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Ich schrieb den HTML-Code unten, um Vollbild anzuzeigen. Da meine Bilder manchmal sehr groß sind, wollte ich zoomen und die Details sehen können. Ich habe diesen JavaScript-Code hier gefunden http://www.jacklmoore.com/wheelzoom/. Es funktioniert sehr gut, aber ich möchte unbegrenztes Vergrößern verhindern. Ich muss es durch die Größe des Bildes begrenzt werden. Wie kann ich den Code ändern, um dies zu tun? Vielen Dank.Wie Sie diesen JavaScript-Code ändern, um unbegrenzten Zoom zu verhindern
HTML
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Zoom</title>
<style>
html, body {
background:#333333;
height: 100%;
margin: 0;
padding: 0;
}
#image {
padding: 0;
display: block;
margin: 0 auto;
max-height: 100%;
max-width: 100%;
}
</style>
</head>
<body>
<img class='zoom' src='MyImage.jpg' id='image'/>
<script src="wheelzoom.js"></script>
<script>
wheelzoom(document.querySelector('img.zoom'));
</script>
</body>
</html>
JavaScript
/*!
Wheelzoom 3.0.4
license: MIT
http://www.jacklmoore.com/wheelzoom
*/
window.wheelzoom = (function(){
var defaults = {
zoom: 0.10
};
var canvas = document.createElement('canvas');
var main = function(img, options){
if (!img || !img.nodeName || img.nodeName !== 'IMG') { return; }
var settings = {};
var width;
var height;
var bgWidth;
var bgHeight;
var bgPosX;
var bgPosY;
var previousEvent;
var cachedDataUrl;
function setSrcToBackground(img) {
img.style.backgroundImage = 'url("'+img.src+'")';
img.style.backgroundRepeat = 'no-repeat';
canvas.width = img.naturalWidth;
canvas.height = img.naturalHeight;
cachedDataUrl = canvas.toDataURL();
img.src = cachedDataUrl;
}
function updateBgStyle() {
if (bgPosX > 0) {
bgPosX = 0;
} else if (bgPosX < width - bgWidth) {
bgPosX = width - bgWidth;
}
if (bgPosY > 0) {
bgPosY = 0;
} else if (bgPosY < height - bgHeight) {
bgPosY = height - bgHeight;
}
img.style.backgroundSize = bgWidth+'px '+bgHeight+'px';
img.style.backgroundPosition = bgPosX+'px '+bgPosY+'px';
}
function reset() {
bgWidth = width;
bgHeight = height;
bgPosX = bgPosY = 0;
updateBgStyle();
}
function onwheel(e) {
var deltaY = 0;
e.preventDefault();
if (e.deltaY) { // FireFox 17+ (IE9+, Chrome 31+?)
deltaY = e.deltaY;
} else if (e.wheelDelta) {
deltaY = -e.wheelDelta;
}
// As far as I know, there is no good cross-browser way to get the cursor position relative to the event target.
// We have to calculate the target element's position relative to the document, and subtrack that from the
// cursor's position relative to the document.
var rect = img.getBoundingClientRect();
var offsetX = e.pageX - rect.left - window.pageXOffset;
var offsetY = e.pageY - rect.top - window.pageYOffset;
// Record the offset between the bg edge and cursor:
var bgCursorX = offsetX - bgPosX;
var bgCursorY = offsetY - bgPosY;
// Use the previous offset to get the percent offset between the bg edge and cursor:
var bgRatioX = bgCursorX/bgWidth;
var bgRatioY = bgCursorY/bgHeight;
// Update the bg size:
if (deltaY < 0) {
bgWidth += bgWidth*settings.zoom;
bgHeight += bgHeight*settings.zoom;
} else {
bgWidth -= bgWidth*settings.zoom;
bgHeight -= bgHeight*settings.zoom;
}
// Take the percent offset and apply it to the new size:
bgPosX = offsetX - (bgWidth * bgRatioX);
bgPosY = offsetY - (bgHeight * bgRatioY);
// Prevent zooming out beyond the starting size
if (bgWidth <= width || bgHeight <= height) {
reset();
} else {
updateBgStyle();
}
}
function drag(e) {
e.preventDefault();
bgPosX += (e.pageX - previousEvent.pageX);
bgPosY += (e.pageY - previousEvent.pageY);
previousEvent = e;
updateBgStyle();
}
function removeDrag() {
document.removeEventListener('mouseup', removeDrag);
document.removeEventListener('mousemove', drag);
}
// Make the background draggable
function draggable(e) {
e.preventDefault();
previousEvent = e;
document.addEventListener('mousemove', drag);
document.addEventListener('mouseup', removeDrag);
}
function load() {
if (img.src === cachedDataUrl) return;
var computedStyle = window.getComputedStyle(img, null);
width = parseInt(computedStyle.width, 10);
height = parseInt(computedStyle.height, 10);
bgWidth = width;
bgHeight = height;
bgPosX = 0;
bgPosY = 0;
setSrcToBackground(img);
img.style.backgroundSize = width+'px '+height+'px';
img.style.backgroundPosition = '0 0';
img.addEventListener('wheelzoom.reset', reset);
img.addEventListener('wheel', onwheel);
img.addEventListener('mousedown', draggable);
}
var destroy = function (originalProperties) {
img.removeEventListener('wheelzoom.destroy', destroy);
img.removeEventListener('wheelzoom.reset', reset);
img.removeEventListener('load', load);
img.removeEventListener('mouseup', removeDrag);
img.removeEventListener('mousemove', drag);
img.removeEventListener('mousedown', draggable);
img.removeEventListener('wheel', onwheel);
img.style.backgroundImage = originalProperties.backgroundImage;
img.style.backgroundRepeat = originalProperties.backgroundRepeat;
img.src = originalProperties.src;
}.bind(null, {
backgroundImage: img.style.backgroundImage,
backgroundRepeat: img.style.backgroundRepeat,
src: img.src
});
img.addEventListener('wheelzoom.destroy', destroy);
options = options || {};
Object.keys(defaults).forEach(function(key){
settings[key] = options[key] !== undefined ? options[key] : defaults[key];
});
if (img.complete) {
load();
}
img.addEventListener('load', load);
};
// Do nothing in IE8
if (typeof window.getComputedStyle !== 'function') {
return function(elements) {
return elements;
};
} else {
return function(elements, options) {
if (elements && elements.length) {
Array.prototype.forEach.call(elements, main, options);
} else if (elements && elements.nodeName) {
main(elements, options);
}
return elements;
};
}
}());
schwer zu sagen, nur aus, während wir einen Blick, warum nicht den Kerl, der es gemacht? Ziemlich coole kleine Lib dort – JordanHendrix