1 files changed, 88 insertions, 0 deletions
diff --git a/themes/itheme/static/js/animation.js b/themes/itheme/static/js/animation.js
new file mode 100644
index 0000000..f7bceb5
--- /dev/null
+++ b/themes/itheme/static/js/animation.js
@@ -0,0 +1,88 @@
+var animationElements = [];
+var imageElements = [];
+var animationElementName = ".small-load";
+
+
+// Hookable function
+var loadAnimation = function (item) {
+  let img = new Image();
+  img.src = item.children[0].children[0].dataset.src;
+  img.onload = function () {
+    item.classList.remove("small-load", "medium-load", "large-load");
+    item.classList.add("small-loaded", "medium-loaded", "large-loaded");
+  }
+}
+
+// Hookable function
+var loadImage = function (index) {
+  if (index >= imageElements.length) return;
+  let item = imageElements[index];
+  let image = new Image();
+  item.src = item.dataset.src;
+  image.src = item.src;
+
+  // if the image is loaded, load the next image
+  image.onload = function () {
+    loadImage(index + 1);
+  }
+  // if the image is not loaded, load the next image
+  image.onerror = function () {
+    loadImage(index + 1);
+  }
+}
+
+
+function initImage() {
+  // get all the images with data-src attribute
+  imageElements = document.querySelectorAll('img[data-src]')
+  // load the images one by one
+  loadImage(0);
+
+
+  animationElements = document.querySelectorAll(animationElementName);
+  // load the images which are in the viewport
+  viewPortLoad(0);
+  const debouncedHandleScroll = debounce(lazyAnimation, 10);
+  // add the event listener
+  window.addEventListener('scroll', debouncedHandleScroll);
+}
+
+
+function viewPortLoad(index) {
+  if (index >= animationElements.length) return;
+  let item = animationElements[index];
+  if (!isElementInView(item)) {
+    viewPortLoad(index + 1)
+    return;
+  };
+
+  loadAnimation(item)
+  viewPortLoad(index + 1);
+}
+
+
+function lazyAnimation() {
+  images = document.querySelectorAll(animationElementName);
+  viewPortLoad(0);
+}
+
+
+// check if the element is in the viewport
+function isElementInView(element) {
+  const rect = element.getBoundingClientRect();
+  const elementTop = rect.top;
+  const elementBottom = rect.bottom;
+  return (elementTop >= 0 && elementBottom - 200 <= window.innerHeight);
+}
+
+function debounce(fn, delay) {
+  let timer = null;
+  return function () {
+    let context = this;
+    let args = arguments;
+    clearTimeout(timer);
+    timer = setTimeout(function () {
+      fn.apply(context, args);
+    }, delay);
+  };
+}