javascript - 如何淡入 - 淡出随机位置和随机大小的三个图像？

Question

我想放置一个随机大小和随机位置的随机淡入/淡出的 div。

我可以通过淡入/淡出随机显示三张图像，但我无法将它们随机放置在随机位置。

http://jsfiddle.net/qq68m/139/

j查询:

jQuery(function(){
    function random(n) {
        return Math.floor(Math.random() * n);
    }
    var transition_time = 2500;
    var waiting_time = 100;
    var images = $('div#block img');
    var n = images.length;
    var current = random(n);
    images.hide();
    images.eq(current).show();

    var interval_id = setInterval(function () {
        images.eq(current).fadeOut(transition_time, function () {
            current = random(n);
            images.eq(current).fadeIn(transition_time);
        });
    }, 2 * transition_time + waiting_time);
})

html:

<div id="block">
    <img src="http://mobler.com.tr/wp-content/uploads/2017/07/rand1.png">
    <img src="http://mobler.com.tr/wp-content/uploads/2017/07/rand2.png">
        <img src="http://mobler.com.tr/wp-content/uploads/2017/07/rand3.png">

</div>

Answer 1

这是我的解决方案。它允许您指定图像比例大小的范围，并确保无论比例如何，随机选择的位置都不会裁剪到容器之外。希望这能满足您的要求。

编辑:我更新了代码，现在非四边形图像也将保持它们的比例(如 Phil Murray 示例所示)。

如果通过 css 高度/宽度设置大小对您不起作用，也许使用 CSS3 scaleX/scaleY 属性可能会给您带来更平滑的图像缩放结果。

如果您有任何其他问题，请在此帖子评论中提问。

jQuery(function(){
    function random(n) {
        return Math.floor(Math.random() * n);
    }
    var transition_time = 200;
    var waiting_time = 100;
    var images = $('div#block img');
    var n = images.length;
    var current = random(n);
    images.hide();
    images.eq(current).show();
    
    //get the size of the container
    var boxHeight = document.getElementById('block').offsetHeight;
    var boxWidth = document.getElementById('block').offsetWidth;
    
    //range of possible image scales
    var objectMaxHeight = 60;
    var objectMinHeight = 20;
    
    var interval_id = setInterval(function () {
        images.eq(current).fadeOut(transition_time, function () {
            current = random(n);
            
            //gets reference to selected image
            var $domImage = images.eq(current);
            
            //generates random heights and widths for the image to be shown in
            var generatedHeight = 
            		Math.floor(
                	Math.random() * (objectMaxHeight - objectMinHeight)
                 ) + objectMinHeight;

						// assigns values to the image
            $domImage.css('height', generatedHeight); 
            $domImage.css('width', "auto"); 
            
            var imageAutoWidth = $domImage.width();
            
            var generatedYLocation = Math.floor(
              Math.random() * (boxHeight - generatedHeight + 1)
            ) + 0;
            
            var generatedXLocation = Math.floor(
                Math.random() * (boxWidth - imageAutoWidth)
            ) + 0;
            
            $domImage.css('top', generatedYLocation);
            $domImage.css('left', generatedXLocation);
            $domImage.fadeIn(transition_time);
        });
    }, 2 * transition_time + waiting_time);
})

#block { 
  position: fixed;
  width: 300px;
  height: 300px;
  border: 1px solid red;
  background: yellow;
  overflow: hidden;
}

img {
  position:relative; 
  top: 0;
  left: 0;
  height: 100px;
  width: 100px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="block">
    <img src="http://mobler.com.tr/wp-content/uploads/2017/07/rand1.png">
    <img src="http://mobler.com.tr/wp-content/uploads/2017/07/rand2.png">
    <img src="http://mobler.com.tr/wp-content/uploads/2017/07/rand3.png">
    <img src="https://www.fillmurray.com/g/200/500">
    <img src="https://www.fillmurray.com/g/500/200">
</div>