Add support for alt attribute on structured content images (#359)

* Add support for alt attribute on structured content images

* Add new `alt` property for structured content images

* Update test script with new media file count

---------

Co-authored-by: stephenmk <stephenmk@users.noreply.github.com>

2 files changed, 4 insertions, 1 deletions

diff --git a/ext/js/display/sandbox/structured-content-generator.js b/ext/js/display/sandbox/structured-content-generator.js
index a28464ae..ad63667a 100644
--- a/ext/js/display/sandbox/structured-content-generator.js
+++ b/ext/js/display/sandbox/structured-content-generator.js
@@ -65,6 +65,7 @@ export class StructuredContentGenerator {
             preferredWidth,
             preferredHeight,
             title,
+            alt,
             pixelated,
             imageRendering,
             appearance,
@@ -102,7 +103,7 @@ export class StructuredContentGenerator {
         imageContainer.appendChild(imageBackground);
 
         const image = /** @type {HTMLImageElement} */ (this._createElement('img', 'gloss-image'));
-        image.alt = '';
+        image.alt = typeof alt === 'string' ? alt : '';
         imageContainer.appendChild(image);
 
         const overlay = this._createElement('span', 'gloss-image-container-overlay');
diff --git a/ext/js/language/dictionary-importer.js b/ext/js/language/dictionary-importer.js
index 2b9792ea..2c0c7e9c 100644
--- a/ext/js/language/dictionary-importer.js
+++ b/ext/js/language/dictionary-importer.js
@@ -503,6 +503,7 @@ export class DictionaryImporter {
             width: preferredWidth,
             height: preferredHeight,
             title,
+            alt,
             description,
             pixelated,
             imageRendering,
@@ -518,6 +519,7 @@ export class DictionaryImporter {
         if (typeof preferredWidth === 'number') { target.preferredWidth = preferredWidth; }
         if (typeof preferredHeight === 'number') { target.preferredHeight = preferredHeight; }
         if (typeof title === 'string') { target.title = title; }
+        if (typeof alt === 'string') { target.alt = alt; }
         if (typeof description === 'string') { target.description = description; }
         if (typeof pixelated === 'boolean') { target.pixelated = pixelated; }
         if (typeof imageRendering === 'string') { target.imageRendering = imageRendering; }