hammer.js实现背景图手势缩放调整位置

时间：2021-08-21 14:16:50
<!DOCTYPE html>

<html>

<head>

<script>

function getxy(e){

    var a=new Array()

    var t=e.offsetTop;

    var l=e.offsetLeft;

    var w=e.offsetWidth;

    var h=e.offsetHeight;

    while(e=e.offsetParent){

        t+=e.offsetTop;

        l+=e.offsetLeft;

    }

    a[0]=w;a[1]=h;

    a[2]=l;a[3]=t;

    return a;

}

</script>

    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1, maximum-scale=1">

    <link rel="stylesheet" href="assets/style.css">

    <title>Hammer.js</title>

    <style>

		*, *:after, *:before {

			box-sizing: border-box;

			-moz-box-sizing: border-box;

		}

		html, body {

			margin: 0;

			padding: 0;

			height: 100%;

			min-height: 100%;

			background: #eee;

			font: 13px/1.5em 'Open Sans', Helvetica, Arial, sans-serif;

		}

		a {

			color: #4986e7;

		}

		.bg1, .green { background: #42d692; }

		.bg2, .blue { background: #4986e7; }

		.bg3, .red { background: #d06b64; }

		.bg4, .purple { background: #cd74e6; }

		.bg5, .azure { background: #9fe1e7; }

		body {

			margin: 20px;

		}

		pre {

			background: #fff;

			padding: 20px;

			margin-bottom: 20px;

		}

		.container {

			max-width: 900px;

			margin: 0 auto;

		}

		.clear { clear: both; }

        html, body {

            overflow: hidden;

            margin: 0;

        }

        body {

            -webkit-perspective: 500;

            -moz-perspective: 500;

            perspective: 500;

        }

        .animate {

            -webkit-transition: all .3s;

            -moz-transition: all .3s;

            transition: all .3s;

        }

        #hit {

            padding: 10px;

        }

        #log {

            position: absolute;

            padding: 10px;

        }

		.bg2{

			width:15em; height:40em; margin:0 auto;

			/*background-image:url(1.jpg);*/

			position:fixed;

			z-index:-2;

			background-repeat:no-repeat;

		}

    </style>

</head>

<body>

<div class="bg2" id="bg2">

</div>

<script src="hammer.js"></script>

<script>

    var reqAnimationFrame = (function () {

        return window[Hammer.prefixed(window, 'requestAnimationFrame')] || function (callback) {

            window.setTimeout(callback, 1000 / 60);

        };

    })();

	var bg = document.getElementById("bg2");

	var xy = getxy(bg);

	var bgP = {

				x:0,y:0,dx:0,dy:0,

				s:1,ls:1,bdw:xy[0],bdh:xy[1]

			};

    var mc = new Hammer.Manager(bg);

	function imgLoaded(){

		bgP.bgw = this.width;

		bgP.bgh = this.height;

		if(bgP.bgw / bgP.bgh > bgP.bdw / bgP.bdh)

			bgP.useW = false;

		else

			bgP.useW = true;

		this.style.display = 'none';

		bg.style.backgroundImage = 'url('+this.src+')';

		bg.style.backgroundSize = bgP.useW? (bgP.bgw+'px auto') : ('auto '+bgP.bgh+'px');

		mc.add(new Hammer.Pan({ threshold: 0, pointers: 0 }));

		mc.add(new Hammer.Rotate({ threshold: 0 })).recognizeWith(mc.get('pan'));

		mc.add(new Hammer.Pinch({ threshold: 0 })).recognizeWith([mc.get('pan'), mc.get('rotate')]);

		mc.on("panstart panmove", onPan);

		//mc.on("rotatestart rotatemove", onRotate);

		mc.on("pinchstart pinchmove", onPinch);

		mc.on("hammer.input", function(ev) {

			if(ev.isFinal) {

				bgP.dx = 0;

				bgP.dy = 0;

				bgP.ls = 1;

			}

		});

	}

    function onPan(ev) {

        bgP.x += ev.deltaX - bgP.dx;

		bgP.y += ev.deltaY - bgP.dy;

		console.log('x='+(ev.deltaX - bgP.dx)+', y='+(ev.deltaY - bgP.dy));

		bgP.dx = ev.deltaX;

		bgP.dy = ev.deltaY;

		if(bgP.x>0) bgP.x = 0;

		if(bgP.y>0) bgP.y = 0;

		if(bgP.x+bgP.bgw*bgP.s<bgP.bdw)

			bgP.x = bgP.bdw - bgP.bgw*bgP.s;

		if(bgP.y+bgP.bgh*bgP.s<bgP.bdh)

			bgP.y = bgP.bdh - bgP.bgh*bgP.s;

		var pos = bgP.x+'px '+bgP.y+'px';

		bg.style.backgroundPosition = pos;

    }

    var initScale = 1;

    function onPinch(ev) {

        if(ev.type == 'pinchstart') {

            initScale = transform.scale || 1;

        }

		var add = ev.scale - bgP.ls;

		bgP.s += add;

		bgP.ls = ev.scale;

		if(bgP.useW){

			var w = (bgP.bgw*bgP.s);

			if(w<bgP.bdw)

			{

				bgP.s = bgP.bdw/bgP.bgw;

				w = (bgP.bgw*bgP.s);

			}

			bg.style.backgroundSize = w +'px auto';

		}else{

			var h = (bgP.bgh*bgP.s);

			if(h<bgP.bdh)

			{

				bgP.s = bgP.bdh/bgP.bgh;

				h = (bgP.bgh*bgP.s);

			}

			bg.style.backgroundSize = 'auto '+h +'px';

		}

    }

	function bgStart(src){

		var img = document.createElement('img');

		img.src = src;

		img.style.opacity = '0.01';

		img.onload = imgLoaded;

	}

	bgStart('1.jpg');

</script>

</body>

</html>

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