/*

File: GoodbyeWorld.js

Abstract: JavaScript for GoodbyeWorld sample widget

    This is the fifth milestone, including preference

    cleanup in the onremove handler as well as response to

    onfocus and onblur events

Version: 1.0

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*/

/***********************************/

// SAVING AND RETRIEVING PREFERENCES

/***********************************/

// setup() is run when the body loads.  It checks to see if there is a preference for this widget

// and if so, applies the preference to the widget.

function setup()

{

    if(window.widget)       // always check to make sure that you are running in Dashboard

    {

        // The preferences are retrieved:

        var worldString = widget.preferenceForKey(makeKey("worldString"));

        if (worldString && worldString.length > 0)  // if the retrieved preferences are not empty,

        {                                           // they are restored.

            document.getElementById("worldText").innerText = worldString;

            if( worldString == "Goodbye, World!" )  // if Goodbye is the retreived value...

            {

                document.getElementById("worldPopup").selectedIndex = 1;    // set the popup to reflect that.

            }

        }

    }

}

// changeWorld() is called whenever a menu item is chosen in the widget's preferences.  It queries the

// menu to find out which option was chosen, applies the change to the widget, and saves the preference.

function changeWorld(elem)

{   

    var world = document.getElementById("worldText");

    switch( parseInt(elem.options[elem.selectedIndex].value) )                  // find out which option was chosen

    {

        case 1:                                     // if option #1 ("Hello, World!")   

            world.innerText="Hello, World!";        // change the front text to "Hello, World!" & adjust the style

            if(window.widget)

            {

                widget.setPreferenceForKey("Hello, World!",makeKey("worldString"));     // and save the new preference to disk

            }

            break;

        case 2:                                     // if option #2 ("Goodbye, World!")

            world.innerText="Goodbye, World!";      // change the front text to "Goodbye, World!" & adjust the style

            if(window.widget)

            {

                widget.setPreferenceForKey("Goodbye, World!",makeKey("worldString"));   // and save the new preference to disk

            }

            break;

    }

} 

/*********************************/

// HIDING AND SHOWING PREFERENCES

/*********************************/

// showPrefs() is called when the preferences flipper is clicked upon.  It freezes the front of the widget,

// hides the front div, unhides the back div, and then flips the widget over.

function showPrefs()

{

    var front = document.getElementById("front");

    var back = document.getElementById("back");

    if (window.widget)

        widget.prepareForTransition("ToBack");      // freezes the widget so that you can change it without the user noticing

    front.style.display="none";     // hide the front

    back.style.display="block";     // show the back

    if (window.widget)

        setTimeout ('widget.performTransition();', 0);      // and flip the widget over 

    document.getElementById('fliprollie').style.display = 'none';  // clean up the front side - hide the circle behind the info button

}

// hidePrefs() is called by the done button on the back side of the widget.  It performs the opposite transition

// as showPrefs() does.

function hidePrefs()

{

    var front = document.getElementById("front");

    var back = document.getElementById("back");

    if (window.widget)

        widget.prepareForTransition("ToFront");     // freezes the widget and prepares it for the flip back to the front

    back.style.display="none";          // hide the back

    front.style.display="block";        // show the front

    if (window.widget)

        setTimeout ('widget.performTransition();', 0);      // and flip the widget back to the front

}

// makeKey makes the widget multi-instance aware

function makeKey(key)

{

    return (widget.identifier + "-" + key);

}

/***************/

// WIDGET EVENTS

/***************/

// removed is called when the widget is removed from the Dashboard

function removed()

{

    widget.setPreferenceForKey(null,makeKey("worldString"));

}

// focused is called when the widget gets key focus

function focused()

{

    document.getElementById('worldText').style.color = 'white'; 

}

// blurred is called when the widget looses key focus

function blurred()

{

    document.getElementById('worldText').style.color = 'gray'; 

}

// Here we register for some widget events

if(window.widget)

{

    widget.onremove = removed;

    window.onfocus = focused;

    window.onblur = blurred;

}   

// PREFERENCE BUTTON ANIMATION (- the pref flipper fade in/out)

var flipShown = false;      // a flag used to signify if the flipper is currently shown or not.

// A structure that holds information that is needed for the animation to run.

var animation = {duration:0, starttime:0, to:1.0, now:0.0, from:0.0, firstElement:null, timer:null};

// mousemove() is the event handle assigned to the onmousemove property on the front div of the widget. 

// It is triggered whenever a mouse is moved within the bounds of your widget.  It prepares the

// preference flipper fade and then calls animate() to performs the animation.

function mousemove (event)

{

    if (!flipShown)         // if the preferences flipper is not already showing...

    {

        if (animation.timer != null)            // reset the animation timer value, in case a value was left behind

        {

            clearInterval (animation.timer);

            animation.timer  = null;

        }

        var starttime = (new Date).getTime() - 13;      // set it back one frame

        animation.duration = 500;                                               // animation time, in ms

        animation.starttime = starttime;                                        // specify the start time

        animation.firstElement = document.getElementById ('flip');      // specify the element to fade

        animation.timer = setInterval ("animate();", 13);                       // set the animation function

        animation.from = animation.now;                                         // beginning opacity (not ness. 0)

        animation.to = 1.0;                                                     // final opacity

        animate();                                                              // begin animation

        flipShown = true;                                                       // mark the flipper as animated

    }

}

// mouseexit() is the opposite of mousemove() in that it preps the preferences flipper

// to disappear.  It adds the appropriate values to the animation data structure and sets the animation in motion.

function mouseexit (event)

{

    if (flipShown)

    {

        // fade in the flip widget

        if (animation.timer != null)

        {

            clearInterval (animation.timer);

            animation.timer  = null;

        }

        var starttime = (new Date).getTime() - 13;

        animation.duration = 500;

        animation.starttime = starttime;

        animation.firstElement = document.getElementById ('flip');

        animation.timer = setInterval ("animate();", 13);

        animation.from = animation.now;

        animation.to = 0.0;

        animate();

        flipShown = false;

    }

}

// animate() performs the fade animation for the preferences flipper. It uses the opacity CSS property to simulate a fade.

function animate()

{

    var T;

    var ease;

    var time = (new Date).getTime();

    T = limit_3(time-animation.starttime, 0, animation.duration);

    if (T >= animation.duration)

    {

        clearInterval (animation.timer);

        animation.timer = null;

        animation.now = animation.to;

    }

    else

    {

        ease = 0.5 - (0.5 * Math.cos(Math.PI * T / animation.duration));

        animation.now = computeNextFloat (animation.from, animation.to, ease);

    }

    animation.firstElement.style.opacity = animation.now;

}

// these functions are utilities used by animate()

function limit_3 (a, b, c)

{

    return a < b ? b : (a > c ? c : a);

}

function computeNextFloat (from, to, ease)

{

    return from + (to - from) * ease;

}

// these functions are called when the info button itself receives onmouseover and onmouseout events

function enterflip(event)

{

    document.getElementById('fliprollie').style.display = 'block';

}

function exitflip(event)

{

    document.getElementById('fliprollie').style.display = 'none';

}