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index.js
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index.js
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'use strict';
const ಠ = 'data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=='; // transparent image, used as accessor and replacing image
const propRegex = /(object-fit|object-position)\s*:\s*([-\w\s%]+)/g;
const testImg = new Image();
const supportsObjectFit = 'object-fit' in testImg.style;
const supportsObjectPosition = 'object-position' in testImg.style;
const supportsCurrentSrc = typeof testImg.currentSrc === 'string';
const nativeGetAttribute = testImg.getAttribute;
const nativeSetAttribute = testImg.setAttribute;
let autoModeEnabled = false;
function getStyle(el) {
const style = getComputedStyle(el).fontFamily;
let parsed;
const props = {};
while ((parsed = propRegex.exec(style)) !== null) {
props[parsed[1]] = parsed[2];
}
return props;
}
function fixOne(el, requestedSrc) {
if (el[ಠ].parsingSrcset) {
return;
}
const style = getStyle(el);
style['object-fit'] = style['object-fit'] || 'fill'; // default value
// If the fix was already applied, don't try to skip fixing,
// - because once you go ofi you never go back.
// - Wait, that doesn't rhyme.
// - This ain't rap, bro.
if (!el[ಠ].s) {
// fill is the default behavior so no action is necessary
if (style['object-fit'] === 'fill') {
return;
}
// Where object-fit is supported and object-position isn't (Safari < 10)
if (
!el[ಠ].skipTest && // unless user wants to apply regardless of browser support
supportsObjectFit && // if browser already supports object-fit
!style['object-position'] // unless object-position is used
) {
return;
}
}
let src = el[ಠ].ios7src || el.currentSrc || el.src;
if (requestedSrc) {
// explicitly requested src takes precedence
// TODO: this still should overwrite srcset
src = requestedSrc;
} else if (el.srcset && !supportsCurrentSrc && window.picturefill) {
const pf = window.picturefill._;
// prevent infinite loop
// fillImg sets the src which in turn calls fixOne
el[ಠ].parsingSrcset = true;
// parse srcset with picturefill where currentSrc isn't available
if (!el[pf.ns] || !el[pf.ns].evaled) {
// force synchronous srcset parsing
pf.fillImg(el, {reselect: true});
}
if (!el[pf.ns].curSrc) {
// force picturefill to parse srcset
el[pf.ns].supported = false;
pf.fillImg(el, {reselect: true});
}
delete el[ಠ].parsingSrcset;
// retrieve parsed currentSrc, if any
src = el[pf.ns].curSrc || src;
}
// store info on object for later use
if (el[ಠ].s) {
el[ಠ].s = src;
if (requestedSrc) {
// the attribute reflects the user input
// the property is the resolved URL
el[ಠ].srcAttr = requestedSrc;
}
} else {
el[ಠ] = {
s: src,
srcAttr: requestedSrc || nativeGetAttribute.call(el, 'src'),
srcsetAttr: el.srcset
};
el.src = ಠ;
try {
// remove srcset because it overrides src
if (el.srcset) {
el.srcset = '';
// restore non-browser-readable srcset property
Object.defineProperty(el, 'srcset', {
value: el[ಠ].srcsetAttr
});
}
keepSrcUsable(el);
} catch (err) {
el[ಠ].ios7src = src;
}
}
el.style.backgroundImage = 'url("' + src + '")';
el.style.backgroundPosition = style['object-position'] || 'center';
el.style.backgroundRepeat = 'no-repeat';
if (/scale-down/.test(style['object-fit'])) {
// `object-fit: scale-down` is either `contain` or `auto`
if (!el[ಠ].i) {
el[ಠ].i = new Image();
el[ಠ].i.src = src;
}
// naturalWidth is only available when the image headers are loaded,
// this loop will poll it every 100ms.
// There's currently no check to prevent this loop from starting twice
// as a consequence of calling ofi() twice on the same image, but it's light
// and causes no issues, so it's not worth ensuring that it doesn't.
(function loop() {
// https://bugs.chromium.org/p/chromium/issues/detail?id=495908
if (el[ಠ].i.naturalWidth) {
if (el[ಠ].i.naturalWidth > el.width || el[ಠ].i.naturalHeight > el.height) {
el.style.backgroundSize = 'contain';
} else {
el.style.backgroundSize = 'auto';
}
return;
}
setTimeout(loop, 100);
})();
} else {
el.style.backgroundSize = style['object-fit'].replace('none', 'auto').replace('fill', '100% 100%');
}
}
function keepSrcUsable(el) {
const descriptors = {
get() {
return el[ಠ].s;
},
set(src) {
delete el[ಠ].i; // scale-down's img sizes need to be updated too
fixOne(el, src);
return src;
}
};
Object.defineProperty(el, 'src', descriptors);
Object.defineProperty(el, 'currentSrc', {get: descriptors.get}); // it should be read-only
}
function hijackAttributes() {
if (!supportsObjectPosition) {
HTMLImageElement.prototype.getAttribute = function (name) {
if (this[ಠ] && (name === 'src' || name === 'srcset')) {
return this[ಠ][name + 'Attr'];
}
return nativeGetAttribute.call(this, name);
};
HTMLImageElement.prototype.setAttribute = function (name, value) {
if (this[ಠ] && (name === 'src' || name === 'srcset')) {
this[name === 'src' ? 'src' : name + 'Attr'] = String(value);
} else {
nativeSetAttribute.call(this, name, value);
}
};
}
}
export default function fix(imgs, opts) {
const startAutoMode = !autoModeEnabled && !imgs;
opts = opts || {};
imgs = imgs || 'img';
if (supportsObjectPosition && !opts.skipTest) {
return false;
}
// use imgs as a selector or just select all images
if (typeof imgs === 'string') {
imgs = document.querySelectorAll('img');
} else if (!'length' in imgs) {
imgs = [imgs];
}
// apply fix to all
for (let i = 0; i < imgs.length; i++) {
imgs[i][ಠ] = imgs[i][ಠ] || opts;
fixOne(imgs[i]);
}
if (startAutoMode) {
document.body.addEventListener('load', e => {
if (e.target.tagName === 'IMG') {
fix(e.target, {
skipTest: opts.skipTest
});
}
}, true);
autoModeEnabled = true;
imgs = 'img'; // reset to a generic selector for watchMQ
}
// if requested, watch media queries for object-fit change
if (opts.watchMQ) {
window.addEventListener('resize', fix.bind(null, imgs, {
skipTest: opts.skipTest
}));
}
}
fix.supportsObjectFit = supportsObjectFit;
fix.supportsObjectPosition = supportsObjectPosition;
hijackAttributes();