Add support for full configuration of reveal slides in notebook metadata

.github/workflows/prep-release.yml

@@ -36,7 +36,7 @@ jobs:
           post_version_spec: ${{ github.event.inputs.post_version_spec }}
           target: ${{ github.event.inputs.target }}
           branch: ${{ github.event.inputs.branch }}
-          since: ${{ github.event.inputs.since }}
+          since: ${{ steps.since.outputs.since }}
           since_last_stable: ${{ github.event.inputs.since_last_stable }}
 
       - name: "** Next Step **"

nbconvert/exporters/slides.py

@@ -6,7 +6,7 @@
 from copy import deepcopy
 from warnings import warn
 
-from traitlets import Bool, Unicode, default
+from traitlets import Bool, Dict, Unicode, default
 
 from nbconvert.preprocessors.base import Preprocessor
 
@@ -195,15 +195,61 @@ def _reveal_url_prefix_default(self):
         """,
     ).tag(config=True)
 
-    def _init_resources(self, resources):
-        resources = super()._init_resources(resources)
+    reveal_config = Dict(
+        {},
+        help="""A dictionary of configuration options for reveal.js.
+        This is passed directly to the Reveal.initialize() call.
+        """,
+    ).tag(config=True)
+
+    def from_notebook_node(self, nb, resources=None, **kw):
+        """
+        Convert a notebook from a notebook node instance.
+        This method extends the parent implementation to override reveal.js
+        configuration with metadata from the notebook.
+        It reads reveal.js settings from the `reveal` key in the notebook's
+        metadata and merges them with the existing configuration.
+        The precedence for settings is:
+        1. Command-line arguments (highest)
+        2. Notebook metadata
+        3. Config file
+        4. Default values (lowest)
+        Parameters
+        ----------
+        nb : :class:`~nbformat.NotebookNode`
+            Notebook node
+        resources : dict
+            Additional resources that can be accessed by exporters and preprocessors.
+        """
+        if resources is None:
+            resources = {}
+
+        # 1. Start with the config file settings
+        reveal_config = self.reveal_config.copy()
+
+        # 2. Layer notebook metadata on top
+        if "reveal" in nb.metadata:
+            self.log.info("Applying reveal config from notebook metadata")
+            reveal_config.update(nb.metadata.get("reveal", {}))
+
+        # 3. Layer command-line options on top
+        traitlet_map = {
+            "reveal_url_prefix": "url_prefix",
+            "reveal_theme": "theme",
+            "reveal_transition": "transition",
+            "reveal_scroll": "scroll",
+            "reveal_number": "number",
+            "reveal_height": "height",
+            "reveal_width": "width",
+        }
+        for trait_name, config_key in traitlet_map.items():
+            # Check if the trait was set via command-line config
+            if trait_name in self.config.SlidesExporter:
+                reveal_config[config_key] = getattr(self, trait_name)
+
+        # Update the resources dictionary
         if "reveal" not in resources:
             resources["reveal"] = {}
-        resources["reveal"]["url_prefix"] = self.reveal_url_prefix
-        resources["reveal"]["theme"] = self.reveal_theme
-        resources["reveal"]["transition"] = self.reveal_transition
-        resources["reveal"]["scroll"] = self.reveal_scroll
-        resources["reveal"]["number"] = self.reveal_number
-        resources["reveal"]["height"] = self.reveal_height
-        resources["reveal"]["width"] = self.reveal_width
-        return resources
+        resources["reveal"].update(reveal_config)
+
+        return super().from_notebook_node(nb, resources=resources, **kw)

share/templates/reveal/index.html.j2

@@ -9,6 +9,9 @@
 {% set reveal_width = resources.reveal.width | default('960', true) %}
 {% set reveal_height = resources.reveal.height | default('700', true) %}
 {% set reveal_scroll = resources.reveal.scroll | default(false, true) | json_dumps %}
+{% set reveal_controls = resources.reveal.controls | default(true, true) | json_dumps %}
+{% set reveal_progress = resources.reveal.progress | default(true, true) | json_dumps %}
+{% set reveal_history = resources.reveal.history | default(true, true) | json_dumps %}
 
 {%- block header -%}
 <!DOCTYPE html>
@@ -150,17 +153,38 @@ require(
 
     function(Reveal, RevealNotes){
         // Full list of configuration options available here: https://github.com/hakimel/reveal.js#configuration
-        Reveal.initialize({
-            controls: true,
-            progress: true,
-            history: true,
-            transition: "{{reveal_transition}}",
-            slideNumber: "{{reveal_number}}",
-            plugins: [RevealNotes],
-            width: {{reveal_width}},
-			      height: {{reveal_height}},
-
-        });
+        var config = {
+            // Pass in reveal.js options from template's default arguments
+            controls: {{ reveal_controls }},
+            progress: {{ reveal_progress }},
+            history: {{ reveal_history }},
+            transition: "{{ reveal_transition }}",
+            slideNumber: "{{ reveal_number }}",
+            width: {{ reveal_width }},
+            height: {{ reveal_height }},
+            scroll: {{ reveal_scroll }},
+        }
+        // Then override with any metadata passed in from the notebook or config.
+        var reveal_opts = {{ resources.reveal | json_dumps }};
+
+        function isEmpty(obj) {
+            if (obj === null || obj === "") return true;
+            if (Array.isArray(obj) && obj.length === 0) return true;
+            if (typeof obj === 'object' && Object.keys(obj).length === 0 && obj.constructor === Object) return true;
+            return false;
+        }
+
+        for (var key in reveal_opts) {
+            if (!isEmpty(reveal_opts[key])) {
+                config[key] = reveal_opts[key];
+            }
+        }
+
+        if (config.plugins === undefined) {
+            config.plugins = [];
+        }
+        config.plugins.push(RevealNotes);
+        Reveal.initialize(config);
 
         var update = function(event){
           if(MathJax.Hub.getAllJax(Reveal.getCurrentSlide())){
@@ -171,7 +195,7 @@ require(
         Reveal.addEventListener('slidechanged', update);
 
         function setScrollingSlide() {
-            var scroll = {{ reveal_scroll }}
+            var scroll = config.scroll;
             if (scroll === true) {
               var h = $('.reveal').height() * 0.95;
               $('section.present').find('section')