feat: add shimmer background when image loads

_includes/refactor-content.html

@@ -81,21 +81,22 @@
       {% continue %}
     {% endunless %}
 
-    {% assign _left = _left | remove: ' /'  | replace: ' w=', ' width=' | replace: ' h=', ' height=' %}
+    {% assign _left = _left | remove: ' /' | replace: ' w=', ' width=' | replace: ' h=', ' height=' %}
-    {% assign _attrs = _left | split: ' ' %}
+    {% assign _attrs = _left | split: '" ' %}
 
     {% assign _width = nil %}
     {% assign _height = nil %}
     {% assign _lqip = nil %}
+    {% assign _class = nil %}
 
     {% for _attr in _attrs %}
-      {% assign _pair = _attr | split: '="' %}
+      {% unless _attr contains '=' %}
-      {% if _pair.size < 2 %}
         {% 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 image placeholder -->
-
-    <!-- add 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
  */
 
-$(function () {
+(function() {
-    const IMG_SCOPE = '#main > div.row:first-child > div:first-child';
+    if ($('#core-wrapper img[data-src]') <= 0) {
-
-    if ($(`${IMG_SCOPE} img`).length <= 0) {
         return;
     }
 
-    /* popup */
+    /* See: <https://github.com/dimsemenov/Magnific-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>`);
-        }
-    );
-
     $('.popup').magnificPopup({
         type: 'image',
         closeOnContentClick: true,
@@ -32,8 +19,10 @@ $(function () {
         }
     });
 
-    /* markup the image links */
+    /* Stop shimmer when image loaded */
+    document.addEventListener('lazyloaded', function(e) {
+        const $img = $(e.target);
+        $img.parent().removeClass('shimmer');
+    });
 
-    $(`${IMG_SCOPE} a`).has('img').addClass('img-link');
+})();
-
-});

_layouts/post.html

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

_sass/addon/commons.scss

@@ -83,6 +83,47 @@ a {
 img {
   max-width: 100%;
   height: auto;
+
+  &[data-src] {
+    &.lazyloaded {
+      z-index: 1;
+      -webkit-animation: fade-in 0.4s ease-in;
+      animation: fade-in 0.4s ease-in;
+    }
+
+    &[data-lqip="true"] {
+      &.lazyload,
+      &.lazyloading {
+        -webkit-filter: blur(20px);
+        filter: blur(20px);
+      }
+    }
+
+    &:not([data-lqip="true"]) {
+      &.lazyload,
+      &.lazyloading {
+        background: var(--img-bg);
+      }
+    }
+
+    &.shadow {
+      -webkit-filter: drop-shadow(2px 4px 6px rgba(0, 0, 0, 0.08));
+      filter: drop-shadow(2px 4px 6px rgba(0, 0, 0, 0.08));
+      box-shadow: none !important; /* cover the Bootstrap 4.6.1 styles */
+    }
+
+    @extend %img-caption;
+  }
+
+  @-webkit-keyframes fade-in {
+    from { opacity: 0; }
+    to { opacity: 1; }
+  }
+
+  @keyframes fade-in {
+    from { opacity: 0; }
+    to { opacity: 1; }
+  }
 }
 
 blockquote {
@@ -183,49 +224,6 @@ i { /* fontawesome icons */
   }
 }
 
-img[data-src] {
-  @at-root #main #{&} {
-    margin: 0.5rem 0;
-  }
-
-  &[data-lqip="true"] {
-    &.lazyload,
-    &.lazyloading {
-      filter: blur(20px);
-    }
-  }
-
-  &:not([data-lqip="true"]) {
-    &.lazyload,
-    &.lazyloading {
-      opacity: 0;
-    }
-
-    &.lazyloaded {
-      opacity: 1;
-      transition: opacity 0.5s;
-    }
-  }
-
-  &.left {
-    float: left;
-    margin: 0.75rem 1rem 1rem 0;
-  }
-
-  &.right {
-    float: right;
-    margin: 0.75rem 0 1rem 1rem;
-  }
-
-  &.shadow {
-    -webkit-filter: drop-shadow(2px 4px 6px rgba(0, 0, 0, 0.08));
-    filter: drop-shadow(2px 4px 6px rgba(0, 0, 0, 0.08));
-    box-shadow: none !important; /* cover the Bootstrap 4.6.1 styles */
-  }
-
-  @extend %img-caption;
-}
-
 /* --- Panels --- */
 
 .access {
@@ -406,26 +404,14 @@ img[data-src] {
     margin-bottom: 1.5rem;
   }
 
-  img[data-src]:not(.normal):not(.left):not(.right) {
+  p {
-    @include align-center;
+    > img[data-src],
-  }
+    > a.popup {
-
+      &:not(.normal):not(.left):not(.right) {
-  a {
+        @include align-center;
-    &.img-link {
-      @extend %no-cursor;
-    }
-
-    /* created by `_includes/img-extra.html` */
-    &.popup {
-      cursor: zoom-in;
-    }
-
-    &:hover {
-      code {
-        @extend %link-hover;
       }
     }
-  } /* a */
+  }
 }
 
 .pageviews .fa-spinner {
@@ -457,6 +443,14 @@ img[data-src] {
   overflow-wrap: break-word;
 
   a {
+    &.popup {
+      @extend %no-cursor;
+      @extend %img-caption;
+      @include mt-mb(0.5rem);
+
+      cursor: zoom-in;
+    }
+
     &:not(.img-link) {
       @extend %link-underline;
 
@@ -464,10 +458,6 @@ img[data-src] {
         @extend %link-hover;
       }
     }
-
-    &.img-link {
-      @extend %img-caption;
-    }
   }
 
   ol,
@@ -553,6 +543,39 @@ img[data-src] {
   }
 }
 
+.img-link {
+  color: transparent;
+  display: inline-flex;
+
+  @extend %img-rounded;
+}
+
+.shimmer {
+  overflow: hidden;
+  position: relative;
+  background: var(--img-bg);
+
+  &::before {
+    content: "";
+    position: absolute;
+    background: var(--shimmer-bg);
+    height: 100%;
+    width: 100%;
+    -webkit-animation: shimmer 1s infinite;
+    animation: shimmer 1s infinite;
+  }
+
+  @-webkit-keyframes shimmer {
+    0% { -webkit-transform: translateX(-100%); transform: translateX(-100%); }
+    100% { -webkit-transform: translateX(100%); transform: translateX(100%); }
+  }
+
+  @keyframes shimmer {
+    0% { -webkit-transform: translateX(-100%); transform: translateX(-100%); }
+    100% { -webkit-transform: translateX(100%); transform: translateX(100%); }
+  }
+}
+
 /* --- buttons --- */
 .btn-lang {
   border: 1px solid !important;
@@ -622,6 +645,16 @@ img[data-src] {
   transition: background-color 0.15s ease-in-out, border-color 0.15s ease-in-out;
 }
 
+.left {
+  float: left;
+  margin: 0.75rem 1rem 1rem 0 !important;
+}
+
+.right {
+  float: right;
+  margin: 0.75rem 0 1rem 1rem !important;
+}
+
 /* --- Overriding --- */
 
 /* magnific-popup */

_sass/addon/module.scss

@@ -90,6 +90,10 @@
   font-style: normal;
 }
 
+%img-rounded {
+  border-radius: 10px;
+}
+
 %img-caption {
   + em {
     display: block;
@@ -114,6 +118,11 @@
   text-decoration: none;
 }
 
+@mixin mt-mb($value) {
+  margin-top: $value;
+  margin-bottom: $value;
+}
+
 @mixin ml-mr($value) {
   margin-left: $value;
   margin-right: $value;

_sass/colors/dark-typography.scss

@@ -26,6 +26,14 @@
   --label-color: rgb(108, 117, 125);
   --checkbox-color: rgb(118, 120, 121);
   --checkbox-checked-color: var(--link-color);
+  --img-bg: radial-gradient(circle, rgb(22, 22, 24) 0%, rgb(32, 32, 32) 100%);
+  --shimmer-bg:
+    linear-gradient(
+      90deg,
+      rgba(255, 255, 255, 0) 0%,
+      rgba(58, 55, 55, 0.4) 50%,
+      rgba(255, 255, 255, 0) 100%
+    );
 
   /* Sidebar */
   --sidebar-bg: radial-gradient(circle, #242424 0%, #1d1f27 100%);
@@ -65,7 +73,6 @@
   --card-bg: rgb(39, 40, 43);
   --card-border-color: rgb(53, 53, 60);
   --card-box-shadow: var(--main-bg);
-  --preview-img-bg: radial-gradient(circle, rgb(22, 22, 24) 0%, rgb(32, 32, 32) 100%);
   --kbd-wrap-color: #6a6a6a;
   --kbd-text-color: #d3d3d3;
   --kbd-bg-color: #242424;

_sass/colors/light-typography.scss

@@ -24,6 +24,14 @@
   --btn-box-shadow: #eaeaea;
   --checkbox-color: #c5c5c5;
   --checkbox-checked-color: #07a8f7;
+  --img-bg: radial-gradient(circle, rgb(255, 255, 255) 0%, rgb(249, 249, 249) 100%);
+  --shimmer-bg:
+    linear-gradient(
+      90deg,
+      rgba(250, 250, 250, 0) 0%,
+      rgba(232, 230, 230, 1) 50%,
+      rgba(250, 250, 250, 0) 100%
+    );
 
   /* Sidebar */
   --sidebar-bg: #eeeeee;
@@ -64,7 +72,6 @@
   --tb-odd-bg: #fbfcfd;
   --tb-border-color: #eaeaea;
   --dash-color: silver;
-  --preview-img-bg: radial-gradient(circle, rgb(255, 255, 255) 0%, rgb(249, 249, 249) 100%);
   --kbd-wrap-color: #bdbdbd;
   --kbd-text-color: var(--text-color);
   --kbd-bg-color: white;

_sass/layout/post.scss

@@ -26,12 +26,23 @@
   color: var(--text-color);
 }
 
-img.preview-img {
+%preview-margin {
   margin: 0;
-  border-radius: 6px;
+}
+
+.preview-img {
+  @include align-center;
+  @extend %preview-margin;
 
   &:not(.no-bg) {
-    background: var(--preview-img-bg);
+    img.lazyloaded {
+      background: var(--img-bg);
+    }
+  }
+
+  img {
+    @extend %preview-margin;
+    @extend %img-rounded;
   }
 }