javascript - 背景图像更改时更改菜单颜色

Question

首页正在播放背景幻灯片。问题是，当背景较暗时，菜单不可见，因为菜单本身具有深色字体颜色。当背景改变时，菜单颜色也应该改变。

我正在使用 Vegas 背景 jQuery 插件 ( http://vegas.jaysalvat.com/ )，并且我希望能够(手动)决定每张幻灯片的菜单颜色。

例如，如果背景是黑色，则菜单应为白色，而当背景变为浅色幻灯片时，菜单应变为黑色。

此代码片段在幻灯片更改时触发:

$('body').bind('vegaswalk',
  function(e, bg, step) {
    alert( 'N°' +step+ ' is now displayed' );
  }
);

这就是触发“vegaswalk”时我想做的事情:

slide 1 = black
slide 2 = white
if change to slide 1 => change menu to white
if change to slide 2 => change menu to black

Link to the site

编辑

在 php if 语句中组合脚本。脚本:

<script>
$.vegas('slideshow', { delay: 4000,
    backgrounds: [
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-vardagsrum.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-verkstad.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-urbild.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-kuggar.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-fiber.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-bord.jpg', fade: 1000 },
    ],
    walk: function(step) {
        //alert('N°' + step + ' is now displayed');

        // get a handle on the sidebar
        var $sidebar = $('div.sidebar');

        // change it's class according to the slide we are on
        switch (step) {
        case 0: goGray($sidebar); break;
    case 1: goWhite($sidebar); break;
        case 2: goGray($sidebar); break;
        case 3: goGray($sidebar); break;
        case 4: goGray($sidebar); break;
        case 5: goGray($sidebar); break;
        case 6: goWhite($sidebar); break;
        default: goWhite($sidebar); break;
        }
    }
})('overlay');

function goGray($sidebar){
    $sidebar.removeClass('white').addClass('gray');
}

function goWhite($sidebar){
    $sidebar.removeClass('gray').addClass('white');
}


</script>

每种情况都需要通过 php if 语句来检查它是否应该变灰。像这样的东西吗？在这种情况下如何结合 php 和 jquery？

case 0: <?php if( go gray is chosen ) {
echo "goGray($sidebar);";
}
else{
    echo "goWhite($sidebar);";
} break; 

Answer 1

您尝试使用步行功能的方向是正确的，请像这样尝试:

$.vegas('slideshow', { delay: 4000,
    backgrounds: [
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-vardagsrum.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-verkstad.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-urbild.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-kuggar.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-fiber.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-bord.jpg', fade: 1000 },
    ],
    walk: function(step) {
        //alert('N°' + step + ' is now displayed');

        // get a handle on the sidebar
        var $sidebar = $('div.sidebar');

        // change it's class according to the slide we are on
        switch (step) {
            case 1:
            case 2:
                $sidebar.removeClass('white').addClass('gray');
            break;
            default:
                $sidebar.removeClass('gray').addClass('white');
            break;
        }
    }
})('overlay');

您需要相应地更改 switch case 语句(以及侧边栏和添加/删除类)，但希望您能了解我要向您展示的内容的要点。

编辑

$.vegas('slideshow', { delay: 4000,
    backgrounds: [
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-vardagsrum.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-verkstad.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-urbild.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-kuggar.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-fiber.jpg', fade: 1000 },
        { src: 'http://ff.felipes.se/wp-content/uploads/2014/01/bakgrundsbild-bord.jpg', fade: 1000 },
    ],
    walk: function(step) {
        //alert('N°' + step + ' is now displayed');

        // get a handle on the sidebar
        var $sidebar = $('div.sidebar');

        // change it's class according to the slide we are on
        switch (step) {
            case 1:
            case 2:
                goGray($sidebar);
            break;
            default:
                goWhite($sidebar);
            break;
        }
    }
})('overlay');

function goGray($sidebar){
    $sidebar.removeClass('white').addClass('gray');
}

function goWhite($sidebar){
    $sidebar.removeClass('gray').addClass('white');
}