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October 16, 2018 11:10
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A simple way of panning and zooming an image using Hammer.js.
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// <img id="myimage" src="http://placecage/1280/720"> | |
var image = document.getElementById('myimage'); | |
var mc = new Hammer.Manager(image); | |
var pinch = new Hammer.Pinch(); | |
var pan = new Hammer.Pan(); | |
pinch.recognizeWith(pan); | |
mc.add([pinch, pan]); | |
var adjustScale = 1; | |
var adjustDeltaX = 0; | |
var adjustDeltaY = 0; | |
var currentScale = null; | |
var currentDeltaX = null; | |
var currentDeltaY = null; | |
// Prevent long press saving on mobiles. | |
webpage.addEventListener('touchstart', function (e) { | |
e.preventDefault() | |
}); | |
// Handles pinch and pan events/transforming at the same time; | |
mc.on("pinch pan", function (ev) { | |
var transforms = []; | |
// Adjusting the current pinch/pan event properties using the previous ones set when they finished touching | |
currentScale = adjustScale * ev.scale; | |
currentDeltaX = adjustDeltaX + (ev.deltaX / currentScale); | |
currentDeltaY = adjustDeltaY + (ev.deltaY / currentScale); | |
// Concatinating and applying parameters. | |
transforms.push('scale({0})'.format(currentScale)); | |
transforms.push('translate({0}px,{1}px)'.format(currentDeltaX, currentDeltaY)); | |
webpage.style.transform = transforms.join(' '); | |
}); | |
mc.on("panend pinchend", function (ev) { | |
// Saving the final transforms for adjustment next time the user interacts. | |
adjustScale = currentScale; | |
adjustDeltaX = currentDeltaX; | |
adjustDeltaY = currentDeltaY; | |
}); |
Maybe somebody knows packages where it is implemented?
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Why should recognize pinch and pan? and in my config, the pinch event will always trigger the pan event, This really bother me.