Add :caption and :download options to Kino.Mermaid

assets/packs/mermaid/main.css

@@ -0,0 +1,36 @@
+.container {
+  display: flex;
+  align-items: flex-start;
+  gap: 8px;
+  width: max-content;
+}
+
+.container .download-btn {
+  cursor: pointer;
+  padding: 0.25rem;
+  color: #61758A;
+  background: none;
+  border: none;
+}
+
+.container .download-btn:hover {
+  color: #0D1829;
+}
+
+.container:not(:hover) .download-btn {
+  opacity: 0;
+}
+
+.figure {
+  margin: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  width: max-content;
+}
+
+.caption {
+  margin-top: 8px;
+  font-size: 0.875rem;
+  color: #61758a;
+}

assets/packs/mermaid/main.js

@@ -1,18 +1,61 @@
 import mermaid from "mermaid";
+import "./main.css";
 
 mermaid.initialize({ startOnLoad: false });
 
-export function init(ctx, content) {
+export function init(ctx, { diagram, caption, download }) {
+  ctx.importCSS("main.css");
+
   function render() {
-    mermaid.render("graph1", content).then(({ svg, bindFunctions }) => {
-      ctx.root.innerHTML = svg;
+    mermaid.render("diagram", diagram).then(({ svg, bindFunctions }) => {
+      // Fix for: https://github.com/mermaid-js/mermaid/issues/1766
+      svg = svg.replace(/<br>/gi, "<br/>");
+
+      let container = document.createElement("div");
+      container.classList.add("container");
+      ctx.root.appendChild(container);
+
+      const figure = document.createElement("figure");
+      figure.classList.add("figure");
+      figure.innerHTML = svg;
+      container.appendChild(figure);
+
+      if (caption) {
+        const figcaption = document.createElement("figcaption");
+        figcaption.classList.add("caption");
+        figcaption.textContent = caption;
+        figure.appendChild(figcaption);
+      }
+
+      if (download) {
+        const downloadBtn = document.createElement("button");
+        downloadBtn.classList.add("download-btn");
+        downloadBtn.title = "Download";
+        downloadBtn.innerHTML = `<svg width="20" height="20" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="currentColor"><path d="M13 10H18L12 16L6 10H11V3H13V10ZM4 19H20V12H22V20C22 20.5523 21.5523 21 21 21H3C2.44772 21 2 20.5523 2 20V12H4V19Z"></path></svg>`;
+        container.appendChild(downloadBtn);
+
+        downloadBtn.addEventListener("click", (event) => {
+          const blobURL = URL.createObjectURL(
+            new Blob([svg], { type: "image/svg+xml" }),
+          );
+
+          const a = document.createElement("a");
+          a.style.display = "none";
+          a.href = blobURL;
+          a.download = "diagram.svg";
+
+          container.appendChild(a);
+          a.click();
+          container.removeChild(a);
+        });
+      }
 
       if (bindFunctions) {
         bindFunctions(ctx.root);
       }
 
       // A workaround for https://github.com/mermaid-js/mermaid/issues/1758
-      const svgEl = ctx.root.querySelector("svg");
+      const svgEl = figure.querySelector("svg");
       svgEl.removeAttribute("height");
     });
   }

lib/kino/mermaid.ex

@@ -1,10 +1,10 @@
 defmodule Kino.Mermaid do
   @moduledoc ~S'''
-  A kino for rendering Mermaid graphs.
+  A kino for rendering Mermaid diagrams.
 
   > #### Relation to Kino.Markdown {: .info}
   >
-  > Mermaid graphs can also be generated dynamically with `Kino.Markdown`,
+  > Mermaid diagrams can also be generated dynamically with `Kino.Markdown`,
   > however the output of `Kino.Markdown` is never persisted in the
   > notebook source. `Kino.Mermaid` doesn't have this limitation.
 
@@ -25,10 +25,24 @@ defmodule Kino.Mermaid do
   @type t :: Kino.JS.t()
 
   @doc """
-  Creates a new kino displaying the given Mermaid graph.
+  Creates a new kino displaying the given Mermaid diagram.
+
+  ## Options
+
+    * `:caption` - an optional caption for the rendered diagram.
+
+    * `:download` - whether or not to show a button for downloading
+      the diagram as a SVG. Defaults to `true`.
+
   """
-  @spec new(binary()) :: t()
-  def new(content) do
-    Kino.JS.new(__MODULE__, content, export: fn content -> {"mermaid", content} end)
+  @spec new(binary(), keyword()) :: t()
+  def new(diagram, opts \\ []) do
+    opts = Keyword.validate!(opts, caption: nil, download: true)
+
+    Kino.JS.new(
+      __MODULE__,
+      %{diagram: diagram, caption: opts[:caption], download: opts[:download]},
+      export: fn diagram -> {"mermaid", diagram} end
+    )
   end
 end

lib/kino/process.ex

@@ -35,6 +35,9 @@ defmodule Kino.Process do
     * `:render_ets_tables` - determines whether ETS tables associated with the
       supervision tree are rendered. Defaults to `false`.
 
+    * `:caption` - an optional caption for the diagram. Either a custom
+      caption as string, or `nil` to disable the default caption.
+
   ## Examples
 
   To view the applications running in your instance run:
@@ -86,13 +89,18 @@ defmodule Kino.Process do
     {:dictionary, dictionary} = process_info(root_supervisor, :dictionary)
     [ancestor] = dictionary[:"$ancestors"]
 
-    Mermaid.new("""
-    graph #{direction};
-    application_master(#{inspect(master)}):::supervisor ---> supervisor_ancestor;
-    supervisor_ancestor(#{inspect(ancestor)}):::supervisor ---> 0;
-    #{edges}
-    #{@mermaid_classdefs}
-    """)
+    caption = Keyword.get(opts, :caption, "Application tree for #{inspect(application)}")
+
+    Mermaid.new(
+      """
+      graph #{direction};
+      application_master(#{inspect(master)}):::supervisor ---> supervisor_ancestor;
+      supervisor_ancestor(#{inspect(ancestor)}):::supervisor ---> 0;
+      #{edges}
+      #{@mermaid_classdefs}
+      """,
+      caption: caption
+    )
   end
 
   @doc """
@@ -108,6 +116,9 @@ defmodule Kino.Process do
     * `:direction` - defines the direction of the graph visual. The
       value can either be `:top_down` or `:left_right`. Defaults to `:top_down`.
 
+    * `:caption` - an optional caption for the diagram. Either a custom
+      caption as string, or `nil` to disable the default caption.
+
   ## Examples
 
   With a supervisor definition like so:
@@ -162,11 +173,16 @@ defmodule Kino.Process do
 
     edges = traverse_supervisor(supervisor_pid, opts)
 
-    Mermaid.new("""
-    graph #{direction};
-    #{edges}
-    #{@mermaid_classdefs}
-    """)
+    caption = Keyword.get(opts, :caption, "Supervisor tree for #{inspect(supervisor)}")
+
+    Mermaid.new(
+      """
+      graph #{direction};
+      #{edges}
+      #{@mermaid_classdefs}
+      """,
+      caption: caption
+    )
   end
 
   @doc """
@@ -236,6 +252,9 @@ defmodule Kino.Process do
       is used. However, if the function returns a `String.t()`, then
       that will be used for the label.
 
+    * `:caption` - an optional caption for the diagram. Either a custom
+      caption as string, or `nil` to disable the default caption.
+
   ## Examples
 
   To generate a trace of all the messages occurring during the execution of the
@@ -412,13 +431,18 @@ defmodule Kino.Process do
       |> Enum.reverse()
       |> Enum.join("\n")
 
+    caption = Keyword.get(opts, :caption, "Messages traced from #{inspect(trace_pids)}")
+
     sequence_diagram =
-      Mermaid.new("""
-      %%{init: {'themeCSS': '.actor:last-of-type:not(:only-of-type) {dominant-baseline: hanging;}'} }%%
-      sequenceDiagram
-      #{participants}
-      #{messages}
-      """)
+      Mermaid.new(
+        """
+        %%{init: {'themeCSS': '.actor:last-of-type:not(:only-of-type) {dominant-baseline: hanging;}'} }%%
+        sequenceDiagram
+        #{participants}
+        #{messages}
+        """,
+        caption: caption
+      )
 
     {func_result, sequence_diagram}
   end

lib/kino/shorts.ex

@@ -162,7 +162,7 @@ defmodule Kino.Shorts do
   def text(text), do: Kino.Text.new(text)
 
   @doc ~S'''
-  Renders Mermaid graphs.
+  Renders Mermaid diagrams.
 
   It is a wrapper around `Kino.Mermaid.new/1`.
 
@@ -178,8 +178,8 @@ defmodule Kino.Shorts do
         C-->D;
       """)
   '''
-  @spec mermaid(String.t()) :: Kino.Mermaid.t()
-  def mermaid(mermaid), do: Kino.Mermaid.new(mermaid)
+  @spec mermaid(String.t(), keyword()) :: Kino.Mermaid.t()
+  def mermaid(diagram, opts \\ []), do: Kino.Mermaid.new(diagram, opts)
 
   @doc """
   A placeholder for static outputs that can be dynamically updated.

test/kino/process_test.exs

@@ -227,7 +227,7 @@ defmodule Kino.ProcessTest do
     send(Kino.JS.DataStore, {:connect, self(), %{origin: "client:#{inspect(self())}", ref: ref}})
     assert_receive {:connect_reply, data, %{ref: ^ref}}
 
-    data
+    data.diagram
   end
 
   defp supervision_tree_with_ets_table do