From b5fd3d69cd517d4566a5378dc29bce103b9a0507 Mon Sep 17 00:00:00 2001
From: "shentong.martin" <shentong.martin@bytedance.com>
Date: Mon, 1 Dec 2025 11:03:46 +0800
Subject: [PATCH] feat: enable mermaid with zoom, pan and download

Change-Id: I6063e0e66e0787cc55299fbf08c33d97f687198b
---
 assets/js/mermaid.js             | 114 +++++++++++++++++++++++++++++++
 assets/scss/_styles_project.scss |  34 +++++++++
 assets/scss/markdown.scss        |   6 ++
 config.toml                      |   6 ++
 4 files changed, 160 insertions(+)

diff --git a/assets/js/mermaid.js b/assets/js/mermaid.js
index 821e5678729..501d0ffa8e2 100644
--- a/assets/js/mermaid.js
+++ b/assets/js/mermaid.js
@@ -33,6 +33,120 @@
     var settings = norm(mermaid.mermaidAPI.defaultConfig, params);
     settings.startOnLoad = true;
     mermaid.initialize(settings);
+
+    function ensureModal() {
+        if (!$('#mermaidModal').length) {
+            var html = '' +
+            '<div class="modal fade" id="mermaidModal" tabindex="-1" role="dialog" aria-hidden="true">' +
+            '<div class="modal-dialog modal-dialog-centered modal-xl" role="document">' +
+            '<div class="modal-content">' +
+            '<div class="modal-body">' +
+            '<div class="mermaid-zoom-controls">' +
+            '<button type="button" class="btn btn-sm btn-light" id="mermaidZoomIn">+</button>' +
+            '<button type="button" class="btn btn-sm btn-light" id="mermaidZoomOut">-</button>' +
+            '<button type="button" class="btn btn-sm btn-light" id="mermaidZoomReset">Reset</button>' +
+            '<button type="button" class="btn btn-sm btn-light" id="mermaidDownload">Download</button>' +
+            '</div>' +
+            '<div class="mermaid-zoom-wrapper"><div class="mermaid-zoom-content"></div></div>' +
+            '</div>' +
+            '</div>' +
+            '</div>' +
+            '</div>';
+            $('body').append(html);
+        }
+    }
+
+    var scale = 1;
+    function applyScale() {
+        $('.mermaid-zoom-content').css('transform', 'scale(' + scale + ')');
+    }
+
+    $(document).on('click', 'pre.mermaid, .mermaid', function() {
+        ensureModal();
+        var $svg = $(this).find('svg').clone();
+        var $content = $('#mermaidModal .mermaid-zoom-content');
+        $content.empty().append($svg);
+        scale = 1;
+        applyScale();
+        $('#mermaidModal').modal('show');
+    });
+
+    $(document).on('click', '#mermaidZoomIn', function() {
+        scale = Math.min(scale + 0.2, 5);
+        applyScale();
+    });
+    $(document).on('click', '#mermaidZoomOut', function() {
+        scale = Math.max(scale - 0.2, 0.2);
+        applyScale();
+    });
+    $(document).on('click', '#mermaidZoomReset', function() {
+        scale = 1;
+        applyScale();
+    });
+    $(document).on('wheel', '.mermaid-zoom-wrapper', function(e) {
+        e.preventDefault();
+        var dy = e.originalEvent.deltaY;
+        scale += (dy > 0 ? -0.1 : 0.1);
+        scale = Math.max(0.2, Math.min(5, scale));
+        applyScale();
+    });
+
+    var isDragging = false;
+    var startX = 0;
+    var startY = 0;
+    var scrollLeft = 0;
+    var scrollTop = 0;
+
+    $(document).on('mousedown touchstart', '.mermaid-zoom-wrapper', function(e) {
+        var $wrap = $(this);
+        isDragging = true;
+        $wrap.addClass('dragging');
+        var ev = e.type === 'touchstart' ? e.originalEvent.touches[0] : e;
+        startX = ev.pageX - $wrap.offset().left;
+        startY = ev.pageY - $wrap.offset().top;
+        scrollLeft = $wrap.scrollLeft();
+        scrollTop = $wrap.scrollTop();
+    });
+
+    $(document).on('mousemove touchmove', '.mermaid-zoom-wrapper', function(e) {
+        if (!isDragging) return;
+        var $wrap = $(this);
+        var ev = e.type === 'touchmove' ? e.originalEvent.touches[0] : e;
+        var x = ev.pageX - $wrap.offset().left;
+        var y = ev.pageY - $wrap.offset().top;
+        var dx = x - startX;
+        var dy = y - startY;
+        $wrap.scrollLeft(scrollLeft - dx);
+        $wrap.scrollTop(scrollTop - dy);
+    });
+
+    $(document).on('mouseup mouseleave touchend', '.mermaid-zoom-wrapper', function() {
+        isDragging = false;
+        $(this).removeClass('dragging');
+    });
+
+    $(document).on('click', '#mermaidDownload', function() {
+        var $svg = $('#mermaidModal .mermaid-zoom-content svg');
+        if (!$svg.length) return;
+        var node = $svg.get(0);
+        if (!node.getAttribute('xmlns')) {
+            node.setAttribute('xmlns', 'http://www.w3.org/2000/svg');
+        }
+        var serializer = new XMLSerializer();
+        var source = serializer.serializeToString(node);
+        var blob = new Blob([source], { type: 'image/svg+xml;charset=utf-8' });
+        var url = URL.createObjectURL(blob);
+        var a = document.createElement('a');
+        var name = (document.title || 'diagram') + '-' + Date.now() + '.svg';
+        a.href = url;
+        a.download = name;
+        document.body.appendChild(a);
+        a.click();
+        setTimeout(function() {
+            URL.revokeObjectURL(url);
+            a.remove();
+        }, 0);
+    });
 })(jQuery);
 {{ end }}
 {{ end }}
diff --git a/assets/scss/_styles_project.scss b/assets/scss/_styles_project.scss
index 9a6ec356c75..d9f6d793e1d 100644
--- a/assets/scss/_styles_project.scss
+++ b/assets/scss/_styles_project.scss
@@ -23,3 +23,37 @@ assets/scss/_styles_project.scss
     margin-bottom: initial;
   }
 }
+
+pre.mermaid {
+  padding: 0;
+  margin: 0;
+  background: transparent;
+  border: 0;
+}
+
+.mermaid svg {
+  width: 100%;
+  height: auto;
+}
+
+.mermaid-zoom-wrapper {
+  overflow: auto;
+  max-height: 85vh;
+  cursor: grab;
+  user-select: none;
+}
+
+.mermaid-zoom-content {
+  transform-origin: 0 0;
+}
+
+.mermaid-zoom-wrapper.dragging {
+  cursor: grabbing;
+}
+
+.mermaid-zoom-controls {
+  position: absolute;
+  right: 1rem;
+  top: 1rem;
+  z-index: 10;
+}
diff --git a/assets/scss/markdown.scss b/assets/scss/markdown.scss
index 85d8e9e3b59..f903a83f79f 100644
--- a/assets/scss/markdown.scss
+++ b/assets/scss/markdown.scss
@@ -39,6 +39,12 @@
   overflow: auto
 }
 
+.markdown pre.mermaid {
+  padding: 0;
+  margin: 0;
+  overflow: visible
+}
+
 .markdown div[class*=language-] pre code {
   color: rgba(0,0,0,.5)
 }
diff --git a/config.toml b/config.toml
index 1749593ccd9..35257deb1b0 100644
--- a/config.toml
+++ b/config.toml
@@ -161,6 +161,12 @@ offlineSearch = false
 # Enable syntax highlighting and copy buttons on code blocks with Prism
 prism_syntax_highlighting = true
 
+# Mermaid diagrams configuration
+[params.mermaid]
+enable = true
+theme = "default"
+securitylevel = "strict"
+
 # User interface configuration
 [params.ui]
 # Enable to show the side bar menu in its compact state.