Make narrative file name, type, and time-to-slide configurable in editor

src/js/Storage.js

@@ -315,6 +315,10 @@ export class Storage {
      * @param {string} htmlFileName - The name of the presentation HTML file.
      */
     async createNarratedHTMLFile(name, location, htmlFileName) {
+        const t = this.presentation.narrativeType;
+        if (!t || t === "none") {
+            return;
+        }
         try {
             const fileDescriptor = await this.backend.find(name, location);
             await this.backend.save(fileDescriptor, this.exportNarratedHTML(htmlFileName));

src/js/model/Presentation.js

@@ -701,6 +701,25 @@ export class Presentation extends EventEmitter {
          * @type {boolean} */
         this.updateURLOnFrameChange = true;
 
+        /** The narrative file type or "none" if narration is disabled.
+         *
+         * @default
+         * @type {string} */
+        this.narrativeType = "none";
+
+        /** The narrative file name or relative path.
+         *
+         * @default
+         * @type {string} */
+        this.narrativeFile = "narrative.flac";
+
+        /** The narrative time-to-slide data mapping the time
+         * moments (in seconds) to their corresponding frame number (one-based).
+         *
+         * @default
+         * @type {string} */
+        this.narrativeTimeToSlide = "0";
+
         /** The last export document type.
          *
          * @default
@@ -846,6 +865,9 @@ export class Presentation extends EventEmitter {
             enableMouseRotation       : this.enableMouseRotation,
             enableMouseNavigation     : this.enableMouseNavigation,
             updateURLOnFrameChange    : this.updateURLOnFrameChange,
+            narrativeType             : this.narrativeType,
+            narrativeFile             : this.narrativeFile,
+            narrativeTimeToSlide      : this.narrativeTimeToSlide,
             exportType                : this.exportType,
             exportToPDFPageSize       : this.exportToPDFPageSize,
             exportToPDFPageOrientation: this.exportToPDFPageOrientation,
@@ -902,6 +924,9 @@ export class Presentation extends EventEmitter {
         copyIfSet(this, storable, "enableMouseRotation");
         copyIfSet(this, storable, "enableMouseNavigation");
         copyIfSet(this, storable, "updateURLOnFrameChange");
+        copyIfSet(this, storable, "narrativeType");
+        copyIfSet(this, storable, "narrativeFile");
+        copyIfSet(this, storable, "narrativeTimeToSlide");
         copyIfSet(this, storable, "exportType");
         copyIfSet(this, storable, "exportToPDFPageSize");
         copyIfSet(this, storable, "exportToPDFPageOrientation");

src/js/view/Properties.js

@@ -74,6 +74,7 @@ export class Properties extends VirtualDOMView {
     render() {
         switch (this.mode) {
             case "preferences": return this.renderPreferences();
+            case "narration":   return this.renderNarrationProperties();
             case "export":      return this.renderExportTool();
             default:            return this.renderPresentationProperties();
         }
@@ -351,6 +352,86 @@ export class Properties extends VirtualDOMView {
         ]);
     }
 
+    /** Render the properties view for a presentation-wide narrative.
+     *
+     * Three properties will be configured:
+     *   1. narrativeType: the audio tag type; this field is a hint to
+     *      guide user in selection of an appropriate format, although
+     *      the browser can automatically detect the correct type by
+     *      itself. If this value is set to "none", narration will be
+     *      disabled. If it is set to flac or ogg, the corresponding
+     *      mimetype will be set for the <audio> type:
+     *        audio/flac or audio/ogg
+     *   2. narrativeFile: the name (or relative path) of the narrative
+     *      file which must be available in side of the HTML file.
+     *   3. narrativeTimeToSlide: the time-to-slide data value
+     *      Check the {narrativeTimeToSlideHelp} for details.
+     *
+     * @returns {VNode} - A virtual DOM tree.
+     */
+    renderNarrationProperties() {
+        const controller = this.controller;
+        const _ = controller.gettext;
+        const disabled = controller.presentation.narrativeType === "none";
+        const toDefaultMode = () => this.toggleMode("default");
+
+        return h("div.properties", [
+            h("div.back", {
+                title: _("Back to presentation properties"),
+                onClick() { toDefaultMode(); }
+            }, h("i.fas.fa-arrow-left", )),
+
+            h("h1", _("Narration")),
+
+            h("label", {for: "field-narrativeType"}, _("Narrative file type")),
+            this.renderSelectField("narrativeType", controller.getPresentationProperty, controller.setPresentationProperty, {
+                none: _("None (disable narration)"),
+                flac: _("Free Lossless Audio Codec (FLAC)"),
+                ogg:  _("Ogg (a container for Vorbis or Opus)"),
+            }),
+
+            h("label.side-by-side", {for: "field-narrativeFile"}, [
+                _("Narrative file name"),
+                this.renderHelp(_("Name or path of the narrative file"),
+                  () => controller.info(
+                    _("Name or path of the narrative file (relative to the HTML file location)"),
+                    true
+                  )
+                )
+            ]),
+            this.renderTextField("narrativeFile", disabled, controller.getPresentationProperty, controller.setPresentationProperty, false),
+
+            h("label.side-by-side", {for: "field-narrativeTimeToSlide"}, [
+                _("Time to frame number mapping"),
+                this.renderHelp(_("Click here to see the syntax for this field"), () => controller.info(this.narrativeTimeToSlideHelp, true))
+            ]),
+            this.renderTextField("narrativeTimeToSlide", disabled, controller.getPresentationProperty, controller.setPresentationProperty, false)
+        ]);
+    }
+
+    /** The HTML of the help message for time-to-slide data.
+     *
+     * @readonly
+     * @type {string}
+     */
+    get narrativeTimeToSlideHelp() {
+        const _ = this.controller.gettext;
+        return [
+            _("Format of the narrative time-to-slide data:"),
+            "<ul><li>" + [
+                _("A string of comma-separated descriptors"),
+                _("Each descriptor specifies the time instant (in seconds) which should trigger a slide transition"),
+                _("Descriptor can specify the target slide number (counting from one); for this purpose the time and slide index must be separated by a colon"),
+            ].join("<li>") + "</ul>",
+            _("Examples:"),
+            "<ul><li>" + [
+                _("\"0\": Switch to the first slide when narrative is at zero second without any other slide transition"),
+                _("\"0,5,7\": Switch to the 1st, 2nd, and 3rd slides at 0, 5, and 7 seconds of narrative"),
+                _("\"0,5,7:1,10:4\": At time 7s, return to the 1st slide and at 10s resume to the 4th slide"),
+            ].join("<li>") + "</ul>",
+        ].join("<br>");
+    }
+
     /** The HTML of the help message for include/exclude lists in export.
      *
      * @readonly

src/js/view/Toolbar.js

@@ -141,6 +141,11 @@ export class Toolbar extends VirtualDOMView {
                     title: _("Reload the SVG document"),
                     onclick() { controller.reload(); }
                 }, h("i.fas.fa-sync")),
+                h("button", {
+                    title: _("Narrate the presentation"),
+                    className: properties.mode === "narration" ? "active" : undefined,
+                    onclick() { properties.toggleMode("narration"); }
+                }, h("i.fas.fa-voicemail")), // alternatives are file-audio, microphone-alt, and volume-up
                 // TODO disable the Export button if the feature is not available
                 h("button", {
                     title: _("Export the presentation"),

src/templates/narrated.html

@@ -37,8 +37,8 @@
         <iframe class="presentation-container" src="{{ soziHtml }}">
             The Sozi presentation should play here.
         </iframe>
-        <audio id="narrative" controls data-time-to-slide="0:1,1:3,2:6">
-             <source src="narrative.flac" type="audio/flac" preload="auto">
+        <audio id="narrative" controls data-time-to-slide="{{ pres.narrativeTimeToSlide }}">
+             <source src="{{ pres.narrativeFile }}" type="audio/{{ pres.narrativeType }}" preload="auto">
              Audio HTML5 tag is not supported!
         </audio>
 {% endraw %}