fix: add img alt attributes for diagrams and other images

They're not great, but we can't make them great without forcing the
user to specify a caption for each diagram.

Sponsored-by: author

2 files changed, 14 insertions, 10 deletions

diff --git a/src/html.rs b/src/html.rs
index 23579f9..1e0dafa 100644
--- a/src/html.rs
+++ b/src/html.rs
@@ -156,6 +156,7 @@ pub fn parse(filename: &Path, markdown: &str) -> Result<Element, HtmlError> {
                 Tag::Image(_, url, title) => {
                     let mut e = Element::new(ElementTag::Img);
                     e.push_attribute(Attribute::new("src", url.as_ref()));
+                    e.push_attribute(Attribute::new("alt", title.as_ref()));
                     if !title.is_empty() {
                         e.push_attribute(Attribute::new("title", title.as_ref()));
                     }
@@ -334,9 +335,11 @@ impl Element {
 
     fn fix_up_img_alt(&mut self) {
         if self.tag == ElementTag::Img {
-            let alt = as_plain_text(self.children());
-            self.push_attribute(Attribute::new("alt", &alt));
-            self.children.clear();
+            if !self.attrs.iter().any(|a| a.name() == "alt") {
+                let alt = as_plain_text(self.children());
+                self.push_attribute(Attribute::new("alt", &alt));
+                self.children.clear();
+            }
         } else {
             for child in self.children.iter_mut() {
                 if let Content::Elt(kid) = child {
diff --git a/src/md.rs b/src/md.rs
index 042bade..8573167 100644
--- a/src/md.rs
+++ b/src/md.rs
@@ -382,19 +382,19 @@ mod typeset {
     fn typeset_dot(e: &Element) -> Result<Element, SubplotError> {
         let dot = e.content();
         let svg = DotMarkup::new(&dot).as_svg()?;
-        Ok(svg_to_element(svg))
+        Ok(svg_to_element(svg, "Dot diagram"))
     }
 
     fn typeset_plantuml(e: &Element) -> Result<Element, SubplotError> {
         let markup = e.content();
         let svg = PlantumlMarkup::new(&markup).as_svg()?;
-        Ok(svg_to_element(svg))
+        Ok(svg_to_element(svg, "UML diagram"))
     }
 
     fn typeset_pikchr(e: &Element) -> Result<Element, SubplotError> {
         let markup = e.content();
         let svg = PikchrMarkup::new(&markup, None).as_svg()?;
-        Ok(svg_to_element(svg))
+        Ok(svg_to_element(svg, "Pikchr diagram"))
     }
 
     fn typeset_roadmap(e: &Element) -> Result<Element, SubplotError> {
@@ -404,12 +404,12 @@ mod typeset {
         let roadmap = roadmap::from_yaml(&yaml)?;
         let dot = roadmap.format_as_dot(WIDTH)?;
         let svg = DotMarkup::new(&dot).as_svg()?;
-        Ok(svg_to_element(svg))
+        Ok(svg_to_element(svg, "Road map"))
     }
 
-    fn svg_to_element(svg: Svg) -> Element {
+    fn svg_to_element(svg: Svg, alt: &str) -> Element {
         let url = svg_as_data_url(svg);
-        let img = html_img(&url);
+        let img = html_img(&url, alt);
         html_p(vec![Content::Elt(img)])
     }
 
@@ -426,9 +426,10 @@ mod typeset {
         new
     }
 
-    fn html_img(src: &str) -> Element {
+    fn html_img(src: &str, alt: &str) -> Element {
         let mut new = Element::new(ElementTag::Img);
         new.push_attribute(Attribute::new("src", src));
+        new.push_attribute(Attribute::new("alt", alt));
         new
     }
 }