我正在使用HTML / Javascript工作,并且根据窗口大小调整图像大小。图像将占用所有窗口空间,但在调整大小时保持其纵横比。此外,如果窗口大小大于其最长边,则图像将旋转并调整大小。
例如,如果图像比高度更宽,并且窗口大小变得非常高,则图像应该旋转并调整大小以便最大化窗口空间,同时保持图像的纵横比相同。图像也应该在屏幕上居中,这样它在图像的两侧都会有相同的死角。
我无法让它发挥作用。到目前为止,这是我的代码。
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="Content-Style-Type" content="text/css" />
<link href="test.css" rel="stylesheet" type="text/css" />
<script type="text/javascript">
function resize_canvas(){
var main_canvas=document.getElementById("test");
var cxt=main_canvas.getContext("2d");
var img=new Image();
var ratio = 1;
var changed = 1;
var mid = 1;
var srcLink = "tall.JPG"; // test with tall and wide pics
main_canvas.width = window.innerWidth;
main_canvas.height = window.innerHeight;
img.src=srcLink;
if(window.innerWidth > window.innerHeight){ // if window port is wider than tall
changed = window.innerWidth / (img.width / img.height);
mid = window.innerHeight / 2;
img.onload = function()
{
if (img.width < img.height){
ratio = window.innerHeight / img.height;
changed = img.width * ratio;
cxt.rotate(90 * Math.PI / 180);
cxt.drawImage(img, 0, -img.height,changed,window.innerWidth);
} else {
cxt.drawImage(img,0,mid,window.innerWidth,changed);
}
} // end img onload call
}else{ // if window port is taller than wide
ratio = window.innerHeight / img.height;
changed = img.width * ratio;
mid = window.innerWidth / 2;
img.onload = function()
{
if (img.width > img.height){
ratio = window.innerWidth / img.width;
changed = img.height * ratio;
mid = window.innerHeight / 2 - changed / 2;
cxt.rotate(90 * Math.PI / 180);
cxt.drawImage(img, 0, -img.height,window.innerHeight,changed);
} else {
cxt.drawImage(img,mid,0,changed,window.innerHeight);
}
} // end img on load
} // end window size else block
} // end resize function
</script>
</head>
<body onload="resize_canvas();" onresize="resize_canvas();">
<canvas id="test"> canvas not supported </canvas>
</body>
</html>
css file
html, body {
width: 100%;
height: 100%;
margin: 0px;
}
#test
{
width: 100%; height: auto;
}
我花了很多天才研究这个问题,但是我对如何解决这个问题的想法已经不多了。任何帮助将非常感激。
感谢。
答案 0 :(得分:1)
<html>
<head>
<script type="text/javascript" charset="utf-8">
window.onload = function() {
var fitAspectRatio = function(srcWidth, srcHeight, fitWidth, fitHeight) {
if(fitHeight > fitWidth) {
theta = Math.PI / 2;
var temp = srcWidth;
srcWidth = srcHeight;
srcHeight = temp;
} else {
theta = 0;
}
var ratio = [fitWidth / srcWidth, fitHeight / srcHeight];
ratio = Math.min(ratio[0], ratio[1]);
return {
width : srcWidth * ratio,
height : srcHeight * ratio,
angle : theta
};
};
var img = new Image();
img.src = 'tall.JPG';
var canvas = document.getElementById("canvas1");
var ctx = canvas.getContext("2d");
window.onresize = function() {
var newsize = fitAspectRatio(img.width, img.height, window.innerWidth, window.innerHeight);
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
img.centerX = canvas.width / 2;
img.centerY = canvas.height / 2;
if(newsize.angle != 0) {
ctx.translate(img.centerX, img.centerY);
ctx.rotate(newsize.angle);
ctx.translate(-img.centerX, -img.centerY);
ctx.drawImage(img, (canvas.width - newsize.height) / 2, (canvas.height - newsize.width) / 2, newsize.height, newsize.width);
} else {
ctx.drawImage(img, (canvas.width - newsize.width) / 2, (canvas.height - newsize.height) / 2, newsize.width, newsize.height);
}
};
window.onresize();
};
</script>
<style>
body {
background: #001;
}
#canvas1 {
position: absolute;
top: 0;
left: 0;
padding: 0;
margin: 0;
}
</style>
</head>
<body>
<canvas id="canvas1"></canvas>
</body>
</html>