Support folding code blocks (#679)

_config.yml

@@ -373,6 +373,10 @@ codeblock:
     enable: false
     # Available values: default | flat | mac
     style:
+  # Fold code block
+  fold:
+    enable: false
+    height: 500
 
 back2top:
   enable: true

scripts/helpers/next-config.js

@@ -19,6 +19,7 @@ hexo.extend.helper.register('next_config', function() {
     exturl    : theme.exturl,
     sidebar   : theme.sidebar,
     copycode  : theme.codeblock.copy_button,
+    fold      : theme.codeblock.fold,
     bookmark  : theme.bookmark,
     mediumzoom: theme.mediumzoom,
     lazyload  : theme.lazyload,

source/css/_common/scaffolding/highlight/fold.styl

@@ -0,0 +1,29 @@
+.expand-btn {
+  bottom: 0;
+  color: var(--highlight-foreground);
+  cursor: pointer;
+  display: none;
+  left: 0;
+  right: 0;
+  position: absolute;
+  text-align: center;
+}
+
+.fold-cover {
+  background-image: linear-gradient(to top, var(--highlight-background) 0, rgba(0, 0, 0, 0) 100%);
+  bottom: 0;
+  display: none;
+  height: 50px;
+  left: 0;
+  right: 0;
+  position: absolute;
+}
+
+.highlight-fold {
+  max-height: unit(hexo-config('codeblock.fold.height'), 'px');
+  overflow-y: hidden !important;
+
+  .expand-btn, .fold-cover {
+    display: block;
+  }
+}

source/css/_common/scaffolding/highlight/index.styl

@@ -13,6 +13,7 @@ if (hexo-config('darkmode')) {
 }
 
 @require 'copy-code' if (hexo-config('codeblock.copy_button.enable'));
+@require 'fold' if (hexo-config('codeblock.fold.enable'));
 
 // Placeholder: $code-inline $code-block
 $code-inline {

source/js/next-boot.js

@@ -46,7 +46,7 @@ NexT.boot.refresh = function() {
 
   CONFIG.exturl && NexT.utils.registerExtURL();
   NexT.utils.wrapTableWithBox();
-  NexT.utils.registerCopyCode();
+  NexT.utils.registerCodeblock();
   NexT.utils.registerTabsTag();
   NexT.utils.registerActiveMenuItem();
   NexT.utils.registerLangSelect();

source/js/utils.js

@@ -39,30 +39,48 @@ NexT.utils = {
     });
   },
 
-  /**
-   * One-click copy code support.
-   */
-  registerCopyCode: function() {
+  registerCodeblock: function() {
     let figure = document.querySelectorAll('figure.highlight');
-    let needWrap = false;
+    let isHljsWithWrap = true;
     if (figure.length === 0) {
       figure = document.querySelectorAll('pre:not(.mermaid)');
-      needWrap = true;
+      isHljsWithWrap = false;
     }
     figure.forEach(element => {
-      element.querySelectorAll('.code .line span').forEach(span => {
-        span.classList.forEach(name => {
-          span.classList.replace(name, `hljs-${name}`);
+      let span = element.querySelectorAll('.code .line span');
+      if (span.length === 0) {
+        // Hljs without line_number and wrap
+        span = element.querySelectorAll('code.highlight span');
+      }
+      span.forEach(s => {
+        s.classList.forEach(name => {
+          s.classList.replace(name, `hljs-${name}`);
         });
       });
-      if (!CONFIG.copycode.enable) return;
-      let target = element;
-      if (needWrap) {
+      const height = parseInt(window.getComputedStyle(element).height.replace('px', ''), 10);
+      const needFold = CONFIG.fold.enable && (height > CONFIG.fold.height);
+      if (!needFold && !CONFIG.copycode.enable) return;
+      let target;
+      if (isHljsWithWrap && CONFIG.copycode.style === 'mac') {
+        target = element;
+      } else {
+        // https://github.com/next-theme/hexo-theme-next/issues/98
+        // https://github.com/next-theme/hexo-theme-next/pull/508
+        const container = element.querySelector('.table-container') || element;
         const box = document.createElement('div');
         box.className = 'code-container';
-        element.wrap(box);
+        container.wrap(box);
         target = box;
       }
+      if (needFold) {
+        target.classList.add('highlight-fold');
+        target.insertAdjacentHTML('beforeend', '<div class="fold-cover"></div><div class="expand-btn"><i class="fa fa-angle-down fa-fw"></i></div>');
+        target.querySelector('.expand-btn').addEventListener('click', () => {
+          target.classList.remove('highlight-fold');
+        });
+      }
+      if (!CONFIG.copycode.enable) return;
+      // One-click copy code support.
       target.insertAdjacentHTML('beforeend', '<div class="copy-btn"><i class="fa fa-copy fa-fw"></i></div>');
       const button = target.querySelector('.copy-btn');
       button.addEventListener('click', () => {