[enh] simple theme: image detail

When an image is selected, the detail with the full size image is displayed
on the right side of the screen (or full screen on tablet and phone).

When Javascript is disabled, the thumbnail is a linked to the full size image,
as it was before.

When the image proxy is enabled, the full size image is also proxied,
in consequence this commit increases the bandwidth usage of instances.

The detail can be closed by the close button or the Esc key.
It is possible to go to the next and previous images using the j and k keys
or the button on the top right of the screen.

7 files changed, 360 insertions, 25 deletions

diff --git a/searx/static/themes/__common__/js/image_layout.js b/searx/static/themes/__common__/js/image_layout.js
index fa96f62c5..653da95a0 100644
--- a/searx/static/themes/__common__/js/image_layout.js
+++ b/searx/static/themes/__common__/js/image_layout.js
@@ -11,11 +11,12 @@
 */
 
 (function (w, d) {
-  function ImageLayout(container_selector, results_selector, img_selector, margin, maxHeight) {
+  function ImageLayout(container_selector, results_selector, img_selector, verticalMargin, horizontalMargin, maxHeight) {
     this.container_selector = container_selector;
     this.results_selector = results_selector;
     this.img_selector = img_selector;
-    this.margin = margin;
+    this.verticalMargin = verticalMargin;
+    this.horizontalMargin = horizontalMargin;
     this.maxHeight = maxHeight;
     this.isAlignDone = true;
   }
@@ -45,7 +46,7 @@
       }
     }
 
-    return (width - images.length * this.margin) / r; //have to round down because Firefox will automatically roundup value with number of decimals > 3
+    return (width - images.length * this.verticalMargin) / r; //have to round down because Firefox will automatically roundup value with number of decimals > 3
   };
 
   ImageLayout.prototype._setSize = function (images, height) {
@@ -62,10 +63,10 @@
       }
       img.style.width = imgWidth + 'px';
       img.style.height = height + 'px';
-      img.style.marginLeft = '3px';
-      img.style.marginTop = '3px';
-      img.style.marginRight = this.margin - 7 + 'px'; // -4 is the negative margin of the inline element
-      img.style.marginBottom = this.margin - 7 + 'px';
+      img.style.marginLeft = this.horizontalMargin + 'px';
+      img.style.marginTop = this.horizontalMargin + 'px';
+      img.style.marginRight = this.verticalMargin - 7 + 'px'; // -4 is the negative margin of the inline element
+      img.style.marginBottom = this.verticalMargin - 7 + 'px';
       resultNode = img.parentNode.parentNode;
       if (!resultNode.classList.contains('js')) {
         resultNode.classList.add('js');
diff --git a/searx/static/themes/oscar/src/js/element_modifiers.js b/searx/static/themes/oscar/src/js/element_modifiers.js
index e9de297e0..dff1a5e97 100644
--- a/searx/static/themes/oscar/src/js/element_modifiers.js
+++ b/searx/static/themes/oscar/src/js/element_modifiers.js
@@ -103,6 +103,6 @@ $(document).ready(function(){
     /**
      * Layout images according to their sizes
      */
-    searxng.image_thumbnail_layout = new searxng.ImageLayout('#main_results', '#main_results .result-images', 'img.img-thumbnail', 15, 200);
+    searxng.image_thumbnail_layout = new searxng.ImageLayout('#main_results', '#main_results .result-images', 'img.img-thumbnail', 15, 3, 200);
     searxng.image_thumbnail_layout.watch();
 });
diff --git a/searx/static/themes/simple/src/js/main/searx_keyboard.js b/searx/static/themes/simple/src/js/main/searx_keyboard.js
index c00a1a45e..394f97730 100644
--- a/searx/static/themes/simple/src/js/main/searx_keyboard.js
+++ b/searx/static/themes/simple/src/js/main/searx_keyboard.js
@@ -4,7 +4,7 @@
 searxng.ready(function() {
 
   searxng.on('.result', 'click', function() {
-    highlightResult(this)(true);
+    highlightResult(this)(true);  
   });
 
   searxng.on('.result a', 'focus', function(e) {
@@ -124,9 +124,7 @@ searxng.ready(function() {
     if (Object.prototype.hasOwnProperty.call(vimKeys, e.keyCode) && !e.ctrlKey && !e.altKey && !e.shiftKey && !e.metaKey) {
       var tagName = e.target.tagName.toLowerCase();
       if (e.keyCode === 27) {
-        if (tagName === 'input' || tagName === 'select' || tagName === 'textarea') {
-          vimKeys[e.keyCode].fun();
-        }
+        vimKeys[e.keyCode].fun(e);
       } else {
         if (e.target === document.body || tagName === 'a' || tagName === 'button') {
           e.preventDefault();
@@ -213,9 +211,12 @@ searxng.ready(function() {
     document.location.reload(true);
   }
 
-  function removeFocus() {
-    if (document.activeElement) {
+  function removeFocus(e) {
+    const tagName = e.target.tagName.toLowerCase();
+    if (document.activeElement && (tagName === 'input' || tagName === 'select' || tagName === 'textarea')) {
       document.activeElement.blur();
+    } else {
+      searxng.closeDetail();
     }
   }
 
@@ -285,6 +286,9 @@ searxng.ready(function() {
   function openResult(newTab) {
     return function() {
       var link = document.querySelector('.result[data-vim-selected] h3 a');
+      if (link === null) {
+        link = document.querySelector('.result[data-vim-selected] > a');
+      }
       if (link !== null) {
         var url = link.getAttribute('href');
         if (newTab) {
@@ -368,4 +372,8 @@ searxng.ready(function() {
       return;
     }
   }
+
+  searxng.scrollPageToSelected = scrollPageToSelected;
+  searxng.selectNext = highlightResult('down');
+  searxng.selectPrevious = highlightResult('up');
 });
diff --git a/searx/static/themes/simple/src/js/main/searx_results.js b/searx/static/themes/simple/src/js/main/searx_results.js
index 79af25af8..5ccbb38b5 100644
--- a/searx/static/themes/simple/src/js/main/searx_results.js
+++ b/searx/static/themes/simple/src/js/main/searx_results.js
@@ -3,7 +3,7 @@
   'use strict';
 
   searxng.ready(function() {
-    searxng.image_thumbnail_layout = new searxng.ImageLayout('#urls', '#urls .result-images', 'img.image_thumbnail', 10, 200);
+    searxng.image_thumbnail_layout = new searxng.ImageLayout('#urls', '#urls .result-images', 'img.image_thumbnail', 14, 6, 200);
     searxng.image_thumbnail_layout.watch();
 
     searxng.on('.btn-collapse', 'click', function() {
@@ -31,17 +31,74 @@
       }
     });
 
+    function selectImage(e) {
+      /*eslint no-unused-vars: 0*/
+      let t = e.target;
+      while (t && t.nodeName != 'ARTICLE') {
+        t = t.parentNode;
+      }
+      if (t) {
+        // load full size image in background
+        const imgElement = t.querySelector('.result-images-source img');
+        const thumbnailElement = t.querySelector('.image_thumbnail');
+        const detailElement = t.querySelector('.detail');
+        if (imgElement) {
+          const imgSrc = imgElement.getAttribute('data-src');
+          if (imgSrc) {
+            const loader = d.createElement('div');
+            const imgLoader = new Image();
+
+            loader.classList.add('loader');
+            detailElement.appendChild(loader);
+
+            imgLoader.onload = e => {
+              imgElement.src = imgSrc;
+              loader.remove();
+            };
+            imgLoader.onerror = e => {
+              loader.remove();
+            };
+            imgLoader.src = imgSrc;
+            imgElement.src = thumbnailElement.src;
+            imgElement.removeAttribute('data-src');
+          }
+        }
+      }
+      d.getElementById('results').classList.add('image-detail-open');
+      searxng.image_thumbnail_layout.align();
+      searxng.scrollPageToSelected();
+    }
+
+    searxng.closeDetail = function(e) {
+      d.getElementById('results').classList.remove('image-detail-open');
+      searxng.image_thumbnail_layout.align();
+      searxng.scrollPageToSelected();
+    }
+
+    searxng.on('.result-images', 'click', e => {
+      e.preventDefault();
+      selectImage(e);
+    });
+    searxng.on('.result-images a', 'focus', selectImage, true);
+    searxng.on('.result-detail-close', 'click', e => { 
+      e.preventDefault();
+      searxng.closeDetail();
+    });
+    searxng.on('.result-detail-previous', 'click', e => searxng.selectPrevious(false));
+    searxng.on('.result-detail-next', 'click', e => searxng.selectNext(false));
+
     w.addEventListener('scroll', function() {
       var e = d.getElementById('backToTop'),
-      scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
+      scrollTop = document.documentElement.scrollTop || document.body.scrollTop,
+      results = d.getElementById('results');
       if (e !== null) {
-        if (scrollTop >= 200) {
-          e.style.opacity = 1;
+        if (scrollTop >= 100) {
+          results.classList.add('scrolling');
         } else {
-          e.style.opacity = 0;
+          results.classList.remove('scrolling');
         }
       }
-    });
+    }, true);
 
   });
 
diff --git a/searx/static/themes/simple/src/less/definitions.less b/searx/static/themes/simple/src/less/definitions.less
index 9caf4f3f5..6a199b56b 100644
--- a/searx/static/themes/simple/src/less/definitions.less
+++ b/searx/static/themes/simple/src/less/definitions.less
@@ -71,6 +71,14 @@ html {
   /// Settings Colors
   --color-settings-tr-hover: #f7f7f7;
   --color-settings-engine-description-font: darken(#dcdcdc, 30%);
+  /// Detail modal
+  --color-result-detail-font: #fff;
+  --color-result-detail-label-font: lightgray;
+  --color-result-detail-background: #000;
+  --color-result-detail-hr: #333;
+  --color-result-detail-link: #8af;
+  --color-result-detail-loader-border: rgba(255, 255, 255, 0.2);
+  --color-result-detail-loader-borderleft: rgba(0, 0, 0, 0);
   /// Toolkit Colors
   --color-toolkit-badge-font: #fff;
   --color-toolkit-badge-background: #777;
@@ -156,6 +164,14 @@ html {
     --color-result-engines-font: #777;
     --color-result-search-url-border: #333;
     --color-result-search-url-font: #fff;
+    /// Detail modal : same as the light version
+    --color-result-detail-font: #fff;
+    --color-result-detail-label-font: lightgray;
+    --color-result-detail-background: #000;
+    --color-result-detail-hr: #333;
+    --color-result-detail-link: #8af;
+    --color-result-detail-loader-border: rgba(255, 255, 255, 0.2);
+    --color-result-detail-loader-borderleft: rgba(0, 0, 0, 0);
     // Images Colors
     --color-result-image-span-background-hover: rgba(0, 0, 0, 0.6);
     --color-result-image-span-font: #fff;
@@ -183,8 +199,8 @@ html {
     --color-toolkit-engine-tooltip-border: #333;
     --color-toolkit-engine-tooltip-shadow: #444;
     --color-toolkit-engine-tooltip-background: #222;
-    --color-toolkit-loader-border: rgba(0, 0, 0, 0.2);
-    --color-toolkit-loader-borderleft: rgba(255, 255, 255, 0);
+    --color-toolkit-loader-border: rgba(255, 255, 255, 0.2);
+    --color-toolkit-loader-borderleft: rgba(0, 0, 0, 0);
   }
 }
 
diff --git a/searx/static/themes/simple/src/less/detail.less b/searx/static/themes/simple/src/less/detail.less
new file mode 100644
index 000000000..6c4022765
--- /dev/null
+++ b/searx/static/themes/simple/src/less/detail.less
@@ -0,0 +1,243 @@
+#main_results #results.image-detail-open.only_template_images {
+  width: 59.25rem !important;
+}
+
+#main_results #results.only_template_images.image-detail-open #backToTop {
+  left: 56.75rem !important;
+  right: inherit;
+}
+
+article.result-images .detail {
+  display: none;
+}
+
+#results.image-detail-open article.result-images[data-vim-selected] .detail {
+  display: flex;
+  flex-direction: column;
+  position: fixed;
+  left: 60rem;
+  right: 0;
+  top: 7rem;
+  bottom: 0;
+  background: var(--color-result-detail-background);
+  border: 1px solid var(--color-result-detail-background);
+  z-index: 10000;
+  padding: 4rem 3rem 3rem 3rem;
+
+  a.result-images-source {
+    display: block;
+    flex: 1;
+    text-align: left;
+    width: 100%;
+    border: none;
+    text-decoration: none;
+
+    img {
+      padding: 0;
+      margin: 0;
+      border: none;
+      object-fit: contain;
+      width: inherit;
+      max-width: 100%;
+      min-height: inherit;
+      max-height: calc(100vh - 25rem - 7rem);
+      background: inherit;
+    }
+  }
+
+  .result-images-labels {
+    color: var(--color-result-detail-font);
+    max-height: 16rem;
+    min-height: 16rem;
+
+    hr {
+      border-top: 1px solid var(--color-result-detail-hr);
+      border-bottom: none;
+    }
+
+    h4 {
+      height: 2rem;
+      overflow: hidden;
+      text-overflow: ellipsis;
+      font-size: 0.9rem;
+    }
+
+    p {
+      color: var(--color-result-detail-label-font);
+      font-size: 0.9rem;
+
+      span {
+        display: inline-block;
+        width: 12rem;
+      }
+    }
+
+    h4,
+    p,
+    a {
+      text-align: left;
+    }
+
+    p.result-content {
+      height: 2rem;
+      overflow: hidden;
+      text-overflow: ellipsis;
+    }
+
+    p.result-url {
+      white-space: nowrap;
+      overflow-x: hidden;
+      text-overflow: ellipsis;
+    }
+
+    p.result-content:hover,
+    p.result-url:hover {
+      position: relative;
+      overflow: inherit !important;
+      background: var(--color-result-detail-background);
+      text-overflow: inherit !important;
+    }
+
+    a,
+    a:visited,
+    a:hover,
+    a:active {
+      color: var(--color-result-detail-link);
+    }
+
+    a:hover {
+      text-decoration: underline;
+    }
+  }
+
+  a.result-detail-close {
+    top: 1rem;
+    left: 1rem;
+    padding: 0.4rem;
+  }
+
+  a.result-detail-previous {
+    top: 1rem;
+    right: 6rem;
+    // center the icon by moving it slightly on the left
+    padding: 0.4rem 0.5rem 0.4rem 0.3rem;
+  }
+
+  a.result-detail-next {
+    top: 1rem;
+    right: 2rem;
+    padding: 0.4rem;
+  }
+
+  a.result-detail-close,
+  a.result-detail-next,
+  a.result-detail-previous {
+    border-radius: 50%;
+    display: block;
+    width: 1.5rem;
+    height: 1.5rem;
+    position: absolute;
+    filter: opacity(40%);
+    z-index: 2000002;
+
+    span {
+      display: block;
+      width: 1.5rem;
+      height: 1.5rem;
+      text-align: center;
+    }
+  }
+
+  a.result-detail-next,
+  a.result-detail-previous {
+    span::before {
+      // vertical center small icons
+      vertical-align: sub;
+    }
+  }
+
+  a.result-detail-close,
+  a.result-detail-close:visited,
+  a.result-detail-close:hover,
+  a.result-detail-close:active,
+  a.result-detail-previous,
+  a.result-detail-previous:visited,
+  a.result-detail-previous:hover,
+  a.result-detail-previous:active,
+  a.result-detail-next,
+  a.result-detail-next:visited,
+  a.result-detail-next:hover,
+  a.result-detail-next:active {
+    color: var(--color-result-detail-font);
+    background: var(--color-result-detail-background);
+    border: 1px solid var(--color-result-detail-font);
+  }
+
+  a.result-detail-close:focus,
+  a.result-detail-close:hover,
+  a.result-detail-previous:focus,
+  a.result-detail-previous:hover,
+  a.result-detail-next:focus,
+  a.result-detail-next:hover {
+    filter: opacity(80%);
+  }
+
+  .loader {
+    position: absolute;
+    top: 1rem;
+    right: 50%;
+    border-top: 0.5em solid var(--color-result-detail-loader-border);
+    border-right: 0.5em solid var(--color-result-detail-loader-border);
+    border-bottom: 0.5em solid var(--color-result-detail-loader-border);
+    border-left: 0.5em solid var(--color-result-detail-loader-borderleft);
+  }
+}
+
+#results.image-detail-open.scrolling article.result-images[data-vim-selected] .detail {
+  top: 0;
+
+  a.result-images-source img {
+    max-height: calc(100vh - 25rem);
+  }
+}
+
+@media screen and (max-width: @tablet) {
+  #results.image-detail-open article.result-images[data-vim-selected] .detail {
+    top: 0;
+    left: 0;
+
+    a.result-images-source {
+      display: flex;
+      flex-direction: column;
+      justify-content: center;
+
+      img {
+        width: 100%;
+        max-height: calc(100vh - 24rem);
+      }
+    }
+
+    a.result-detail-next {
+      right: 1rem;
+    }
+  }
+}
+
+@media screen and (max-width: @phone) {
+  #results.image-detail-open article.result-images[data-vim-selected] .detail {
+    top: 0;
+    left: 0;
+    padding: 1rem;
+
+    a.result-images-source img {
+      width: 100%;
+      max-height: calc(100vh - 20rem);
+      margin: 0;
+    }
+
+    .result-images-labels p span {
+      width: inherit;
+      margin-right: 1rem;
+    }
+  }
+}
diff --git a/searx/static/themes/simple/src/less/style.less b/searx/static/themes/simple/src/less/style.less
index 261e36792..ea95e3682 100644
--- a/searx/static/themes/simple/src/less/style.less
+++ b/searx/static/themes/simple/src/less/style.less
@@ -16,6 +16,7 @@
 @import "code.less";
 @import "toolkit.less";
 @import "autocomplete.less";
+@import "detail.less";
 
 // for index.html template
 @import "index.less";
@@ -138,6 +139,10 @@ article[data-vim-selected]::before {
 
 article.result-images[data-vim-selected] {
   background: var(--color-result-vim-arrow);
+
+  .image_thumbnail {
+    filter: opacity(60%);
+  }
 }
 
 article.result-images[data-vim-selected]::before {
@@ -283,25 +288,26 @@ article.result-images[data-vim-selected]::before {
 
   img {
     float: inherit;
-    margin: 0;
+    margin: 0.125rem;
     padding: 0;
     border: none;
     max-height: 200px;
     background: var(--color-result-image-background);
   }
 
-  span a {
+  span.title {
     display: none;
     color: var(--color-result-image-span-font);
   }
 
-  &:hover span a {
+  &:hover span.title {
     display: block;
     position: absolute;
     bottom: 0;
     right: 0;
     padding: 4px;
     margin: 0 0 4px 4px;
+    // color: @color-result-image-span-font;
     background-color: var(--color-result-image-span-background-hover);
     font-size: 0.7em;
   }
@@ -569,6 +575,10 @@ article.result-images[data-vim-selected]::before {
   }
 }
 
+#results.scrolling #backToTop {
+  opacity: 1;
+}
+
 @media screen and (max-width: @tablet) {
   #main_preferences,
   #main_about,