl, alt, pause, caps lock
        0x2A, 0x1D, 0x38, 0, 0x3A, 0, 0, 0,

        // 0x18: escape
        0, 0, 0, 0x01, 0, 0, 0, 0,

        // 0x20: spacebar, page down/up, end, home, arrow keys, ins, del
        0x39, 0xE049, 0xE051, 0xE04F, 0xE047, 0xE04B, 0xE048, 0xE04D,
        0x50, 0, 0, 0, 0, 0x52, 0x53, 0,

        // 0x30: numbers
        0x0B, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 
        0x09, 0x0A,

        // 0x3B: ;= (firefox only)
        0, 0x27, 0, 0x0D, 0, 0, 0,

        // 0x65: letters
        0x1E, 0x30, 0x2E, 0x20, 0x12, 0x21, 0x22, 0x23, 0x17, 0x24, 0x25, 0x26, 0x32, 
        0x31, 0x18, 0x19, 0x10, 0x13, 0x1F, 0x14, 0x16, 0x2F, 0x11, 0x2D, 0x15, 0x2C,

        0, 0, 0, 0, 0,

        // 0x60: keypad
        0x52, 0x4F, 0x50, 0x51, 0x4B, 0x4C, 0x4D, 0x47,
        0x48, 0x49, 0, 0, 0, 0, 0, 0,

        // 0x70: F1 to F12
        0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x57, 0x58,

        0, 0, 0, 0,

        // 0x80
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0,

        // 0x90: Numlock
        0x45, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0,

        // 0xA0: - (firefox only)
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0x0C, 0, 0,

        // 0xB0
        // ,
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0x27, 0x0D, 0x33, 0x0C, 0x34, 0x35,
        
        // 0xC0
        // `
        0x29, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0,

        // 0xD0
        // [']\
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0x1A, 0x2B, 0x1B, 0x28, 0
    ]);

    this.init = function(code_fn)
    {
        this.destroy();

        send_code = code_fn;

        window.addEventListener("keyup", keyup_handler, false);
        window.addEventListener("keydown", keydown_handler, false);
        window.addEventListener("blur", blur_handler, false);
    };

    this.destroy = function() 
    {
        window.removeEventListener("keyup", keyup_handler, false);
        window.removeEventListener("keydown", keydown_handler, false);
        window.removeEventListener("blur", blur_handler, false);
    };


    function may_handle(e)
    {
        if(
            (e.shiftKey && e.ctrlKey && e.keyCode === 74) ||
            e.keyCode === 116
        ) {
              // don't prevent opening chromium dev tools or F5
              // maybe add other important combinations here, too
              return false;
        }

        if(!keyboard.enabled)
        {
            return false;
        }

        if(e.target)
        {
            // className shouldn't be hardcoded here
            return e.target.className === "phone_keyboard" ||
                (e.target.nodeName !== "INPUT" && e.target.nodeName !== "TEXTAREA");
        }
        else
        {
            return true;
        }
    }

    function keyup_handler(e)
    {
        if(!may_handle(e))
        {
            return;
        }

        var code = e.keyCode;

        if(!keys_pressed[code])
        {
            // stray keyup
            return false;
        }

        keys_pressed[code] = false;

        if(!handler(code, false))
        {
            e.preventDefault();
        }
    }

    function keydown_handler(e)
    {
        if(!may_handle(e))
        {
            return;
        }

        var code = e.keyCode;

        if(keys_pressed[code])
        {
            handler(code, false);
        }

        keys_pressed[code] = true;


        if(!handler(code, true))
        {
            e.preventDefault();
        }
    }

    function blur_handler(e)
    {
        // trigger keyup for all pressed keys
        var keys = Object.keys(keys_pressed),
            key;

        for(var i = 0; i < keys.length; i++)
        {
            key = +keys[i];

            if(keys_pressed[key])
            {
                handler(key, false);
            }
        }

        keys_pressed = {};
    }

    /**
     * @param {number} chr
     * @param {boolean} keydown
     */
    function handler(chr, keydown)
    {
        if(chr >= charmap.length || charmap[chr] === 0)
        {
            console.log("Missing char in map: " + chr.toString(16));
            return true;
        }

        var code = charmap[chr];

        if(!keydown)
        {
            code |= 0x80;
        }
        //console.log("Key: " + code.toString(16) + " from " + chr.toString(16) + " down=" + keydown);

        if(code > 0xFF)
        {
            // prefix
            send_code(code >> 8);
            send_code(code & 0xFF);
        }
        else
        {
            send_code(code);
        }

        return false;
    }
}