模拟背景大小:在< video>或< img> [英] simulate background-size:cover on <video> or <img>
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问题描述
如何在像< video>
这样的HTML元素上模拟 background-size:cover
或< img>
?
How can I simulate the functionality of background-size:cover
on an html element like <video>
or <img>
?
我希望它像
background-size: cover;
background-position: center center;
推荐答案
一个工作示例在 this jsFiddle 中。
var min_w = 300; // minimum video width allowed
var vid_w_orig; // original video dimensions
var vid_h_orig;
jQuery(function() { // runs after DOM has loaded
vid_w_orig = parseInt(jQuery('video').attr('width'));
vid_h_orig = parseInt(jQuery('video').attr('height'));
$('#debug').append("<p>DOM loaded</p>");
jQuery(window).resize(function () { resizeToCover(); });
jQuery(window).trigger('resize');
});
function resizeToCover() {
// set the video viewport to the window size
jQuery('#video-viewport').width(jQuery(window).width());
jQuery('#video-viewport').height(jQuery(window).height());
// use largest scale factor of horizontal/vertical
var scale_h = jQuery(window).width() / vid_w_orig;
var scale_v = jQuery(window).height() / vid_h_orig;
var scale = scale_h > scale_v ? scale_h : scale_v;
// don't allow scaled width < minimum video width
if (scale * vid_w_orig < min_w) {scale = min_w / vid_w_orig;};
// now scale the video
jQuery('video').width(scale * vid_w_orig);
jQuery('video').height(scale * vid_h_orig);
// and center it by scrolling the video viewport
jQuery('#video-viewport').scrollLeft((jQuery('video').width() - jQuery(window).width()) / 2);
jQuery('#video-viewport').scrollTop((jQuery('video').height() - jQuery(window).height()) / 2);
// debug output
jQuery('#debug').html("<p>win_w: " + jQuery(window).width() + "</p>");
jQuery('#debug').append("<p>win_h: " + jQuery(window).height() + "</p>");
jQuery('#debug').append("<p>viewport_w: " + jQuery('#video-viewport').width() + "</p>");
jQuery('#debug').append("<p>viewport_h: " + jQuery('#video-viewport').height() + "</p>");
jQuery('#debug').append("<p>video_w: " + jQuery('video').width() + "</p>");
jQuery('#debug').append("<p>video_h: " + jQuery('video').height() + "</p>");
jQuery('#debug').append("<p>vid_w_orig: " + vid_w_orig + "</p>");
jQuery('#debug').append("<p>vid_h_orig: " + vid_h_orig + "</p>");
jQuery('#debug').append("<p>scale: " + scale + "</p>");
};
#video-viewport {
position: absolute;
top: 0;
overflow: hidden;
z-index: -1; /* for accessing the video by click */
}
#debug {
position: absolute;
top 0;
z-index: 100;
color: #fff;
font-size: 12pt;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="video-viewport">
<video autoplay controls preload width="640" height="360">
<source src="http://www.quirksmode.org/html5/videos/big_buck_bunny.mp4"type="video/mp4" />
<source src="http://www.quirksmode.org/html5/videos/big_buck_bunny.webm"type="video/webm" />
<source src="http://www.quirksmode.org/html5/videos/big_buck_bunny.ogv"type="video/webm" />
</video>
</div>
<div id="debug"></div>
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