feat: add shimmer background when image loads

Author: cotes2020

_includes/refactor-content.html

@@ -81,21 +81,22 @@
       {% continue %}
     {% endunless %}
 
-    {% assign _left = _left | remove: ' /'  | replace: ' w=', ' width=' | replace: ' h=', ' height=' %}
-    {% assign _attrs = _left | split: ' ' %}
+    {% assign _left = _left | remove: ' /' | replace: ' w=', ' width=' | replace: ' h=', ' height=' %}
+    {% assign _attrs = _left | split: '" ' %}
 
     {% assign _width = nil %}
     {% assign _height = nil %}
     {% assign _lqip = nil %}
+    {% assign _class = nil %}
 
     {% for _attr in _attrs %}
-      {% assign _pair = _attr | split: '="' %}
-      {% if _pair.size < 2 %}
+      {% unless _attr contains '=' %}
         {% continue %}
-      {% endif %}
+      {% endunless %}
 
+      {% assign _pair = _attr | remove: '"' | split: '=' %}
       {% capture _key %}{{ _pair | first }}{% endcapture %}
-      {% capture _value %}{{ _pair | last | remove: '"' }}{% endcapture %}
+      {% capture _value %}{{ _pair | last }}{% endcapture %}
 
       {% case _key %}
         {% when 'width' %}
@@ -106,10 +107,20 @@
           {% assign _src = _value %}
         {% when 'lqip' %}
           {% assign _lqip = _value %}
+        {% when 'class' %}
+          {% assign _class = _value %}
       {% endcase %}
 
     {% endfor %}
 
+    <!-- take out classes -->
+    {% if _class %}
+      {% capture _old_class %}class="{{ _class }}"{% endcapture %}
+      {% assign _left = _left | remove: _old_class %}
+    {% endif %}
+
+    {% assign _final_src = nil %}
+
     {% unless _src contains '//' %}
       {% assign _final_src = _path_prefix | append: _src %}
       {% capture _src_from %}"{{ _src }}"{% endcapture %}
@@ -127,31 +138,51 @@
     {% endif %}
 
     <!-- lazy-load images <https://github.com/aFarkas/lazysizes#readme> -->
+    {% assign _left = _left | replace: 'src=', 'data-src=' %}
     {% if _left contains 'class=' %}
-      {% assign _left = _left | replace: 'class="', 'class="lazyload ' %}
+      {% assign _left = _left | replace: 'class="', 'class="lazyload '%}
     {% else %}
-      {% assign _left = _left | replace: 'src=', 'class="lazyload" src=' %}
+      {% assign _left = _left | append: ' class="lazyload"' %}
     {% endif %}
 
-    {% assign _left = _left | replace: 'src=', 'data-src=' %}
-
-    <!-- add placeholder -->
+    <!-- add image placeholder -->
     {% if _lqip %}
       {% assign _left = _left | replace: ' lqip=', ' data-lqip="true" src=' %}
     {% else %}
       {% if _width and _height %}
-        <!-- Add SVG placehoder to prevent layout reflow -->
+        <!-- add SVG placehoder -->
         {%- capture _svg -%}
           src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 {{ _width  }} {{ _height }}'%3E%3C/svg%3E"
         {%- endcapture -%}
         {% assign _left =  _svg | append: ' ' | append: _left %}
+        {% assign _class = _class | append: ' shimmer' %}
       {% endif %}
     {% endif %}
 
     <!-- Bypass the HTML-proofer test -->
     {% assign _left = _left | append: ' data-proofer-ignore' %}
 
-    <!-- Combine -->
+    <!-- make sure the `<img>` is wrapped by `<a>` -->
+    {% assign _parent = _right | slice: 1, 4 %}
+
+    {% if _parent == '</a>' %}
+      <!-- add class to exist <a> tag -->
+      {% assign _size = _img_content | size | minus: 1 %}
+      {% capture _class %}
+        class="img-link{% unless _lqip %} shimmer{% endunless %}"
+      {% endcapture %}
+      {% assign _img_content = _img_content | slice: 0, _size | append: _class | append: '>'  %}
+
+    {% else %}
+      <!-- create the image wrapper -->
+      {%- capture _wrapper_start -%}
+        <a href="{{ _final_src | default: _src  }}" class="popup img-link {{ _class }}">
+      {%- endcapture -%}
+      {% assign _img_content = _img_content | append: _wrapper_start %}
+      {% assign _right = _right | prepend: '></a' %}
+    {% endif %}
+
+    <!-- combine -->
     {% assign _img_content = _img_content | append: IMG_TAG | append: _left | append: _right %}
 
   {% endfor %}

_javascript/utils/img-extra.js

@@ -1,26 +1,13 @@
 /**
- Set up image popup stuff (https://github.com/dimsemenov/Magnific-Popup)
+ * Set up image stuff
  */
 
-$(function () {
-    const IMG_SCOPE = '#main > div.row:first-child > div:first-child';
-
-    if ($(`${IMG_SCOPE} img`).length <= 0) {
+(function() {
+    if ($('#core-wrapper img[data-src]') <= 0) {
         return;
     }
 
-    /* popup */
-
-    $(`${IMG_SCOPE} p > img[data-src], ${IMG_SCOPE} img[data-src].preview-img`).each(
-        function () {
-            let nextTag = $(this).next();
-            const title = nextTag.prop('tagName') === 'EM' ? nextTag.text() : '';
-            const src = $(this).attr('data-src'); // created by lozad.js
-
-            $(this).wrap(`<a href="${src}" title="${title}" class="popup"></a>`);
-        }
-    );
-
+    /* See: <https://github.com/dimsemenov/Magnific-Popup> */
     $('.popup').magnificPopup({
         type: 'image',
         closeOnContentClick: true,
@@ -32,8 +19,10 @@ $(function () {
         }
     });
 
-    /* markup the image links */
-
-    $(`${IMG_SCOPE} a`).has('img').addClass('img-link');
+    /* Stop shimmer when image loaded */
+    document.addEventListener('lazyloaded', function(e) {
+        const $img = $(e.target);
+        $img.parent().removeClass('shimmer');
+    });
 
-});
+})();

_layouts/post.html

@@ -27,32 +27,37 @@ <h1 data-toc-skip>{{ page.title }}</h1>
     {% endif %}
 
   {% if page.image %}
-    <div class="mt-3 mb-3">
-      <img src="{{ page.image.path | default: page.image }}"
-        class="preview-img{% if page.image.no_bg %}{{ ' no-bg' }}{% endif %}"
-        alt="{{ page.image.alt | default: "Preview Image" }}"
+    {% capture src %}src="{{ page.image.path | default: page.image }}"{% endcapture %}
+    {% capture class %}class="preview-img{% if page.image.no_bg %}{{ ' no-bg' }}{% endif %}"{% endcapture %}
+    {% capture alt %}alt="{{ page.image.alt | default: "Preview Image" }}"{% endcapture %}
 
+    {% capture w %}
       {% if page.image.width %}
         width="{{ page.image.width }}"
       {% elsif page.image.w %}
         width="{{ page.image.w }}"
       {% endif %}
+    {% endcapture %}
 
+    {% capture h %}
       {% if page.image.height %}
         height="{{ page.image.height }}"
       {% elsif page.image.h %}
-        height="{{ page.image.h }}"
+        h="{{ page.image.h }}"
       {% endif %}
+    {% endcapture %}
 
+    {% capture lqip %}
       {% if page.image.lqip %}
         lqip="{{ page.image.lqip }}"
       {% endif %}
+    {% endcapture %}
 
-      ><!-- endof img tag -->
-
-      {% if page.image.alt %}
+    <div class="mt-3 mb-3">
+      <img {{ src }} {{ class }} {{ w | strip }} {{ h | strip }} {{ lqip | strip }} {{ alt }}>
+      {%- if page.image.alt -%}
         <figcaption class="text-center pt-2 pb-2">{{ page.image.alt }}</figcaption>
-      {% endif %}
+      {%- endif -%}
     </div>
   {% endif %}