[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.

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');
 });

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 @@
       }
     });
 
-    w.addEventListener('scroll', function() {
-      var e = d.getElementById('backToTop'),
-      scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
-      if (e !== null) {
-        if (scrollTop >= 200) {
-          e.style.opacity = 1;
-        } else {
-          e.style.opacity = 0;
+    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,
+      results = d.getElementById('results');
+      if (e !== null) {
+        if (scrollTop >= 100) {
+          results.classList.add('scrolling');
+        } else {
+          results.classList.remove('scrolling');
+        }
+      }
+    }, true);
 
   });