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+{{*
+Force the browser to reload an image from the server instead of the cache.
+based on an answer from http://stackoverflow.com/a/22429796/3343347
+
+Usage: Set $imgUrl to the src url you want to be re-fetched from the server
+
+*}}
+
+<script>
+ $(document).ready(
+ function() {
+ forceImgReload("{{$imgUrl}}");
+ }
+ );
+
+ {{*
+ * find and return any existing img tags with a matching src url, and set them to an intermediate
+ * src url so they can later be reverted back once the cached version has been updated.
+ *}}
+ function prepareImagesForReload(srcUrl) {
+
+ var result = $("img[src='" + srcUrl + "']").get();
+
+ for (i = 0; i < result.length; i++) {
+ {{*
+ * Set the image to a reloading image, in this case an animated "reloading" svg
+ * Ideally this wont be displayed long enough to matter.
+ *}}
+ result[i].src = "data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100' preserveAspectRatio='xMidYMid' class='uil-reload'%3E%3Cpath fill='none' class='bk' d='M0 0h100v100H0z'/%3E%3Cg%3E%3Cpath d='M50 15a35 35 0 1 0 24.787 10.213' fill='none' stroke='%23777' stroke-width='12'/%3E%3Cpath d='M50 0v30l16-15L50 0' fill='%23777'/%3E%3CanimateTransform attributeName='transform' type='rotate' from='0 50 50' to='360 50 50' dur='1s' repeatCount='indefinite'/%3E%3C/g%3E%3C/svg%3E";
+ }
+
+ return result;
+ }
+
+ function restoreImages(srcUrl, imgList) {
+
+ for (i = 0; i < imgList.length; i++) {
+ imgList[i].src = srcUrl;
+ }
+ }
+
+ function forceImgReload(srcUrl) {
+ var imgList;
+ var step = 0;
+ var iframe = window.document.createElement("iframe"); // Hidden iframe, in which to perform the load+reload.
+
+ {{* Callback function, called after iframe load+reload completes (or fails).
+ Will be called TWICE unless twostage-mode process is cancelled. (Once after load, once after reload). *}}
+ var iframeLoadCallback = function(e) {
+
+ if (step === 0) {
+ // initial load just completed. Note that it doesn't actually matter if this load succeeded or not.
+
+ step = 1;
+ imgList = prepareImagesForReload(srcUrl);
+ iframe.contentWindow.location.reload(true); // initiate forced-reload!
+
+ } else if (step === 1) {
+ // forced re-load is done
+
+ restoreImages(srcUrl, imgList);
+ if (iframe.parentNode) iframe.parentNode.removeChild(iframe);
+ }
+ }
+
+ iframe.style.display = "none";
+ window.parent.document.body.appendChild(iframe); {{* NOTE: if this is done AFTER setting src, Firefox MAY fail to fire the load event! *}}
+ iframe.addEventListener("load", iframeLoadCallback, false);
+ iframe.addEventListener("error", iframeLoadCallback, false);
+ iframe.src = srcUrl;
+ }
+</script>