Demonstration of playlist shuffler for the foobar2000 plugin WSH Panel Mod

shuffler-demo.js

// Use with GdiDrawText() 
// {{
var DT_TOP = 0x00000000;
var DT_CENTER = 0x00000001;
var DT_VCENTER = 0x00000004;
var DT_WORDBREAK = 0x00000010;
var DT_CALCRECT = 0x00000400;
var DT_NOPREFIX = 0x00000800;
// }}

// {{
// Used in window.GetColorCUI()
ColorTypeCUI = {
    text: 0,
    selection_text: 1,
    inactive_selection_text: 2,
    background: 3,
    selection_background: 4,
    inactive_selection_background: 5,
    active_item_frame: 6
};

// Used in window.GetFontCUI()
FontTypeCUI = {
    items: 0,
    labels: 1
};

// Used in window.GetColorDUI()
ColorTypeDUI = {
    text: 0,
    background: 1,
    highlight: 2,
    selection: 3
};

// Used in window.GetFontDUI()
FontTypeDUI = {
    defaults: 0,
    tabs: 1,
    lists: 2,
    playlists: 3,
    statusbar: 4,
    console: 5
};
//}}

//{{
// Used in window.SetCursor()
var IDC_HAND = 32649;
//}}

var g_instancetype = window.InstanceType;
var g_font = null;
var g_text = "Click here to create\na new shuffled playlist\nbased on the active playlist.";
var ww = 0, wh = 0;
var g_textcolor = 0, g_textcolor_hl = 0;
var g_backcolor = 0;
var g_hot = false;

function get_font() {
    if (g_instancetype == 0) { // CUI
        g_font = window.GetFontCUI(FontTypeCUI.items);
    } else if (g_instancetype == 1) { // DUI
        g_font = window.GetFontDUI(FontTypeDUI.defaults);
    } else {
        // None
    }
}
get_font();

function get_colors() {
    if (g_instancetype == 0) { // CUI
        g_textcolor = window.GetColorCUI(ColorTypeCUI.text);
        g_textcolor_hl = window.GetColorCUI(ColorTypeCUI.text);
        g_backcolor = window.GetColorCUI(ColorTypeCUI.background);
    } else if (g_instancetype == 1) { // DUI
        g_textcolor = window.GetColorDUI(ColorTypeDUI.text);
        g_textcolor_hl = window.GetColorDUI(ColorTypeDUI.highlight);
        g_backcolor = window.GetColorDUI(ColorTypeDUI.background);
    } else {
        // None
    }
}
get_colors();

// START
function on_size() {
    ww = window.Width;
    wh = window.Height;
}

function on_paint(gr) {
    var text_color = g_hot ? g_textcolor_hl : g_textcolor;
    gr.FillSolidRect(0, 0, ww, wh, g_backcolor);
    gr.GdiDrawText(g_text, g_font, text_color, 0, 0, ww, wh, DT_VCENTER | DT_CENTER | DT_WORDBREAK | DT_CALCRECT | DT_NOPREFIX);
}

function on_mouse_move() {
    if (!g_hot) {
        window.SetCursor(IDC_HAND);
        g_hot = true;
        window.Repaint();
    }
}

function on_mouse_leave() {
    if (g_hot) {
        g_hot = false;
        window.Repaint();
    }
}

function on_font_changed() {
    get_font();
    window.Repaint();
}

function on_colors_changed() {
    get_colors();
    window.Repaint();
}

var Shuffler = (function () {
    function fyshuffle (items) {
        for (var i = items.length - 1; i >= 1; --i) {
            var j = Math.floor(Math.random() * (i + 1));
            var temp = items[j];
            items[j] = items[i];
            items[i] = temp;
        }
    }
    
    function insert(spl, item, pos) {
        while (true) {
            while (pos >= spl.size) {
                pos = pos - spl.size;
            }
            if (spl.items[pos] === undefined) {
                spl.items[pos] = item;
                break;
            }
            pos = pos + 1;
        }
    }

    var Shuffler = function (size, spacing) {
        if (spacing === undefined) {
            spacing = 8;
        }
        
        this.size = size * spacing;
        this.items = new Array();
    };
    
    Shuffler.prototype.add = function (items) {
        var gap = this.size / items.length;
        var start = Math.floor(Math.random() * this.size);
        fyshuffle(items);
        for (var i = 0; i < items.length; ++i) {
            var pos = Math.floor(start + (i * gap) + Math.random() * Math.floor(gap * 2 / 3));
            insert(this, items[i], pos);
        }
    }
        
    Shuffler.prototype.finish = function () {
        var pl = new Array();
        for (var i = 0; i < this.size; ++i) {
            if (this.items[i] !== undefined) {
                pl.push(this.items[i]);
            }
        }
        this.items = new Array();
        return pl;
    }
    
    return Shuffler;
 })();
 
 function shuffleItems(items, groupFormat) {
    var tf = fb.TitleFormat(groupFormat);
    var groups = {};
    for (var i = 0; i < items.Count; ++i) {
        var item = items.Item(i);
        var groupKey = tf.EvalWithMetadb(item);
        if (groups[groupKey] === undefined) {
            groups[groupKey] = [];
        }
        groups[groupKey].push(item);
    }
    var spl = new Shuffler(items.Count);
    for (var groupKey in groups) {
        spl.add(groups[groupKey]);
    }
    var pl = spl.finish();
    for (var i = 0; i < items.Count; ++i) {
        items.Item(i) = pl[i];
    }
    tf.Dispose();
    return items;
 }

function on_mouse_lbtn_up(x, y) {
    var srcIndex = plman.ActivePlaylist;
    if (srcIndex < 0) return;
    
    var items = plman.GetPlaylistItems(srcIndex);
    var groupFormat = "%album artist% - %album%";
    shuffleItems(items, groupFormat);
    var dstName = plman.GetPlaylistName(srcIndex) + " - Shuffled";
    var dstIndex = plman.CreatePlaylist(plman.PlaylistCount, dstName);
    plman.InsertPlaylistItems(dstIndex, 0, items);
    plman.ActivePlaylist = dstIndex;
    items.Dispose();
}

See http://www.hydrogenaudio.org/forums/index.php?showtopic=105655.